doi:10.1007/s00376-017-7033-2

Anderson T. L., J. A. Ogren, 1998: Determining aerosol radiative properties using the TSI 3563 integrating nephelometer.Aerosol Science and Technology29,57-69,https://doi.org/10.1080/02786829808965551.

10.1080/02786829808965551

5b4523dda16a77fade5faf75c29c5de4

http%3A%2F%2Fwww.tandfonline.com%2Fdoi%2Fabs%2F10.1080%2F02786829808965551

http://www.tandfonline.com/doi/abs/10.1080/02786829808965551Methods for reducing and quantifying the uncertainties in aerosol optical properties measured with the TSI 3563 integrating nephelometer are presented. For nearly all applications, the recommended calibration gases are air and CO2. By routinely characterizing the instrumental response to these gases, a diagnostic record of instrument performance can be created. This record can be used to improve measurement accuracy and quantify uncertainties due to instrumental noise and calibration drift. When measuring scattering by particles, size segregation upstream of the nephelometer at about 1 0204m aerodynamic diameter greatly increases the information content of the data for two reasons: one stemming from the independence of coarse and fine particles in the atmosphere, and the second stemming from the size dependence of the nephelometer response. For many applications (e.g., extinction budget studies) it is important to correct nephelometer data for the effects of angular nonidealities. Correction factors appropriate to a broad range of sampling conditions are given herein and are shown to be constrained by the wavelength dependence of light scattering, as measured by the nephelometer. Finally, the nephelometer measurement is nondestructive, such that the sampled aerosol can be further analyzed downstream. Data from two nephelometers operated in series are used to evaluate this procedure. A small loss of super-0204m particles (509000910%) is found, while the sub-0204m data demonstrates measurement reproducibility within 00± 1%.

Bergin M. H., 2000: Aerosol radiative properties and their impacts. From Weather Forecasting to Exploring the Solar System, C. Boutron, Ed., EDP Sciences, 51- 65.

Buchard, V., Coauthors, 2015: Using the OMI aerosol index and absorption aerosol optical depth to evaluate the NASA MERRA Aerosol Reanalysis.Atmos. Chem. Phys.15,5743-5760,https://doi.org/10.5194/acp-15-5743-2015.10.5194/acp-15-5743-2015

271dc95dae9f735a4ccba123201bcff1

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2014ACPD...1432177B

http://www.atmos-chem-phys.net/15/5743/2015/A radiative transfer interface has been developed to simulate the UV Aerosol Index (AI) from the NASA Goddard Earth Observing System version 5 (GEOS-5) aerosol assimilated fields. The purpose of this work is to use the AI and Aerosol Absorption Optical Depth (AAOD) derived from the Ozone Monitoring Instrument (OMI) measurements as independent validation for the Modern Era Retrospective analysis for Research and Applications Aerosol Reanalysis (MERRAero). MERRAero is based on a version of the GEOS-5 model that is radiatively coupled to the Goddard Chemistry, Aerosol, Radiation, and Transport (GOCART) aerosol module and includes assimilation of Aerosol Optical Depth (AOD) from the Moderate Resolution Imaging Spectro-radiometer (MODIS) sensor. Since AI is dependent on aerosol concentration, optical properties and altitude of the aerosol layer, we make use of complementary observations to fully diagnose the model, including AOD from the Multi-angle Imaging Spectro-Radiometer (MISR), aerosol retrievals from the Aerosol Robotic Network (AERONET) and attenuated backscatter coefficients from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission to ascertain potential misplacement of plume height by the model. By sampling dust, biomass burning and pollution events in 2007 we have compared model produced AI and AAOD with the corresponding OMI products, identifying regions where the model representation of absorbing aerosols was deficient. As a result of this study over the Saharan dust region, we have obtained a new set of dust aerosol optical properties that retains consistency with the MODIS AOD data that were assimilated, while resulting in better agreement with aerosol absorption measurements from OMI. The analysis conducted over the South African and South American biomass burning regions indicates that revising the spectrally-dependent aerosol absorption properties in the near-UV region improves the modeled-observed AI comparisons. Finally, during a period where the Asian region was mainly dominated by anthropogenic aerosols, we have performed a qualitative analysis in which the specification of anthropogenic emissions in GEOS-5 is adjusted to provide insight into discrepancies observed in AI comparisons.

Camponogara G., M. A. F. Silva Dias, and G. G. Carri贸, 2014: Relationship between Amazon biomass burning aerosols and rainfall over the La Plata Basin.Atmos. Chem. Phys.14,4397-4407,https://doi.org/10.5194/acp-14-4397-2014.10.5194/acp-14-4397-2014

218d2329231ae93111f0a3ae9e7c9767

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2014ACP....14.4397C

http://www.atmos-chem-phys.net/14/4397/2014/High aerosol loads are discharged into the atmosphere by biomass burning inthe Amazon and central Brazil during the dry season. These particles caninteract with clouds as cloud condensation nuclei (CCN) changing cloudmicrophysics and radiative properties and, thereby, affecting the radiativebudget of the region. Furthermore, the biomass burning aerosols can betransported by the low-level jet (LLJ) to the La Plata Basin, where manymesoscale convective systems (MCS) are observed during spring and summer.This work proposes to investigate whether the aerosols from biomass burningmay affect the MCS in terms of rainfall over the La Plata Basin duringspring. Aerosol effects are very difficult to isolate because convectiveclouds are very sensitive to small environment disturbances; for that reason,detailed analyses using different techniques are used. The binplot,2-D histograms and combined empirical orthogonal function (EOF)methods are used to identify certain environmental conditions with thepossible effects of aerosol loading. Reanalysis 2, TRMM-3B42 and AERONET dataare used from 1999 up to 2012 during September揇ecember. The results showthat there are two patterns associated with rainfallerosol interaction inthe La Plata Basin: one in which the dynamic conditions are more importantthan aerosols to generation of rain; and a second one where the aerosolparticles have a more important role in rain formation, acting mainly tosuppress rainfall over the La Plata Basin. However, these results needfurther investigation to strengthen conclusions, especially because thereare limitations and uncertainties in the methodology and data set used.

Dong X. Q., P. Minnis, T. P. Ackerman, E. E. Clothiaux, G. G. Mace, C. N. Long, and J. C. Liljegren, 2000: A 25-month database of stratus cloud properties generated from ground-based measurements at the Atmospheric Radiation Measurement Southern Great Plains Site.J. Geophys. Res.,105,4529-4537,https://doi.org/10.1029/1999JD901159.10.1029/1999JD901159

a34d7a793294068b0e94e687fc7c2c88

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F1999JD901159%2Ffull

http://doi.wiley.com/10.1029/1999JD901159A 25-month database of the macrophysical, microphysical, and radiative properties of isolated and overcast low-level stratus clouds has been generated using a newly developed parameterization and surface measurements from the Atmospheric Radiation Measurement central facility in Oklahoma. The database (5-min resolution) includes two parts: measurements and retrievals. The former consist of cloud base and top heights, layer-mean temperature, cloud liquid water path, and solar transmission ratio measured by a ground-based lidar/ceilometer and radar pair, radiosondes, a microwave radiometer, and a standard Eppley precision spectral pyranometer, respectively. The retrievals include the cloud-droplet effective radius and number concentration and broadband shortwave optical depth and cloud and top-of-atmosphere albedos. Stratus without any overlying mid or high-level clouds occurred most frequently during winter and least often during summer. Mean cloud-layer altitudes and geometric thicknesses were higher and greater, respectively, in summer than in winter. Both quantities are positively correlated with the cloud-layer mean temperature. Mean cloud-droplet effective radii range from 8.1 m in winter to 9.7 m during summer, while cloud-droplet number concentrations during winter are nearly twice those in summer. Since cloud liquid water paths are almost the same in both seasons, cloud optical depth is higher during the winter, leading to greater cloud albedos and lower cloud transmittances.

Dong X. Q., P. Minnis, and B. K. Xi, 2005: A climatology of midlatitude continental clouds from the ARM SGP central facility: Part I: Low-level cloud macrophysical,microphysical, and radiative properties.J. Climate,18,1391-1410,https://doi.org/10.1175/JCLI3342.1.10.1175/JCLI3342.1

73b72acfd0e2206e5b64ce9484575cad

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2005JCli...18.1391D

http://journals.ametsoc.org/doi/abs/10.1175/JCLI3342.1A record of single-layer and overcast low cloud (stratus) properties has been generated using approximately 4000 h of data collected from January 1997 to December 2002 at the Atmospheric Radiation Measurement (ARM) Southern Great Plains Central Facility (SCF). The cloud properties include liquid-phase and liquid-dominant mixed-phase low cloud macrophysical, microphysical, and radiative properties including cloud-base and -top heights and temperatures, and cloud physical thickness derived from a ground-based radar and lidar pair, and rawinsonde sounding; cloud liquid water path (LWP) and content (LWC), and cloud-droplet effective radius (r) and number concentration (N) derived from the macrophysical properties and radiometer data; and cloud optical depth (), effective solar transmission (纬), and cloud/top-of-atmosphere albedos (R/R) derived from Eppley precision spectral pyranometer measurements. The cloud properties were analyzed in terms of their seasonal, monthly, and hourly variations. In general, more stratus clouds occur during winter and spring than in summer. Cloud-layer altitudes and physical thicknesses were higher and greater in summer than in winter with averaged physical thicknesses of 0.85 and 0.73 km for day and night, respectively. The seasonal variations of LWP, LWC, N, , R, and Rbasically follow the same pattern with maxima and minima during winter and summer, respectively. There is no significant variation in mean r, however, despite a summertime peak in aerosol loading. Although a considerable degree of variability exists, the 6-yr average values of LWP, LWC, r, N, , 纬, R, and Rare 151 gm(138), 0.245 gm(0.268), 8.7 m (8.5), 213 cm(238), 26.8 (24.8), 0.331, 0.672, and 0.563 for daytime (nighttime). A new conceptual model of midlatitude continental low clouds at the ARM SGP site has been developed from this study. The low stratus cloud amount monotonically increases from midnight to early morning (0930 LT), and remains large until around local noon, then declines until 1930 LT when it levels off for the remainder of the night. In the morning, the stratus cloud layer is low, warm, and thick with less LWC, while in the afternoon it is high, cold, and thin with more LWC. Future parts of this series will consider other cloud types and cloud radiative forcing at the ARM SCF.

Dong X. Q., B. K. Xi, and P. Minnis, 2006: A climatology of midlatitude continental clouds from the ARM SGP central facilityPart II: Cloud fraction and surface radiative forcing. J. Climate19,1765-1783,https://doi.org/10.1175/JCLI3710.1.10.1175/JCLI3710.1

338270bed7f1d68102e3025a73b06416

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2006JCli...19.1765D

http://journals.ametsoc.org/doi/abs/10.1175/JCLI3710.1Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Central Facility (SCF) are analyzed to determine the monthly and hourly variations of cloud fraction and radiative forcing between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layered low (009“3 km), middle (309“6 km), and high clouds (>6 km) using ARM SCF ground-based paired lidar09“radar measurements. Shortwave (SW) and longwave (LW) fluxes are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements with uncertainties of 09030410 W m-2. The annual averages of total and single-layered low-, middle-, and high-cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Both total- and low-cloud amounts peak during January and February and reach a minimum during July and August; high clouds occur more frequently than other types of clouds with a peak in summer. The average annual downwelling surface SW fluxes for total and low clouds (151 and 138 W m-2, respectively) are less than those under middle and high clouds (188 and 201 W m-2, respectively), but the downwelling LW fluxes (349 and 356 W m-2) underneath total and low clouds are greater than those from middle and high clouds (337 and 333 W m-2). Low clouds produce the largest LW warming (55 W m-2) and SW cooling (-91 W m-2) effects with maximum and minimum absolute values in spring and summer, respectively. High clouds have the smallest LW warming (17 W m-2) and SW cooling (-37 W m-2) effects at the surface. All-sky SW cloud radiative forcing (CRF) decreases and LW CRF increases with increasing cloud fraction with mean slopes of -0.984 and 0.616 W m-2 %-1, respectively. Over the entire diurnal cycle, clouds deplete the amount of surface insolation more than they add to the downwelling LW flux. The calculated CRFs do not appear to be significantly affected by uncertainties in data sampling and clear-sky screening. Traditionally, cloud radiative forcing includes not only the radiative impact of the hydrometeors, but also the changes in the environment. Taken together over the ARM SCF, changes in humidity and surface albedo between clear and cloudy conditions offset 09030420% of the NET radiative forcing caused by the cloud hydrometeors alone. Variations in water vapor, on average, account for 10% and 83% of the SW and LW CRFs, respectively, in total cloud cover conditions. The error analysis further reveals that the cloud hydrometeors dominate the SW CRF, while water vapor changes are most important for LW flux changes in cloudy skies. Similar studies over other locales are encouraged where water and surface albedo changes from clear to cloudy conditions may be much different than observed over the ARM SCF.

Dong X. Q., B. K. Xi, A. Kennedy, P. Minnis, and R. Wood, 2014: A 19-month record of marine aerosol-cloud-radiation properties derived from DOE ARM mobile facility deployment at the Azores Part I: Cloud fraction and single-layered MBL cloud properties. J. Climate27,3665-3682,https://doi.org/10.1175/JCLI-D-13-00553.1.10.1175/JCLI-D-13-00553.1

9d98c5b06216161eb0c3ebaee805342e

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F274494158_A_19-Month_Record_of_Marine_AerosolCloudRadiation_Properties_Derived_from_DOE_ARM_Mobile_Facility_Deployment_at_the_Azores._Part_I_Cloud_Fraction_and_Single-Layered_MBL_Cloud_Properties

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-13-00553.1ABSTRACT A 19-month record of total and single-layered low (6 km) cloud fractions (CFs) and the single-layered marine boundary layer (MBL) cloud macrophysical and microphysical properties was generated from ground-based measurements at the Atmospheric Radiation Measurement Program (ARM) Azores site between June 2009 and December 2010. This is the most comprehensive dataset of marine cloud fraction and MBL cloud properties. The annual means of total CF and single-layered low, middle, and high CFs derived from ARM radar and lidar observations are 0.702, 0.271, 0.01, and 0.106, respectively. Greater total and single-layered high (>6 km) CFs occurred during the winter, whereas single-layered low (<3 km) CFs were more prominent during summer. Diurnal cycles for both total and low CFs were stronger during summer than during winter. The CFs are bimodally distributed in the vertical with a lower peak at similar to 1 km and a higher peak between 8 and 11 km during all seasons, except summer when only the low peak occurs. Persistent high pressure and dry conditions produce more single-layered MBL clouds and fewer total clouds during summer, whereas the low pressure and moist air masses during winter generate more total and multilayered clouds, and deep frontal clouds associated with midlatitude cyclones.The seasonal variations of cloud heights and thickness are also associated with the seasonal synoptic patterns. The MBL cloud layer is low, warm, and thin with large liquid water path (LWP) and liquid water content (LWC) during summer, whereas during winter it is higher, colder, and thicker with reduced LWP and LWC. The cloud LWP and LWC values are greater at night than during daytime. The monthly mean daytime cloud droplet effective radius r(e) values are nearly constant, while the daytime droplet number concentration N-d basically follows the LWC variation. There is a strong correlation between cloud condensation nuclei (CCN) concentration N-CCN and N-d during January-May, probably due to the frequent low pressure systems because upward motion brings more surface CCN to cloud base (well-mixed boundary layer). During summer and autumn, the correlation between N-d and N-CCN is not as strong as that during January-May because downward motion from high pressure systems is predominant. Compared to the compiled aircraft in situ measurements during the Atlantic Stratocumulus Transition Experiment (ASTEX), the cloud microphysical retrievals in this study agree well with historical aircraft data. Different air mass sources over the ARM Azores site have significant impacts on the cloud microphysical properties and surface CCN as demonstrated by great variability in N-CCN and cloud microphysical properties during some months.

Dong X. Q., A. C. Schwantes, B. K. Xi, and P. Wu, 2015: Investigation of the marine boundary layer cloud and CCN properties under coupled and decoupled conditions over the Azores.J. Geophys. Res.,120,6179-6191,https://doi.org/10.1002/2014JD022939.10.1002/2014JD022939

e236a155d6980d63818659c7c7307d77

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2F2014JD022939%2Fpdf

http://onlinelibrary.wiley.com/doi/10.1002/2014JD022939/pdfAbstract Six coupled and decoupled marine boundary layer (MBL) clouds were chosen from the 1965month Atmospheric Radiation Measurement Mobile Facility data set over the Azores. Thresholds of liquid water potential temperature difference Δ θL 650.565K) and total water mixing ratio difference Δ qt 650.565g/kg) below the cloud base were used for selecting the coupled (decoupled) cases. A schematic diagram was given to demonstrate the coupled and decoupled MBL vertical structures and how they associate with nondrizzle, virga, and rain drizzle events. Out of a total of 2676 565min samples, 34.5% were classified as coupled and 65.5% as decoupled, 36.2% as nondrizzle and 63.8% as drizzle (47.7% as virga and 16.1% as rain), and 33.4% as daytime and 66.6% as nighttime. The decoupled cloud layer is deeper (0.40665km) than coupled cloud layer (0.30465km), and its liquid water path and cloud droplet effective radius ( re ) values (122.165gm612 and 13.06508m) are higher than coupled ones (83.765gm612 and 10.46508m). Conversely, decoupled stratocumuli have lower cloud droplet number concentration ( Nd ) and surface cloud condensation nucleus (CCN) concentration ( N CCN) (74.565cm613 and 150.965cm613) than coupled stratocumuli (111.765cm613 and 216.465cm613). The linear regressions between re and Nd with N CCN have demonstrated that coupled re and Nd strongly depend on N CCN and have higher correlations (610.56 and 0.59) with N CCN than decoupled results (610.14 and 0.25). The MBL cloud properties under nondrizzle and virga drizzle conditions are similar to each other but significantly different to those of rain drizzle.

Draxler R. R., G. D. Rolph, 2013: HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) Model access via NOAA ARL READY Website. NOAA Air Resources Laboratory, Silver Spring, MD. [Available online from http://ready.arl.noaa.gov/HYSPLIT.php]

Fan, J. W., Coauthors, 2015: Improving representation of convective transport for scale-aware parameterization: 1.Convection and cloud properties simulated with spectral bin and bulk microphysics. J. Geophys. Res.,120,3485-3509,https://doi.org/10.1002/2014JD022142.

Graf H.-F., J. Yang, and T. M. Wagner, 2009: Aerosol effects on clouds and precipitation during the 1997 smoke episode in Indonesia.Atmos. Chem. Phys.9,743-756,https://doi.org/10.5194/acp-9-743-2009.10.5194/acp-9-743-2009

6fcf181414d316d479695d74f547f891

http%3A%2F%2Fwww.oalib.com%2Fpaper%2F2700328

http://www.atmos-chem-phys.net/9/743/2009/In 1997/98 a severe smoke episode due to extensive biomass burning, especially of peat, was observed over Indonesia. September 1997 was the month with the highest aerosol burden. This month was simulated using the limited area model REMOTE driven at its lateral boundaries by ERA40 reanalysis data. REMOTE was extended by a new convective cloud parameterization mimicking individual clouds competing for instability energy. This allows for the interaction of aerosols and convective clouds and precipitation. Results show that convective precipitation is diminished at all places with high aerosol loading, but at some areas with high background humidity precipitation from large-scale clouds may over-compensate the loss in convective rainfall. At individual time steps, very few cases were found when polluted convective clouds produced intensified rainfall via mixed phase microphysics. However, these cases are not unequivocal and opposite results were also simulated, indicating that other than aerosol-microphysics effects have important impact on the results. Overall, the introduction of the new cumulus parameterization and of aerosol-cloud interaction improved the simulation of precipitation patterns and total amount.

Guo X. L., D. H. Fu, X. Guo, and C. M. Zhang, 2014: A case study of aerosol impacts on summer convective clouds and precipitation over northern China.Atmos. Res.,142,142-157,https://doi.org/10.1016/j.atmosres.2013.10.006.10.1016/j.atmosres.2013.10.006

dc3316187bb3141e54ecbadcdd2e85a1

http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0169809513002792

http://linkinghub.elsevier.com/retrieve/pii/S0169809513002792The emissions such as greenhouse gases, precursor gases and particulate matters may directly alter the Earth radiative budget or indirectly modify cloud and precipitation processes, and possibly induce changes in climate and the hydrological cycle at the regional to global scale. The previous publications reported a few quantitative assessments and inconsistent results on the effects of the emissions on cloud and precipitation. The aerosol properties and possible impacts on a convective precipitation case on 4 July 2008 over the urban region of northern China are investigated based on the Moderate Resolution Imaging Spectroradiometer (MODIS) data and the Weather Research and Forecast (WRF) model coupled with Chemistry (WRF–Chem). Results show that the Aerosol Optical Depth (AOD) is over 0.9 in the study area, indicating a high concentration of aerosol pollution. The value of Angstrom exponent in the study area is larger than 1.0, indicating that the main particles in the area are industrial and biomass burning pollution aerosols with radii less than 0.25–0.502μm. The modeling results show that the domain-averaged precipitation amount under polluted conditions can be increased up to 17% during the whole cloud lifetime. However, the maximum rainfall rate above 3002mm/h is enhanced, whereas that below 3002mm/h is suppressed in most cloud lifetime. The differences of cloud microphysics and dynamics between polluted and clean conditions indicate that both warm and ice microphysics and updraft are suppressed at the storm's initial and dissipating stages, whereas those at the storm's mature stage are obviously enhanced under polluted conditions.

Hudson J. G., S. Noble, 2014: CCN and vertical velocity influences on droplet concentrations and supersaturations in clean and polluted stratus clouds.J. Atmos. Sci.,71,312-331,https://doi.org/10.1175/JAS-D-13-086.1.10.1175/JAS-D-13-086.1

d375a0a7d39af00b29ace75920a86f96

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2014JAtS...71..312H

http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-13-086.1ABSTRACT Cloud microphysics and cloud condensation nuclei (CCN) measurements from two marine stratus cloud projects are presented and analyzed. Results show that the increase of cloud droplet concentrations N-c with CCN concentrations N-CCN rolls off for N-CCN at 1% supersaturation (S)N-1% above 400 cm(-3). Moreover, at such high concentrations N-c was not so well correlated with N-CCN but tended to be more closely related to vertical velocity W or variations of W (sigma(w)). This changeover from predominate N-c dependence on N-CCN to N-c dependence on W or sigma(w) is due to the higher slope k of CCN spectra at lower S, which is made more relevant by the lower cloud S that is forced by higher N-CCN. Higher k makes greater influence of W or sigma(w) variations than N-CCN variations on N-c. This changeover at high N-CCN thus seems to limit the indirect aerosol effect (IAE).On the other hand, in clean-air stratus cloud S often exceeded 1% and decreased to slightly less than 0.1% in polluted conditions. This means that smaller CCN [those with higher critical S (S-c)], which are generally more numerous than larger CCN (lower S-c), are capable of producing stratus cloud droplets, especially when they are advected into clean marine air masses where they can induce IAE. Positive correlations between turbulence sigma(w) and N-CCN are attributed to greater differential latent heat exchange of smaller more numerous cloud droplets that evaporate more readily. Such apparent CCN influences on cloud dynamics tend to support trends that oppose conventional IAE, that is, less rather than greater cloudiness in polluted environments.

Hudson, P. K., Coauthors, 2004: Biomass-burning particle measurements: Characteristic composition and chemical processing.J. Geophys. Res.,109,D23S27,https://doi.org/10.1029/2003JD004398.10.1029/2003JD004398

dfb6e848a9c9fad7e0bd3613adc4c0fb

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2003JD004398%2Fpdf

http://onlinelibrary.wiley.com/doi/10.1029/2003JD004398/pdf[1] The NOAA Lockheed Orion WP-3D aircraft intercepted a forest fire plume over Utah on 19 May 2002 during the Intercontinental Transport and Chemical Transformation (ITCT) mission. Large enhancements in acetonitrile (CH3CN), carbon monoxide (CO) and particle number were measured during the fire plume interception. In the 100 s plume crossing, the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument acquired 202 positive mass spectra from ionizing single particles in the 0.20900095 0204m size range. These particles contained carbon, potassium, organics, and ammonium ions. No pure soot particles were sampled directly from the plume. By characterizing these particle mass spectra, a qualitative biomass-burning particle signature was developed that was then used to identify biomass-burning particles throughout ITCT. The analysis was extended to identify biomass-burning particles in four other missions, without the benefit of gas-phase biomass-burning tracers. During ITCT, approximately 33% of the particles sampled in the North American troposphere and 37% of the particles transported from Asia, not influenced by North American sources, were identified as biomass-burning particles. During the WB-57 Aerosol Mission (WAM), Atmospheric Chemistry of Combustion Emissions near the Tropopause (ACCENT) and ACCENT 2000 missions, 7% of stratospheric particles were identified as biomass-burning particles. During the Cirrus Regional Study of Tropical Anvils and Cirrus Layers 090009 Florida Area Cirrus Experiment (CRYSTAL-FACE) this percentage increased to 52% because the regional stratosphere was strongly affected by an active fire season.

Jefferson A., 2011: Aerosol Observing System (AOS) handbook. Tech. Rep. DOE/SC-ARM/TR-014, U.S. Department of Energy, Washington, D. C.

Jensen, M. P., Coauthors, 2016: The midlatitude continental convective clouds experiment (MC3E).Bull. Amer. Meteor. Soc.,97,1667-1686,https://doi.org/10.1175/BAMS-D-14-00228.1.10.1175/BAMS-D-14-00228.1http://journals.ametsoc.org/doi/10.1175/BAMS-D-14-00228.1

Kalnay, E., Coauthors, 1996: The NCEP/NCAR 40-year reanalysis project. Bull. Amer. Meteor. Soc., 77, 437-471, https://doi.org/10.1175/1520-0477(1996)077<0437:TNYRP>2.0.CO; 2.10.1175/1520-0477(1996)077<0437:TNYRP>2.0.CO;2

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http://journals.ametsoc.org/doi/abs/10.1175/1520-0477%281996%29077%3C0437%3ATNYRP%3E2.0.CO%3B2

Koren I., Y. J. Kaufman, D. Rosenfeld, L. A. Remer, and Y. Rudich, 2005: Aerosol invigoration and restructuring of Atlantic convective clouds.Geophys. Res. Lett.,32,L14828,https://doi.org/10.1029/2005GL023187.10.1029/2005GL023187

c486203e42931b9f9c31457daacae4e4

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2005GL023187%2Ffull

http://onlinelibrary.wiley.com/doi/10.1029/2005GL023187/fullClouds and precipitation play crucial roles in the Earth's energy balance, global atmospheric circulation and the availability of fresh water. Aerosols may modify cloud properties and precipitation formation by modifying the concentration and size of cloud droplets, and consequently the strength of cloud convection, and height of glaciation levels thus affecting precipitation patterns. Here we evaluate the aerosol effect on clouds, using large statistics of daily satellite data over the North Atlantic Ocean. We found a strong correlation between the presence of aerosols and the structural properties of convective clouds. These correlations suggest systematic invigoration of convective clouds by pollution, desert dust and biomass burning aerosols. On average increase in the aerosol concentration from a baseline to the average values is associated with a 0.05 +/- 0.01 increase in the cloud fraction and a 40 +/- 5mb decrease in the cloud top pressure.

Kreidenweis S. M., L. A. Remer, R. Bruintjes, and O. Dubovik, 2001: Smoke aerosol from biomass burning in Mexico: Hygroscopic smoke optical model.J. Geophys. Res.,106,4831-4844,https://doi.org/10.1029/2000JD900488.10.1029/2000JD900488

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2000JD900488%2Ffull

http://doi.wiley.com/10.1029/2000JD900488The May 1998 transport of smoke from fires in Mexico and Central America into the United States is examined. We combine data from ground-based Interagency Monitoring of Protected Visual Environments aerosol chemical sampling sites with in situ airborne and Sun photometer measurements to develop a consistent picture of the transported smoke-impacted aerosol optical and chemical properties. The aerosol observed in Mexico and the southern United States is found to have a higher sulfate mass fraction, higher single-scattering albedo, and larger accumulation mode radius than biomass burning aerosols observed by similar instrumentation in South America and Africa. We postulate that the smoke-impacted aerosol in the 1998 event was more hygroscopic than that observed in the other locations, because of the higher mass fractions of sulfate, and show that a simple model of corresponding changes in aerosol water content yields agreement with the observed variations in refractive index and radii. We further show that the single-scattering albedo cannot be fully explained by hygroscopic growth alone. Modifications to the model invoking variations in aerosol light-absorbing carbon content, which are consistent with differences in observed composition among the various smoke-impacted aerosols, bring the predictions of single-scattering albedo into alignment with our observations. The model demonstrates that the particle size, single-scattering albedo, and real refractive index of smoke-impacted aerosols are not independent but vary in tandem with variations in particle hygroscopicity and with variations in black carbon content. This relationship is an important consideration in the assessment of the effects of biomass burning aerosols, particularly those subject to long-range transport, on radiative forcing and climate.

Leng, C., Coauthors, 2014: Variations of cloud condensation nuclei (CCN) and aerosol activity during fog-haze episode: A case study from Shanghai.Atmos. Chem. Phys.14,12 499-12 512,https://doi.org/10.5194/acp-14-12499-2014.10.5194/acpd-14-16997-2014

64c0e5670a54a55c573fb3371c46a12a

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2014ACPD...1416997L

http://www.atmos-chem-phys.net/14/12499/2014/Measurements of cloud condensation nuclei (CCN), condensation nuclei (CN)and aerosol chemical composition were performed simultaneously at an urbansite in Shanghai from 6 to 9 November 2010. The variations of CCN numberconcentration (N) and aerosol activity (activated aerosol fraction,N/N) were examined during a fog揾aze co-occurring event.Anthropogenic pollutants emitted from vehicles and unfavorablemeteorological conditions such as low planetary boundary layer (PBL) heightexerted a great influence on PMand black carbon (BC) loadings.Nat 0.2% supersaturation (SS) mostly fell in the range of 994 to6268 cm, and the corresponding N/Nvaried between 0.09and 0.57. Nand

Li Z. Q., F. Niu, J. W. Fan, Y. G. Liu, D. Rosenfeld, and Y. N. Ding, 2011: Long-term impacts of aerosols on the vertical development of clouds and precipitation.Nat. Geosci.,4,888-894,https://doi.org/10.1038/ngeo1313.10.1038/ngeo1313

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http%3A%2F%2Fwww.nature.com%2Fabstractpagefinder%2F10.1038%2Fngeo1313

http://www.nature.com/articles/ngeo1313Aerosols alter cloud density and the radiative balance of the atmosphere. This leads to changes in cloud microphysics and atmospheric stability, which can either suppress or foster the development of clouds and precipitation. The net effect is largely unknown, but depends on meteorological conditions and aerosol properties. Here, we examine the long-term impact of aerosols on the vertical development of clouds and rainfall frequencies, using a 10-year dataset of aerosol, cloud and meteorological variables collected in the Southern Great Plains in the United States. We show that cloud-top height and thickness increase with aerosol concentration measured near the ground in mixed-phase clouds攚hich contain both liquid water and icehat have a warm, low base. We attribute the effect, which is most significant in summer, to an aerosol-induced invigoration of upward winds. In contrast, we find no change in cloud-top height and precipitation with aerosol concentration in clouds with no ice or cool bases. We further show that precipitation frequency and rain rate are altered by aerosols. Rain increases with aerosol concentration in deep clouds that have a high liquid-water content, but declines in clouds that have a low liquid-water content. Simulations using a cloud-resolving model confirm these observations. Our findings provide unprecedented insights of the long-term net impacts of aerosols on clouds and precipitation.

Liljegren J. C., E. E. Clothiaux, G. G. Mace, S. Kato, and X. Q. Dong, 2001: A new retrieval for cloud liquid water path using a ground-based microwave radiometer and measurements of cloud temperature.J. Geophys. Res.,106,14 485-14 500,https://doi.org/10.1029/2000JD900817.10.1029/2000JD900817

e07426e9ad44e4c5b0a306cd36ada90a

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2000JD900817%2Ffull

http://doi.wiley.com/10.1029/2000JD900817A new method to retrieve cloud liquid water path using 23.8 and 31.4 GHz microwave radiometer brightness temperature measurements is developed. This method does not depend on climatological estimates of either the mean radiating temperature of the atmosphere Tmr or the mean cloud liquid water temperature Tcloud. Rather, Tmr is estimated from surface temperature and relative humidity measurements, while Tcloud is estimated using millimeter-wave cloud radar data, together with atmospheric temperature profiles obtained from either radiosonde or rapid update cycle (RUC) model output. Simulations demonstrate that the new retrieval method significantly reduces the biases in the liquid water path estimates that are apparent in a site-specific retrieval based on monthly stratified, local climatology. An analysis of the liquid water path estimates produced by the two retrievals over four case study days illustrates trends and retrieval performances consistent with the model simulations.

Liu J. J., Z. Q. Li, 2014: Estimation of cloud condensation nuclei concentration from aerosol optical quantities: Influential factors and uncertainties.Atmos. Chem. Phys.14,471-483,https://doi.org/10.5194/acp-14-471-2014.10.5194/acpd-13-23023-2013

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http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2014ACP....14..471L

http://adsabs.harvard.edu/abs/2014ACP....14..471LCloud condensation nuclei (CCN) is a key variable for understanding cloud formation, but it is hard to obtain on large scales on a routine basis, whereas aerosol optical quantities are more readily available. This study presents an in-depth investigation on the relationship between CCN and aerosol optical quantities in regions of distinct aerosol types using extensive measurements collected at multiple Atmospheric Radiation Measurement (ARM) Climate Research Facility (CRF) sites around the world. The influences of relative humidity (RH), aerosol hygroscopicity (if/isubRH/sub) and single scattering albedo (SSA) on the relationship are analyzed. Better relationships are found between aerosol optical depth (AOD) and CCN at the Southern Great Plains (US), Ganges Valley (India) and Black Forest sites (Germany) than those at the Graciosa Island and Niamey (Niger) sites, where sea salt and dust aerosols dominate, respectively. In general, the correlation between AOD and CCN decreases as the wavelength of AOD measurement increases, suggesting that AOD measured at a shorter wavelength is a better proxy of CCN. The correlation is significantly improved if aerosol index (AI) is used together with AOD. The highest correlation exists between CCN and aerosol scattering coefficients (sigma;subsp/sub) and scattering AI measured in-situ. The CCN-AOD (AI) relationship deteriorates with increasing RH. If RH exceeds 75%, the relationship becomes almost invalid for using AOD as a CCN proxy, whereas a tight sigma;subsp/sub-CCN relationship exists for dry particles. Aerosol hygroscopicity has a weak impact on the sigma;subsp/sub-CCN relationship. Particles with low SSA are generally associated with higher CCN concentrations, suggesting that SSA affects the relationship between CCN concentration and aerosol optical quantities. It may thus be used as a constraint to reduce uncertainties in the relationship. A significant increase in sigma;subsp/sub and decrease in CCN with increasing SSA is observed, leading to a significant decrease in their ratio (CCN/sigma;subsp/sub) with increasing SSA. The relationships and major influential factors are parameterization for improving CCN estimation with varying amount of information on RH, particle size and SSA.

Logan T., B. K. Xi, X. Q. Dong, R. Obrecht, Z. Q. Li, and M. Cribb, 2010: A study of Asian dust plumes using satellite,surface, and aircraft measurements during the INTEX-B field experiment.J. Geophys. Res.,115,D00K25,https://doi.org/10.1029/2010JD014134.

10.1029/2010JD014134

e319a5f4a596342e1ce4aa8a91662a39

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2010JD014134%2Fpdf

http://onlinelibrary.wiley.com/doi/10.1029/2010JD014134/pdf[1] Asian dust events occur frequently during the boreal spring season. Their optical properties have been analyzed by using a combination of source region (ground-based and satellite) and remote Pacific Ocean (aircraft) measurements during the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B) field campaign which lasted from 7 April to 15 May 2006. A strong dust event originating from the Gobi Desert and passing over the Xianghe surface site on 17 April 2006 has been extensively analyzed. The surface averaged aerosol optical depth (AOD) values increased from 0.17 (clear sky) to 4.0 (strong dust), and the Angstr0109m exponent () dropped from 1.26 (clear sky) to below 0.1. Its total downwelling SW flux over the Xianghe site (thousands of kilometers away from the dust source region) is only 46% of the clear-sky value with almost no direct transmission and nearly double the diffuse SW clear-sky value. This event was also captured 6 days later by satellite observations as well as the UND/NASA DC-8 aircraft over the eastern Pacific Ocean. The DC-8 measurements in the remote Pacific region further classified the plumes into dust dominant, pollution dominant, and a mixture of dust and pollution events. HYSPLIT backward trajectories not only verified the origins of each case we selected but also showed (1) two possible origins for the dust: the Gobi and Taklimakan deserts; and (2) pollution: urban areas in eastern China, Japan, and other industrialized cities east of the two deserts. Based on the averaged satellite retrieved AOD data (0.500° 0103 0.500° grid box), declining AOD values with respect to longitude demonstrated the evolution of the transpacific transport pathway of Asian dust and pollution over the period of the field campaign.

Logan T., B. K. Xi, and X. Q. Dong, 2014: Aerosol properties and their influences on marine boundary layer cloud condensation nuclei at the ARM mobile facility over the Azores.J. Geophys. Res.,119,4859-4872,https://doi.org/10.1002/2013JD021288.10.1002/2013JD021288

13c87376ee4ba298f56e0aa50de36b0e

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2F2013JD021288%2Fabstract

http://onlinelibrary.wiley.com/doi/10.1002/2013JD021288/abstractA multiplatform data set from the Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (MBL) Graciosa, Azores, 20090900092010 field campaign was used to investigate how continental aerosols can influence MBL cloud condensation nuclei (CCN) number concentration (NCCN). The seasonal variations of aerosol properties have shown that the winter and early spring months had the highest mean surface wind speed (> 5090009m090009s0908081) and greatest contribution of sea salt to aerosol optical depth (AOD), while continental fine mode aerosols were the main contributors to AOD during the warm season months (May090009September). Five aerosol events consisting of mineral dust, pollution, biomass smoke, and volcanic ash particles were selected as case studies using Atmospheric Radiation Measurement (ARM) mobile facility measurements. The aerosols in Case I were found to primarily consist of coarse mode, Saharan mineral dust. For Case II, the aerosols were also coarse mode but consisted of volcanic ash. Case III had fine mode biomass smoke and pollution aerosol influences while Cases IV and V consisted of mixtures of North American pollution and Saharan dust that was advected by an extratropical cyclone to the Azores. Cases I, IV, and V exhibited weak correlations between aerosol loading and NCCN due to mineral dust influences, while Cases II and III had a strong relationship with NCCN likely due to the sulfate content in the volcanic ash and pollution particles. The permanent Eastern North Atlantic ARM facility over the Azores will aid in a future long-term study of aerosol effects on NCCN.

Lyons W. A., T. E. Nelson, E. R. Williams, J. A. Cramer, and T. R. Turner, 1998: Enhanced positive cloud-to-ground lightning in thunderstorms ingesting smoke from fires.Science282,77-80,https://doi.org/10.1126/science.282.5386.77.10.1126/science.282.5386.77

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http://www.sciencemag.org/cgi/doi/10.1126/science.282.5386.77

McCarty W., D. Considine, T. Lee, C. Rand les, L. Coy, K. Wargan, M. Bosilovich, and R. Gelaro, 2015: Use of Satellite Observations in NASA Reanalyses: MERRA-2 and Future Plans. Tech. Rep. NASA CGMS-43 NASA-WP-06, v1, 1- 15.

Ng, N. L., Coauthors, 2011: An aerosol chemical speciation monitor (ACSM) for routine monitoring of the composition and mass concentrations of ambient aerosol.Aerosol Science and Technology45,780-794,https://doi.org/10.1080/02786826.2011.560211.10.1080/02786826.2011.560211

4bbce7caf465f9e348a147536206215e

http%3A%2F%2Fwww.tandfonline.com%2Fdoi%2Ffull%2F10.1080%2F02786826.2011.560211

http://www.tandfonline.com/doi/abs/10.1080/02786826.2011.560211We present a new instrument, the Aerosol Chemical Speciation Monitor (ACSM), which routinely characterizes and monitors the mass and chemical composition of non-refractory submicron particulate matter in real time. Under ambient conditions, mass concentrations of particulate organics, sulfate, nitrate, ammonium, and chloride are obtained with a detection limit <0.2 g/m3 for 30min of signal averaging. The ACSM is built upon the same technology as the widely used Aerodyne Aerosol Mass Spectrometer (AMS), in which an aerodynamic particle focusing lens is combined with high vacuum thermal particle vaporization, electron impact ionization, and mass spectrometry. Modifications in the ACSM design, however, allow it to be smaller, lower cost, and simpler to operate than the AMS. The ACSM is also capable of routine stable operation for long periods of time (months). Results from a field measurement campaign in Queens, NY where the ACSM operated unattended and continuously for 8 weeks, are presented. ACSM data is analyzed with the same well-developed techniques that are used for the AMS. Trends in the ACSM mass concentrations observed during the Queens, NY study compare well with those from co-located instruments. Positive Matrix Factorization (PMF) of the ACSM organic aerosol spectra extracts two components: hydrocarbon-like organic aerosol (HOA) and oxygenated organic aerosol (OOA). The mass spectra and time trends of both components correlate well with PMF results obtained from a co-located high resolution time-of-flight AMS instrument.

Penner J. E., X. Q. Dong, and Y. Chen, 2004: Observational evidence of a change in radiative forcing due to the indirect aerosol effect.Nature427,231-234,https://doi.org/10.1038/nature02234.

10.1038/nature02234

14724634

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fresolve%2Freference%2FPMED%3Fid%3D14724634

http://www.nature.com/doifinder/10.1038/nature02234Anthropogenic aerosols enhance cloud reflectivity by increasing the number concentration of cloud droplets, leading to a cooling effect on climate known as the indirect aerosol effect. Observational support for this effect is based mainly on evidence that aerosol number concentrations are connected with droplet concentrations, but it has been difficult to determine the impact of these indirect effects on radiative forcing. Here we provide observational evidence for a substantial alteration of radiative fluxes due to the indirect aerosol effect. We examine the effect of aerosols on cloud optical properties using measurements of aerosol and cloud properties at two North American sites that span polluted and clean conditions-a continental site in Oklahoma with high aerosol concentrations, and an Arctic site in Alaska with low aerosol concentrations. We determine the cloud optical depth required to fit the observed shortwave downward surface radiation. We then use a cloud parcel model to simulate the cloud optical depth from observed aerosol properties due to the indirect aerosol effect. From the good agreement between the simulated indirect aerosol effect and observed surface radiation, we conclude that the indirect aerosol effect has a significant influence on radiative fluxes.

Peppler, R. A., Coauthors, 2000: ARM southern Great Plains site observations of the smoke pall associated with the 1998 Central American fires. Bull. Amer. Meteor. Soc., 81, 2563-2591, https://doi.org/10.1175/1520-0477(2000)081<2563:ASGPSO>2.3.CO;2.10.1175/1520-0477(2000)0812.3.CO;2

51372c78aa4a22e347df0126196ed301

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2000bams...81.2563p

http://journals.ametsoc.org/doi/abs/10.1175/1520-0477%282000%29081%3C2563%3AASGPSO%3E2.3.CO%3B2Abstract Drought-stricken areas of Central America and Mexico were victimized in 1998 by forest and brush fires that burned out of control during much of the first half of the year. Wind currents at various times during the episode helped transport smoke from these fires over the Gulf of Mexico and into portions of the United States. Visibilities were greatly reduced during favorable flow periods from New Mexico to south Florida and northward to Wisconsin as a result of this smoke and haze. In response to the reduced visibilities and increased pollutants, public health advisories and information statements were issued by various agencies in Gulf Coast states and in Oklahoma. This event was also detected by a unique array of instrumentation deployed at the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program Southern Great Plains Cloud and Radiation Testbed and by sensors of the Oklahoma Department of Environmental Quality/Air Quality Division. Observations from these measurement dev...

Petters M. D., S. M. Kreidenweis, 2007: A single parameter representation of hygroscopic growth and cloud condensation nucleus activity.Atmos. Chem. Phys.7,1961-1971,https://doi.org/10.5194/acp-7-1961-2007.10.5194/acp-7-1961-2007

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fresolve%2Freference%2FXREF%3Fid%3D10.5194%2Facp-7-1961-2007

http://www.atmos-chem-phys.net/7/1961/2007/The ability of a particle to serve as a cloud condensation nucleus in the atmosphere is determined by its size, hygroscopicity and its solubility in water. Usually size and hygroscopicity alone are sufficient to predict CCN activity. Single parameter representations for hygroscopicity have been shown to successfully model complex, multicomponent particles types. Under the assumption of either complete solubility, or complete insolubility of a component, it is not necessary to explicitly include that component's solubility into the single parameter framework. This is not the case if sparingly soluble materials are present. In this work we explicitly account for solubility by modifying the single parameter equations. We demonstrate that sensitivity to the actual value of solubility emerges only in the regime of 2×10611–5×10614, where the solubility values are expressed as volume of solute per unit volume of water present in a saturated solution. Compounds that do not fall inside this sparingly soluble envelope can be adequately modeled assuming they are either infinitely soluble in water or completely insoluble.

Reid J. S., P. V. Hobbs, 1998: Physical and optical properties of young smoke from individual biomass fires in Brazil.J. Geophys. Res.,103,32 013-32 030,https://doi.org/10.1029/98JD00159.10.1029/98JD00159

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F98JD00159%2Fcitedby

http://doi.wiley.com/10.1029/98JD00159Physical and optical characteristics of particles in smoke from 19 fires were measured in Brazil during the 1995 burning season as part of the Smoke, Clouds, and Radiation-Brazil (SCAR-B) project. The University of Washington C-131A measured particle sizes and absorption and scattering properties in very young smoke (<4 min old). These properties are related to fuel type, fire intensity, combustion efficiency, and particle composition. The count median diameter (CMD) of particles from tropical forest fires were strongly and positively correlated with the combustion efficiency. The particle volume median diameter (VMD) of the particles from forest fires did not correlate well with combustion efficiency, but it was highly correlated with the emission factors of particles and unsaturated hydrocarbons. The median diameter and standard deviation of the particle size spectra for smoke from grass and cerrado fires did not correlate with either the combustion efficiency or any emission factor. The measured particle radiative properties correlated well with the measured particle sizes and compositions, and the relationships between these parameters are described fairly well by Mie theory. The optical properties of smoke from individual biomass fires in Brazil differ significantly from those of smoke from biomass burning in North America. In particular, the total light-scattering coefficient for smoke particles in Brazil is, on average, 15% less than for smoke particles in North America. Also, the average values of the single-scattering albedos of smoke particles in Brazil are 0.05 to 0.1 less than those in North America.

Rolph G. D., 2012: Real-time Environmental Applications and Display sYstem (READY) Website (http://ready.arl.noaa. gov). NOAA Air Resources Laboratory, Silver Spring, MD.

Rosenfeld D., 1999: TRMM observed first direct evidence of smoke from forest fires inhibiting rainfall.Geophys. Res. Lett.,26,3105-3108,https://doi.org/10.1029/1999GL006066.

10.1029/1999GL006066

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F1999GL006066%2Ffull

http://doi.wiley.com/10.1029/1999GL006066Although it has been known that smoke from biomass burning suppresses warm rain processes, it was not known to what extent this occurs. The satellite observations of the Tropical-Rainfall-Measuring-Mission (TRMM), presented here, show that warm rain processes in convective tropical clouds infected by heavy smoke from forest fires are practically shut off. The tops of the smoke-infected clouds must exceed the freezing level, i.e., grow to altitudes colder than about -10℃C, for the clouds to start precipitating. In contrast, adjacent tropical clouds in the cleaner air precipitate most of their water before ever freezing. There are indications that rain suppression due to air pollution prevails also in the extra-tropics.

Rosenfeld D., U. Lohmann, G. B. Raga, C. D. O'Dowd, M. Kulmala, S. Fuzzi, A. Reissell, and M. O. Andreae, 2008: Flood or drought: How do aerosols affect precipitation? Science,321, 1309-1313, https://doi.org/10.1126/science.1160606.10.1126/science.1160606

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http://www.sciencemag.org/cgi/doi/10.1126/science.1160606Aerosols serve as cloud condensation nuclei (CCN) and thus have a substantial effect on cloud properties and the initiation of precipitation. Large concentrations of human-made aerosols have been reported to both decrease and increase rainfall as a result of their radiative and CCN activities. At one extreme, pristine tropical clouds with low CCN concentrations rain out too quickly to mature into long-lived clouds. On the other hand, heavily polluted clouds evaporate much of their water before precipitation can occur, if they can form at all given the reduced surface heating resulting from the aerosol haze layer. We propose a conceptual model that explains this apparent dichotomy.

Saide, P. E., Coauthors, 2015: Central American biomass burning smoke can increase tornado severity in the U.S. Geophys. Res. Lett.,42,956-965,https://doi.org/10.1002/2014GL062826.10.1002/2014GL062826

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2F2014GL062826%2Fpdf

http://doi.wiley.com/10.1002/2014GL062826Abstract Tornadoes in the Southeast and central U.S. are episodically accompanied by smoke from biomass burning in central America. Analysis of the 27 April 2011 historical tornado outbreak shows that adding smoke to an environment already conducive to severe thunderstorm development can increase the likelihood of significant tornado occurrence. Numerical experiments indicate that the presence of smoke during this event leads to optical thickening of shallow clouds while soot within the smoke enhances the capping inversion through radiation absorption. The smoke effects are consistent with measurements of clouds and radiation before and during the outbreak. These effects result in lower cloud bases and stronger low-level wind shear in the warm sector of the extratropical cyclone generating the outbreak, two indicators of higher probability of tornadogenesis and tornado intensity and longevity. These mechanisms may contribute to tornado modulation by aerosols, highlighting the need to consider aerosol feedbacks in numerical severe weather forecasting.

Stein A. F., R. R. Draxler, G. D. Rolph, B. J. B. Stunder, M. D. Cohen, and F. Ngan, 2015: NOAA's HYSPLIT atmospheric transport and dispersion modeling system.Bull. Amer. Meteor. Soc.,96,2059-2077,https://doi.org/10.1175/BAMS-D-14-00110.1.10.1175/BAMS-D-14-00110.1

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http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2015BAMS...96.2059S

http://journals.ametsoc.org/doi/10.1175/BAMS-D-14-00110.1A. F. Stein, R. R. Draxler, G. D. Rolph, B. J. B. Stunder, M. D. Cohen, and F. Ngan, 2015: NOAA’s HYSPLIT Atmospheric Transport and Dispersion Modeling System. Bull. Amer. Meteor. Soc., 96, 2059–2077. doi: http://dx.doi.org/10.1175/BAMS-D-14-00110.1

Tao W.-K., J.-P. Chen, Z. Q. Li, C. E. Wang, and C. D. Zhang, 2012: Impact of aerosols on convective clouds and precipitation.Rev. Geophys.,50,RG2001,https://doi.org/10.1029/2011RG000369.10.1029/2011RG000369

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http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2011RG000369%2Fpdf

http://onlinelibrary.wiley.com/doi/10.1029/2011RG000369/pdf[1] Aerosols are a critical factor in the atmospheric hydrological cycle and radiation budget. As a major agent for clouds to form and a significant attenuator of solar radiation, aerosols affect climate in several ways. Current research suggests that aerosol effects on clouds could further extend to precipitation, both through the formation of cloud particles and by exerting persistent radiative forcing on the climate system that disturbs dynamics. However, the various mechanisms behind these effects, in particular, the ones connected to precipitation, are not yet well understood. The atmospheric and climate communities have long been working to gain a better grasp of these critical effects and hence to reduce the significant uncertainties in climate prediction resulting from such a lack of adequate knowledge. Here we review past efforts and summarize our current understanding of the effect of aerosols on convective precipitation processes from theoretical analysis of microphysics, observational evidence, and a range of numerical model simulations. In addition, the discrepancies between results simulated by models, as well as those between simulations and observations, are presented. Specifically, this paper addresses the following topics: (1) fundamental theories of aerosol effects on microphysics and precipitation processes, (2) observational evidence of the effect of aerosols on precipitation processes, (3) signatures of the aerosol impact on precipitation from large-scale analyses, (4) results from cloud-resolving model simulations, and (5) results from large-scale numerical model simulations. Finally, several future research directions for gaining a better understanding of aerosol-cloud-precipitation interactions are suggested.

Tao, W.-K., Coauthors, 2013: Precipitation intensity and variation during MC3E: A numerical modeling study.J. Geophys. Res.,118,7199-7218,https://doi.org/10.1002/jgrd.50410.10.1002/jgrd.50410

f14efbaa699313356e4f9ba644811bc2

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjgrd.50410%2Fabstract

http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50410/abstract[1] Previous observational studies have identified three different types of diurnal precipitation variation over the conterminous U.S.: localized afternoon rainfall maxima over the Mississippi and Ohio valleys, propagating mesoscale convective systems (MCSs) from the Rocky Mountain region, and propagating MCSs over the Appalachian Mountains. This study focuses on the second type, which involves nocturnal rainfall maxima from eastward-propagating MCSs on the lee side of the Rocky Mountains. This study evaluates model simulations with regard to rainfall using observations and assesses the impact of microphysics, surface fluxes, radiation, and terrain on the simulated diurnal rainfall variation. A regional high-resolution model was used to conduct a series of real-time forecasts during the Midlatitude Continental Convective Clouds Experiment (MC3E) in 2011 over the Southern Great Plains. The model ably captured most heavy precipitation events. When all forecast days are composited, the mean forecast depicts accurate, propagating precipitation features and thus the overall diurnal variation. However, individual forecasts tend to overestimate the rainfall for light precipitation events, have location errors, and misrepresent convection in some cases. A post mission case study is performed on one multi-cell, eastward-propagating MCS event; the results suggest that cold-pool dynamics were an important physical process. Model results also indicate that terrain effects are important during the initial stages of MCS development. By increasing the terrain height by 10%, the simulated rainfall is increased and in better agreement with observations. On the other hand, surface fluxes, and radiation processes only have a secondary effect for short-term simulations.

Uin J., 2016: Cloud condensation nuclei particle counter instrument handbook. DOE/SC-ARM-TR-168, 1- 9.

Wang J., S. C. van den Heever, and J. S. Reid, 2009: A conceptual model for the link between Central American biomass burning aerosols and severe weather over the south central United States.Environ. Res. Lett.,4,015003,https://doi.org/10.1088/1748-9326/4/1/015003.10.1088/1748-9326/4/1/015003

f496b325a9f7e1a1af79136ed72630d6

http%3A%2F%2Fwww.cabdirect.org%2Fabstracts%2F20093057783.html

http://stacks.iop.org/1748-9326/4/i=1/a=015003?key=crossref.b5ad1980d0022b3588e3acfd65bfdc6aEach spring, smoke particles from fires over the Yucatan Peninsula and south Mexico cross over the Gulf of Mexico into the United States (US) under the control of moist oceanic air flow from the southwestern branch of the subtropical (Bermuda) high. Smoke can be transported deep into the south central US, where dry lines and warm conveyor belts are frequently formed and cause deep convection and severe weather. Lyons et al (1998 Science 282 77-80) and Murray et al (2000 Geophys. Res. Lett. 27 2249-52) noticed a ~50% increase of lightning along the smoke transport path over the south central US during the May 1998 Central American smoke episode. Here we present a conceptual model of coherent microphysical and meteorological mechanisms through which smoke may impact convective clouds and subsequently result in more severe weather over the south central US. The conceptual model depicts a chain of processes in which smoke particles are first activated as cloud condensation nuclei when they are entrained into the warm conveyor belt, a convective zone formed over the south central US as a result of the encounter between the mid-latitude trough and the subtropical Bermuda high. As the convection continues with deepening of the mid-latitude trough, the greater concentration of water cloud condensation nuclei delays the warm rain processes, enhances the development of ice clouds, and invigorates the updrafts, all of which contribute to the formation of severe weather such as hail and lightning. The conceptual model is based on the reasoning of physical mechanisms revealed in previous studies (over the tropical biomass region), and is supported here through the analysis of satellite data, ground observations, aerosol transport model results, and idealized cloud resolving simulations of a day in May 2003 when record tornado events occurred over the south central US. Further assessment of this conceptual model is discussed for future investigations. 2009 IOP Publishing Ltd. Printed in the UK.

Wang J. Y., X. Q. Dong, B. K. Xi, and A. J. Heymsfield, 2016: Investigation of liquid cloud microphysical properties of deep convective systems: 1.Parameterization raindrop size distribution and its application for stratiform rain estimation. J. Geophys. Res.,121,10 739-10 760,https://doi.org/10.1002/2016JD024941.

Wood, R., Coauthors, 2015: Clouds,aerosols, and precipitation in the marine boundary layer: An arm mobile facility deployment. Bull. Amer. Meteor. Soc., 96, 419-440, https://doi.org/10.1175/BAMS-D-13-00180.1.10.1175/BAMS-D-13-00180.1

4afd719ac165bf338292446eb9b50349

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2015BAMS...96..419W

http://journals.ametsoc.org/doi/10.1175/BAMS-D-13-00180.1ABSTRACT A 21-month deployment to Graciosa Island in the northeastern Atlantic Ocean is providing an unprecedented record of the clouds, aerosols, and meteorology in a poorly sampled remote marine environment. (CAP-MBL). CAP-MBL was designed to gather an extended record of high-quality data on clouds and aerosol properties in a remote marine environment needed to improve the treatment of clouds and aerosols in climate models. A feature of the CAP-MBL deployment is the ability to simultaneously observe clouds, aerosols, and precipitation and to understand how these variables interact with each other. Interactions are two way, with aerosols potentially impacting precipitation most likely via the suppression of warm rain but in turn aerosols are strongly scavenged by precipitation, even in the relatively weak drizzle from low clouds. The CAP-MBL deployment's continuous record allows for greater statistical reliability in the observed relationships between aerosols, clouds, and precipitation than is possible with aircraft but retains the advantages of in situ sampling of aerosol properties that are difficult to constrain with satellite data. Given the great variety of aerosol, cloud, and precipitation conditions, the data from CAP-MBL and from the permanent site will continue to challenge understanding and provide an unprecedented dataset for the evaluation and improvement of numerical models from cloud-resolving ones to global weather and climate models.