doi:10.1007/s00376-017-7077-3

Albrecht B. A., 1989: Aerosols,cloud microphysics, and fractional cloudiness.Science,245,1227-1230,https://doi.org/10.1126/science.245.4923.1227.10.1126/science.245.4923.1227

17747885

c9baaf4335e0dd08fd75f5b2eceee53d

http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpubmed%2F17747885

http://www.sciencemag.org/cgi/doi/10.1126/science.245.4923.1227Abstract Increases in aerosol concentrations over the oceans may increase the amount of low-level cloudiness through a reduction in drizzle-a process that regulates the liquid-water content and the energetics of shallow marine clouds. The resulting increase in the global albedo would be in addition to the increase due to enhancement in reflectivity associated with a decrease in droplet size and would contribute to a cooling of the earth's surface.

Beheng K. D., 1994: A parameterization of warm cloud microphysical conversion processes.Atmo. Res.33,193-206,https://doi.org/10.1016/0169-8095(94)90020-5.

10.1016/0169-8095(94)90020-5

dd10183f2ee89e560cdaef79f817a572

http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2F0169809594900205

http://linkinghub.elsevier.com/retrieve/pii/0169809594900205A parameterization scheme is presented by which coagulation growth of drops is simulated. It is oriented at the common parameterization idea of partitioning the total water substance in a cloud water and a rainwater portion. This concept is accordingly applied to the stochastic collection equation by which the time evolution of a drop spectrum is described. Thus, the distinct conversion rates selfcollection, autoconversion and accretion can mathematically be formulated for number and mass densities of cloud water and rainwater which can then be numerically evaluated. With these results as standards a new parameter scheme is developed whose constituting equations consist in rates combining number and mass densities as well as a width parameter. The range of variables for which this parameterization is valid covers a wide range of relevant cloudphysical variables. Comparisons with other parameterizations are presented.

Chiapello I., C. Moulin, and J. M. Prospero, 2005: Understanding the long-term variability of African dust transport across the Atlantic as recorded in both Barbados surface concentrations and large-scale total ozone mapping spectrometer (TOMS) optical thickness.J. Geophys. Res.,110,D18S10,https://doi.org/10.1029/2004JD005132.

Costantino L., F. M. Bréon, 2013: Aerosol indirect effect on warm clouds over South-East Atlantic,from co-located MODIS and CALIPSO observations. Atmospheric Chemistry and Physics, 13, 69-88, https://doi.org/10.5194/acp-13-69-2013.

10.5194/acp-13-69-2013

d728abe27d6516ff591bd6b7e48c8cf2

http%3A%2F%2Fwww.oalib.com%2Fpaper%2F1373862

http://www.oalib.com/paper/1373862In this study, we provide a comprehensive analysis of aerosol interaction with warm boundary layer clouds over the South-East Atlantic. We use aerosol and cloud parameters derived from MODIS observations, together with co-located CALIPSO estimates of the layer altitudes, to derive statistical relationships between aerosol concentration and cloud properties. The CALIPSO products are used to differentiate between cases of mixed cloud-aerosol layers from cases where the aerosol is located well-above the cloud top. This technique allows us to obtain more reliable estimates of the aerosol indirect effect than from simple relationships based on vertically integrated measurements of aerosol and cloud properties. Indeed, it permits us to somewhat distinguish the effects of aerosol and meteorology on the clouds, although it is not possible to fully ascertain the relative contribution of each on the derived statistics.Consistently with the results from previous studies, our statistics clearly show that aerosol affects cloud microphysics, decreasing the Cloud Droplet Radius (CDR). The same data indicate a concomitant strong decrease in cloud Liquid Water Path (LWP), which is inconsistent with the hypothesis of aerosol inhibition of precipitation (Albrecht, 1989). We hypothesise that the observed reduction in LWP is the consequence of dry air entrainment at cloud top. The combined effect of CDR decrease and LWP decrease leads to rather small sensitivity of the Cloud Optical Thickness (COT) to an increase in aerosol concentration. The analysis of MODIS-CALIPSO coincidences also evidences an aerosol enhancement of low cloud cover. Surprisingly, the Cloud Fraction (CLF) response to aerosol invigoration is much stronger when (absorbing) particles are located above cloud top than in cases of physical interaction. This result suggests a relevant aerosol radiative effect on low cloud occurrence: absorbing particles above the cloud top may heat the corresponding atmosphere layer, decrease the vertical temperature gradient, increase the low tropospheric stability and provide favourable conditions for low cloud formation.We also analyse the impact of anthropogenic aerosols on precipitation, through the statistical analysis of CDR-COT co-variations. A COT value of 10 is found to be the threshold beyond which precipitation is mostly formed, in both clean and polluted environments. For larger COT, polluted clouds show evidence of precipitation suppression.Results suggest the presence of two competing mechanisms governing LWP response to aerosol invigoration: a drying effect due to aerosol enhanced entrainment of dry air at cloud top (predominant for optically thin clouds) and a moistening effect due to aerosol inhibition of precipitation (predominant for optically thick clouds).

Dickinson R. E., Henderson-Sellers A., andP. J. Kennedy, 1993: Biosphere-atmosphere transfer scheme (BATS) version 1e as coupled to the NCAR community climate model. National Center for Atmospheric Research Technical Note NCAR. TN-387+STR,72 pp.10.5065/D67W6959

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http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F244419803_Biosphere-atmosphere_transfer_scheme_%28BATS%29_version_1e_as_coupled_to_the_NCAR_Community_Climate_Model

http://www.researchgate.net/publication/244419803_Biosphere-atmosphere_transfer_scheme_(BATS)_version_1e_as_coupled_to_the_NCAR_Community_Climate_ModelA comprehensive model of land-surface processes has been under development suitable for use with various National Center for Atmospheric Research (NCAR) General Circulation Models (GCMs). Special emphasis has been given to describing properly the role of vegetation in modifying the surface moisture and energy budgets. The result of these efforts has been incorporated into a boundary package, referred to as the Biosphere-Atmosphere Transfer Scheme (BATS). The current frozen version, BATS1e is a piece of software about four thousand lines of code that runs as an offline version or coupled to the Community Climate Model (CCM).

Emmons, L. K., Coauthors, 2010: Description and evaluation of the Model for Ozone and Related chemical Tracers, version 4 (MOZART-4). Geoscientific Model Development, 3, 43-67, https://doi.org/10.5194/gmd-3-43-2010.

Fan J. W., Y. Wang, D. Rosenfeld, and X. H. Liu, 2016: Review of aerosol-cloud interactions: Mechanisms,significance, and challenges. J. Atmos. Sci., 73, 4221-4252, https://doi.org/10.1175/JAS-D-16-0037.1.

10.1175/JAS-D-16-0037.1

5914f04f895edb29cec3843d95b1737f

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F305218594_Review_of_Aerosol-Cloud_Interactions_Mechanisms_Significance_and_Challenges

http://journals.ametsoc.org/doi/10.1175/JAS-D-16-0037.1Abstract Over the past decade, the number of studies that investigate aerosol-cloud interactions has increased considerably. Although tremendous progress has been made to improve the understanding of basic physical mechanisms of aerosol-cloud interactions and reduce their uncertainties in climate forcing, there is still poor understanding of 1) some of the mechanisms that interact with each other over multiple spatial and temporal scales, 2) the feedbacks between microphysical and dynamical processes and between local-scale processes and large-scale circulations, and 3) the significance of cloud-aerosol interactions on weather systems as well as regional and global climate. This review focuses on recent theoretical studies and important mechanisms on aerosol-cloud interactions and discusses the significances of aerosol impacts on radiative forcing and precipitation extremes associated with different cloud systems. The authors summarize the main obstacles preventing the science from making a leap-for example, the lack of concurrent profile measurements of cloud dynamics, microphysics, and aerosols over a wide region on the observation side and the large variability of cloud microphysics parameterizations resulting in a large spread of modeling results on the modeling side. Therefore, large efforts are needed to escalate understanding. Future directions should focus on obtaining concurrent measurements of aerosol properties and cloud microphysical and dynamic properties over a range of temporal and spatial scales collected over typical climate regimes and closure studies, as well as improving understanding and parameterizations of cloud microphysics such as ice nucleation, mixed-phase properties, and hydrometeor size and fall speed.

Fritsch J. M., C. F. Chappell, 1980: Numerical prediction of convectively driven mesoscale pressure systems. Part 1: Convective parameterization. J. Atmos. Sci., 37, 1722-1733, https://doi.org/10.1175/1520-0469(1980)037<1722:NPOCDM>2.0.CO;2.

10.1175/1520-0469(1980)0372.0.CO;2

20ff2a4cbbc7539e74f9a441f5611dbd

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1980JAtS...37.1722F

http://adsabs.harvard.edu/abs/1980JAtS...37.1722FA parameterization formulation for incorporating the effects of midlatitude deep convection into mesoscale-numerical models is presented. The formulation is based on the hypothesis that the buoyant energy available to a parcel, in combination with a prescribed period of time for the convection to remove that energy, can be used to regulate the amount of convection in a mesoscale numerical model grid element.Individual clouds are represented as entraining moist updraft and downdraft plumes. The fraction of updraft condensate evaporated in moist downdrafts is determined from an empirical relationship between the vertical shear of the horizontal wind and precipitation efficiency. Vertical transports of horizontal momentum and warming by compensating subsidence are included in the parameterization. Since updraft and downdraft areas are sometimes a substantial fraction of mesoscale model grid-element areas, grid-point temperatures (adjusted for convection) are an area-weighted mean of updraft, downdraft and environmental temperatures.

Gautam, R., Coauthors, 2011: Accumulation of aerosols over the Indo-Gangetic plains and southern slopes of the Himalayas: Distribution,properties and radiative effects during the 2009 pre-monsoon season. Atmos. Chem. Phys., 11, 12 841-12 863, https://doi.org/10.5194/acp-11-12841-2011.10.5194/acpd-11-15697-2011

a7e5f2584df8f076cab897dcdfcd094e

http%3A%2F%2Fwww.oalib.com%2Fpaper%2F1374450

http://www.oalib.com/paper/1374450We examine the distribution of aerosols and associated optical/radiative properties in the Gangetic-Himalayan region from simultaneous radiometric measurements over the Indo-Gangetic Plains (IGP) and the foothill/slopes of the Himalayas during the 2009 pre-monsoon season. Enhanced dust transport extending from the Southwest Asian arid regions into the IGP, results in seasonal mean (April–June) aerosol optical depths of over 0.6 – highest over southern Asia. The influence of dust loading is greater over the western IGP as suggested by pronounced coarse mode peak in aerosol size distribution and spectral single scattering albedo (SSA). The transported dust in the IGP, driven by prevailing westerly airmass, is found to be more absorbing (SSAlt;subgt;550 nmlt;/subgt; ~0.89) than the near-desert region in NW India (SSAlt;subgt;550 nmlt;/subgt; ~0.91) suggesting mixing with carbonaceous aerosols in the IGP. On the contrary, significantly reduced dust transport is observed over eastern IGP and foothill/elevated slopes in Nepal where strongly absorbing haze is prevalent, associated with upslope transport of pollution, as indicated by low values of SSA (0.85–0.9 for the wavelength range of 440–1020 nm), suggesting presence of more absorbing aerosols compared to IGP. Assessment of the radiative impact of aerosols over NW India suggests diurnal mean reduction in solar radiation fluxes of 19–23 Wmlt;supgt;612lt;/supgt; at surface (12–15 % of the surface solar insolation). Based on limited observations of aerosol optical properties during the pre-monsoon period and comparison of our radiative forcing estimates with published literature, there exists spatial heterogeneity in the regional aerosol forcing, associated with the absorbing aerosol distribution over northern India, with both diurnal mean surface forcing and forcing efficiency over the IGP exceeding that over NW India. Additionally, the role of the seasonal progressive buildup of aerosol loading and water vapor is investigated in the observed net aerosol forcing over NW India. The radiative impact of water vapor is found to amplify the net regional aerosol radiative forcing suggesting that the two exert forcing in tandem leading to enhanced surface cooling. It is suggested that water vapor contribution should be taken into account while assessing aerosol forcing impact for this region and other seasonally similar environments.

Giorgi F., 1989: Two-dimensional simulations of possible mesoscale effects of nuclear war fires.I: Model description. J. Geophys. Res.,94,1127-1144,https://doi.org/10.1029/JD094iD01p01127.

Giorgi F., W. L. Chameides, 1986: Rainout lifetimes of highly soluble aerosols and gases as inferred from simulations with a general circulation model.J. Geophys. Res.,91,14 367-14 376,https://doi.org/10.1029/JD091iD13p14367.10.1029/JD091iD13p14367

0713b7c2b105b0f3cf2b1c9e1e53512b

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2FJD091iD13p14367%2Ffull

http://doi.wiley.com/10.1029/JD091iD13p14367The rainout-determined lifetimes of highly soluble particulate and gaseous atmospheric compounds are investigated using general circulation model simulations in which removal is explicitly calculated in terms of the local, model-produced precipitation rates. Our calculations indicate that because of the episodic and asymmetric nature of rainout, species' lifetimes depend not only on the amount of precipitation but also on the characteristics of the precipitation regime (such as duration and frequency of the precipitation events) and on the direction of the tracer main flow (determined by the species' average mixing ratio gradient). For this reason, averaged rainout lifetimes of tracers flowing downward from the stratosphere are found to differ substantially from those of tracers of surface origin flowing upward or tracers of a more ubiquitous tropospheric source. These results imply that the use of a first-order parameterization to simulate rainout in a photochemical model that does not explicitly calculate precipitation can be inadequate in representing this process. A computationally efficient parameterization that includes the effects of intermittence and asymmetry of rainout is proposed, and it is shown how this parameterization can be used to estimate rainout-determined tropospheric residence times from observational data sets. A review of published estimates of submicron aerosol tropospheric residence times based on observations shows that these are consistent with our model results.

Giorgi, F., Coauthors, 2012: RegCM4: Model description and preliminary tests over multiple CORDEX domains.Climate Research52,7-29,https://doi.org/10.3354/cr01018.

10.3354/cr01018

6ab91cdef78caa6e0d8a1a48d2b7dcbe

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2012ClRes..52....7G

http://www.int-res.com/abstracts/cr/v52/p7-29/A new version of the RegCM regional climate modeling system, RegCM4, has been recently developed and made available for community use. Compared to previous versions, RegCM4 includes new land surface, planetary boundary layer and air-sea flux schemes, a mixed convection and tropical band configuration, modifications to the pre-existing radiative transfer and boundary layer schemes and a full upgrade of the model code towards improved flexibility, portability and user friendliness. The model can be interactively coupled to a 1D lake model, a simplified aerosol scheme(including OC, BC, SO4, dust and sea spray) and a gas phase chemistry module (CBM-Z). After a general description of the model, a series of test experiments are presented over four domains prescribed under the CORDEX framework (Africa, South America, East Asia and Europe) to provide illustrative examples of the model behavior and sensitivities under different climatic regimes. These experiments indicate that, overall, RegCM4 shows an improved performance in several respects compared to previous versions, although further testing by the user community is needed to fully explore its sensitivities and range of applications.

Giorgi F., M. R. Marinucci, and G. T. Bates, 1993: Development of a second-generation regional climate model (RegCM2). Part I: Boundary-layer and radiative transfer processes. Mon. Wea. Rev., 121, 2794-2813, https://doi.org/10.1175/1520-0493(1993)121<2794:DOASGR>2.0.CO;2.10.1175/1520-0493(1993)1212.0.CO;2

21d14709deeac7520a50643b89fd63c5

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1993MWRv..121.2794G

http://adsabs.harvard.edu/abs/1993MWRv..121.2794GDuring the last few years the development of a second-generation regional climate modeling system (RegCM2) has been completed at the National Center for Atmospheric Research (NCAR). Based upon the National Center for Atmospheric Research-Pennsylvania State University Mesoscale Model (MM4), RegCM2 includes improved formulations of boundary layer, radiative transfer, surface physics, cumulus convection, and time integration technique, which make it more physically comprehensive and more computationally efficient than the previous regional climate model version. This paper discusses a number of month-long simulations over the European region that were conducted to test the new RegCM2 boundary-layer parameterization (the scheme developed by Holtsag et al.) and radiative transfer formulation [the package developed for the NCAR Community Climate Model 2 (CCM2)]. Both schemes significantly affect the model precipitation, temperature, moisture, and cloudiness climatology, leading to overall more realistic results, while they do not substantially modify the model performance in simulating the aggregated characteristics of synoptic patterns. Description of the convective processes and procedures of boundary condition assimilation included in RegCM2 is presented in companion paper by Giorgi et al. 26 refs., 11 figs., 10 tabs.

Grell, G. A, 1993: Prognostic evaluation of assumptions used by cumulus parameterizations. Mon. Wea. Rev., 121, 764-787, https://doi.org/10.1175/1520-0493(1993)121<0764:PEOAUB>2.0.CO;2.

10.1175/1520-0493(1993)1212.0.CO;2

160d692faa9624cf3dcf1cd28c663c1d

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1993MWRv..121..764G

http://adsabs.harvard.edu/abs/1993MWRv..121..764GUsing a spectral-type cumulus parameterization that includes moist downdrafts within a three-dimensional mesoscale model, various disparate closure assumptions are systematically tested within the generalized framework of dynamic control, static control, and feedback. Only one assumption at a time is changed and tested using a midlatitude environment of severe convection. A control run is presented, which shows good agreement with observations in many aspects. Results of the sensitivity tests are compared to observations in terms of sea level pressure, rainfall patterns, and domain-averaged bias errors (compared to the control run) of various properties. The dynamic control is the part that determines the modulation of the convection by the environment. It is shown that rate of destabilization, as well as instantaneous stability, work well for the dynamic control. Integrated moisture convergence leads to underprediction of rainfall rates and subsequent degrading of the results in terms of movement and structure of the mesoscale convective system (MCS). The feedback determines the modification of the environment by the convection, and in this study is considered together with the static control, which determines cloud properties. All feedback and static-control assumptions tested here seem very important for the prediction of sea level pressure and rainfall. The most

Gu Y., K. N. Liou, J. H. Jiang, H. Su, and X. Liu, 2012: Dust aerosol impact on North Africa climate: A GCM investigation of aerosol-cloud-radiation interactions using A-Train satellite data.Atmos. Chem. Phy. Discuss.11,1667-1679,https://doi.10.5194/acpd-11-31401-2011.10.5194/acpd-11-31401-2011

ff6e1279e890d10fe4c3efbed97ac36c

http%3A%2F%2Fwww.oalib.com%2Fpaper%2F1369042

http://www.oalib.com/paper/1369042The climatic effects of dust aerosols in North Africa have been investigated using the atmospheric general circulation model (AGCM) developed at the University of California, Los Angeles (UCLA). The model includes an efficient and physically based radiation parameterization scheme developed specifically for application to clouds and aerosols. Parameterization of the effective ice particle size in association with the aerosol first indirect effect based on ice cloud and aerosol data retrieved from A-Train satellite observations have been employed in climate model simulations. Offline simulations reveal that the direct solar, IR, and net forcings by dust aerosols at the top of the atmosphere (TOA) generally increase with increasing aerosol optical depth (AOD). When the dust semi-direct effect is included with the presence of ice clouds, positive IR radiative forcing is enhanced since ice clouds trap substantial IR radiation, while the positive solar forcing with dust aerosols alone has been changed to negative values due to the strong reflection of solar radiation by clouds, indicating that cloud forcing associated with aerosol semi-direct effect could exceed direct aerosol forcing. With the aerosol first indirect effect, the net cloud forcing is generally reduced for an ice water path (IWP) larger than 20 g mlt;supgt;2lt;/supgt;. The magnitude of the reduction increases with IWP. lt;brgt;lt;brgt; AGCM simulations show that the reduced ice crystal mean effective size due to the aerosol first indirect effect results in less OLR and net solar flux at the top of the atmosphere over the cloudy area of the North Africa region because ice clouds with smaller size trap more IR radiation and reflect more solar radiation. The precipitation in the same area, however, increases due to the aerosol indirect effect on ice clouds, corresponding to the enhanced convection as indicated by reduced OLR. The increased precipitation appears to be associated with enhanced ice water content in this region. The 200 mb radiative heating rate shows more cooling with the aerosol first indirect effect since greater cooling is produced at the cloud top with smaller ice crystal size. The 500 mb omega indicates stronger upward motion, which, together with the increased cooling effect, results in the increased ice water content. Adding the aerosol direct effect into the model simulation reduces the precipitation in the normal rainfall band over North Africa, where precipitation is shifted to the south and the northeast produced by the absorption of sunlight and the subsequent heating of the air column by dust particles. As a result, rainfall is drawn further inland to the northeast. lt;brgt;lt;brgt; This study represents the first attempt to quantify the climate impact of the aerosol indirect effect using a GCM in connection with A-train satellite data. The parameterization for the aerosol first indirect effect developed in this study can be readily employed for application to other GCMs.

Gu Y., K. N. Liou, Y. Xue, C. R. Mechoso, W. Li, and Y. Luo, 2006: Climatic effects of different aerosol types in China simulated by the UCLA general circulation model.J. Geophys. Res.,111,D15201,https://doi.org/10.1029/2005JD006312.10.1029/2005JD006312

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2005JD006312%2Fpdf

http://doi.wiley.com/10.1029/2005JD006312[1] The climatic effects of various types of aerosol in China have been investigated by using the atmospheric general circulation model (AGCM) developed at the University of California, Los Angeles (UCLA). The model includes an efficient and physically based radiation parameterization scheme specifically developed for application to clouds and aerosols. Simulation results show that inclusion of a background aerosol optical depth of 0.2 reduces the global mean net surface solar flux by about 5 W m0908082 and produces a decrease in precipitation in the tropics as a result of decreased temperature contrast between this area and the middle to high latitudes, which suppresses tropical convection. These decreases have partially corrected the overestimates in the surface solar flux and precipitation in the UCLA AGCM simulations without the aerosol effect. The experiment with increased aerosol optical depths in China shows a noticeable increase in precipitation in the southern part of China in July due to the cooling in the midlatitudes that leads to the strengthening of the Hadley circulation. Aerosol types play an important role in the determination of the global mean radiation budget and regional climate. While sulfates mainly reflect solar radiation and induce negative forcing at the surface, black carbon and large dust particles absorb substantial solar radiation and have a positive solar forcing at the top of the atmosphere, but reduce the solar radiation reaching the surface. Large dust particles also have a significant effect on thermal IR radiation under clear conditions, but this effect is largely masked by clouds generated from the model in AGCM simulations. Black carbon and large dust particles in China would heat the air column in the middle to high latitudes and tend to move the simulated precipitation inland, i.e., toward the Himalayas. The inclusion of black carbon in our simulations has not produced the 090008north drought/south flooding090009 precipitation pattern that has frequently occurred in China during the past 50 years.

Gultepe I., G. A. Isaac, 1997: Liquid water content and temperature relationship from aircraft observations and its applicability to GCMs. J. Climate, 10, 446-452, https://doi.org/10.1175/1520-0442(1997)010<0446:LWCATR>2.0.CO;2.10.1175/1520-0442(1997)0102.0.CO;2

bd9a9632f4025c8adbcf853e5db9ffce

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1997JCli...10..446G

http://adsabs.harvard.edu/abs/1997JCli...10..446GThe vertical distribution of liquid water content (LWC) and its relationship with temperature (T) strongly affect the heat budget of the atmosphere. Some large-scale models of the atmosphere use a relationship between LWC and T to diagnostically obtain LWC from T under saturated conditions. Airborne observations conducted within clouds over northeastern North America during the 1984–93 time period are used to study the relationship between LWC and T. Observed frequency distributions of LWC are approximated by lognormal distribution curves and are best represented by median values. The median LWC values monotonically increase with warmer temperatures. However, the mean LWC reaches 0.23 g mat about T = 2.5°C. LWC decreases below and above 2.5°C, except that it reaches a maximum value of 0.26 g mat 22.5°C. The relationship between LWC and T from the present study is compared with that of earlier studies from the former Soviet Union. Differences can be attributed to the design and limits of the probes, natural variability in the 35 years, and the limited dataset for some temperature intervals. The LWC versus T relationship developed from observations in this study can be compared with large-scale model simulations.

Hegg D. A., 1994: Cloud condensation nucleus-sulphate mass relationship and cloud albedo.J. Geophys. Res.,99,25 903-25 907,https://doi.org/10.1029/94JD02224.10.1029/94JD02224

8d72f3225bc7539e1598eb17adebf2cd

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F94JD02224%2Ffull

http://doi.wiley.com/10.1029/94JD02224Analysis of previously published, simultaneous measurements of cloud condensation nucleus number concentration and sulfate mass concentration suggest a nonlinear relationship between the two variables. This nonlinearity reduces the sensitivity of cloud albedo to changes in the sulfur cycle.

Holtslag A. A. M., E. I. F. de Bruijn, and H. L. Pan, 1990: A high resolution air mass transformation model for short-range weather forecasting. Mon. Wea. Rev., 118, 1561-1575, https://doi.org/10.1175/1520-0493(1990)118<1561:AHRAMT>2.0.CO;2.

10.1175/1520-0493(1990)1182.0.CO;2

cae49a460d55681ff2fa3da9b74e40cc

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1990MWRv..118.1561H

http://adsabs.harvard.edu/abs/1990MWRv..118.1561HABSTRACT This paper describes a high resolution air mass transformation (AMT) model.

Hsu N. C., S. C. Tsay, M. D. King, and J. R. Herman, 2006: Deep blue retrievals of Asian aerosol properties during ACE-Asia. IEEE Trans. Geosci. Remote Sens., 44, 3180-3195, https://doi.org/10.1109/TGRS.2006.879540.10.1109/TGRS.2006.879540

f331145c29cbe96bde6654304470bdf4

http%3A%2F%2Fieeexplore.ieee.org%2Fdocument%2F1717707%2F

http://ieeexplore.ieee.org/document/1717707/During the ACE-Asia field campaign, unprecedented amounts of aerosol property data in East Asia during springtime were collected from an array of aircraft, shipboard, and surface instruments. However, most of the observations were obtained in areas downwind of the source regions. In this paper, the newly developed satellite aerosol algorithm called "Deep Blue" was employed to characterize the properties of aerosols over source regions using radiance measurements from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS). Based upon the Aringngstroumlm exponent derived from the Deep Blue algorithm, it was demonstrated that this new algorithm is able to distinguish dust plumes from fine-mode pollution particles even in complex aerosol environments such as the one over Beijing. Furthermore, these results were validated by comparing them with observations from AERONET sites in China and Mongolia during spring 2001. These comparisons show that the values of satellite-retrieved aerosol optical thickness from Deep Blue are generally within 20%-30% of those measured by sunphotometers. The analyses also indicate that the roles of mineral dust and anthropogenic particles are comparable in contributing to the overall aerosol distributions during spring in northern China, while fine-mode particles are dominant over southern China. The spring season in East Asia consists of one of the most complex environments in terms of frequent cloudiness and wide ranges of aerosol loadings and types. This paper will discuss how the factors contributing to this complexity influence the resulting aerosol monthly averages from various satellite sensors and, thus, the synergy among satellite aerosol products

Huang J. F., C. D. Zhang, and J. M. Prospero, 2009: African aerosol and large-scale precipitation variability over West Africa.Environ. Res. Lett.,4,015006,https://doi.org/10.1088/1748-9326/4/1/015006.10.1088/1748-9326/4/1/015006

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http://stacks.iop.org/1748-9326/4/i=1/a=015006?key=crossref.1753750a73a23717531513dc986eb582

Huang Y., 2005: Assessments of the direct and indirect effects of anthropogenic aerosols on regional precipitation over east Asia using a coupled regional climate-chemistry-aerosol model. PhD dissertation, Georgia Institute of Technology.

02638ea7682bb7b38b2323a068cb147c

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2005PhDT........60H

http://adsabs.harvard.edu/abs/2005PhDT........60HAn aerosol module is developed and coupled to a regional climate model to investigate the direct and indirect effect of anthropogenic aerosols (sulfate and carbonaceous aerosols) on climate with a focus on precipitation over East Asia. This fully coupled regional climate chemistry-aerosol model is capable of understanding the interactions between the aerosol perturbation and climate change. The simulated aerosol spatial and seasonal distributions are generally consistent with the observations. The magnitude of the simulated total aerosol concentration and optical depth is about 2/3 of the observed value, suggesting the estimated climatic effects in this work are reasonable and conservative. With the implementation of various aerosol effect, i.e., direct, semi-direct, 1st and 2nd indirect effect, the aerosols' impacts on climate are assessed over the region. The direct, semi-direct and 1 st indirect effects generate a negative surface solar forcing, leading to a surface cooling, and the semi-direct effect also heats the atmosphere by BC absorption. This, in turn, increases the atmospheric stability and tends to inhibit the precipitation. The precipitation reduction is largest in the fall and winter, up to -10% with the inclusion of both direct and 1 st indirect effects. The 2nd indirect effect using BH94 scheme produces a comparable magnitude in long-wave heating as the solar cooling, leading to the nighttime temperature warming of 0.5K, and a reduction in the diurnal temperature range. The precipitation reduction from the 2 nd indirect effect strongly depends on the auto-conversion scheme, with about -30% in the fall and winter, and -15% in the spring and summer using BH94 scheme, while less than -5% using TC80 scheme. By allowing the feedbacks between aerosols and climate, the coupled model generally decreases the discrepancies between the model-simulated and observed precipitation and aerosols over the region. The EOF analysis of the climatological precipitation from last century over East Asia shows a decreasing mode in the EOF leading modes in the fall and winter, and is generally geographically consistent with the distribution of the model simulated precipitation reduction from anthropogenic aerosols.

Huang Y., W. L. Chameides, and R. E. Dickinson, 2007: Direct and indirect effects of anthropogenic aerosols on regional precipitation over east Asia.J. Geophys. Res.,112,D03212,https://doi.org/10.1029/2006JD007114.10.1029/2006JD007114

31804cdb879b6123d84a09e44ca71e50

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2006JD007114%2Ffull

http://onlinelibrary.wiley.com/doi/10.1029/2006JD007114/full[1] A regional coupled climate-chemistry-aerosol model is developed. It is used to assess the direct and indirect effects of anthropogenic sulfate and carbonaceous aerosols on regional climate over east Asia with a focus on precipitation. The simulated direct and first indirect effects for the most part reduce the solar radiation and hence decrease the surface temperature, while the second indirect effect generates both negative solar forcing and a substantial positive long-wave forcing. It decreases the precipitation, but because of the cancelling effect, surface temperature does not change very much. With the interactively model-calculated current aerosol loading and the combined direct/semidirect/first indirect effect, the simulated precipitation is reduced by about 10% in the fall and winter and by about 5% in the spring and summer. The second indirect effect has the largest impact, by itself decreasing the fall and winter precipitation from about 3% to 20%, depending on the autoconversion scheme assumed. The semidirect effect on precipitation is relatively small. An empirical orthogonal function analysis of climatological precipitation over east Asia since the last century shows a decreasing trend of the leading modes over most of China in the fall and winter, which is generally geographically consistent with the distribution of the model-simulated precipitation reduction from anthropogenic aerosols.

IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press,1535 pp.

Ji Z. M., G. L. Wang, J. S. Pal, and M. Yu, 2016: Potential climate effect of mineral aerosols over West Africa Part I: Model validation and contemporary climate evaluation. Climate Dyn.,46,1223-1239,https://doi.org/10.1007/s00382-015-2641-y.10.1007/s00382-015-2641-y

1d0ff2b90f4cddc1b754e806eca8bac8

http%3A%2F%2Flink.springer.com%2F10.1007%2Fs00382-015-2641-y

http://link.springer.com/10.1007/s00382-015-2641-yMineral dusts present in the atmosphere can play an important role in climate over West Africa and surrounding regions. However, current understanding regarding how dust aerosols influence climate of West Africa is very limited. In this study, a regional climate model is used to investigate the potential climatic impacts of dust aerosols. Two sets of simulations driven by reanalysis and Earth System Model boundary conditions are performed with and without the representation of dust processes. The model, regardless of the boundary forcing, captures the spatial and temporal variability of the aerosol optical depth and surface concentration. The shortwave radiative forcing of dust is negative at the surface and positive in the atmosphere, with greater changes in the spring and summer. The presence of mineral dusts causes surface cooling and lower troposphere heating, resulting in a stabilization effect and reduction in precipitation in the northern portion of the monsoon close to the dust emissions region. This results in an enhancement of precipitation to the south. While dusts cause the lower troposphere to stabilize, upper tropospheric cooling makes the region more prone to intense deep convection as is evident by a simulated increase in extreme precipitation. In a companion paper, the impacts of dust emissions on future West African climate are investigated.

Kessler E., 1969: On the distribution and continuity of water substance in atmospheric circulations.Meteorological Monographs. Vol. 10American Meteorological Society,84 pp,https://doi.org/10.1007/978-1-935704-36-2_1.

10.1007/978-1-935704-36-2_1

52f5e3b8676d0cb15b276284c895dfa3

http%3A%2F%2Flink.springer.com%2F978-1-935704-36-2

http://link.springer.com/978-1-935704-36-2On the Distribution and Continuity of Water Substance in Atmospheric Circulations KESSLER E. Meteor. Monogr., 1969

Kiehl J. T., J. J. Hack, G. B. Bonan, B. A. Boville, B. P. Briegleb, D. L. Williamson, and P. J. Rasch, 1996: Description of the NCAR community climate model (CCM3). Technical Report NCAR/TN-420+STR.

Kim K. M., W. K. M. Lau, Y. C. Sud, and G. K. Walker, 2010: Influence of aerosol-radiative forcings on the diurnal and seasonal cycles of rainfall over West Africa and Eastern Atlantic Ocean using GCM simulations.Climate Dyn.,35(1),115-126,https://doi.org/10.1007/s00382-010-0750-1.10.1007/s00382-010-0750-1

f981dd99198ba0ba46ba9b101798e264

http%3A%2F%2Flink.springer.com%2F10.1007%2Fs00382-010-0750-1

http://link.springer.com/10.1007/s00382-010-0750-1Effects of aerosol radiative forcing on the diurnal and seasonal cycles of precipitation over West Africa and eastern Atlantic Ocean are investigated for the boreal summer season: June–July–August. An eight year (2000–2007) average of GCM simulated rainfall data is compared with the corresponding TRMM rainfall data. The comparison shows that the amplitude of the diurnal cycles of rainfall over land and ocean are reasonably well simulated. Over land, the phase of the simulated diurnal cycle of precipitation peaks several hours earlier than that of the TRMM data. Corresponding differences over the ocean(s) are relatively smaller. Some of the key features of the aerosol induced model simulated field anomalies are: (a) aerosol direct radiative forcing which increases the atmospheric stability and reduces the daytime moist convection and convective precipitation; (b) the aerosol induced changes in the diurnal cycle of precipitation are out of phase with those of the TRMM data over land, but are in-phase over the ocean; (c) aerosols reduce the amplitude of the diurnal cycle of precipitation over land and enhance it over ocean. However, the phase of the diurnal cycle is not affected much by the aerosol radiative forcing both over land and ocean. During the boreal summer, aerosol radiative forcing and induced circulation and precipitation cool the Sahel and the southern part of Sahara desert more than the adjacent areas to the north and south, thereby shifting the peak meridional temperature gradient northward. Consequently, an anomalous easterly jet is found north of its climatological location. This anomalous jet is associated with increased cyclonic circulation to the south of its axis, resulting in an anomalous monsoon rain belt in the Sahel.

Kodros J. K., C. E. Scott, S. C. Farina, Y. H. Lee, C. L'Orange J. Volckens, and J. R. Pierce2015: Uncertainties in global aerosols and climate effects due to biofuel emissions, Atmos. Chem. Phys., 15, 8577-8596, https://doi.org/10.5194/acp-15-8577-2015.10.5194/acpd-15-10199-2015

23e6c40c5322426fbe23e772e767ae40

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2015ACPD...1510199K

http://adsabs.harvard.edu/abs/2015ACPD...1510199KAerosol emissions from biofuel combustion impact both health and climate; however, while reducing emissions through improvements to combustion technologies will improve health, the net effect on climate is largely unconstrained. In this study, we examine sensitivities in global aerosol concentration, direct radiative climate effect, and cloud-albedo aerosol indirect climate effect to uncertainties in biofuel emission factors, optical mixing-state, and model nucleation and background SOA. We use the Goddard Earth Observing System global chemical-transport model (GEOS-Chem) with TwO Moment Aerosol Sectional (TOMAS) microphysics. The emission factors include: amount, composition, size and hygroscopicity, as well as optical mixing-state properties. We also evaluate emissions from domestic coal use, which is not biofuel but is also frequently emitted from homes. We estimate the direct radiative effect assuming different mixing states (internal, core-shell, and external) with and without absorptive organic aerosol (brown carbon). We find the global-mean direct radiative effect of biofuel emissions ranges from -0.02 to +0.06 W macross all simulation/mixing state combinations with regional effects in source regions ranging from -0.2 to +1.2 W m. The global-mean cloud-albedo aerosol indirect effect ranges from +0.01 to -0.02 W mwith regional effects in source regions ranging from -1.0 to -0.05 W m. The direct radiative effect is strongly dependent on uncertainties in emissions mass, composition, emissions aerosol size distributions and assumed optical mixing state, while the indirect effect is dependent on the emissions mass, emissions aerosol size distribution and the choice of model nucleation and secondary organic aerosol schemes. The sign and magnitude of these effects have a strong regional dependence. We conclude that the climate effects of biofuel aerosols are largely unconstrained, and the overall sign of the aerosol effects is unclear due to uncertainties in model inputs. This uncertainty limits our ability to introduce mitigation strategies aimed at reducing biofuel black carbon emissions in order to counter warming effects from greenhouse-gases. To better understand the climate impact of particle emissions from biofuel combustion, we recommend field/laboratory measurements to narrow constraints on: (1) emissions mass, (2) emission size distribution, (3) mixing state, and (4) ratio of black carbon to organic aerosol.

Konare A., A. S. Zakey, F. Solmon, F. Giorgi, S. Rauscher, S. Ibrah, and X. Bi, 2008: A regional climate modeling study of the effect of desert dust on the West African monsoon. J Geophys. Res.,113: D12206, https://doi.org/10.1029/2007JD009322.10.1029/2007JD009322

ff2048cb0431b3019587e5d334d3dff5

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2007JD009322%2Ffull

http://onlinelibrary.wiley.com/doi/10.1029/2007JD009322/full[1] We investigate the effect of the shortwave radiative forcing of Saharan dust on the West African monsoon with a regional climate model interactively coupled to a dust model. Toward this purpose we intercompare sets of 38 summer monsoon season simulations (1969-2006) with and without dust effects over a domain encompassing most of the African continent and adjacent regions. We find that the main effect of the dust radiative shortwave forcing is to reduce precipitation over the Sahel region. This is in response to cooling over the Sahara, which decreases the meridional gradient of moist static energy and results in a weakening of the monsoon energy pump. The dust effects also cause a strengthening of the southern branch of the African Easterly Jet and a weakening of Tropical Easterly Jet. Over the Sahel the dust forcing causes climate response patterns that are similar to those found during dry years over the Sahel, which suggests that Saharan dust feedbacks might have a role in maintaining drought events over the region. Overall, the inclusion of dust also tends to improve the model simulation of the West African monsoon, as well as African and Tropical Easterly jets. This work focuses on climatic feedback associated to shortwave radiation forcing and should be further completed by the study of dust effect on long-wave radiation.

Levy R. C., L. A. Remer, S. Mattoo, E. F. Vermote, and Y. J. Kaufman, 2007: Second-generation operational algorithm: Retrieval of aerosol properties over land from inversion of Moderate Resolution Imaging Spectroradiometer spectral reflectance.J. Geophys. Res.,112,D13211,https://doi.org/10.1029/2006JD007811.10.1029/2006JD007811

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http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0005796799000467

http://www.sciencedirect.com/science/article/pii/S0005796799000467[1] Since first light in early 2000, operational global quantitative retrievals of aerosol properties over land have been made from Moderate Resolution Imaging Spectroradiometer (MODIS) observed spectral reflectance. These products have been continuously evaluated and validated, and opportunities for improvements have been noted. We have replaced the surface reflectance assumptions, the set of aerosol model optical properties, and the aerosol lookup table (LUT). This second-generation operational algorithm performs a simultaneous inversion of two visible (0.47 and 0.66 μ m) and one shortwave-IR (2.12 μ m) channel, making use of the coarse aerosol information content contained in the 2.12 μ m channel. Inversion of the three channels yields three nearly independent parameters, the aerosol optical depth ( τ ) at 0.55 μ m, the nondust or fine weighting ( η ), and the surface reflectance at 2.12 μ m. Retrievals of small-magnitude negative τ values (down to 610.05) are considered valid, thus balancing the statistics of τ in near zero τ conditions. Preliminary validation of this algorithm shows much improved retrievals of τ , where the MODIS/Aerosol Robotic Network τ (at 0.55 μ m) regression has an equation of: y = 1.01x + 0.03, R = 0.90. Global mean τ for the test bed is reduced from 650.28 to 650.21.

Liu Y. G., P. H. Daum, 2004: Parameterization of the autoconversion process. Part I: Analytical formulation of the Kessler-type parameterizations. J. Atmos. Sci., 61, 1539-1548, https://doi.org/10.1175/1520-0469(2004)061 <1539:POTAPI>2.0.CO;2.

10.1175/1520-0469(2004)0612.0.CO;2

63329be392ddc5cfd8d1d64ffdaba559

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2005JAtS...62.3003W

http://adsabs.harvard.edu/abs/2005JAtS...62.3003WABSTRACT Various commonly used Kessler-type parameterizations of the autoconversion of cloud droplets to embryonic raindrops are theoretically derived from the same formalism by applying the generalized mean value theorem for integrals to the general collection equation. The new formalism clearly reveals the approximations and assumptions that are implicitly embedded in these different parameterizations. A new Kessler-type parameterization is further derived by eliminating the incorrect and/or unnecessary assumptions inherent in the existing Kessler-type parameterizations. The new parameterization exhibits a different dependence on liquid water content and droplet concentration, and provides theoretical explanations for the multitude of values assigned to the tunable coefficients associated with the commonly used parameterizations. Relative dispersion of the cloud droplet size distribution (defined as the ratio of the standard deviation to the mean radius of the cloud droplet size distribution) is explicitly included in the new parameterization, allowing for investigation of the influences of the relative dispersion on the autoconversion rate and, hence, on the second indirect aerosol effect. The new analytical parameterization compares favorably with those parameterizations empirically obtained by curve-fitting results from simulations of detailed microphysical models.

Liu Y. G., P. H. Daum, and R. McGraw, 2004: An analytical expression for predicting the critical radius in the autoconversion parameterization.Geophys. Res. Lett.,31,L06121,https://doi.org/10.1029/2003GL019117.10.1029/2003GL019117

79e8724b55d751f8f12b56eba250cd4e

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2003GL019117%2Ffull

http://onlinelibrary.wiley.com/doi/10.1029/2003GL019117/fullAn analytical expression for the critical radius associated with Kessler-type parameterizations of the autoconversion process is derived. The expression can be used to predict the critical radius from the cloud liquid water content and the droplet number concentration, eliminating the need to prescribe the critical radius as an empirical constant in numerical models. Data from stratiform clouds are analyzed, indicating that on average continental clouds have larger critical radii than maritime clouds. This work further suggests that anthropogenic aerosols affect the autoconversion process by increasing the critical radius and decreasing the characteristic radius, which in turn inhibits the initiation of embryonic raindrops, and by decreasing the autoconversion rate after the initiation process. The potential impact of this work on the evaluation of the second indirect aerosol effect is discussed.

Liu Y. G., P. H. Daum, R. L. McGraw, M. A. Miller, and S. J. Niu, 2007: Theoretical expression for the autoconversion rate of the cloud droplet number concentration.Geophys. Res. Lett.,34,L16821,https://doi.org/10.1029/2007GL030389.10.1029/2007GL030389

90213c1326054a2330ff7e1e9acc4972

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2007GL030389%2Fpdf

http://onlinelibrary.wiley.com/doi/10.1029/2007GL030389/pdfAccurate parameterization of the autoconversion rate of the cloud droplet concentration (number autoconversion rate in cms) is critical for evaluating aerosol indirect effects using climate models; however, existing parameterizations are empirical at best. A theoretical expression is presented in this contribution that analytically relates the number autoconversion rate to the liquid water content, droplet concentration and relative dispersion of the cloud droplet size distribution. The analytical expression is theoretically derived by generalizing the analytical formulation previously developed for the autoconversion rate of the cloud liquid water content (mass autoconversion rate in g cms). Further examination of the theoretical number and mass autoconversion rates reveals that the former is not linearly proportional to the latter as commonly assumed in existing parameterizations. The formulation forms a solid theoretical basis for developing multi-moment representation of the autoconversion process in atmospheric models in general.

Lohmann U., J. Feichter, 1997: Impact of sulfate aerosols on albedo and lifetime of clouds: A sensitivity study with the ECHAM4 GCM.J. Geophys. Res.,102,13 685-13 700,https://doi.org/10.1029/97JD00631.10.1029/97JD00631

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F97JD00631%2Fabstract

http://doi.wiley.com/10.1029/97JD00631A coupled sulfur chemistry-cloud microphysics scheme (COUPL) is used to study the impact of sulfate aerosols on cloud lifetime and albedo. The cloud microphysics scheme includes precipitation formation, which depends on the cloud droplet number concentration (CDNC) and on the liquid water content. On the basis of different observational data sets, CDNC is proportional to the sulfate aerosol mass, which is calculated by the model. Cloud cover is a function of relative humidity only. Additional sensitivity experiments with another cloud cover parameterization (COUPL-CC), which also depends on cloud water, and with a different autoconversion rate of cloud droplets (COUPL-CC-Aut) are conducted to investigate the range of the indirect effect due to uncertainties in cloud physics. For each experiment, two simulations, one using present-day and one using preindustrial sulfur emissions are carried out. The increase in liquid water path, cloud cover, and shortwave cloud forcing due to anthropogenic sulfur emissions depends crucially upon the parameterization of cloud cover and autoconversion of cloud droplets. In COUPL the liquid water path increases by 17% and cloud cover increases by 1% because of anthropogenic sulfur emissions, yielding an increase in shortwave cloud forcing of 611.4 W m 612 . In COUPL-CC the liquid water path increases by 32%, cloud cover increases by 3% and thus shortwave cloud forcing increases by 614.8 W m 612 . This large effect is caused by the strong dependence of cloud cover on cloud water and of the autoconversion rate on CDNC, cloud water, and cloud cover. Choosing a different autoconversion rate (COUPL-CC-Aut) with a reduced dependence on CDNC and cloud water results in an increase of liquid water path by only 11% and of cloud cover by 1%, and the increase in shortwave cloud forcing amounts to 612.2 W m 612 . These results clearly show that the uncertainties linked to the indirect aerosol effect are higher than was previously suggested.

Martin G. M., D. W. Johnson, and A. Spice, 1994: The measurement and parameterization of effective radius of droplets in warm stratocumulus clouds. J. Atmos. Sci., 51, 1823-1842, https://doi.org/10.1175/1520-0469(1994)051<1823:TMAPOE>2.0.CO;2.10.1175/1520-0469(1994)0512.0.CO;2

d1ba65244d7022ba90e29ed46b6f3a2d

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1994JAtS...51.1823M

http://adsabs.harvard.edu/abs/1994JAtS...51.1823MObservations from the Meteorological Research Flight's Hercules C-130 aircraft of the microphysical characteristics of warm stratocumulus clouds have been analyzed to investigate the variation of the effective radius of cloud droplets in layer clouds. Results from experiments in the eastern Pacific, South Atlantic, subtropical regions of the North Atlantic, and the sea areas around the British Isles are presented. In situations where entrainment effects are small the (effective radius)is found to be a linear function of the (volume-averaged radius)in a given cloud and can thus be parameterized with respect to the liquid water content and the droplet number concentration in the cloud. However, the shape of the droplet size spectrum is very dependent on the cloud condensation nuclei (CCN) characteristics below cloud base, and the relationship between effective radius and volume-averaged radius varies between maritime air masses and continental air masses. This study also details comparisons that have been made in stratocumulus between the droplet number concentrations and (a) aerosol concentrations below cloud base in the size range 0.1 to 3.0 m and (b) CCN supersaturation spectra in the boundary layer. A parameterization relating droplet concentration and aerosol concentration is suggested. The effects of nonadiabatic processes on the parameterization of effective radius are discussed. Drizzle is found to have little effect near cloud top, but in precipitating stratocumulus clouds the parameterization breaks down near cloud base. Comparisons are made between this parameterization of effective radius and others used currently or in the past.

Mitchell T. D., P. D. Jones, 2005: An improved method of constructing a database of monthly climate observations and associated high-resolution grids.International Journal of Climatology25(6),693-712,https://doi.org/10.1002/joc.1181.10.1002/joc.1181

fde1a91db2d30a9d77329dd7148d4007

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjoc.1181%2Ffull

http://doi.wiley.com/10.1002/%28ISSN%291097-0088Abstract A database of monthly climate observations from meteorological stations is constructed. The database includes six climate elements and extends over the global land surface. The database is checked for inhomogeneities in the station records using an automated method that refines previous methods by using incomplete and partially overlapping records and by detecting inhomogeneities with opposite signs in different seasons. The method includes the development of reference series using neighbouring stations. Information from different sources about a single station may be combined, even without an overlapping period, using a reference series. Thus, a longer station record may be obtained and fragmentation of records reduced. The reference series also enables 1961–90 normals to be calculated for a larger proportion of stations. The station anomalies are interpolated onto a 0.5° grid covering the global land surface (excluding Antarctica) and combined with a published normal from 1961–90. Thus, climate grids are constructed for nine climate variables (temperature, diurnal temperature range, daily minimum and maximum temperatures, precipitation, wet-day frequency, frost-day frequency, vapour pressure, and cloud cover) for the period 1901–2002. This dataset is known as CRU TS 2.1 and is publicly available ( http://www.cru.uea.ac.uk/ ). Copyright 08 2005 Royal Meteorological Society

Olivier J. G. J., J. J. M. Berdowski, J. A. H. W. Peters, J. Bakker, A. J. H. Visschedijk, and J.-P. J. Bloos, 2001: Applications of EDGAR. Including a description of EDGAR 3.0: Reference database with trend data for 1970-1995. RIVM, Bilthoven. RIVM report no. 773301 001/NOP report no. 410200 051.

Pal J. S., E. E. Small, and E. A. B. Eltahir, 2000: Simulation of regional-scale water and energy budgets: Representation of subgrid cloud and precipitation processes within RegCM.J. Geophys. Res.,105,29 579-29 594,https://doi.org/10.1029/2000JD900415.10.1029/2000JD900415

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2000JD900415%2Ffull

http://doi.wiley.com/10.1029/2000JD900415A new large-scale cloud and precipitation scheme, which accounts for the sub-grid-scale variability of clouds, is coupled to NCAR's Regional Climate Model (RegCM). This scheme partitions each grid cell into a cloudy and noncloudy fraction related to the average grid cell relative humidity. Precipitation occurs, according to a specified autoconversion rate, when a cloud water threshold is exceeded. The specification of this threshold is based on empirical in-cloud observations of cloud liquid water amounts. Included in the scheme are simple formulations for raindrop accretion and evaporation. The results from RegCM using the new scheme, tested over North America, show significant improvements when compared to the old version. The outgoing longwave radiation, albedo, cloud water path, incident surface shortwave radiation, net surface radiation, and surface temperature fields display reasonable agreement with the observations from satellite and surface station data. Furthermore, the new model is able to better represent extreme precipitation events such as the Midwest flooding observed in the summer of 1993. Overall, RegCM with the new scheme provides for a more accurate representation of atmospheric and surface energy and water balances, including both the mean conditions and the variability at daily to interannual scales. The latter suggests that the new scheme improves the model's sensitivity, which is critical for both climate change and process studies.

Pruppacher H. R., J. D. Klett, 1997: Microphysics of Clouds and Precipitation. 2nd ed., Springer, 954 pp.

Qian Y., F. Giorgi, 1999: Interactive coupling of regional climate and sulfate aerosol models over eastern Asia.J. Geophys. Res.,104,6477-6499,https://doi.org/10.1029/98JD02347.10.1029/98JD02347

2fa79025a0143aaa55c6c07a3e0b01c1

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F98JD02347%2Fcitedby

http://doi.wiley.com/10.1029/98JD02347The NCAR regional climate model (RegCM) is interactively coupled to a simple radiatively active sulfate aerosol model over eastern Asia. Both direct and indirect aerosol effects are represented. The coupled model system is tested for two simulation periods, November 1994 and July 1995, with aerosol sources representative of present-day anthropogenic sulfur emissions. The model sensitivity to the intensity of the aerosol source is also studied. The main conclusions from our work are as follows: (1) The aerosol distribution and cycling processes show substantial regional spatial variability, and temporal variability varying on a range of scales, from the diurnal scale of boundary layer and cumulus cloud evolution to the 3-10 day scale of synoptic scale events and the interseasonal scale of general circulation features; (2) both direct and indirect aerosol forcings have regional effects on surface climate; (3) the regional climate response to the aerosol forcing is highly nonlinear, especially during the summer, due to the interactions with cloud and precipitation processes; (4) in our simulations the role of the aerosol indirect effects is dominant over that of direct effects; (5) aerosol-induced feedback processes can affect the aerosol burdens at the subregional scale. This work constitutes the first step in a long term research project aimed at coupling a hierarchy of chemistry/aerosol models to the RegCM over the eastern Asia region.

Rogers R. R., M. K. Yau, 1989: A Short Course in Cloud Physics. 3rd ed., Oxford, Pergamon, UK.

Rotstayn L. D., Y. G. Liu, 2005: A smaller global estimate of the second indirect aerosol effect.Geophys. Res. Lett.,32,L05708,https://doi.org/10.1029/2004GL021922.10.1029/2004GL021922

7efbfef72364f6e8d9648f71b849a429

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2004GL021922%2Ffull

http://onlinelibrary.wiley.com/doi/10.1029/2004GL021922/fullGlobal estimates of the indirect aerosol effect much larger than 1 W min magnitude are difficult to reconcile with observations, yet climate models give estimates between -1 and -4.4 W m. We use a climate model with a new treatment of autoconversion to reevaluate the second indirect aerosol effect. We obtain a global-mean value of -0.28 W m, compared to -0.71 W mwith the autoconversion treatment most often used in climate models. The difference is due to (1) the new scheme's smaller autoconversion rate, and (2) an autoconversion threshold that increases more slowly with cloud droplet concentration. The impact of the smaller autoconversion rate shows the importance of accurately modeling this process. Our estimate of the total indirect aerosol effect on liquid-water clouds changes from -1.63 to -1.09 W m.

Schultz, M. G., Coauthors, 2007: REanalysis of the TROpospheric chemical composition over the past 40 years long-term global modeling study of tropospheric chemistry funded under the 5th EU Framework Programme 2007. Technical Report, EU-Contract No. EVK2-CT-2002-00170, 20 pp. [Available online at http://retro.enes.org/reports/D1-6_final.pdf]

Seinfeld J. H., S. N. Pandis, 2006: Atmospheric Chemistry and Physics: From Air Pollution to Climate Change. 2nd ed., Wiley-Interscience.

ad092c076ece5331639dd5fc3273603e

http%3A%2F%2Feu.wiley.com%2Fremtitle.cgi%3FISBN%3D1118591364

http://eu.wiley.com/remtitle.cgi?ISBN=1118591364ABSTRACT Diss.--Königsberg.

Solmon F., F. Giorgi, and C. Liousse, 2006: Aerosol modelling for regional climate studies: Application to anthropogenic particles and evaluation over a European/African domain.Tellus58B,51-72,https://doi.org/10.1111/j.1600-0889.2005.00155.x.

10.1111/j.1600-0889.2005.00155.x

77b4bd92316f8d1c4ca29678dd4d7944

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1111%2Fj.1600-0889.2005.00155.x%2Fcitedby

http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0889.2005.00155.x/citedbyA simplified anthropogenic aerosol model for use in climate studies is developed and implemented within the regional climate model RegCM. The model includes sulphur dioxide, sulphate, hydrophobic and hydrophilic black carbon (BC) and organic carbon (OC) and is run for the winter and summer seasons of 2000 over a large domain extending from northern Europe to south tropical Africa. An evaluation of the model performance is carried out in terms of surface concentrations and aerosol optical depths (AODs). For sulphur dioxide and sulphate concentration, comparison of simulated fields and experimental data collected over the EMEP European network shows that the model generally reproduces the observed spatial patterns of near-surface sulphate. Sulphate concentrations are within a factor of 2 of observations in 34% (JJA) to 57% (DJF) of cases. For OC and BC, simulated concentrations are compared to different datasets. The simulated and observed values agree within a factor of 2 in 56% (DJF) to 62% (JJA) of cases for BC and 33% (JJA) to 64% (DJF) for OC. Simulated AODs are compared with ground-based (AERONET) and satellite (MODIS, MISR, TOMS) AOD datasets. Simulated AODs are in the range of AERONET and MISR data over northern Europe, and AOD spatial patterns show consistency with MODIS and TOMS retrievals both over Europe and Africa. The main model deficiencies we find are: (i) an underestimation of surface concentrations of sulphate and OC during the summer and especially over the Mediterranean region and (ii) a general underestimation of AOD, most pronounced over the Mediterranean basin. The primary factors we identify as contributing to these biases are the lack of natural aerosols (in particular, desert dust, secondary biogenic aerosols and nitrates), uncertainties in the emission inventories and aerosol cycling by moist convection. Also, in view of the availability of better observing datasets (e.g. as part of the AMMA project), we are currently working on improving these aspects of the model before applying it to climate studies. Despite the deficiencies identified above, we assess that our model shows a performance in line with that other coupled climate/aerosol models and can presently provide a useful tool for sensitivity and process studies.

Solmon F., N. Elguindi, and M. Mallet, 2012: Radiative and climatic effects of dust over West Africa,as simulated by a regional climate model.Climate Research,52,97-113,https://doi.org/10.3354/cr01039.

10.3354/cr01039

82af0a82a0ebcc8caeef82ab2b1809c5

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F271253581_Radiative_and_climatic_effects_of_dust_over_West_Africa_as_simulated_by_a_regional_climate_model

http://www.int-res.com/abstracts/cr/v52/p97-113/We used the Regional Circulation Model (RegCM) to investigate the direct effect of dust aerosol on climate over West Africa, with a specific focus on the Sahel region. First, we characterized the mechanisms linking dust radiative forcing and convective activity over Sahel and the net impact of dust on precipitation: The mean effect of dust over 11 summer seasons is to reduce precipitation over most of the Sahel region as a result of strong surface cooling and elevated diabatic warming inhibiting convection. However, on the very northern Sahel and in the vicinity of dust sources, a relative increase of precipitation is obtained as a result of enhanced diabatic warming in the lower atmosphere associated with high dust concentrations at low altitude. In the second part of the paper, we investigated the robustness of this signal with regards to different modeling conditions that are thought to be sensitive, namely the extension of the domain, the effect of dust on sea surface temperature, the land surface scheme, the convective scheme and the dust single scattering albedo. The simulated dust induced precipitation anomaly over West Africa is consistent and robust in these tests, but significant variations over the northern Sahel region are nevertheless pointed out. Among different factors, single scattering and surface albedo, as well as the nature of the convective scheme, have the greatest influence on the simulated response of West African climate to dust forcing

Sylla M. B., E. Coppola, L. Mariotti, F. Giorgi, P. M. Ruti, A. Dell'Aquila, and X. Bi, 2010: Multiyear simulation of the african climate using a regional climate model (RegCM3) with the high resolution ERA-interim reanalysis.Climate Dyn.,35,231-274,https://doi.org/10.1007/s00382-009-0613-9.10.1007/s00382-009-0613-9

3d6c20d382de65810d70547b253684f8

http%3A%2F%2Fonlinelibrary.wiley.com%2Fresolve%2Freference%2FXREF%3Fid%3D10.1007%2Fs00382-009-0613-9

http://link.springer.com/10.1007/s00382-009-0613-9This study examines the ability of the latest version of the International Centre for Theoretical Physics (ICTP) regional climate model (RegCM3) to reproduce seasonal mean climatologies, annual cycle and interannual variability over the entire African continent and different climate subregions. The new European Center for Medium Range Weather Forecast (ECMWF) ERA-interim reanalysis is used to provide initial and lateral boundary conditions for the RegCM3 simulation. Seasonal mean values of zonal wind profile, temperature, precipitation and associated low level circulations are shown to be realistically simulated, although the regional model still shows some deficiencies. The West Africa monsoon flow is somewhat overestimated and the Africa Easterly Jet (AEJ) core intensity is underestimated. Despite these biases, there is a marked improvement in these simulated model variables compared to previous applications of this model over Africa. The mean annual cycle of precipitation, including single and multiple rainy seasons, is well captured over most African subregions, in some cases even improving the quality of the ERA-interim reanalysis. Similarly, the observed precipitation interannual variability is well reproduced by the regional model over most regions, mostly following, and sometimes improving, the quality of the ERA-interim reanalysis. It is assessed that the performance of this model over the entire African domain is of sufficient quality for application to the study of climate change and climate variability over the African continent.

Tripoli G. J., W. R. Cotton, 1980: A numerical investigation of several factors contributing to the observed variable intensity of deep convection over South Florida. J. Atmos. Sci., 19, 1037-1063, https://doi.org/10.1175/1520-0450(1980)019<1037:ANIOSF>2.0.CO;2.

7b834b4a606dba3e067a3d6e4d7374a4

http%3A%2F%2Fwww.bioone.org%2Fservlet%2Flinkout%3Fsuffix%3Di0276-4741-33-4-424-Tripoli1%26amp%3Bdbid%3D16%26amp%3Bdoi%3D10.1659%252FMRD-JOURNAL-D-13-00033.1%26amp%3Bkey%3D10.1175%252F1520-0450%281980%290192.0.CO%253B2

年度引用

Twomey S., 1977: The influence of pollution on the shortwave albedo of clouds. J. Atmos. Sci., 34, 1149-1152, https://doi.org/10.1175/1520-0469(1977)034<1149:TIOPOT>2.0.CO;2.

10.1175/1520-0469(1977)0342.0.CO;2

87d30a8ee5cb88296547d53b6f7b6dba

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1977JAtS...34.1149T

http://adsabs.harvard.edu/abs/1977JAtS...34.1149TBy increasing droplet concentration and thereby the optical thickness of a cloud, pollution acts to increase the reflectance (albedo) of clouds; by increasing the absorption coefficient it acts to decrease the reflectance. Calculations suggest that the former effect (brightening of the clouds in reflection, hence climatically a cooling effect) dominates for thin to moderately thick clouds, whereas for sufficiently thick clouds the latter effect (climatically a warming effect) can become dominant.