Plateau Meteorology

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28 August 2004, Volume 23 Issue 4   
  • Analyses of the Impacts of Upper-Level Temperature and Height Anomalies on Surface Air Temperature and Precipitation in China
  • QIAN Yong-fu;ZHOU Ning-fang;BI Yun
  • 2004 Vol. 23 (4): 417-428. 
  • Abstract ( ) PDF (628KB) ( )
  • The time-lag and the spatial coupling relationships between the anomalies of the monthly mean 300 hPa temperature (hereafter the upper level temperature) and the 100 hPa height (hereafter the upper level height) fields taken from the NCEP/NCAR 1958-1997 reanalysis data and the anomalies of Chinese monthly mean surface air temperature and monthly precipitation observed at the 160 stations are diagnosed by use of the SVD technique.The influences of the spatial and temporal variations of the upper-level temperature and height anomalies on anomalies of Chinese temperature and precipitation are carefully analyzed.It is found that the integral spatial distribution patterns of the upper-level temperature and height anomalies have important impacts on China's temperature and precipitation anomalies, the upper-level anomaly fields in different regions are responsible to anomalies of surface temperature and precipitation in different areas in China.The Iranian and the Qinghai-Xizang Plateaus and the low-latitude zone in the tropics and subtropics to the south of the Plateau are the key regions of the upper level fields.The influences of the anomaly of the upper-level temperature(height) are of evident interannual(interdecadal) on the temperature and precipitation in China.The Yangtze River basin, the Yellow River valley, South China and the south-of-the-Yangtze-River district are the most influenced areas by the upper-level temperature and height anomalies.
  • Climate Characters and Changes in Global Land Precipitation Field From 1920 to 2000
  • SHI Neng;CHEN Lu-wen;FEN Guo-ling;GAO Hong;LING Zhen-min;GUO Li-na
  • 2004 Vol. 23 (4): 435-443. 
  • Abstract ( ) PDF (374KB) ( )
  • Analyses of global land precipitation data fields from 1920 to 2000 show that the largest rainfall occurred in the monsoon areas where it exists clear rainy and dry seasons.The latitudinal distribution of global land mean annual rainfall showed continuity, i.e.climate in the tropics was wet, and rainfall was reduced northwards and southwards from the equator respectively.However, rainfall in the southern mid-high latitudes of 40°~50°S was relatively larger, thus precipitation in the Southern Hemisphere displayed a latitudinal distribution of double peaks.Period and trend analyses of annual and seasonal average precipitation series over global land show that the global land precipitation series showed obvious 2~7 years and interdecadal variations.During 1920_2000, except precipitation in winter exhibited a weak positive trend, it showed no clear trend in the other seasons.The long term trend of annual and seasonal precipitation over global land and its geographic distribution were also analyzed and compared with each over in this paper, and it is pointed out that precipitation in 0°~10°S of the Southern Hemisphere showed a weak negative trend in spring, and a positive one in the other seasons.The positive trend in winter was obvious but not significant.Precipitation in the zone 10°~25°S displayed a positive trend in winter and autumn, and a negative one in summer, and those trends all were not significant yet.In the zone 20°~40°S, the positive trends of summer/autumn precipitation were significant at 0.01 level.In the Northern Hemisphere, the tropical area to the south of 25°N, precipitation showed a negative trend in all seasons, and especially the negative trend of autumn was significant at 0.01 level.In the area to the north of 30°N, except the precipitation trend in the zone 30°~40°N was negative in winter, those in other seasons all were positive.In the zone 45° ~55°N, the positive trend of precipitation was most obvious in spring, and in the further north area, the positive trend of winter precipitation was especially evident.
  • Relation Between 300 hPa Temperature Anomalies over Iranianand Qinghai-Xizang Plateaus and Precipitation of China
  • BI Yun;XU li;QIAN Yong-fu
  • 2004 Vol. 23 (4): 465-471. 
  • Abstract ( ) PDF (340KB) ( )
  • Since 300 hPa temperature field can reflect the thermodynamic anomalies of Iranian and Qinghai-Xizang Plateaus(IQXP), the relation between 300 hPa temperature and precipitation of China is analyzed by using SVD expansion.The results include: (1) There exists the obvious positivie correlation between the 300 hPa temperature in April over the south of Iranian Plateau and the mid- and east-Qinghai-Xiang Plateau and the precipitation in May to the south of upper reach of Yellow River.(2) There are the clear negative correlation between the 300 hPa temperature from April to June over most of IQXP and the precipitation in July (especially their south part) and to the south of mid- and lower-reaches of the Changjiang River.(3) Between the 300 hPa temperature from April to August over most of IQXP(especially their south part) and the precipitation in September to the south of lower reach of Yellow River has positive correlation.(4) Negative correlation between 300 hPa temperature from June to Octomber of last year over the middle part of IQXP and precipitation in January of this year in mid- and lower-reaches of the Changjiang River and to the south of it is obtained.(5) Negative correlation between 300 hPa temperature from June to Octomber of last year over Iranian Plateau(in particular its mid- and south-parts) and precipitation from April to May of this year in mid- and lower reaches of the Changjiang River is obtained.(6) And also there are the negative correlation between 300 hPa temperature from September to Octomber over mid- and south-parts of IQXP and precipitation in November over the partial area to the south of mid- and lower reaches of the Changjiang River.
  • Calculation of Global Characteristics of NO X Produced by Lightning
  • SUN An-ping;DU Jian;ZHANG Yi-jun;YAN Mu-hong
  • 2004 Vol. 23 (4): 481-487. 
  • Abstract ( ) PDF (321KB) ( )
  • The Optical Transient Detector(OTD) lightning data provided by NASA were used to estimate the temporal and spatial distributions of lightning-produced NO X.The results indicate that the maximum concentration of LNO X occurred in lower latitude region, making up approximately 65% of global total LNO X.The LNO X amount was symmetry in low latitude and unsymmetry in mid- and high latitude regions between Northern and Southern Hemispheres.The LNO X amount was far larger in Northern than in Southern Hemispheres.There were 6 thunderstorm groups in global area.The largest NO X was produced in Africa thunderstorm group with one fourth of global total amount, the two secondary maximum occurred in North and South Americans.The main regions of LNO X in China appeared to the south regions of Changjiang River and all of the LNO X in China makes up 7.8% of global total amount.The LNO X in Qinghai-Xizang Plateau was 9.1%~12.2% of the total amount in China with an average of 10.2%.The average global LNO X amountin four seasons were 42.5 kt (spring), 67.0 kt (summer), 51.4 kt (autumn) and 37.4 kt (winter), respectively.The annual global LNO X was estimated as 200 kt.
  • Spatial and Temporal Distributions of Lightning Activitiesin China from Satellite Observation
  • YUAN Tie;QIE Xiu-shu
  • 2004 Vol. 23 (4): 488-494. 
  • Abstract ( ) PDF (585KB) ( )
  • The spatial distribution, seasonal and diurnal variations of lightning activities in China are examined by using the eight years (from April 1995 throughout March 2003) observation data from the optical sensors on satellites.The result indicates that there are four belts of lightning activities that run parallel to the seashore: Near to the sea region, middle region, western region, and western boundary region of China.The flash densities in southeastern seaboard is the highest, and it is gradually decreasing to western region of China, so that in western region is the lowest.The lightning activities clearly show seasonal and diurnal variations in China.On the average, the summer is the main lightning activity season with a percentage of 68 in a whole year lightning activity, spring season follows with a percentage of 24, then autumn, and the minimum lightning activity season is winter.The maximum Lightning activity is in August, and the mimimum is in November.There is a clear tendency that lightning activities increase with the decreasing of latitude in every season.It is shown that lightning activities in China primarily occur between afternoon and early evening, and a few lighting occurs during nighttime.

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