Analysis of the Observation Results of Temperature and Precipitation over an Alpine Mountain, the Lhasa River Basin
XIE Jian1,2, LIU Jingshi1, DU Mingyuan3, KANG Shichang1, WANG Kuikui1,2 (1. Institute of Tibetan Plateau Research, CAS, Beijing 100085, China; 2. Graduate University of Chinese Academy of Sciences, Beijing 100080, China; 3. Department of Agro-Meteorology, National Institute for Agro-Environmental Sciences, 3050053, Tsukuba, Japan)
Altitudinal and temporal distribution of surface based air temperatures and monsoon period precipitation were analysed, using an original data set, spanning Aug. 1, 2006 to Jul. 31, 2007, from 9 automated weather stations set up along an altitudinal gradient from 4300 to 5500 m a.s.l. on the southern slope of Nyainqentanglha Mountains, the Lhasa River basin. Surface based inversion was found typically during October to the following April. The annual inversion frequen- cy was 11.5% (i.e. 42 days). The lapse rate of mean annual air temperature was 0.61℃/100m for the elevation interval of 4300～5500 m. Analysis on the precipitation indicated the presence of the maximum precipitation belt (MPB) at about 5100 m a.s.l, with an increasing rate of 4～7mm/100m below the MPB. The precipitation decreased at a rate of 1.6～2.3 times of the increasing rate over the MPB. The precipitation amounts in July and August were larger than those in June and September. The intra-month distributions of precipitation were generally more homogeneous for the upper hillslope than for the lower. The precipitation events generally occurred at any time ex- cept for 4:00～10:00, with the heavy rainfall(3~14mm/h) mainly occurring within 18:00～22:00. The larger precipitation events concentrated roughly between 4650 m a.s.l. and 5100 m a.s.l.