Chen L. X., W. Q. Zhu, and X. J. Zhou, 2000: Characteristics of environmental and climate change in Changjiang Delta and its possible mechanism. Acta Meteorologica Sinica, 14( 2), 129- 140. (in Chinese) of climate change in the Changjiang Delta were analyzed based on the annualmean meteorological data since 1961,including air temperature,maximum and minimum airtemperature,precipitation,sunshine duration and visibility at 48 stations in that area(southernJiangsu and northern Zhejiang),and its adjacent areas(northern Jiangsu,eastern Anhui andsouthern Zhejiang),together with the environmental data.The results indicate that it is gettingwarmer in the Changjiang Delta and cooler in adjacent areas,thus the Changjiang Delta becomes a bigheat island,containing many little heat islands consisting of central cities,in which Shanghai City isthe strongest heat island.The intensity of heat islands enhances as economic development goes up.From the year 1978.the beginning year of reform and opening policy,to the year 1997,the intensityof big heat island of Changjiang Delta has increased 0.5℃ and Shanghai heat island increased 0.8℃.However.since 1978 the constituents of SO 2 ,NO x and TSP(total suspended particles)in theatmosphere,no matter whether in the Changjiang Delta or in the adjacent areas,have all increased,but pH values of precipitation decreased.In the meantime,both sunshine duration and visibility arealso decreased,indicating that there exists a mechanism for climate cooling in these areas.Ouranalyses show that the mechanism for climate warming in the Changjiang Delta may be associatedwith heating increase caused by,economic development and increasing energy consumption.It isestimated that up to 1997 the intensity of warming caused by this mechanism in the Changjiang Deltahas reached 0.8—0.9℃,about 4—4.5 times as large as the mean values before 1978.Since then,the increase rate has become 0. 035℃/a for the Changjiang Delta.It has reached 1.3℃ for Shanghaiin 1997,about 12—13 times as large as the mean values before 1978.This is a rough estimation ofincreasing energy consumption rate caused by economic development.
Hu X. M., P. M. Klein, and M. Xue, 2013: Impact of low-level jets on the nocturnal urban heat island intensity in Oklahoma Journal of Applied Meteorology and Climatology, 52( 8), 1779- 1802.
Jauregui E., E. Romales, 1996: Urban effects on convective precipitation in Mexico City. Atmos. Environ., 30( 20), 3383- 3389.10.1016/1352-2310(96) paper reports on urban-related convective precipitation anomalies in a tropical city. Wet season (May–October) rainfall for an urban site (Tacubaya) shows a significant trend for the period 1941–1985 suggesting an urban effect that has been increasing as the city grew. On the other hand, rainfall at a suburban (upwind) station apparently unaffected by urbanization, has remained unchanged. Analysis of historical records of hourly precipitation for an urban station shows that the frequency of intense (> 20 mm h 611 ) rain showers has increased in recent decades. Using a network of automatic rainfall stations, areal distribution of 24 h isoyets show a series of maxima within the urban perimeter which may be associated to the heat island phenomenon. Isochrones of the beginning of rain are used to estimate direction and speed of movement of the rain cloud cells. The daytime heat island seems to be associated with the intensification of rain showers.
Li S. Y., H. B. Chen, and W. Li, 2008: The impact of urbanization on city climate of Beijing region. Plateau Meteorology, 27( 5), 1102- 1110. (in Chinese)10.3724/ impact of urban growth on city climate variation is studied using the daily mean data of temperature/velocity and precipitation at 20 meteorological stations from 1970 to 2005.The results show that:(1)In the past 36 years the urban heat island(UHI) area is increasing,the UHI intensity is enhancing,and the UHI centers are evolving from single to several centers.In 2000′s,the maximal UHI intensity is 2.11℃.In the past 36 years the mean temperature in winter increases 0.298℃/10a.(2)The urbanization has made the precipitation show a tendency of uneven distribution.In 1970′s,the precipitation in the west of the city is much,while in the southeast of the city is little;in 1980′s,all the urban zone′s precipitation is little;in 1990′s,the precipitation in both west and south of the city is much,while in the northeast of the city is little;in 2000′s,the little precipitation zone extends from urban district to the southeast.(3)The urban wind speed has a decreasing tendency.The wind speed in 1970′s is 2.49 m·s-1,in 1980′s,is 2.32 m·s-1,in 1990′s,is 2.16 m·s-1,and in 2000′s,is 2.28 m·s-1.In the past 36 years the wind speed decreases 0.05 m·s-1·(10a)-1.(4)The temperature and the population density logarithm have a linear correlation,the correlative coefficient is 0.65;the temperature and the city land area have a linear correlation,the correlative coefficient is 0.6387.
Liao J. B., X. M. Wang, Y. X. Li, and B. C. Xia, 2011: An analysis study of the impacts of urbanization on precipitation in Guangzhou. Scientia Meteorologica Sinica, 31( 4), 384- 390. (in Chinese)10.1007/ the observation data from 1959 to 2009,the precipitation variation in Guangzhou was studied.We found that the trends of annual total precipitation in suburban Zengcheng station is not obvious,but number of the heavy rain days has increased;the total annual precipitation in Guangzhou fluctuated and there is a slight upward trend with the increasing rate of 10.5 mm/a since 1991.The total precipitation days tend to decrease with the decreasing rate of 7.2 d/10a since 1982,what's more,the heavy rain days and rainfall precipitation levels were significantly rising,the increasing rate of heavy precipitation days is 2.8 d/10a while the growth rate of precipitation load is 2.4%/10a.Urbanization in Guangzhou have caused heavy rain to occur more frequently in Guangzhou.Compared to pre-urbanization,the precipitation in Guangzhou indicated a significant increase since 1991.The contribution rate to the precipitation increase due to urbanization in Guangzhou is 44.7%.
Lowry W. P., 1998: Urban effects on precipitation amount. Progress in Physical Geography, 22( 4), 477- 520.10.1177/ reviews of urban effects on local climate, extending from Kratzer in 1937 through to Landsberg in 1981, have dealt primarily with radiation, temperature, wind, and air quality. To a much lesser extent they have examined moisture-related elements including humidity, cloud, precipitation, and storminess. Selecting air temperature to represent the former group and precipitation amount to represent the latter, the author asserts that, because of the intrinsic physical differences between them, there are necessarily important differences in the methods to be used for their proper observation, analysis, presentation, and interpretation pertaining to urban effects. The principal differences are based in the fact that temperature is continuous in both time and space, whereas precipitation is continuous in neither. The author maintains that because of these differences, urban climatologists have had much greater success in specifying and explaining urban effects on temperature than on precipitation amount. Further, he makes the case that, lack of recognition that methods used for the study of urban effects on temperature are too often inappropriate for study of urban effects on precipitation amount, has led to a state of affairs where there remains basic uncertainty about the specification of urban effects on precipitation amount, and even greater uncertainty about their explanation. In making that case, the author includes 1) an historical perspective, 2) a critical evaluation of methods, 3) an overview of the status of urban precipitation climatology, and 4) recommendations concerning future research.
Miao S. G., F. Chen, Q. C. Li, and S. Y. Fan, 2011: Impacts of urban processes and urbanization on summer precipitation: A case study of heavy rainfall in Beijing on 1 August 2006. Journal of Applied Meteorology and Climatology, 50( 4), 806- 825.10.1007/ and climate changes caused by human activities (e.g., greenhouse gas emissions, deforestation, and urbanization) have received much attention because of their impacts on human lives as well as scientific interests. The detection, understanding, and future projection of weather and climate changes due to urbanization are important subjects in the discipline of urban meteorology and climatology. This article reviews urban impacts on precipitation. Observational studies of changes in convective phenomena over and around cities are reviewed, with focus on precipitation enhancement downwind of cities. The proposed causative factors (urban heat island, large surface roughness, and higher aerosol concentration) and mechanisms of urban-induced and/or urban-modified precipitation are then reviewed and discussed, with focus on downwind precipitation enhancement. A universal mechanism of urban-induced precipitation is made through a thorough literature review and is as follows. The urban heat island produces updrafts on the leeward or downwind side of cities, and the urban heat island-induced updrafts initiate moist convection under favorable thermodynamic conditions, thus leading to surface precipitation. Surface precipitation is likely to further increase under higher aerosol concentrations if the air humidity is high and deep and strong convection occurs. It is not likely that larger urban surface roughness plays a major role in urbaninduced precipitation. Larger urban surface roughness can, however, disrupt or bifurcate precipitating convective systems formed outside cities while passing over the cities. Such urban-modified precipitating systems can either increase or decrease precipitation over and/or downwind of cities. Much effort is needed for in-depth or new understanding of urban precipitation anomalies, which includes local and regional modeling studies using advanced numerical models and analysis studies of long-term radar data.
Rosenfeld D., 2000: Suppression of rain and snow by urban and industrial air pollution. Science, 287( 5459), 1793- 1796.10.1016/ method for the analysis of quantitative microbial data shows a good performance in the estimation of true prevalence and the parameters of the distribution of concentrations, which indicates that it is a useful data analysis tool in the field of QMRA.
Shepherd J. M., H. Pierce, and A. J. Negri, 2002: Rainfall modification by major urban areas: Observations from spaceborne rain radar on the TRMM satellite. J. Appl. Meteor., 41( 7), 689- 701.10.1175/1520-0450(2002)041<0689:RMBMUA>2.0.CO; from the Tropical Rainfall Measuring Mission (TRMM) satellite's precipitation radar (PR) were employed to identify warm-season rainfall (1998-2000) patterns around Atlanta, Georgia; Montgomery, Alabama; Nashville, Tennessee; and San Antonio, Waco, and Dallas, Texas. Results reveal an average increase of about 28% in monthly rainfall rates within 30-60 km downwind of the metropolis, with a modest increase of 5.6% over the metropolis. Portions of the downwind area exhibit increases as high as 51%. The percentage changes are relative to an upwind control area. It was also found that maximum rainfall rates in the downwind impact area exceeded the mean value in the upwind control area by 48%-116%. The maximum value was generally found at an average distance of 39 km from the edge of the urban center or 64 km from the center of the city. Results are consistent with the Metropolitan Meteorological Experiment (METROMEX) studies of St. Louis, Missouri, almost two decades ago and with more recent studies near Atlanta. The study establishes the possibility of utilizing satellite-based rainfall estimates for examining rainfall modification by urban areas on global scales and over longer time periods. Such research has implications for weather forecasting, urban planning, water resource management, and understanding human impact on the environment and climate.
Skamarock W.C., Coruthors, 2008: A description of the advanced research WRF version 3. NCAR Tech. Note NCAR/ TN-475+STR,88 pp.10.5065/ development of the Weather Research and Forecasting (WRF) modeling system is a multiagency effort intended to provide a next-generation mesoscale forecast model and data assimilation system that will advance both the understanding and prediction of mesoscale weather and accelerate the transfer of research advances into operations. The model is being developed as a collaborative effort ort among the NCAR Mesoscale and Microscale Meteorology (MMM) Division, the National Oceanic and Atmospheric Administration's (NOAA) National Centers for Environmental Prediction (NCEP) and Forecast System Laboratory (FSL), the Department of Defense's Air Force Weather Agency (AFWA) and Naval Research Laboratory (NRL), the Center for Analysis and Prediction of Storms (CAPS) at the University of Oklahoma, and the Federal Aviation Administration (FAA), along with the participation of a number of university scientists. The WRF model is designed to be a flexible, state-of-the-art, portable code that is an efficient in a massively parallel computing environment. A modular single-source code is maintained that can be configured for both research and operations. It offers numerous physics options, thus tapping into the experience of the broad modeling community. Advanced data assimilation systems are being developed and tested in tandem with the model. WRF is maintained and supported as a community model to facilitate wide use, particularly for research and teaching, in the university community. It is suitable for use in a broad spectrum of applications across scales ranging from meters to thousands of kilometers. Such applications include research and operational numerical weather prediction (NWP), data assimilation and parameterized-physics research, downscaling climate simulations, driving air quality models, atmosphere-ocean coupling, and idealized simulations (e.g boundary-layer eddies, convection, baroclinic waves).*WEATHER FORECASTING
Song J., J. P. Tang, and J. N. Sun, 2009: Simulation study of the effects of urban canopy on the local meteorological field in the Nanjing area. Journal of Nanjing University (Natural Sciences), 45( 6), 779- 789. (in Chinese)10.1360/ experiments were made to investigate the effects of urban canopy on local meteorological field in Nanjing area,from July 17th to July 18th,2005,by using the Weather Research and Forecasting Model(WRF).Three types of surface conditions were employed in the simulations: the wrf-no urban case,in which the natural surface was chosen;the wrf-ucm case,in which the urban surface was chosen but the Urban Canopy Model(UCM) was not used;the wrf+ucm case,in which the urban surface was chosen,and the UCM was employed.The results of numerical experiments were compared with the data of the field observations.This study shows that the temperature at 2 m in the wrf+ucm case is slightly lower than that in the wrf-ucm case,and both are higher than that in the wrf-no urban case.Meanwhile,the sensible heat flux of the urban surface with canopy is similar to that of urban surface without canopy in the daytime,while the former is slightly higher than the latter during the night.The values in the two cases are obviously higher than in the case with natural surface in the area.However,the latent heat flux in the wrf+ucm case is lower than that in the wrf-ucm case,and both are much lower than that in the wrf-no urban case.That is to say,urban ground makes the urban fields drier than the natural ones.On the other hand,the effects of urban canopy influence the air flow in the area,which makes the horizontal wind be reduced over the city,and consequently the vertical motion is enhanced.It seems that this influence is more obvious during the night than in the daytime.
Song Y. Q., H. N. Liu, X. Y. Wang, N. Zhang, and J. N. Sun, 2014a: The influence of urban heterogeneity on the surface energy balance and characters of temperature and wind. Journal of Nanjing University (Natural Sciences), 50( 6), 810- 819. (in Chinese)
Song Y. Q., H. N. Liu, Y. Zhu, and X. Y. Wang, 2014b: Numerical simulation of urban heterogeneity's influence on urban meteorological characteristic. Plateau Meteorology, 33( 6), 1579- 1588. (in Chinese)10.7522/j.issn.1000-0534.2013.00080b831a731-2894-4551-8b54-079b61be6255mag4842620143361579The Nanjing city was divided into three types according the building density: Commercial, Hi-dens Res(High intensity residential), Low-dens Res(Low intensity residential). The influence of urban heterogeneity on urban meteorological characteristic in Nanjing was researched by WRF model. The results show that: After considering the effect of the urban heterogeneity, the spatial distribution of temperature, the urban heat island, the relative humidity and the winds exhibit are more complex in the urban region. In the simulations of urban canopy, urban heterogeneity has obvious effects on the heat island and other meteorological characters.The simulated mean heat island intensity, dry island intensity and decrease of wind of city will decrease 0.02℃, 0.2% and 0.11 m&#183;s<sup>-1</sup>. But the maximum heat island intensity and dry island intensity of city will increase 0.28℃ and 1.51%. In the city of considering heterogeneity, the spaial distribution variances of urban heat island, dry island and decrease of wind will increase 0.06, 2.08 and 0.28.
Sun J. S., B. Yang, 2008: Meso- scale torrential rain affected by topography and the urban circulation. Chinese Journal of Atmospheric Sciences, 32( 6), 1352- 1364. (in Chinese)10.3878/j.issn.1006-9895.2008.06.105208fcfa-da3b-481c-8734-ddc4e916ae8c4825320083269Some theoretical features of meso-β scale torrential rain, which are caused by joint action of topography and the urban heat island, are gained by mesoscale dynamic meteorology theory and scale analysis. Using observation datasets with high spatial-temporal resolution based on auto-weather station network and wind profile data from two profilers which are located at different positions, most of the theoretical features are confirmed by three cases which occurred in Beijing in the summer of 2006. The results indicate that (1) the temperature gradient in front of mountains, mainly caused by the urban heat island, is able to engender a relatively isolated vertical wind shear near the windward slope, and the shear is much more important to grow, develop and maintain the mesoscale convective system. The closer the mountain is to urban areas, the stronger the temperature gradient in front of mountains is, and the local stronger vertical wind shear is easy to be at the position. On the other hand, the response time of strong vertical wind shear depends on the intensity of temperature gradient. (2) Once stronger convective precipitation begins on the windward slope, the positive feedback between rainfall intensity and horizontal wind velocity toward the windward slope will appear, and the process is an essential condition to form meso-β scale torrential rain. (3) The stronger the terrain grade is, the stronger ascending motion will be forced and the smaller horizontal-scale mesoscale weather system will be stirred; in front of smoother topography, however, the mesoscale system at a relatively larger horizontal scale is easy to be formed. (4) generally, most of the mesoscale torrential rain processes, which are caused by joint influence of topography and thermodynamic urban circulation, should occur in front of mountains in the evening or the early morning.
Sun J. S., H. Wang, L. Wang, F. Liang, Y. X. Kang, and X. Y. Jiang, 2006: The role of urban boundary layer in local convective torrential rain happening in Beijing on 10 July 2004. Chinese J. Atmos. Sci., 30( 2), 221- 234. (in Chinese) isolated mesoscale convective torrential rain which happened in Beijing urban on 10 July 2004("7.10") made a great traffic trouble because of serious inundation cross the urban areas and caught various social attention.The triggering mechanism of the convective torrential rain and the reason that the downpour occurred only in urban center are studied by analyzing a large number of observation data sets,such as observational data with high spatial-temporal resolution based on auto-weather station network,Doppler radar observational products,available vertical distribution of wind detected by a boundary wind profiler,TBB data from GOES and conventional weather observational data sets.Based on a simple mesoscale theoretical analysis and detail observational investigation,the spatial structure of the weather system is proposed.The research results indicate that(1) the local vapor condition and the large-scale vapor transportation are favorable during the torrential rain.However,the large-scale descending area has been keeping inhibition during the weather event,and this is a great difference between the isolated meso-scale convective storm system(MCSS) and other mesoscale torrential rain events which happen in regional precipitation;(2) The convective activities in Beijing area are closely related to gravity wave.At the initial stage of "7.10" local torrential rainfall,the local convective instable energy is possible to be triggered by gravity wave which is motivated by the stronger convective activities in Laishui and Yixian counties of Hebei Province to the southwest of Beijing and a series of relatively isolated meso- scale convection cells (MCCs),which appear to be linear,develop in Beijing.Finally,a meso- scale convective storm system is organized by urban mesoscale convergence line.The MCSS not only causes the heaviest rain intensity in the urban center,but also excites gravity wave and brings forth the similar meso- scale convection cells again.When the meso- scale convection cells are reorganized,a meso- scale convective storm system reappears in the urban areas.However,the second heaviest rain intensity is debilitated obviously compared with the former MCSS because the local instable energy have been released partly during the first precipitation period;(3) prior to the torrential rain,a mesoscale convergence line can be observed not only in urban surface but also in total boundary layer above,which plays a key role in organizing the isolated meso- scale convection cells(MCCs).The research confirms that the thermodynamic forcing caused by the temperature difference between urban areas and suburbs,is a fundamental factor in the development of the convergence line.On the other hand,because of the thermodynamic difference between urban areas and suburbs,the vertical wind shear is strengthened in the urban center,and the horizontal flow in lower layer is accelerated in suburbs,in other words,the thermodynamic forcing is advantageous to keeping the stronger convergence motion toward central convection area and providing enough compensated moisture current around a relative large field.
Wu X., X. Y. Wang, X. N. Zeng, and L. Xu, 2000: The effect of urbanization on short duration precipitation in Beijing. Journal of Nanjing Institute of Meteorology, 23( 1), 68- 72. (in Chinese)10.1142/ precipitation from AWS in urban and suburb of Beijing is analysed to study the effects of urbanization on short duration precipitation.Results show that hour precipitation can be fitted to logarithm Weibull distribution and that the enhancement of rainfall due to urbanization is remarkable in downwind under moderate/heavy short duration precipitation process,and that the increase of probability and intensity of torrential rain is significant in urban center.
Zhang C. L., S. G. Miao, Q. C. Li, and F. Chen, 2007: Impacts of fine-resolution land use information for Beijing on a summer, severe rainfall simulation. Chinese Journal of Geophysics, 50( 5), 1373- 1382. (in Chinese)10.1002/ the land use data around Beijing in 2000 with the resolution of 500 m,we updated the U.S.Geological Survey global land use classification data for numerical weather model,in which there are 25 types with 30 s lat-lon equidistant grids(1 km resolution).And then by 24-hour numerical experiments with the MM5V3.6 coupled with Noah LSM system,two domain two-way nested with the resolution of 10-3.3 km,we investigated the impact of fine-resolution land use information incorporation on a summer severe rainfall in Beijing.Analyses show that,the new land use data can not only represent better the real characteristic of underlying surface around Beijing area,especially the rapid expanding of urban/built-up areas since 1990s',but also help to correct the unreasonable classification Savanna in the original USGS data for the middle-latitudes of Asia data as the deciduous broadleaf.Furthermore,numerical experiments prove that incorporation of the fine-resolution land use information has a significant impact on the short-range severe rainfall weather event.For the intensity and location of major rainfall centers,their difference ranges of 12 h rainfall amount are beyond 30 km,and the relative difference of the maximum rainfall amount reaches up to 30%.One important interaction mechanism between urban underlying surface and atmosphere is also revealed,that is,the urban expansion reduces natural vegetation cover,and then it can help to decrease ground evaporation and local water vapor supply,enlarge surface sensible heat flux,deepen PBL height and enhance the mixing of water vapor.Hence it is not conducive to the occurrence of the rainfall.