Plateau Meteorology

Current Issue

28 April 2020, Volume 39 Issue 2   
  • Variation of Snow Cover and its Influence on Spring Runoff in the Source Region of Yellow River
  • Xiaojiao LIU;Rensheng CHEN;Junfeng LIU;Xiqiang WANG;Baogui ZHANG;Guohua LIU
  • 2020 Vol. 39 (2): 226-233.  DOI:10.7522/j.issn.1000-0534.2019.00074
  • Abstract ( ) HTML ( ) PDF (2119KB) ( )
  • Snow cover is an important component of cryosphere, and strongly affects the hydrology and climate.The eastern part of the Qinghai-Tibetan Plateau, one of the three major snow-covered areas in China, is the source region of Yellow River, which has great impact on both climate change and water resource system.Based on the Yellow River source region data of snow depth, meteorological and measured runoff from 1978 to 2016, the characteristics of snow cover and its influence on spring runoff of this area were studied through the Mann-Kendall test, linear analysis and correlation analysis.The results showed that: (1) From 1978 to 2016, the source region of Yellow River revealed a tendency of a delayed initial snow date, forwarded final snow date, and declination of both duration and number of snow days.Particularly, the initial snow date, the final snow date and the duration of snow days passed the significant tests of p <0.05, p<0.05 and p<0.01, respectively.(2) The annual average snow depth had no significant change from 1978 to 2016 in this area.However, it showed a significant upward trend since the end of the 21 century and passed the significance test of p<0.1.(3) In general, compared with the snow depth, the number of snow days has more impact on the spring runoff in the source region of Yellow River.More specifically, according to the sensitivity analysis of the data from 1978 to 2016, 1% change of the of snow day number would induce of 0.60% spring runoff change, while the same amount change of the snow depth would only induce 0.25% spring runoff change.In addition, the spring runoff in April and May is more sensitive to snow cover change than March due to the increased average temperature and the larger amount of melted snow.(4) Different precipitation and temperature generates different snow cover, which results different responses to spring runoff.The snowmelt runoff is advanced under the climate warming, which shows an upward runoff trend in March while a downward trend in April and May.Meanwhile, due to the change of the regional atmospheric water vapor content, the spring runoff in the Yellow River source region significantly increased since the end of the 21 century.
  • Change Characteristics of Precipitation and its Cause During 1979 -2016over the Qinghai-Tibetan Plateau
  • Jianwei XU;Yanhong GAO;Baofa PENG;Xiaqing WANG
  • 2020 Vol. 39 (2): 234-244.  DOI:10.7522/j.issn.1000-0534.2019.00029
  • Abstract ( ) HTML ( ) PDF (6690KB) ( )
  • Precipitation change characteristics and its cause based on water vapor flux change in 1979 -2016 over the Qinghai-Tibetan Plateau (QTP) was analyzed, using precipitation observation from 83 stations and upper atmospheric fields from ERA-Interim.Main conclusions are drawn as following: (1) Annual precipitation averaged over the QTP shows increasing but non-significant trend in 1979 -2016.Precipitation significantly increases with the trend of 4.25 mm·(10a)-1 in May, but significantly decreases in December.Precipitation in September decreases at first and then increases.Annual variation shows different change characteristics in different climatic regions over the QTP.According to the changes in intra-annual distribution and peak value, 11 climatic regions can be classified into three types: 3 regions with large increase in peak value including southern Tibet, southern Qinghai and Chang Tang Plateau semi-arid region, 4 regions with large change in intra-annual distribution including east Himalaya and Southeast Hengduan Mountains humid region, north central Hengduan Mountains semi-humid region and Ali arid region, 4 regions with less change including Qilian Mountains semi-arid region, Chaidamu arid region, Ruoergai humid region and Guoluo semi-humid region.(2) In the case of precipitation trend distribution, most of the stations show increasing trend over the QTP in May, particularly for the middle region with significant change.Trends in December show overall decrease.(3) The distributions of water vapor flux divergence change are in good agreement with the distributions of precipitation trends in May, September and December.Advance and enhancement of South Asia monsoon brings more humid southwesterly, making more precipitation over the QTP in May.While in December, an anomalous anticyclone exists in the East Asia at 500 hPa, resulting in intensified northerly and associated dry cold air over the QTP, which leads to less precipitation.
  • Analysis of Thermal-Moisture Conditions of Active Layer and Energy-Water Balance of Land-Atmosphere System in Tanggula Area
  • Linmao GUO;Juan CHANG;Jian ZHOU;Hongliang XU
  • 2020 Vol. 39 (2): 254-265.  DOI:10.7522/j.issn.1000-0534.2019.00088
  • Abstract ( ) HTML ( ) PDF (2434KB) ( )
  • The thermal-moisture conditions of the active layer and the energy-water exchange between land-atmosphere system directly affect the ecological environment, hydrological process and the stability of the permafrost in cold regions.The soil temperature and moisture contents within the active layer at Tanggula station in 2007 were simulated by SHAW model.In terms of soil temperature, the Nash efficiency coefficient (NSE) is greater than 0.93, and the average value of the NSE between simulated and measured soil moisture is 0.69, indicating that the SHAW model can perfectly simulate the thermal-moisture dynamics within the active layer of permafrost regions.Based on the output of SHAW model, the variation characteristics of water dynamics and surface energy budget during the process of soil freezing and thawing in the active layer of Tanggula station were analyzed and discussed.Results showed that: (1) During the freezing and thawing process of the active layer, the soil moisture freezing and thawing response time gradually lagged with the increase of soil depth, and the water migration flux decreased with soil depth, and during the freezing period, the soil moisture has a characteristic of two-way convergence to the surface and deep layers; (2) Under the combined influence of the monsoon activities and the freezing-thawing process in the active layer, the surface energy budget showed obvious seasonal variation characteristics.The effect of vegetation on soil evapotranspiration in permafrost regions was investigated by changing the leaf area index in the vegetation input parameters of the SHAW model.Results showed that there was a positive correlation between vegetation transpiration, soil evaporation and total evapotranspiration and leaf area index of vegetation, while shallow soil moisture content (at 20 cm) showed a negative correlation when leaf area index varied from -100% (bare soil) to 100%, the total evapotranspiration varied from -5% to 13%.
  • Bias Correction of Climate Model Precipitation in the Upper Heihe River Basin based on Quantile Mapping Method
  • Huajin LEI;Jiapei MA;Hongyi LI;Jian WANG;Donghang SHAO;Hongyu ZHAO
  • 2020 Vol. 39 (2): 266-279.  DOI:10.7522/j.issn.1000-0534.2019.00104
  • Abstract ( ) HTML ( ) PDF (4882KB) ( )
  • Regional climate model precipitation makes up for the deficiency of scarce meteorological stations in the alpine and cold mountains, which is an important variable of hydrological simulation.However, there is great uncertainty of model outputs in alpine region, both in the total amount and frequency.In view of this, we have improved the existing quantile mapping method (QM) for precipitation frequency correction, and corrected the daily precipitation simulated by WRF model of the upper reaches of Heihe river.Precipitation at the 95th and 98th percentiles were selected as the threshold, and 2004 -2009 as the modeling period and 2010 -2013 as the validation period.The transfer function was established by piecewise fitting method, focusing on correct the simulated extreme precipitation separately.The results show that the method not only has a significant improvement on the spatial distribution of precipitation, but also has a great correction effect on extreme precipitation.Before the correction, the RMSE between the sinulated and the stations precipitation was 3.41 mm·d-1, and the absolute deviation was 115.67 mm·y-1.After correction, the RMSE was reduced to 3.11 mm·d-1, and the absolute deviation was significantly improved to 60.3 mm·y-1.The spatial distribution of annual precipitation in the basin improved obviously, and the annual precipitation amount is closer to the precipitation interpolated, the spation correlation coefficient increased from 0.74 to 0.94.The correction effect in spring and summer is better than that in autumn and winter, among which the correction effect in summer is the most obvious.Before the correction, precipitation deviation during -0.1~0.1 only accounts for 28% of the total area of the basin, while after the correction the proportion increased to 66%.At the same time, this method performs well in extreme precipitation correction, reduces the simulation deviation of simple daily intensity index (SDII) and very extremely precipitation(R99p), the correlation coefficient of simulated and interpolated precipitation at the 95th percentiles was improved from 0.15 to 0.48.This study provides a more effective bias correction method for the upper Heihe river with scarce stations, which is conducive to obtaining more accurate precipitation data for the hydrological research of the cold regions.
  • A Case Study of a Heavy Rainstorm in Hunan Triggered by the Induced Cyclone of Southwest Vortex
  • Jinqing LIU;Ziliang LI
  • 2020 Vol. 39 (2): 311-320.  DOI:10.7522/j.issn.1000-0534.2019.00028
  • Abstract ( ) HTML ( ) PDF (12578KB) ( )
  • Based on the NCEP reanalysis data and the conventional station precipitation data, the structural evolution features and the dynamic mechanism of the large-scale heavy rainstorm in Hunan Province of the induced cyclone of a Southwest Vortex (SWV) that took place from 14 to 15 May 2013 were studied, and the Okubo-Weiss (OW) parameter and the Potential Vorticity (PV) were used to analyze the development of the shear line and the induced cyclone of SWV.The results show that: （1）The strong precipitation in Hunan Province was a typical heavy rainstorm process triggered by the induced cyclone of SWV.At the generation stage of the cyclone wave, the SWV wind field changed from a symmetrical structure to an asymmetric structure.At the maturity stage of the induced cyclone, the SWV wind field developed into a symmetrical structure again.The instability on the horizontal shear line provided favorable environmental conditions for the generation of cyclonic disturbances, which caused the cyclone wave induced by SWV to move eastward along the horizontal wind shear and produce a heavy rainstorm.（2）Before the cyclone wave was generated, the SWV and the vorticity band of the westerly flow were shown as the OW parameter and the PV large value area, and the periphery of SWV was a surrounding negative-value area of the OW parameter, which was conducive to the generation and stability of the shear line.After the vorticity band was combined with the wind shear, the rotation of shear line is enhanced, and the rotation of the wind field induced cyclonic disturbance.（3）The main reason for the development of the induced vortex was that the cyclone wave accumulated positive vorticity under the favorable high and low altitude situations, and the area of OW maxima and the area of PV maxima overlapped to exceed the stagnant SWV.
  • Influence of the South-North Displacement of South Asia High on the Distribution of Atmospheric Composition in the Upper Troposphere-Lower Stratosphere over the Asian Monsoon Region
  • Houwang TU;Hongying TIAN;Xiran XU;Ruhua ZHANG
  • 2020 Vol. 39 (2): 333-346.  DOI:10.7522/j.issn.1000-0534.2019.00054
  • Abstract ( ) HTML ( ) PDF (19544KB) ( )
  • Using the ERA-Interim reanalysis data provided by the European Centre for Medium-range Weather Forecasts (ECMWF) and the atmospheric composition data provided by the Microwave Limb Sounder (MLS)， the impacts of the south-north displacement in the South Asia High (SAH) on the distribution of water vapor， ozone (O3) and carbon monoxide (CO) in the Upper Troposphere Lower Stratosphere (UTLS) of the Asian monsoon region are analyzed.The results show that： (1) Water vapor and CO at 200 hPa are higher over the Iranian plateau， northeastern Tibetan Plateau and northeastern China during northward displaced SAH (NSAH) than those during southward displaced SAH (SSAH)， except in the north of the Bay of Bengal and in the northern part of the Indochina Peninsula.At 100 hPa， the water vapor in the SAH range during NSAH is higher than those during SSAH， while the CO is higher during SSAH than those during NSAH.At 68 hPa， CO in the SAH range during NSAH are weaker than those during SSAH.The distribution of ozone at different heights is roughly opposite to those of CO.(2) During NSAH the convection activities in the west and north side of SAH is stronger than those during SSAH and the intensity of SAH north of the 30°N is also stronger than those during SSAH.Stronger convection during NSAH leads to more lower-tropospheric air transporting upwards， resulting in the higher (lower) values of water vapor and CO (O3) at 215 hPa over the Iranian plateau and Qinghai-Tibet Plateau to the northeastern China than those during SSAH.(3) At 100 hPa， the geopotential height in the south of the anticyclonic circulation is higher and the vertical ascending motion is stronger during SSAH than those during NSAH.Thus， tropospheric air with high concentration water vapor and CO and low concentration ozone are transported upward.As a result， the concentration of 100-hPa CO (O3) at 100 hPa is stronger (lower) during SSAH than that during NSAH.For the water vapor， the tropopause temperature in the SAH area is lower during SSAH.Effected of “condensation and dehydration”， the 100-hPa water vapor in the SSAH is lower than that in the SSAH.(4) The “trapping” effect during SSAH is weaker than those during NSAH， causing the stronger ascending motion and transporting more air with higher (lower) concentrated CO (O3) to 68 hPa.
  • Multi-Scale Analysis of Shallow Soil Temperature Changes of Jianghuai Region in Recent 36 Years
  • Tian LIU;Xiaoqing GAO;Liwei YANG;Ya ZHOU
  • 2020 Vol. 39 (2): 357-366.  DOI:10.7522/j.issn.1000-0534.2019.00038
  • Abstract ( ) HTML ( ) PDF (2326KB) ( )
  • Based on shallow soil temperature series of 28 meteorological stations in Jianghuai region of China from 1981 to 2016, the Empirical Orthogonal Function (EOF) and Ensemble Empirical Mode Decomposition (EEMD) methods were used to analyze the oscillation rules of 0~20 cm soil temperature and air temperature on multiple time scales in Jianghuai region.The result shows that there is obvious spatial consistency in Jianghuai region, and the feature vector shows negative all over Jianghuai region.And the time coefficient changed from positive to negative in the middle and late 1990s.The interannual and decadal variation characteristics of the soil temperature in the range of 0~20 cm and air temperature and the variation characteristics of the soil temperature for the extended-range were analyzed by using EEMD.The results show that from 1980 to 2016, the shallow soil temperature and air temperature in Jianghuai region fluctuated and rose, in which the climate inclination rate of the 0 cm soil temperature was 0.65 ℃·(10a)-1, and the rise was greater than that of the air temperature and the 5~20 cm soil temperature.The cycles of the IMF1 and IMF2 components of the four-layer shallow soil temperature and air temperature after EEMD decomposition were quasi-3 and quasi-7-years, and the amplitude in the 1980s was smaller than that in the following years, it means that the shallow soil temperature and air temperature were stable and less variable in the 1980s, and the fluctuation amplitude increased in the 1990s.Interannual change is dominant in the long-term variation of air temperature and shallow soil temperature from 0 to 20 cm in Jianghuai region.The climatological normal of 0~20 cm soil temperature in 36 years was decomposed.The extension scale cycles of the shallow soil temperature of each station in Jianghuai region are basically distributed in two cycles of quasi-12 to 16 and quasi-26 to 33 days.
  • Study on the Variation Characteristics of Photosynthetic Parameters and Environmental Influencing Factors of Populus Euphratica in Desert Riparian Forest
  • Huan LUO;Jianhua SI;Chunyan ZHAO;Duan LI;Chunlin WANG
  • 2020 Vol. 39 (2): 393-401.  DOI:10.7522/j.issn.1000-0534.2019.00037
  • Abstract ( ) HTML ( ) PDF (1068KB) ( )
  • Photosynthesis is the basis of primary productivity of green plants and plays an important role in plant growth.The net photosynthetic rate is not only related to the difference of plant species, but also the influence of external environment.In this study, photosynthetic physiological parameters and meteorological environmental factors of Populus euphratica in desert riparian forest of Ejina Banner were measured under the field conditions, and their variation characteristics and influencing factors were analyzed in order to reveal the limiting factors of photosynthesis of Populus euphratica and understand the drought resistance mechanism in arid desert areas.The results showed that: (1) The diurnal variation of net photosynthetic rate of Populus euphratica showed a trend of increasing first and then decreasing.The main reasons for this change was that net photosynthetic radiation increased gradually from the morning and photosynthetic rate increased accordingly.The decrease of photosynthetic rate after 14:00 (Beijing time, the same after) is due to the gradual decrease of photosynthetic active radiation and atmospheric temperature.(2) The midday depression of photosynthesis appeared between 11:00 and 13:00 in June, July and August, and the stomatal limitation value increased first and then decreased in June, July and August.The reason for the midday depression of photosynthesis in Populus euphratica is the decrease of stomatal conductance and intercellular CO2 concentration, which belongs to the stomatal limitation of photosynthesis.(3) The variation of stomatal conductance of Populus euphratica showed a periodic fluctuation pattern, in which the fluctuation period in June and July was approximately 1 hour, that in August was 2 hours, and that in September was 4 hours.(4) The transpiration rate of Populus euphratica corresponds to stomatal conductance and fluctuates periodically, its purpose is to help improve water use efficiency of Populus euphratica and to enable Populus euphratica to pass through the extremely hot and dry summer safely.
  • The Variety of Ozone and its Relationship with Meteorological Conditions in Typical Cities in China
  • Xiaoyu YAN;Xiaohui GOU;Jing YANG;Wei ZHAO;Qing XU;Yulan LIU
  • 2020 Vol. 39 (2): 416-430.  DOI:10.7522/j.issn.1000-0534.2019.00033
  • Abstract ( ) HTML ( ) PDF (5900KB) ( )
  • Based on the ozone concentration and the meteorological elements data of the Beijing, Shenyang, Yinchuan, Chengdu, Nanjing and Guangzhou representative cities in 2014 -2016, the variation of ozone concentration and its relationship with meteorological conditions in typical cities were analyzed and compared.The results showed that the average annual ozone concentration from high to low was Nanjing>Shenyang>Beijing>Yinchuan>Chengdu>Guangzhou during 2014 -2016, and during these three years, the ozone concentration of Guangzhou decreased, the ozone concentration of Shenyang changed little, while the ozone concentration generally increased in the other cities, among which Yinchuan increased the most, and Beijing increased the least.The monthly variation of ozone concentration was greatly affected by latitude, the higher latitude, the more obvious the single peak structure of ozone concentration, and the ozone concentration in clean control point was generally higher than that in the urban area in all months.The maximum value of diurnal ozone all appeared at 15:00 (Beijing Time, the same as after)or 16:00 for the 6 cities, and the minimum value mostly appeared at 07:00 or 08:00, but the peak value, the valley value and the daily variation were obviously different in different cities.The ozone in clean control point was significantly higher than that in urban area in Guangzhou all-day, but for another cities, the difference between clean control point and urban area was small during 11:00 -17:00, and the peak concentration of clean control point in Chengdu, Nanjing and Yinchuan was even slightly lower than that in urban areas.The ozone had the strongest correlation with the temperature and sunshine time for all 6 cities, followed by relative humidity and the wind speed.The high temperature, the long sunshine and the low humidity were beneficial to the formation of ozone.In comparison, for the Beijing, Yinchuan and Shenyang with longer sunshine time, the change of ozone was more sensitive to temperature than other cities, and had a weak positive correlation with wind speed, while for the Guangzhou, Nanjing and Chengdu with higher temperature and humidity, the correlation between ozone and sunshine hours and relative humidity was better than that of the other three cities, and ozone is weakly negatively correlated with wind speed.As to regions, the correlation between ozone concentration and meteorological elements in urban was generally better than that in clean control point.

NewsDownloadMore+More+

DynamicsVideo InformationMore+More+

Links E-journal More+ More+

Official Wechat

QQ Group Chat

The system is designed and developed by Beijing magtec Technology Development Co., Ltd. with technical support: support@magtech.com.cn