Plateau Meteorology

Current Issue

28 February 2016, Volume 35 Issue 1   
  • Analysis of the Influence of ENSO on Snow Depth over Qinghai-Xizang Plateau and Its Continuity
  • XU Xiaoyu;WANG Yafei
  • 2016 Vol. 35 (1): 1-12.  DOI:10.7522/j.issn.1000-0534.2014.00128
  • Abstract ( ) PDF (18993KB) ( )
  • Using the monthly Qinghai-Xizang Plateau snow depth derived from satellite data,the observations of surface temperature for 101 stations in the plateau,the extended reconstructed SST in the Pacific for earlier periods and so on,this study analyzes the correlations between ENSO and snow depth averaged over the whole plateau,the eastern plateau or the western plateau and their continuity for nearly 20 years.The results are:(1) The correlations are greatly different between SST in the eastern equatorial Pacific and snow depth averaged over the eastern and western plateau.The positive correlation is over 95% confidence level between snow depth averaged over the western plateau and SST in the eastern equatorial Pacific to the east of 130°W of prior late autumn and early winter,which persists to April;however,there is no significant positive correlation in the eastern equatorial Pacific corresponding to the eastern plateau.(2) During April and May after the occurrence of El Niño,surface temperature in the eastern plateau is higher than normal greatly,and the correlation coefficients with the mean SST for early November and December in the region of Niño3 are respectively 0.44 and 0.52,which is over 95% confidence level.(3) From the mature phase of El Niño in winter and before April,the extratropical westerly jet at 200 hPa is very active,which benefits the propagation along the jet to the plateau of the Rossby waves excited by SST anomaly in the eastern equatorial Pacific in the upper troposphere and then results in the enhancement of local convective activities and increased rainfall and snowfall.With weakening of ENSO signal and the westerly jet as waveguide,the Rossby waves tend to disappear and the snow depth anomaly in the plateau caused by ENSO also becomes not important.
  • Study on Variation of Snow Cover and Its Orographic Impact over Qinghai-Xizang Plateau during 2001-2012
  • GUO Jianping;LIU Huan;AN Linchang;WANG Pengxiang;GAO Mei
  • 2016 Vol. 35 (1): 24-33.  DOI:10.7522/j.issn.1000-0534.2014.00140
  • Abstract ( ) PDF (9553KB) ( )
  • The snow cover fraction(SCF) data during the period 2001 through 2012 from MODIS aboard Terra of NASA are used to derive the spatio-temporal distribution of snow,and to calculate its variation trend over the Qinghai-Xizang Plateau(QXP) using statistic analysis methods.The SCF during the months from October through the following April dominates compared with other months.Persistent snow area reaches the maximum of 92.93×104 km2 in February.It begins to decrease gradually as of May,hits to the bottom line of 12.37×104 km2 in July.Beginning in September,SCF goes up sharply,leveling off in October.Overall,the annual mean snow area over the QXP oscillates between 55×104~80×104 km2,showing a three-year variation cycle.Also,altitude is found to be able to exert significant influence on SCF.The higher the altitude is,the higher the SCF is over most parts of the QXP except over southwest QXP.For regions below 5 km,there is a monotonic seasonal variation trend,i.e.,higher winter SCF and lower summer SCF.In contrast,for regions above 5 km,there is a bi-modal variation trend.Aspect derived from digital elevation model can exert great influence on SCF as well.Northerly aspect corresponds to the maximum SCF,followed by westerly and easterly,and then southerly aspects.This is likely due to the solar radiation difference caused by various aspects.Similarly,SCF increases rapidly with slope during October to the following April,and then almost stays invariant during May through September.
  • Validation of Satellite Precipitation Products over Qinghai-Xizang Plateau Region
  • ZHANG Meng;HUANG Anning;JI Xiaolong;WANG Mengyao;TAN Yuhong
  • 2016 Vol. 35 (1): 34-42.  DOI:10.7522/j.issn.1000-0534.2014.00152
  • Abstract ( ) PDF (12903KB) ( )
  • The differences and consistencies of five products of satellite retrieved precipitation,which are CMORPH(Climate Prediction Center Morphing Technique),PERSIANN(Precipitation Estimation From Remotely Sensed Information Using Artificial Neural Network),TRMM(Tropical Rainfall Measuring Mission) precipitation product 3B42 version 7 and its real-time version 3B41RT,3B42RT,are validated by the gauge data over the Tibetan Plateau.The gauge data are observed from 2000 to 2012 at 251 stations over the Qinghai-Xizang Plateau.The results indicate that all these five satellite derived precipitation products can well capture the features of the distribution of rainfall amounts.The rainfall amounts decrease from the southeast to the northwest,and there are the most rainfall amounts in summer,the least in winter.By analyzing the relative bias and the spatial correlation coefficient,it is shown that the five satellite derived precipitation product perform the best in summer but the worst in winter,and they are better in the daytime than at night as well.Compared with the gauge data,TRMM3B42RTV7 has the best consistency and the least deviation among the 5 satellite precipitation products.The spatial correlation coefficients between TRMM3B42V7 and gauge data are over 0.5 in most periods in a year except in winter.CMORPH also shows good performance but with relatively weak ability compared to 3B42RTV7.By studying frequency of different grades of precipitation from CMORPH and TRMM3B42V7,the results indicate that both satellite precipitation products have good agreement with the gauge observed light rain frequency,but overestimated the frequency of the heavy and torrential rain.The TRMM3B42V7 data shows higher accuracy in the moderate rain frequency compared to CMORPH dataset.
  • Analysis of Typical Sustained Plateau Vortexes after Departure
  • XIAO Dixiang;YU Shuhua;TU Nini
  • 2016 Vol. 35 (1): 43-54.  DOI:10.7522/j.issn.1000-0534.2015.00002
  • Abstract ( ) PDF (3628KB) ( )
  • Based on NCEP reanalysis dataset of 1°×1°resolution,three typical plateau vortexes which were sustained for more than 48 hours after leaving the Qinghai-Xizang Plateau under the background respectively of "westerly-trough" ,"shear line"and "sheared flow field" are analyzed in terms of their environment,main influence system,both vorticity and temperature advection on 500 hPa,as well as situations on 200 hPa and vertical dynamical structure,in addition,total vorticity source and each forcing items are also diagnosed by using of the vorticity equation.The main characteristics during the maintenance of the plateau vortexes are as follows:(1) the plateau vortex accompanied by westerly-trough shifts following the southwest airflow in the front of westerly-trough;the plateau vortex influenced by shear line moves eastward along with the shear line;the vortex situated in a sheared flow field migrates led by subtropical high,as a result,the vortex may even recede backward if subtropical high stretches westward largely;both positive vorticity and cold advection are transported continuously to the vortexes area in three cases.(2) South Asia high on 200 hPa appears as zonal distribution under the circumstances of "westerly-trough" and "shear line" ,but as northward-arcuation in the case of "sheared flow field" .(3) Trough or low pressure emerges on 200 hPa when three vortexes reach up to their most powerful status,in other word,deep positive vorticity columnar comes into being.(4) There is a variability center of positive vorticity on 500 hPa,along which vortexes move;positive vorticity variability is mainly caused by horizontal transport when upper-trough or sheared flow field play a leading role,but mainly by convergence and divergence while shear line is dominant.
  • Comparative Analysis of Persistent Heavy Rainfall Events in West and East Sichuan Basin
  • LI Juan;SUN Jianhua;ZHANG Yuanchun;SHEN Xinyong
  • 2016 Vol. 35 (1): 64-76.  DOI:10.7522/j.issn.1000-0534.2014.00150
  • Abstract ( ) PDF (12250KB) ( )
  • Based on the conventional observation data,reanalysis data from NCEP/NCAR,satellite data and so on,the characteristics of circulation background,source of cold air and water vapor,convective systems over the Qinghai-Xizang Plateau and southwest vortex are analyzed on the two persistent heavy rainfall in western Sichuan basin and eastern Sichuan basin.The results show that in the western basin event,the location of high-level jet on 200 hPa was norther,the subtropical high was northeaster,the westerly trough and southwest vortex were westerner than the eastern basin event;cold air in the middle troposphere came from central Asia and western edge of the Qinghai-Xizang Plateau,water vapor in low level was transported by southwest airflow from the bay of Bengal in the western basin event;cold air came from mid-latitude at the early stage of event,while during the later period,the westerly flow in the middle troposphere mainly came from Bengal and southern Qinghai-Xizang Plateau,water vapor in low level was transported by southeast airflow that from South China Sea in the eastern basin event.The convective activities in western Sichuan plateau and basin have significant diurnal variation:from the afternoon to early evening in western Sichuan plateau,from the late evening to the next early morning in Sichuan basin,the difference is the eastward propagation of convective system from the edge of the Qinghai-Xizang Plateau merged with the clusters over western basin in the western basin event,but for the eastern basin event,convective system weakened as it moved eastward,there was no merging process.
  • Relation between Heavy Precipitation Process and Atmospheric Low-Frequency Oscillation in the Eastern Part of Northwest China
  • LIU Yuanpu;SUN Guowu;FENG Jianying;LI Yaohui;WANG Zhilan
  • 2016 Vol. 35 (1): 86-93.  DOI:10.7522/j.issn.1000-0534.2014.00126
  • Abstract ( ) PDF (1510KB) ( )
  • The precipitation,wind,relative vorticity and OLR were filtered of 30~50 days period with Butterworth band-pass filter.Analyzed the low frequency characters of heavy precipitation and the relationship between heavy precipitation and atmospheric low-frequency in the eastern part of northwest China.The results indicated that the precipitation occurred from middle ten days of June to middle ten days of September,especially at the end of June July and August during May to September 2012.There was occurred about 30 days period oscillation at this precipitation period,and the heavy precipitation occurred at the positive phase of the low-frequency filtered curve.The heavy precipitation occurred at the diffuse period of southern low-frequency wind which followed the convergence of northern and southern low-frequency wind;it also occurred at the positive phase of 30~50 days oscillation relative vorticity;and also occurred at negative phase of convective activity which was the severe convection region.The heavy precipitation was formed from convective oscillation's negative phase diffused from southern and eastern to this region.Used atmospheric low-frequency approach to forecast heavy precipitation in the eastern part of northwest China.It showed that the forecast accuracy can reach to 67%,and the forecast effectiveness was 10-30 days in recent 4 years.It joined forecast time gap of weather and climate.
  • Aridity Change Characteristics over Northern Region of China under RCPs Scenario
  • ZHAI Yingjia;LI Yaohui;XU Ying
  • 2016 Vol. 35 (1): 94-106.  DOI:10.7522/j.issn.1000-0534.2014.00078
  • Abstract ( ) PDF (10582KB) ( )
  • By using a horizontal resolution of 50 km×50 km regional climate model RegCM4,single nested BCC CSM1.1 global climate system model results.With the eastern Northwest China to North China as the study area,estimated the characterization of temperature and precipitation and drought trends.The results showed that:RegCM4 had a certain ability to simulate temperature and precipitation in the study area,and it can simulate their spatial distribution and time trends,but because the model had some systematic error,so some regional simulation results were slightly higher than the actual number;2041-2050 compared to 2006-2010,in study area of temperature would rise 1.0℃ in RCP4.5 scenario,and temperature would rise 1.4℃ in RCP8.5 scenarios.Under the two scenarios,in study area of precipitation showed fluctuations and they were not obviously consistent trend,but they were involved in the precipitation decreased channel from 2014;Generally speaking,Under the two scenarios,they might be more obvious drought with the study area in 2041-2050.In RCP4.5 scenario,the study area's drought trend would be aggravated in summer and autumn with the 2041-2050,and the SPI values were generally low and might be appear to drought in autumn from 2042.In RCP8.5 scenario,the study area's drought had an overall increasing trend in summer,and the study area's drought showed the decreasing trend in autumn,but then turned into drier period from 2045.
  • Analysis on Water Vapor Characteristics of Two Extreme Rainstorm Events in Western Gansu Corridor
  • TAO Jianhong;KONG Xiangwei;LIU Xinwei
  • 2016 Vol. 35 (1): 107-117.  DOI:10.7522/j.issn.1000-0534.2014.00144
  • Abstract ( ) PDF (6888KB) ( )
  • Based on observation and NCEP reanalysis data,using the water vapor flux diagnostic analysis and HYSPLIT model,the water vapor characteristics of two extreme rainstorm events which occurred on 4-5 June 2012 and 15-16 June 2011 in the Western Gansu Corridor arid zone were studied.The results are as follow:The abnormal easterlies in middle troposphere over the central and Western Gansu province resulting from the plateau low vortex and the weak ridge,which is the key of water vapor transport for rainstorm in the Western Gansu Corridor.This abnormal easterlies can transport the water vapor from the bay of Bengal to the western Gansu Corridor in the baton-form,causing water vapor convergence in the region.The intensity and location of weak ridge determine the intensity and location of abnormal easterlies which determine the main water vapor source of rainstorm.Two abnormal water vapor transportation path which included west path and east around the plateau path existed in the two extreme rainstorm events.The intensity and location of weak ridge in the "0605" process were weak and eastward shift,and the abnormal easterlies expanded from east to west until it reached Zhangye.Moreover,the west path contributed 90.02% in the total water transport.However,the intensity and location of weak ridge in the "0616" process were strong and westward shift,forming the anticyclone circulation in western Inner Mongolia,and the abnormal easterlies expanded from west to east,until it reached Jiuquan.The east path contributed 84.6% in the total water vapor transport.Therefore,the west(east) path in the lower(middle) troposphere is more significant.
  • Applicability Analysis of Nonparametric Evapotranspiration Approach over Heihe River Basin
  • WANG Ning;JIA Li;LI Zhansheng;LI Nana;HU Guangcheng
  • 2016 Vol. 35 (1): 118-128.  DOI:10.7522/j.issn.1000-0534.2014.00124
  • Abstract ( ) PDF (2119KB) ( )
  • Terrestrial evapotranspiration(ET) is essential to the global hydrological cycle and climate systems.A nonparametric evapotranspiration approach based on Hamilton principle was verified in Heihe river basin.This approach can estimate ET without parameterization of the surface transfer coefficients,and need not to go into detailed micro-processes for complex ET.Furthermore,all the associated variables are measurable,so this approach can avoid the complicated parametric process of other models,and reduce the uncertainty in the process of calculation.At present,nonparametric ET approach was verified only in a few sites.There is no sufficient research on the applicability of this approach in other ecosystems and the regional scale.The applicability of the nonparametric approach in different underlying surface and different seasons were analyzed.The results show that the nonparametric approach will underestimate the ET in humid area and overestimate ET in arid area.Sensitivity analysis show that net radiation has the great impact on the result of the nonparametric approachin humid areas,but in arid area,land surface temperature is also a significantly sensitive parameter.The regional ET over the Heihe river basin was calculated using nonparametric approach combined with remote sensing data and atmospheric driven data,and validated the results against ground based flux measurements.And then the applicability of the nonparametric approach in regional ET was analyzed.The nonparametric approach results can reflect the surface flux distribution characteristics of this region,but there were some errors compared with the ground based flux measurements.The root mean square errors were range 50 to 100 W·m-2 over different land cover types.
  • Analysis of Warm Zone Mesoscale Environmental and Heavy Snowfall Drop Zone in Northern Xinjiang
  • ZHUANG Xiaocui;CUI Caixia;LI Boyuan;ZHANG Linmei
  • 2016 Vol. 35 (1): 129-142.  DOI:10.7522/j.issn.1000-0534.2014.00132
  • Abstract ( ) PDF (16726KB) ( )
  • By used the conventional meteorological data,FY-2C satellite data,ECMWF data and reanalysis data of T639(1°×1°),the meso-scale environmental characteristics and snowfall area were analyzed of 26 warm-zone 12 hours of heavy snowfall weather processes from 2003 to 2013(November to next March) in northern Xinjiang.The results showed that heavy snowfall produce in two kinds of atmospheric circulation,polar vortex type and short wave trough type,heavy snowfall area were located the front of the low trough,the front of exit area of low level jet;convergence zone and entrance area of high altitude jet,divergence area on it right;the northeast of convergence line of 700 hPa and 850 hPa warm shear line,the southeast of dry line;overlap area of the relief and heating-up near the ground convergence line.Over the heavy snowfall area,the whole troposphere be > 80% humidity;Below 500 hPa with unstable stratification,strong vertical wind shear,strong baroclinicity;700 hPa convergence line and 850 hPa warm shear line and dry line,ground dry line and convergence line are easy to make the unstable energy release,thus providing conditions of water vapor,thermodynamic and dynamic for the production of Heavy Snow.Warm-zone snowfall mainly occurs when it began to moving eastward the front of meso-scale cold cloud cluster and the front of the biggest area of TBB genting bright temperature gradient.Finally,the three-dimensional space model is summarized for warm-zone heavy snowfall.
  • Comparative Analysis of Mesoscale Characteristics between Two MCSs of A Torrectial Rain in Jiangxi Province
  • WANG Xiaokang;ZHAO Yuchun;WANG Xiaofang;LIAO Yishan;XU Ming
  • 2016 Vol. 35 (1): 143-157.  DOI:10.7522/j.issn.1000-0534.2014.00094
  • Abstract ( ) PDF (9640KB) ( )
  • Using of the satellite TBB data,Doppler radar data,and the results of WRF mesoscale non-hydrostatic model,compared the characteristics of two mesoscale convective systems(MCS) with similar Black Body Temperature(TBB) value but quite different surface precipitation in the heavy rainfall in Jiangxi province on 19 June 2010.The results showed that in beneficial water vapor,dynamic and thermal conditions,newborn convective cell grows to strong mesoscale convective system(MCS1).Wind field present convergent in the middle and lower layer and divergent in the higher layer.Cyclonic vortex develops from ground surface to 150 hPa.Plenty water vapor is transported to mid-high layer in the troposphere by vertical upward motion in convective cloud column,causing content of liquid cloud water and cloud ice increased and overlap layer of them deepened.Then total water substances content increase,causing low TBB value and heavy surface rainfall.Weak convergence in middle layer cause the content of water vapor convergence and total liquid water substances of MCS2 are significantly less than MCS1,so only weak surface rainfall occur.But in high troposphere,the cloud ice content and radar reflectivity in tailing stratus cloud of MCS2 is similar to the cloud ice content and radar reflectivity in convective cloud of MCS1 respectively,so the satellite TBB value of MCS2 is similar to MCS1.
  • Variations of Tropospheric Ozone in the 20th Century Simulated by BCC-AGCM-Chem0 Model
  • ZHANG Fang;WU Tongwen;ZHANG Jie;LI Shubo;WANG Jun
  • 2016 Vol. 35 (1): 158-171.  DOI:10.7522/j.issn.1000-0534.2014.00118
  • Abstract ( ) PDF (10422KB) ( )
  • The global chemistry-general circulation model BCC-AGCM-Chem0,newly developed in Beijing Climate Center,is evaluated using the data provided by CMIP5 and WOUDC.BCC-AGCM-Chem0 can simulate the variations of tropospheric ozone well.The increasing trend of ozone concentration at different heights in the troposphere simulated by BCC-AGCM-Chem0 is in a good agreement with the CMIP5 data.BCC-AGCM-Chem0 can well capture zonal mean of concentration of ozone column anomalies in the troposphere from 1871 to 1999.Increasing trend in the Northern Hemisphere is higher than that in the Southern Hemisphere,the location and intensity of the strongest increasing trend are agree with CMIP5 data.Spatial distributions of the trend of the concentration of ozone column integrated from 1000 to 300 hPa from 1871 to 1999 are also well reproduced.In comparison with the CMIP5 data,BCC-AGCM-Chem0 overestimated the trend of the concentration of ozone column at lower troposphere,and underestimated it at higher troposphere.The ozone concentrations show increasing trends at Sapporo station in Asia and Hohenpeissenberg station in Europe at lower troposphere,the model results are closed to the ground-based data,and closed to CMIP5 data as well.In the upper and middle troposphere,ozone concentrations anomalies simulated by BCC-AGCM-Chem0 show distinct periodic variations,consistent with the ground-based data.
  • Discussion on Application of Statistical Extrapolation Method for Whole Integrated Water Vapor Content
  • SHEN Yanbo;WANG Bingzhong;WANG Xiangyun;GUO Peng
  • 2016 Vol. 35 (1): 181-187.  DOI:10.7522/j.issn.1000-0534.2014.00139
  • Abstract ( ) PDF (694KB) ( )
  • Surface water vapor pressure could be used to extrapolate the whole integrated water vapor content,but the calculation methods of different temporal scales should be distinct in specific application,which is still in confusion in the domestic existing research.Adopting the hourly data from 24 aerological meteorological stations in the year of 2010 and 2011 in China,basing on the specific calculations and tests of the synoptic scale atmospheric vapor content and combined with the existing statistical studies of the climatology,discussing the differences of the calculation method between climate scales and weather scale,and finally this paper comes to the conclusion that there are obvious differences between the extrapolation methods for the whole integrated water vapor content of two kinds of temporal scale,and it's not suitable to confuse them,much less replace each other.Climatology statistical extrapolation methods of the whole integrated water vapor content have good rules to follow.However,calculations of weather scale still have big uncertainty,and there is remarkable inconsistency in time and space.If there is no aerological data and the extrapolation of synoptic scale atmospheric vapor content is needed,it's workable to choose nearby aerological stations in similar climate areas as far as possible to extrapolate,but the data which are used to establish the regression equation should not be less than 2 years.
  • Possible Influence of SST Anomaly in Maritime Continent on Summer Climate of China in Association with Variations of Australian High
  • ZHANG Pengbo;GUAN Zhaoyong;LIU Lei;JIANG Yuehong;HE Jing
  • 2016 Vol. 35 (1): 188-197.  DOI:10.7522/j.issn.1000-0534.2014.00085
  • Abstract ( ) PDF (5663KB) ( )
  • By using the NCEP/NCAR reanalysis and in situ station data of precipitation and surface air temperature in China,we have investigated influences of the sea surface temperature anomalies(SSTA) in Maritime Continent(MC) region on the summer climate of China in association with variations of Australian High(AH).It is found that large SSTA occur in Maritime Continent region when Australian High changes on inter-annual timescales.The Indonesia region is hence fixed as the key area for SST anomalies with which the composite analyses are performed of circulation anomalies along with the summer climate variations in China.The SSTA in key area is highly correlated with the AH index;the correlation coefficient is found to be-0.64.By regressing ENSO signal out,the SSTA variations in key area is found to have close relations with summer climate anomalies in the eastern part of China.When AH is stronger(weaker) than normal,the SST around Indonesia is lower(higher) than normal.Correspondingly,the summer precipitation is simultaneously less(more) than normal in Jianghuai region and most areas of Liaoning and Jilin provinces whereas more(less) precipitation in Yangtze River regions.Meanwhile,summer temperature is higher(lower) in most areas of Liaoning and Jilin province,while it is lower(higher) than normal in Yangtze River regions.The SSTA in key area influence summer climate in eastern China in following ways.When SSTA in area Indonesia is negative,winds in lower troposphere anomalously diverge.This divergence works as the anomalous vorticity source,exciting an EAP/P-J wave-train pattern from South China Sea northeastward into the west Pacific.There is an anomalous cyclonic circulation in region south of 30°N and an anti-cyclonic circulation in region between 30°N and 50°N.Another anomalous cyclonic circulation exists in region north of 50°N.This circulation pattern featured by anomalous cyclone-anticyclone-cyclone from south to north facilitates the western Pacific subtropical high to be more northern than normal,inducing a precipitation pattern as'southern flood-northern drought'in the eastern China.Correspondingly,more than normal precipitation in southern part of East China means more cloud cover and more evaporation in this region,significantly influencing the surface air temperature anomalies in East China.
  • A Statistical Study of Rapid Intensification of Typhoons over Coastal Water of China
  • ZHENG Feng;ZENG Zhihua;LEI Xiaotu;CHEN Lianshou
  • 2016 Vol. 35 (1): 198-210.  DOI:10.7522/j.issn.1000-0534.2014.00148
  • Abstract ( ) PDF (18258KB) ( )
  • Based on NCEP/NCAR Reanalysis data and CMA tropical cyclone Yearbook information(1949 2013),rapid intensification of typhoons over coastal water of China are statistical analyzed.The statistical results suggest that the rapid intensification of coastal typhoons are small probability events which with 10.07% for rapid intensification.It also has distinct temporal and spatial characteristics.Composite data analysis and dynamic diagnosis are employed to reveal the circulation characteristics of the phenomena.The results of height field analysis show that the rapid intensification of typhoon is related with the subtropical high situated to the north of it.In the temperature field,there are always warm ridges encompassing the typhoons during their rapid intensification.In terms of water vapor transportation,the moisture supply to the typhoon of rapid intensification is abundant.As to the sea temperature field,the rapid intensification occurs over warm sea surface temperature(SST) region.At the same time,the low VWS will make a contribution to rapid intensification of tropical cyclones.Statistics showed that high SST configuration,low vertical wind shear and typhoon strength spurt,71.4% of the total accounted for all the rapid intensification in typhoons.But when high SST configuration,high vertical wind shear and low SST,middle vertical wind shear configuration,these two typhoons still appear rapid intensification,accounted for 2.9% of all rapid intensification in total number of typhoons over coastal water of China.
  • Study of Impacts of Dust Aerosol on Precipitation over East Asia
  • SU Xingtao;XU Liren;WEI Qiang;ZHANG Zhibiao;WANG Shengguo;WU Hongxing
  • 2016 Vol. 35 (1): 211-219.  DOI:10.7522/j.issn.1000-0534.2014.00091
  • Abstract ( ) PDF (5273KB) ( )
  • A regional climate model RegCM4 coupled with an on-line dust module is used to simulate the impacts of dust direct effects on the precipitation over East Asia in 20 years(from March 1990 to February 2010).Two sets of experiments are conducted,one with and one without the dust effects.The simulated results show that the precipitation is reduced over most parts of East Asian continent and the average decreased magnitude is 4.46%.The reduction is especially significant over the areas to east of 100°E.The maximum reduction appears both in spring and winter,the secondary maximum reduction in fall,and the minimum in summer.The most contribution to the total precipitation reduction is convective precipitation is summer and fall,which is contrast with the non-convective precipitation in winter.In spring,the convective precipitation change is almost same to the non-convective precipitation.Compared to the increased trace rain days by the dust effects over East Asian continent,the small,medium and large rain days are increased,while the slight and heavy rain days change little.At last,both the descending motion and the reduced water vapor in middle and lower troposphere lead to the decreased precipitation over most parts of East Asian continent.
  • Study of Raindrop Influence of Spectrum Change on Precipitation Estimation
  • WU Yahao;LIU Liping;ZHOU Yunjun;YANG Jie;ZHENG Jiafeng
  • 2016 Vol. 35 (1): 220-230.  DOI:10.7522/j.issn.1000-0534.2014.00093
  • Abstract ( ) PDF (5841KB) ( )
  • A squall line process as the research object which occurs on 20 May 2013,at Sanshui in Guangdong has been selected.Firstly,the precipitation process is divided into three stages by the distribution of radar echo over time and height and the characteristics when the squall line moving towards Sanshui.Secondly,analyzing the change of the raindrop spectrum in this precipitation by calculating the number density of total particles、the median diameter and peak number.Thirdly,stating the relationships between echo and precipitation intensity in the whole process and the grading process respectively according to the data of raindrop spectrum,then discussing the influence of raindrop spectrum's change and radar echo on the rainfall estimation.The following conclusions have been given:The median diameter in stages of convective cloud precipitation is basically in line with stratiform cloud precipitation stages,but its number density is much greater.Convective cloud precipitation phase is given priority to two peaks,and when the precipitation reaches to a stratiform one,the ratio of multi-peak spectrum is increasing.Radar echo is often less than the reflectivity calculated by HSC-OTT Parsivel,their correlation increases with descent height.Between the relationship of echo and precipitation intensity,b fluctuates within the range of 1~2,however,a has major fluctuation,especially when the convective cloud precipitation stages progressing towards stratiform clouds,a value increases and b value decreases;Then a segmented relationship between echo and precipitation intensity is defined according to the characteristics of three stages,the precipitation's inversion of segmented relationship is much better,the relative error given by raindrop spectrum is minimal in the period of transition,but the inversion accuracy in stratiform cloud precipitation stages is higher than convective clouds,which bears on the rapid and dramatic changes of convective clouds raindrop spectrum and its rainfall intensity;In the aspect of radar observations,the precipitation inversion of segmented relationship is better,the deviation caused by radar is smaller in convective clouds,but this value will be higher when the type of precipitation transits to stratiform clouds,which is mainly due to the the minimum error between the distrometer and radar in the phase of convection,the differences of two instruments on time and height,the precision of radar observation and the changes of raindrops spectrum also have important influence on rainfall estimation.
  • C-Band Polarization Radar Data Preprocessing and Its Application to Rainfall Estimation
  • WEI Qing;HU Zhiqun;LIU Liping;WU Linlin
  • 2016 Vol. 35 (1): 231-243.  DOI:10.7522/j.issn.1000-0534.2014.00131
  • Abstract ( ) PDF (9230KB) ( )
  • Radar data processing method and qualitative precipitation estimation are tested based on the data observed at Dingyuan,Anhui Province in June and July 2013 with a C-band polarization radar(PCDJ) which is one of the instrument of Anhui Weather Modification Office.After filtered by median filter and wavelet analysis method respectively,the differential propagation phase shift ΦDP data filtered by wavelet analysis can significantly improve ΦDP data quality.The specific differential propagation phase shift KDP is estimated from ΦDP by least-square fitting approaches in 1.5~4.0 km resolution.ΦDP data filtered by wavelet analysis is more continuous and smooth.And the result of ΦDP data filtered by wavelet analysis applied to precipitation estimation is better.The attenuation of ZH in rain area is corrected by KDP which is estimated from ΦDP data filtered by wavelet analysis,and the corrected ZH values of PCDJ radar are smaller than SA's.Combining with hourly rainfall gauge,the comparison analysis were made between the rain rates estimated from PCDJ and SA.The results suggest that the rain rates estimated from i>R(ZH,KDP) are more accurate than those from i>R(ZH) when the rain rates are greater than 5 mm·h-1,but less accurate when the rain rates are smaller than 5 mm·h-1.In addition,SA radar rain rates estimated from i>R(ZH) is more accurate than PCDJ radar's.Also,PCDJ radar rain rates estimated from i>R(ZH,KDP) can further improve the accuracy than SA radar when the rain rates are greater than 5 mm·h-1.
  • Review on Improving Land Surface Model Simulations by Assimilating Polar-Orbiting Satellite Observations
  • YIN Jifu;ZHENG Youfei;ZHAN Xiwu;WU Rongjun;LIU Jicheng;FANG Li;GUAN Fulai;YAO Shuran
  • 2016 Vol. 35 (1): 260-276.  DOI:10.7522/j.issn.1000-0534.2014.00137
  • Abstract ( ) PDF (7117KB) ( )
  • It is a key issue in drought monitoring to improve Land Surface Model(LSM) simulations by assimilating polar-orbiting satellite observations.By introducing the comprehensive Land surface Models and assimilation methods,this paper reviews the recent progresses of researches on assimilation of polar-orbiting satellite observations of surface type,albedo,green vegetation fraction(GVF),land surface temperature(LST),soil moisture(SM) and precipitation.Major scientific issues,including the structure of land surface model,assimilating method and satellite retrievals,to be addressed in near future research activities in the land data assimilation area are discussed.In particular,newer version land cover and real time green vegetation fraction and albedo products,which have great capabilities to describe land surface conditions,are suggested for land surface model(LSM) simulations.In addition,the land surface temperature data that are more accuracy and have higher temporal-spatial resolution should be used to improve LSM simulations.Estimations on the merits of assimilating ensemble soil moisture product and how to control the satellite data quality in a data assimilation system are also interesting topics.Based on the newer land cover,(near) real time GVF and albedo,the qualified LST,SM and precipitation data and the LSMs development will be helpful to further improve the assimilating effect.

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