Current Issue

• Review of Advances in Water Vapor Transport Studies of Rainstorm in Northwest China
• QIAN Zheng'an;CAI Ying;SONG Minhong;WU Tongwen;ZHOU Jianqing;LUAN Chen
• 2018 Vol. 37 (3): 577-590.  DOI:10.7522/j.issn.1000-0534.2018.00032
• Abstract ( ) HTML PDF (6115KB) ( )
• To break through the bottleneck of water vapor transport (WVT) studies in the past 20 years, the WVT for the center arid areas (CAA) of heavy rain in summer and late spring in Northwest China (NWC)were particularly investigated in the paper. The main conclusions are as follows:(1) Since the NWC covers a large areas, which has many orography obstruct and with changeable precipitation circulation, it is reasonable that there are different water vapor sources for its various subregions of NWC including North-and South-Xinjiang, Qinghai Plateau, and so on. They should be studied by different subregions and seasons, respectively. (2) The prevail precipitation combined circulation patterns in east-and west-part of NWC in summer have already summed up. (3) Under the particularly favorable circulation pattern with 500 hPa subtropical high extending westward (SHEW) in East China and by east wind in Gansu Corridor, the water vapor in Taiwan Strait Region (TSR) can rely on the three jets including Southeast monsoon jet over South China et al, following a counter 'Z' shaped path, which are relayed and transported in the order into the CAA. The moving status detail picture of their WVT process has been constituted. The TSR is the main water vapor source, which is the main WVT pattern in the CAA in summer and autumn rainstorms. (4) And similarly, another kind of WVT pattern in late spring has been explored jointly by Tao Jianhong et al. Under the circulation pattern with the Southwest jet in the Bay of Bengal (BB), the weak and cold high pressure (not the SHEW) in East China and the east wind over Gansu Corridor, the water vapor in BB can rely on the three jets including SW jet in BB et al, following the half circular shaped path around the east edge of the Qinghai-Xizang Plateau, are relayed and transported into the CAA. Namely, the BB might be another water vapor source of the late spring rainstorm in CAA.

• Long-Term Variation of Surface Heating over the Qinghai-Tibetan Plateau Linked to the Westerly Jet
• FAN Weiwei;MA Weiqiang;ZHENG Yan;YANG Zhimin
• 2018 Vol. 37 (3): 591-601.  DOI:10.7522/j.issn.1000-0534.2017.00062
• Abstract ( ) HTML PDF (12774KB) ( )
• Based on a 30-yr set of daily surface heat flux data for 1979-2008 over the Qinghai-Tibetan Plateau (QTP) from ERA-interim, the spatial distribution and long-term trends of sensible and latent heat flux over the QTP were analyzed respectively. The factors responsible for the trends of sensible heat flux and latent heat flux in spring were investigated in this paper and we discussed the relationship between the surface heating and the westerly jet over the QTP emphases. Significant differences in spatial pattern and variability between sensible heat flux and latent heat flux were observed. The spatial distributions of seasonal-mean surface heating show that sensible heat flux increases from the southeast to the northwest over the QTP in seasons except spring, while latent heat flux increases from the northwest to the southeast of QTP throughout the four seasons. The decreasing of sensible heat flux and the increasing of latent heat flux occur in almost the QTP in the four seasons during the study time. Long-term variation of surface heating over the QTP in spring is more remarkable than the other three seasons. The maximum increasing rate of latent heat flux[0.79 W·m^-2·(10a)^-1] and the maximum decreasing rate of sensible heat flux[-1.83 W·m^-2·(10a)^-1] appeare both in spring. In terms of the inter-annual variation of surface heating over the QTP, there is a significant negative correlation (R=-0.69) between latent heat flux and sensible heat flux, which indicates that the changes of latent heat flux and sensible heat flux may be affected by the same climatic factor. Further analysis suggested that there is a close relationship between the surface heating field and the westerly jet over the QTP. The weakening trend of the westerly jet over the QTP has an important impact on the change of sensible heat flux as well as latent heat flux. The possible effect mechanisms are as follows:The weakened of the westerly jet leads to a declining trend in the surface wind speed over the QTP, furthermore, contributes to the decrease of sensible heat flux. Besides, accompanied by the change of westerly jet, the India-Burma trough gets stronger leading to an anomalous cyclonic circulation over the Bay of Bengal. Due to the stronger convection, more water vapor content is found in the region, and also more moisture carried by the anomalous southeast flow forming in the cyclonic to the QTP. Accordingly, the stronger precipitation is found over the QTP in spring. As a result, the latent heat flux over the QTP presents an increasing trend during three recent decades.

• The Possible Influence of Atlantic Sea Surface Temperature Anomalies for Low-Frequency Intensity over Qinghai-Tibetan Plateau during Summer of No-ENSO Events Following Years
• YU Haohui;QI Li;HE Jinhai
• 2018 Vol. 37 (3): 602-613.  DOI:10.7522/j.issn.1000-0534.2017.00082
• Abstract ( ) HTML PDF (20973KB) ( )
• Quasi-biweekly oscillation of atmospheric heat source (〈Q₁〉) over Qinghai-Tibetan Plateau (QTP)is significant according to many previous studies, and it can be used as a predictor of the climate change in Eastern China. In quasi-biweekly oscillation active year, Eastern China is likely to experience a fast conversion from flood to drought or from drought to flood. On the basis of NCEP/NCAR reanalysis data and daily 〈Q₁〉 empirical orthogonal function results, standardized variance was defined as the index of Low-frequency intensity (ITPI) over QTP to describe th e low-frequency activity. The main results showed that there is an annual variance in the low-frequency activity intensity, Pacific Ocean and Atlantic Ocean can both take effects on quasi-biweekly oscillation over QTP, the main influential factor is different in different years. During the following year of the ENSO events, the tropical pacific sea surface temperature anomaly is the key factor; During the following year of the No-ENSO events, the Atlantic Ocean triple anomaly sea surface temperature is the dominant factor which can motivate the anomaly EU wave train thus affecting the atmospheric circulation. Under the same trigger condition, the positive phase of the EU wave train is in favor of the development of cloud radiant feedback and then influence the low-frequency intensity, While the negative phase of EU wave train can suppress the development of cloud radiant feedback which cause weak Quasi-biweekly oscillation of atmosphere heat source over QTP.

• The Role of Solar Radiation and Water Vapor Pressure Deficit on Controlling Latent Heat Flux Density over the Alpine Wetland of the Source Region of the Yellow River
• XIE Yan;WEN Jun;LIU Rong;WANG Xin;JIA Dongyu
• 2018 Vol. 37 (3): 614-625.  DOI:10.7522/j.issn.1000-0534.2017.00063
• Abstract ( ) HTML PDF (2178KB) ( )
• As the alpine wetland underlying surface is moist and sensitive to climate change, quantitative assessments of environmental factors on the influence of latent heat flux over there have important scientific significance. Environmental factors on the influence of latent heat flux are potential to be expressed as sums of the atmosphere and surface factors. By using the datasets collected from the land surface process field experiment which was conducted in the source region of the Yellow River from June 1 to August 31, 2014, the characteristics of solar radiation and water vapour pressure deficit in controlling latent heat flux density were analyzed, and further assessment was evaluated by a defined controlling factor. The main results are as follows:(1) The average values of relative atmospheric controlling factors on latent heat flux density exercised by solar radiation and water vapour pressure deficit are 0.98 and 0.02. Relative atmospheric controlling factor on latent heat flux density is mainly exercised by solar radiation, and the role of water vapour pressure deficit is only marginal. (2) The average values of relative surface controlling factor over latent heat flux density exercised by solar radiation and water vapour pressure deficit are 0.12 and -0.31. The former is larger in the morning and evening, and smaller in the noon. The absolute value of the latter is smaller in the morning and evening, and larger in the noon. (3) The average values of absolute total controlling over the latent heat flux density exercised by solar radiation and water vapour pressure deficit are 0.22 and -0.06 W·m^-2·Pa^-1. The average values of relative total control are 1.10 and -0.29. (4) Solar radiation controls the latent heat flux mainly through a direct effect (atmospheric factor). While the water vapour pressure deficit controls latent heat flux mainly through the indirect effect of altering surface resistance (surface factor). (5) The average value of the decoupling factor over the alpine wetland is 0.38. It implied that the coupling between the alpine wetland and atmospheric is low. It is of practical, the solar radiation is the main factor to control the latent heat flux over alpine wetland. This study provides a new research approach for the study of the parameterization of latent heat flux and evaporation under the context of global climate change.

• Analysis on the Applicability of Reanalysis Soil Temperature and Moisture Datasets over Qinghai-Tibetan Plateau
• DING Xu;LAI Xin;FAN Guangzhou;WEN Jun;YUAN Yuan;WANG Xin;WANG Zuoliang;ZHU Lihua;ZHANG Yongli;WANG Bingyun
• 2018 Vol. 37 (3): 626-641.  DOI:10.7522/j.issn.1000-0534.2017.00060
• Abstract ( ) HTML PDF (30971KB) ( )
• In this paper, according to the observation data of the monitoring network in four areas (Nagri, Shi quanhe, Nagqu, Maqu) in different climate zones and vegetation conditions of 8 sets of soil moisture (ERA-Interim, CFSR, CFSv2, JRA-55, GLDAS-NOAH, GLDAS-CLM, GLDAS-MOS, GLDAS-VIC), we compared and analyzed the data of soil temperature and moisture from Northwest Institute of Eco-Environment and Resource, during 2010-2016, Using correlation coefficient (R), root mean square error (RMSE), mean bias (Bias), unbiased mean-square root error (ubRMSE) and standard deviation ratio (SDV), to compare the simulation performance of the soil moisture products to the observed values. Then searching for the long and large scale soil temperature and moisture products that suitable for the Qinghai-Tibetan Plateau. For soil moisture, the GLDAS-CLM product can reproduce the dynamic process and change details of the two layers of soil moisture over time. Although the result is higher than the observed soil temperature, it is the closest to the observed value, and has a close relationship with the observed value. Soil freezing period cannot show the dynamic characteristics of soil moisture, but the dynamic process characteristics of the two layers of soil moisture changes over time can characterized by non-freezing period products(GLDAS-NOAH and GLDAS-CLM), which showed the best in both error statistics and correlations. GLDAS-MOS, GLDAS-VIC, ERA-interim and CFSv2 products are not ideal to depict the value of an observation, although to a certain extent they can show parts of the change trend of soil moisture, and JRA-55 products cannot describe regional soil temperature and moisture.

• Surface Relative Humidity Decreases and Its Cause over the Qinghai-Tibetan Plateau in Recent Ten Years
• XIE Xinru;YOU Qinglong;LIN Houbo
• 2018 Vol. 37 (3): 642-650.  DOI:10.7522/j.issn.1000-0534.2017.00091
• Abstract ( ) HTML PDF (13380KB) ( )
• Based on the monthly surface relative humidity and surface temperature data of 71 stations over the Qinghai-Tibetan Plateau (QTP) provided by the National Meteorological Information Center/China Meteorological Administration, the changes of surface relative humidity and surface temperature and the reasons of the surface relative humidity decreases in recent ten years over the QTP were studied by using the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Reanalysis data from 1979 to 2014. The results show that the surface temperature over the QTP is sustained warming, but the surface relative humidity has rapidly decreased after 2000. The analysis of the variation of vertically integrated water vapor transport flux over the QTP and its surroundings shows that water vapor is mainly transported into the QTP from the southern boundary, and the water vapor into the QTP carried by wind from the Bay of Bengal is decreased after 2000 due to the weaker wind speed. This could result in the decrease of the vertically integrated water vapor transport flux and the water vapor into the QTP. According to the Clausius-Clapeyron relationship, the reasons of the surface relative humidity decrease over the QTP in recent ten years have been explained:as the surface temperature continues to increase, the ability of water contained by the air become stronger. However, the water vapor into the QTP is not increased correspondingly but decreased. It could cause the decreased rate between the existences of water vapor and the saturated water vapor. That is to say, the surface relative humidity over the QTP is decreased.

• Relationship between Iran High Pattern of South Asia High and Summer Precipitation in Xinjiang
• ZHAO Yong;WANG Qian;HUANG Anning
• 2018 Vol. 37 (3): 651-661.  DOI:10.7522/j.issn.1000-0534.2017.00049
• Abstract ( ) HTML PDF (16293KB) ( )
• Based on the ERA-Interim reanalysis data and daily precipitation data which was provided by 88 observational stations in Xinjiang, the relationship between the Iran High pattern of South Asia High and summer (July and August) precipitation in Xinjiang during 1979-2013 were analyzed. The results showed that the most frequency of South Asia High was Iran High pattern for recent 35 years, which had close relations with summer rainfall in Xinjiang. When the center of Iran High pattern shifted further west, it would cause more summer precipitation in Xinjiang, and vice verse; When the center of Iran High pattern shifted further south or north, it would cause similar anomalies of summer rainfall in Xinjiang, which indicated that the center moving of Iran High pattern along longitude have more important effects than the center moving of Iran High pattern along latitude. The "south and north oscillation" of Iran High pattern showed that when the center of Iran High pattern shifting further west and north, which could cause the anomalous cyclone over Xinjiang and wet air moving into Xinjiang along the east side of Qinghai-Tibetan Plateau, so it received more summer rainfall in Xinjiang; When the center of Iran High pattern shifting further east, the change of high ridge had limited effects on the summer rainfall in Xinjiang. The heating over Qinghai-Tibetan Plateau and Iran Plateau has important effects on the center moving of Iran High pattern along latitude, and the heating over the Pamirs Plateau and Arabian Peninsula has close relations with the center moving of Iran High pattern along longitude.

• Characteristics of Temperature and Precipitation in East Asia and North America
• YANG Zhaohong;ZHANG Lei;YUAN Guanghui;GUO Qi;SUN Naixiu;DU Tao
• 2018 Vol. 37 (3): 662-674.  DOI:10.7522/j.issn.1000-0534.2017.00083
• Abstract ( ) HTML PDF (17602KB) ( )
• The interdecadal and regional differences of temperature and precipitation are one of the important contents of global climate change research. In this paper, the seasonal and regional characteristics of temperature and precipitation variation in East Asia and North America were analyzed by using the CRU TS3.20 data from the Climatic Research Unit (CRU) of the University of East Anglia during the period of 1901-2014. Furthermore, we also analyzed the interannual variation of the area ratio that affected by extreme weather events in East Asia and North America by using the ERA-Interim data from the European Centre for Medium-Range Weather Forecasts (ECMWF) during the period of 1979-2015. It is found that the warming trend in East Asia[0.134℃·(10a)^-1] is higher than that in North America[0.102℃·(10a)^-1] over the past 110 years. The warming trend of arid and semi-arid regions in East Asia is slightly lower than that in East Asia, while the warming trend of arid and semi-arid regions in North America is slightly higher than that in North America. As for seasonal characteristics, the warming trend is obvious in the cold season. It is 2.9 (1.3) times higher in East Asia (North America) during cold season than during warm season. There is a significant latitude difference in seasonal warming trend. The warming rate for high latitude (45°N) region in East Asia and North America is generally greater during cold season than during warm season. The East Asia and North America have a greater increase in precipitation than Northern Hemisphere. The increase of precipitation is obvious during warm season and mainly occurs in the high latitudes of East Asia and North America (45°N). The increase of precipitation is not obvious for arid and semi-arid regions in East Asia[0.04 mm·(10a)^-1] and North America[0.07 mm·(10a)^-1]. In East Asia and North America as well as arid and semi-arid regions, the area affected by extreme high temperature has an increasing trend, while the variation of the area affected by extreme low temperature is not obvious, and the area affected by extreme precipitation has a decreasing trend. The monthly average temperature in North American and East Asia and the arid and semi-arid regions is more responsive to PDO (Pacific Decadal Oscillation) than that to ENSO (El Niño Southern Oscillation), and the monthly average precipitation has a stronger response to ENSO than PDO.

• Characteristics of Short-time Heavy Precipitation Weather Flow and Environmental Parameter of Altay Region in Xinjiang
• ZHUANG Xiaocui;ZHAO Jiangwei;LI Boyuan;LI Jianli;XIE Xiuqin
• 2018 Vol. 37 (3): 675-685.  DOI:10.7522/j.issn.1000-0534.2017.00061
• Abstract ( ) HTML PDF (12553KB) ( )
• In order to understand the characteristics of short-time heavy precipitation(≥ 10 mm·s^-1) in Altay of north Xinjiang, using automatic weather stations, common and EC fine grids and so on in Altay region, The environmental flow patterns, T-logP chart, and key physical parameters from 45 times of short-time heavy precipitation during 2010-2016 were analyzed, and then compared the area with the eastern part of China. The result shows that the short-time heavy precipitation was caused largely by front type of central Asia trough and vortex and the low trough (vortex) type of West Siberia. The first two occur most in June and the latter one most in July, and we extracted the flow pattern configurations of different weather patterns. In most processes, the profile of temperature and humidity looks like a funnel on T-logP chart, the upper part is dry and cold, and the lower part is warm and humid; the water vapor troposphere is better in middle low layer; CAPE shows a thin and weak spindle shape; Uplift condensation height is lower. In this area, average and threshold value of the key environmental parameters of the main weather types were summarized before short-time heavy precipitation, most environmental parameter thresholds are smaller than the central and eastern part of China, which shows that the region is more conducive to trigger short-time heavy precipitation than central and eastern regions of China.

• Environmental Fields Analysis of a Kind of Qinghai-Tibetan Plateau Vortex Abnormal Tracks
• YU Shuhua;TU Nini;GAO Wenliang
• 2018 Vol. 37 (3): 686-701.  DOI:10.7522/j.issn.1000-0534.2017.00039
• Abstract ( ) HTML PDF (53745KB) ( )
• By using the NCEP/NCAR reanalysis data, historical weather graphs, on the base of 2 days or more sustained departure Tibetan Plateau Vortexes (SDPVs) activities analysis during 1998-2015, the geopotential height characters at middle troposphere levels of SDPVs spinning over Hetao region were analyzed. By using the numerical WRF 3.5.1 model, the simulation of environmental field of the spinning Hetao region Jiuzhi Plateau vortex process during July 1 to 5, 2002, and stronger tropical low and weaker tropical low numerical experiments were carried out. The results show that the northward moving typhoon or tropical low between the mainland of eastern China and west 140°E will lead to the abnormal track spinning SDPVs over Hetao region. The circulation background of spinning Hetao region SDPVs, which is mainly the northward moving of typhoon or tropical low that will make the subtropical high go north, can lead to the sustaining of Mongolia High and subtropical high shearing field or sustaining Qinhai High and subtropical high-Mongolia High shearing field, which will block the eastward moving of the SDPVs in the shearing field. The numerical experiments demonstrate that the intensity changing of the tropical low will influence the position of the western Pacific subtropical high, which will affect the shear environment field of the spinning SDPV, resulting in the changes of the position and frequency of the low vortex.

• The Characteristic Analysis of an Eastwards Plateau Vortex by Its Strengthening Process
• YANG Yingcan;LI Yueqing;CHEN Yongren
• 2018 Vol. 37 (3): 702-720.  DOI:10.7522/j.issn.1000-0534.2017.00054
• Abstract ( ) HTML PDF (56307KB) ( )
• A present understanding of Plateau Vortex (PV) is regarded as a shallow vortex. However, some studies have pointed out that PV is not always a shallow system. A case of PV with a vertical thickness greater than 500 hPa were analyzed using the NCAR/NCEP reanalysis data, the conventional observations as well as the TBB data from FY-2E, and we discussed the relationship between the deep plateau vortex and the upper circulation. The results show:(1) In the developing stage, the convergence of vortex is weak while the downdrafts are strong, convergence is not the reason for the development of the deep plateau vortex which extended to the upper troposphere. The downdrafts of the high potential vorticity and high momentum form the upper air transported by the upper-level jet stream which in the north and east of the South Asian High(SAH) led to the generation and development of vortex. The evolution of the deep plateau vortex is related to SAH. Therefore, the eastern ridge of the SAH moved to the north and a "northeast-southwest" pattern was formed, the northeast flow of southeast SAH led the deep plateau vortex to the west. (2) The shallow PV has a warm character in thermal structure with a warm core at 500 hPa. The deep vortex has stratification in thermal structure and complex variety in time and space, Besides, it has a warmer structure as same as the SAH at 250 hPa and a colder structure below 250 hPa, the changes of the cold part of the vortex vary from height in different stages. (3) Comparing the dynamic characters between deep and shallow vortices in various stages, we found the deep PV has a stronger convergence and ascending motion in the early than the shallow PV which dominated by the subsidence movement. During the dissipation stage, horizontal vorticity advection is the main factor which causes the deep PV become weaker. On the other hand, the vertical vorticity conversion to the horizontal is the main reason for the decrease of the shallow PV.

• A Numerical Simulation of the Impact of Vegetation Evolution on the Regional Climate in the Ecotone of Agriculture and Animal Husbandry over China
• ZHU Hanhui;ZHANG Yu;SHEN Xiaoyan;WANG Shaoying;SHANG Lunyu;SU Youqi
• 2018 Vol. 37 (3): 721-733.  DOI:10.7522/j.issn.1000-0534.2018.00050
• Abstract ( ) HTML PDF (28471KB) ( )
• As one of the three human factors that affect climate change, real vegetation cover over the ecotone of agriculture and animal husbandry can affect regional and global climate by changing surface radiative forcing, energy and water circulation, greenhouse gas and aerosol emissions. The ecotone of agriculture and animal husbandry in China is a key area in China's land surface change. The regional climate effect caused by its evolution has important research significance. The impact of real vegetation cover over the ecotone of agriculture and animal husbandry changing in typical years on the regional climate over China during 2001-2010 was studied by using WRF (Weather Research and Forecasting) model and the surface classification data of satellite remote sensing in the years 1981 and 1990. There are some conclusions after analyzing the change of temperature, precipitation and wind. The main conclusions are as follows:(1) In 1990, compared with 1981, vegetation cover over the ecotone of agriculture and animal husbandry increases(decreases) in the north of 38°N, and the surface roughness increases(decreases). (2) When the vegetation cover over the ecotone of agriculture and animal husbandry increases (decreases) and the surface roughness increases (decreases), the temperature of the agriculture and animal husbandry and the nearby areas increases (decreases). (3) The evolution of vegetation cover over the ecotone of agriculture and animal husbandry leads to the "positive-negative-positive" of the precipitation difference over China from the east to the west. The surface roughness increases (decreases) causes the precipitation increases (decreases). When there are more precipitation, there will be more water cycle. The evolution of vegetation cover over the ecotone of agriculture and animal husbandry are more sensitive to places where precipitation is high. The more precipitation with more water circulation causes the more prominent the effect of vegetation evolution on precipitation. (4) The vegetation evolution of the intersected zone mainly affects the middle and high-level circulation fields, the cyclonic (anti-cyclonic) circulation at 500 hPa corresponds well with the increase (decrease) of the precipitation difference field.

• Preliminary Analysis on the Influence of Cloud Amount and Temperature over East Side of Qinghai-Tibetan Plateau
• ZHANG Qi;LI Yueqing;REN Jingxuan
• 2018 Vol. 37 (3): 734-746.  DOI:10.7522/j.issn.1000-0534.2017.00085
• Abstract ( ) HTML PDF (5708KB) ( )
• Based on the meteorological monthly mean temperature data and ISCCP D2 data, using the SVD, statistical analysis and synthetic analysis methods, the relationship and influence of cloud amount and temperature were analyzed over east side of Qinghai-Tibetan Plateau. The research results show that the 1980s were the coldest decade in the Sichuan and Chongqing basin in the last half century, and the mid-90s were an important turning point in the change of the Sichuan and Chongqing basin from cold to warm. The lag of warming is mainly caused by the abnormal temperature of spring and autumn, and the west of the basin is a notable anomaly. The nimbostratus、cirrus and deep convective cloud are positively correlated with temperature, and the degree of influence and relationship are different. Nimbostratus and deep convective cloud has positive correlation with the temperature of "greenhouse effect", the cirrus that reflected solar short wave radiation is negatively related to the temperature. Because nimbostratus、deep convective cloud produce precipitation and weaken the warming effect, so the relationship between cirrus and temperature is better. There is a significant correlation between the nimbostratus, cirrus and deep convective cloud. The correlation coefficient between cirrus and nimbostratus, deep convective cloud is negative, but the nimbostratus is positively correlated with cirrus. The correlation coefficient between cirrus and nimbostratus is the bigger among those correlation coefficients. In view of the fact that the three clouds affect the temperature together and have significantly correlation with it, we built a cloudy regression model that has passed the significance test.

• Intercomparison Study on Precipitation Observations of TRwS204 and Chinese Standard Precipitation Gauge in the Qilian Mountains
• ZHENG Qin;CHEN Rensheng;HAN Chuntan;SONG Yaoxuan
• 2018 Vol. 37 (3): 747-756.  DOI:10.7522/j.issn.1000-0534.2018.00039
• Abstract ( ) HTML PDF (2942KB) ( )
• The type and process of precipitation, and the climate condition are complex in mountainous area, and biases exist in the observations of various precipitation gauges. It is urgent to understand the difference between measurements from manual and automatic gauges, and the difference between the gauge measurements and the real precipitation. Comparison of precipitation measurements was carried out in the Hulu watershed of Heihe river upstream in the Qilian Mountains from September 2014 to August 2017. The Chinese standard precipitation gauge[no wind shield (CSPG_UN) and equipped with single Alter wind shield (CSPG_SA)] and the TRwS204 weighing precipitation gauge[equipped with single Alter wind shield (TRwS_SA)] which was commonly used in the Qilian Mountains were used. Choosing the adjustments of the measurements from the Chinese standard precipitation gauge installed in accordance with the Double Fence Intercomparison Reference recommended by the World Meteorological Organization as standard precipitation. The results show that:(1) The average dynamic losses (the percentage of the average dynamic losses relative to the average standard precipitation) of CSPG_UN, CSPG_SA and TRwS_SA were 0.21 mm (3.4%), 0.12 mm (1.9%) and 0.61 mm (9.8%) for rain, and 0.37 mm (7.6%), 0.16 mm (3.3%) and 0.51 mm (10.5%)for sleet, and 0.27 mm (10.2%), 0.09 mm (3.4%) and 0.57 mm (21.4%) for snow, respectively. (2) The difference between dynamic losses of CSPG_UN and CSPG_SA was mainly related to the effect of the wind shield. The difference between dynamic losses of CSPG_SA and TRwS_SA was mainly related to the different gauge shape, and it could also be affected by the specific errors of TRwS204. (3) For rain, gauge catch ratio decreased a lot when mean wind speed was higher than 2.0 m·s^-1. Because the mean wind speed was relatively low for sleet and snow, only the catch ratio of CSPG_UN decreased with the increase of wind speed for snow.

• Contrastive Analysis of Temperature Interpolation at Different Time Scales in the Alpine Region by Anusplin
• JIA Yang;CUI Peng
• 2018 Vol. 37 (3): 757-766.  DOI:10.7522/j.issn.1000-0534.2017.00072
• Abstract ( ) HTML PDF (9275KB) ( )
• Anusplin is a common method that considering terrain effect during the temperature interpolation and it also has a high accuracy for temperature interpolation in the alpine area. But it is not clear whether there will be different accuracy based on the temperature data at different time scales by this method, especially for mountain temperature interpolation, which is very important for mountain science research. In order to determine the accuracy of temperature interpolation in mountain area at different time scales, we took the most complex mountain area(Hengduan Mountains, a mountain range in Sichuan and Yunnan) as study area. Based on the temperature data recorded by 51 meteorological stations during 1960-2014 and SRTM in the study area, Anusplin was used to interpolate regional temperature at different time scales (decadal, annual, seasonal, monthly, and daily). With the cross-validation and comparison method, the interpolation accuracy of temperature at each time scale was compared by mean absolute error (MAE), mean relative error (MRE) and root mean square error (RMSE). The results showed that:(1) The interpolation of summer temperature shows the minimum value in MAE, MRE and RMSE(0.41℃, 0.03℃ and 0.66℃), while the interpolation of winter temperature shows maximum value in MAE, MRE and RMSE (0.79℃, 0.81℃ and 1.02℃). The MAE value and RMSE value of decadal, annual and autumn temperature interpolation are similar. (2) The temperature interpolation by using Anusplin can well express the climate trends at decadal, annual and seasonal scale. The trend obtained from interpolation data are consistent with the tendency calculated from observed data, and their change rate shows no discrepancy[error < 0.1℃·(10a)^-1]. (3) The MAE, MRE and RMSE value for daily and monthly temperature interpolations in summer are also minimum while in winter are maximum. In addition, the MAE, MRE and RMSE value of daily temperature interpolation are higher than the monthly temperature interpolation. Especially for the mean relative error in winter, the value of daily temperature interpolation error is about twice than that of monthly temperature interpolation error. It is worth noting that the inconsistency of temperature interpolation accuracy at decadal, annual and seasonal scale is mainly attributed to the difference in the relationship between temperature and elevation at different time scale. Moreover, the accuracy error of elevation data and the regional special climatic condition can also cause error for temperature interpolation by using Anusplin.

• Propagation Characteristics of Mesoscale Convection System in an Event of Severe Convection Rainstorm over Both Sides of Liupanshan Mountains
• ZHAO Qingyun;ZHANG Wu;CHEN Xiaoyan;GOU Shang
• 2018 Vol. 37 (3): 767-776.  DOI:10.7522/j.issn.1000-0534.2017.00068
• Abstract ( ) HTML PDF (23527KB) ( )
• Constrained by the subtropical anticyclone at 500 hPa, a severe convection rainstorm process was taking place in the region of middle-east part of Gansu province and the Central Shaanxi Plain from 19:00 Aug 24 to 08:00(Beijing Time) Aug 25, 2016. Arising rainstorm in 19 counties, with the maximum amount of daily precipitation of 158.7 mm and the highest 79.1 mm per hour, accompanied with lightning. It presented the features of a typical severe convection weather. Based on the data of satellite, radar, high resolution ground-base observations, ECMWF, NCEP and routine measurements, the occurrence and development of the mesoscale system, which was the main cause inducing the short time heavy precipitation, were analyzed, as well as the propagation characteristics of Mesoscale Convection System (MCS). The results show that there were two MCSs which were the main causes of the rainstorm. The occurrence and development of the MCS was close linked to the Convergence Line (CL) near the surface. The transmeridional CLs were taken shape near both westside and eastside of Liupanshan mountains due to the Shearing Disturbance(SD) in dynamical fields at low level, the Thunderstorm Cell (TC) was developing intensively near to the CL and moving southward with it overall. The westside CL had impact on the central part of Gansu. The eastside CL split in two parts, east section and west section. The first one moved continuously to southward affecting Longdong of Gansu, the second one changed into the north-south trending CL due to the complicated topography, while prevail north airflow turned to northwest in the west of the Central Shaanxi Plain. The TC moved from west to east along the terrain with the CL. Appropriate dynamical and thermal factors played an important role in the process of the enhancement of MCS and change of propagation direction over the east side of Liupanshan Mountains.

• Analysis of Cloud System and Its Vertical Structure between the Southern and Northern Qinling Based on Satellite Data
• WEI Jing;DUAN Keqin
• 2018 Vol. 37 (3): 777-785.  DOI:10.7522/j.issn.1000-0534.2018.00057
• Abstract ( ) HTML PDF (5192KB) ( )
• The relationship between cloud and climate is very complex. In order to quantitatively understand the feedback effect of clouds on the climate and improve the climate model, it is necessary to determine the cloud's global or local distribution and its internal structural characteristics under different dynamic conditions. Seasonal variations of cloud occurrence frequency and cloud vertical structures in Guanzhong, Qinling and Shannan regions from 2007 to 2010 were studied by using CloudSat/CALIPSO joint product. The results showed that the four seasons in all regions are dominated by cloud-days, the total cloud occurrence frequency is high in the south, but low in the north, and gradually decreases from south to north. However, the month with the highest total cloud occurrence frequency shows earlier in the north than in the south. The highest value of cloudtop/cloudbase height is in the south and the lowest value is in the north. Seasonal variation of cloudlayer height in the north and south of the Qinling Mountains, Guangzhong region is the most significant in single-layer cloud, while Shannan in the multi-layer cloud. The thickness of clouds in each region is 1~3 km, and slightly higher in summer and autumn than in spring and winter. There is no obvious seasonal changes in cloud thickness. In the single-layer cloud, Ci, As, and Sc occupy a considerable proportion, and Ac, Cu, and Dc occupy a certain proportion, while St and Ns have the smallest proportion. In the lower layers of two-layer clouds, Sc is the dominant type. Ci, As, Ns, and Dc decrease in all regions, while Ac, St, and Cu increase. In the lower layers of the three-layer cloud, Ac, Sc, and Cu are predominant, and Ns is the least. The middle layer is dominated by Ci, As, and Ac, and other clouds are rare. In the upper layer of multi-layer clouds, Ci occupies a higher proportion. In short, except for a few cases, occurrence frequency of eight major clouds in different regions has significant seasonal variations. Except for the obvious regional differences of the cloudtop height and cloud thicknesses of the Ns in the lower three-layer cloud and of the cloudtop height, cloutbase height and cloud thickness of the Dc in each cloudlayer, there is no obvious seasonal variation or regional difference in the cloudbase height, cloudtop height and average thicknesses of clouds in different cloudtype. These results provide insights into the nature of precipitation and formation mechanisms of precipitation in the region, and provide scientific basis for rational implementation of water resources deployment.

• Study on Atmospheric Precipitable Water and Precipitation Conversion Efficiency of Muti-Year in Inner Mongolia
• WANG Huiqing;FU Yanan;BAO Fuxiang;MENG Xuefeng
• 2018 Vol. 37 (3): 786-795.  DOI:10.7522/j.issn.1000-0534.2017.00077
• Abstract ( ) HTML PDF (5995KB) ( )
• The spatial and temporal distributions of atmospheric precipitable water and precipitation conversion efficiency in Inner Mongolia region were analised by using the NCEP/NCAR reanalysis data and monthly precipitation data of 119 stations from 1961 to 2015. The results show that:(1) The average of atmospheric precipitable water in Inner Mongolia region is 8~14 mm. The atmospheric precipitable water is gradually decreasing from south to north and from east to west. The interannual variation showed a decreasing trend in recent 65 years. Influenced by front activities and the abrupt change of atmospheric circulation, there were two times of sudden growth in April and June, and one time of sudden reduction from October to November. (2) The number of water cycle in Inner Mongolia region is the highest in summer, the second in spring or autumn, and the lowest in winter, which is decreasing from northeast to southwest, and the interannual variation shows an increasing trend. (3) The main path of water transportation in Inner Mongolia region is westerly, but the southerly transportation directly lead to the increase of precipitation and water cycle. (4) Seasonal water vapor input is less than the output, which leads to an imbalance of water vapor in Inner Mongolia region. (5) The spatial distribution of water vapor flux divergence is consistent with the spatial distribution of water cycle, indicating that the number of water cycles can objectively reflect the transformation of precipitable water vapor.

• Projection of the Daily Precipitation Using CDF-T Method at Meteorological Observation Site Scale
• WU Wei;LIANG Zhuoran;LIU Xiaochen
• 2018 Vol. 37 (3): 796-805.  DOI:10.7522/j.issn.1000-0534.2017.00064
• Abstract ( ) HTML PDF (11585KB) ( )
• Based on climate change scenarios derived from 8 GCMs (Global Climate Models) and daily precipitation data during the period of 1961-2015 in Shanghai, a cumulative distribution function-transform (CDF-T) model was developed to downscale the daily precipitation on the meteorological observation site scale. The results showed that this downscaling method can improve the simulation results, which has more rain days, lower precipitation intensity and less precipitation. It shows that using the daily data in flood season to develop downscaling model can improve the CDF curve, the total amount and intensity of precipitation in flood season compared with that using whole-year daily data. Similarly, this method can improve the correlation of the observed and correct mean value of the days, amount and intensity of the rainstorm as well as the daily maximum precipitation in longer return periods. For the period of 2016-2095, it was found that the precipitation and its intensity will increase, while the rainy days both for the whole year and flood seasons will decrease in Shanghai, compared with the current stage (2006-2015). There is likely to have more drought and flood events and intensify extreme rainfall events with the increased average and extreme values of rainstorm. The daily maximum precipitation of the recurrence intervals over 50 years will decrease in the former 40 years and increase in the later 40 years in the future. Consequently, the downscaling model of CDF-T can be applied in meteorological observation site scale and provide the downscaling method and climate data for climate change projection and assessment.

• Monitoring and Analysis of the Extreme Heavy Rainfall Process on June 10, 2017 in Nanjing Using Five Near Real Time Satellite Rainfall Estimations
• LI Lingjie;HU Qingfang;HUANG Yong;WANG Yintang;CUI Tingting;CAO Shiyi
• 2018 Vol. 37 (3): 806-814.  DOI:10.7522/j.issn.1000-0534.2017.00080
• Abstract ( ) HTML PDF (11174KB) ( )
• Near real time satellite rainfall estimation (NRT-SRE) with high spatial-temporal resolution and timeliness provides an effective approach for monitoring extreme rainfall events, while its performance determines the reliability and applicability of the data. This paper comprehensively evaluated the capabilities of five NRT-SRE (including TRMM 3B42 V7, IMERG Early, IMERG Late, GSMaP NRT, GSMaP NRT Gauge) against a dense rain gauge network, for monitoring the record-broken extreme rainfall process on June 10, 2017 over Nanjing and the surrounding areas. The results demonstrated that, although two kinds of GSMaP data present notable underestimation of the accumulated rainfall, they basically capture the spatial pattern in which the cumulative rainfall is heavy in the central region while light in the northern and southern regions. However, 3B42RT V7 and two IMERG data showed poorer ability to identify the main spatial distribution characteristics of cumulative rainfall. Regarding to temporal variation of rainfall intensity, all NRT-SRE can correctly detect the extremely heavy rainfall process over Nanjing City and Jiangning District, but the dynamic tracking ability is obviously unsatisfactory with severe significant quantitative errors at the regional and grid scales. Comprehensive accuracy of GSMaP NRT is relatively higher among five NRT-SRE, while the performance of IMERG data is still poorer than 3B42RT V7. Overall, the NRT-SRE has exhibited positive performance on monitoring extremely heavy rainfall process at medium and small space scales, whereas their capabilities to capture precipitation falling areas and track temporal fluctuation of rainfall intensity need to be enhanced in practical applications.

• Application of TRIGRS Model on Rainfall-Induced Shallow Landslides Forecasting
• XU Yuanxin;GUO Haiyan;MA Zhengfeng
• 2018 Vol. 37 (3): 815-825.  DOI:10.7522/j.issn.1000-0534.2017.00065
• Abstract ( ) HTML PDF (5644KB) ( )
• The utility of Transient Rainfall Infiltration and Grid-based Regional Slope-stability Model (TRIGRS) in combination with the rainfall distribution data estimates for shallow, rainfall-induced landslides forecasting and response of rainfall are examined through model simulations of July 23th, 2010 heavy rainstorm event in Sichuan, Guangyuan. The target domain is divided into three physical property zones according to the distinct soil sediment concentration. The topographic indices of TOPMODEL (Topography based Hydrological model) are applied to calculate the soil thickness distribution and steady, pre-storm infiltration rate of the study area. Assumptions based on existing studies are used to estimate the simulation parameters. The cohesion and fraction angle values are taken based on actual physical conditions of each zone. The inputs of TRIGRS model includes the digital elevation model (DEM), slope angle distribution, soil thickness distribution and flow direction distribution of the study area, and time-varying rainfall. Combined with the simulation parameters, the TRIGRS model computed transient pore-pressure changes and attendant changes in the factor of safety (FS) due to rainfall infiltration. The every 6 h slope-instability grids given by model results matched the every 6 h rainfall accumulation distribution, consistent with the actual landslide records, indicates that the preliminary assessment of slope-stability is available over large areas. The quantitative indices and results of receiver operating characteristic of the simulation results indicated that the way of model simulating of the study area was valid for shallow landslide forecasting. Comparing the results with the shallow landslide inventory map, more than 71.1% consistency between predicted shallow landslide susceptibility and the inventory, despite the paucity of the input data. The simulation results has reasonable consistency despite some shallow landslides located in hilly area. Based on different types of rainfall forecasting products, the TRIGRS model computed the slope stability variability of target area, enabled the early warning of rainfall-induced landslides. The simulation results also showed that the slope-instability of the mountain area with larger slope degrees tended to increase with a smaller rainfall, region with smaller slope degrees endured heavier rainfall, relatively. The success index of mountain area reaches 86.67% while the success index of the hilly area is only 53.33%, yet the error index is also high in mountain area. The results indicates that the availability of TRIGRS model is impacted by the approximation of the initial topographic conditions of the target area with the infinite slope assumption. Meanwhile, the level of urbanization also generated biases in model simulation results, since the application to areas with marked soil anisotropy or heterogeneity in hydrologic properties might cause errors in the solutions.

• A Case Analysis of Nighttime Stable Boundary Layer Observation in the Hinterland of Taklimakan Desert
• ZHANG Jiantao;HE Qing;WANG Minzhong;JIN Lili
• 2018 Vol. 37 (3): 826-836.  DOI:10.7522/j.issn.1000-0534.2018.00030
• Abstract ( ) HTML PDF (5881KB) ( )
• Based on the data of GPS sounding and ground weather observation data of 13-14 and 26-27 July 2016 in the hinterland of Taklimakan desert, the vertical profile characteristics of meteorological elements was analyzed in summer clear-sky Nighttime in this paper. It is revealed that the thickness of stable boundary layer is found to be 240 m at night[from 21:00 (Beijing time, the same as after) to the next day 08:00]. The maximum thickness of the residual mixing layer is the same as that of the convective mixing layer the previous day. Over time, the maximum thickness is lost about one third at 10:15, and the thickness of the residual temperature inversion layer top cover is up to 400 m; There is a maximum of wind speed in the residual temperature inversion layer top cover, near stable boundary layer roof, there develop a low-altitude jet stream whose maximum wind speed has reached 10.8 m·s^-1 at 07:15; The change trend of specific humidity at the low altitude night is a process of increasing first, then decreasing and last increasing, and the minimum value is 2.95 g·kg^-1, which has appeared near stable boundary layer roof at 04:15. Specific humidity of the residual mixed layer enlarges slightly with height; the night temperature inversion layer has the effect of blocking and polymerization on water vapor flux, and makes it appear the relative maximum value in nighttime near the top of stable boundary layer and residual mixing layer, which reaches the peak value at 07:15. The vertical water vapor flux does the sinking movement in the middle to lower part of residual mixing layer, whereas does the ascending motion in the upper part of residual mixing layer and residual temperature inversion layer top cover at 04:15; At the same time, there are quite strong radiation cooling and relatively small frictional velocity in the nocturnal land surface process, which are also the main thermodynamic factors and turbulent dynamic factors that form the relatively shallow nighttime stable boundary layer.

• Comparative Analysis of Ozone Variation in UTLS due to Different Types and Intensities of Cut-off Lows over East Asia
• ZHOU Tianjiao;CHEN Dan;WANG Yongqing;GUO Dong
• 2018 Vol. 37 (3): 837-849.  DOI:10.7522/j.issn.1000-0534.2017.00079
• Abstract ( ) HTML PDF (23688KB) ( )
• The combinative ERA-Interim high resolution ozone reanalysis data and NCEP reanalysis data were used to comparatively analyze the variation of ozone in the UTLS (Upper Troposphere-Lower Stratosphere) caused by stratospheric intrusion during different types ("shallow" type and "deep" type) and different intensities (focus on "deep" type) of cut-off lows over East Asia. The results showed that the stratospheric ozone intrusion occurs in all the "deep" and "shallow" type of cut-off lows. The ozone increment in the "shallow" type of cut-off low is comparable to the "deep" type at 300 hPa. Therefore, in the process of the STE (Stratosphere-Troposphere Exchange) during cut-off lows, the role of "shallow" type of cut-off lows can not be ignored. In the vertical distribution of ozone variation, due to the vertical structure of the cut-off lows, ozone increase mainly covers from upper troposphere to lower stratosphere in the "deep" type cases, while the "shallow" type cases concentrate on upper troposphere. In addition, the distribution patterns of the UTLS ozone imply that the value of ozone content and the range of high ozone content are related to the intensity of the system itself. The range of ozone positive anomalies is larger and the increase of ozone concentration is higher in stronger "deep" type of cut-off lows than that of weaker cases at 300 hPa. In the "deep" type cut-off lows, the descending depth of dynamical tropopause and the ozone concentration of the intrusion in stronger cut-off lows are much larger than those of weaker cut-off lows. Meanwhile, the jet with different types of cut-off lows has the same intensity, while the vertical range of those with the "deep" type of cut-off lows is much larger. The ozone average of 11 years and the ozone average in the month that the systems happened of 11 years were used as standards of ozone anomalies for comparative analysis respectively. The results showed that the comparison results of ozone in different types and intensities of cut-off lows are not affected by using different mean ozone value as the criterion of anomaly.

• Large Eddy Simulation Study of Effects of Convective Cold Pools on Dust-Uplift and Transportion of Black Storm
• ZHANG Junxia;HUANG Qian;TIAN Wenshou;GUO Zhenhai;TIAN Hongying;WU Xixi
• 2018 Vol. 37 (3): 850-862.  DOI:10.7522/j.issn.1000-0534.2018.00046
• Abstract ( ) HTML PDF (18815KB) ( )
• Using temperature profiles observed from Dunhuang meteorological station during the intensive period of a land-atmosphere interaction field experiment over the arid region of North-west China as initial field for the Large Eddy Model (LEM), characteristics of turbulent structure of convective cold pool and effects of turbulence of the cold pool head and tail on dust uplifting and vertical transportation were investigated by setting cold source in the model. Furthermore, sensitivity tests with varying cooling rate and the size of cold source in the model center were performed to study the effects of intensity and scale of the cold source on the turbulent structure of convective cold pool, the propagation velocity of leading edge of cold pool and the dust uplifted rate, etc. The results show that:(1) The simulated structural characteristics of the convective cold pool are consistent with observations. The head of the convective cold pool is a large turbulent vortex. There is a weaker and smaller turbulence in the tail due to effects of blocking of downdraft from head's vortex and the wind shear. Turbulence in the tail becomes weaker if it is far from the head. (2) Dust uplift potential (DUP) caused by the head vortex is much larger than that of the tail. Dust is largely trapped in the well-mixed cold-pool density current except that only a small fraction of dust diffuses outside the cold pool. The absolute concentration of dust in the head is about twice as much as that in the tail. (3) Simulated results by changing cooling rate and size of cold source in the LEM presented that intensity and moving speed of leading edge of cold-pool density current increases with increasing cooling rate and size. It leads to that more dust is uplifted from the surface and more dust is transported to the higher altitude due to the enhanced turbulence of the cold pool, but cold pool becomes less long-lived because of the stronger entrainment of the ambient air with increasing cooling rate and size.

• Analysis of Continuity of Fog, Light Fog and Haze Climate Series by Automatic Identification and Manual Observation
• REN Zhihua;YU Yu;HAN Rui;FENG Mingnong
• 2018 Vol. 37 (3): 863-871.  DOI:10.7522/j.issn.1000-0534.2018.00007
• Abstract ( ) HTML PDF (15611KB) ( )
• Based on the fog, light fog and haze daily data from more than 2 400 national level surface stations, comparisons were made between the statistics of 2014 and their historical series. Results showed that the national mean fog, light fog and haze days were 20, 154 and 59 respectively and were all highest values from the year of 2000. Especially, haze day of 2014 was 4.2 times of the means from 2000 to 2013, which may not match the actual conditions. Further analysis were presented by dividing the stations into two parts, as about 963 stations were carried out automatic identifications of the vision obstruction weather phenomenon from the beginning of 2014, while the other stations still maintained manual observations. The mean fog, light fog and haze days of manual stations in 2014 were close to their averages of recent decade and the statistics of 2013. As for the automatic stations, the mean values were rocketed to the highest starting from the year of 2000 and were extremely higher than the statistics of 2013. Through the analysis of the differences between automatic and manual observation methods and their data, the unusual higher values in 2014 were mainly ascribed to the weather phenomenon identification employed by automatic stations, as instantaneous occurrences of fog, light fog and haze were improperly written into the daily records. Based on the characteristics of haze persistence, correction method was studied on haze identification at automatic stations by using present weather phenomenon data. When at least six consecutive present weather phenomenon occurred in one day, haze was then written into the consecutive weather phenomenon record, i. e. the daily record and that day was consequently identified as a haze day. This method was verified by comparing the corrected data with the air quality conditions between 2013 and 2014 in 74 cities released by the Ministry of Environmental Protection, which shown a good agreement. The national mean haze day number of 2014 dropped down to about 31 days from about 59 days after correction, and the revised mean value was equal to that of 2013. The corrected data indicated that haze occurrence frequency had an increasing trend, and it peaked at 2013 and 2014 from the year of 2000.