Summer precipitation characteristics on the southern Tibetan plateau

Abstract

Precipitation is an important source of streamflow and a critical parameter in hydrological studies. However, spatiotemporal variation of precipitation in the Tibetan Plateau (TP) has been poorly characterized due to the limited distribution of meteorological stations mostly in the lowlands. In this study, we setup rain gauges to study summer precipitation on mountain slopes in three catchments of the southern TP from 2013 to 2016. We studied the precipitation gradients (PGs) averaged during the Indian monsoon season (PG ms), as well as daily PGs (PG d) and unit PGs (PG u) under various precipitation intensity grades (PIGs) and subdiurnal precipitation distributions. We also analysed the correlations between the PGs and precipitation amounts under various PIGs. Results showed that the mean PG ms , PG d and PG u in the study catchments were 0.0071-0.0082% for monsoon season, 0.11-0.13 mmÁ100 m −1 d −1 and 2.2-3.1%Á100 m −1 for the total (nonintensity-graded) precipitation, but varied widely under different PIGs. PG ms , PG d and PG u were all strongly correlated to precipitation amounts, which were relatively consistent between years but varied between different catchments. In addition, the correlations showed a steep positive slope under fine precipitation but became flat or even negative with increasing PIG. Generally, two distinct precipitation peaks were noted in each of the three catchments: a dispersed peak in the morning, and a stronger but sharper peak at around 18:00 LST; overall, this subdiurnal pattern was temporally stable. The mean precipitation durations of the three catchments were approximately 1.0-1.4 hr (nonintensity-graded) and increased from <0.5 hr, to <1 hr, 2-5 hr and 6-11 hr for trace, light, moderate and heavy precipitation intensities, respectively. Among the various PG units, both PG d and PG u better represented precipitation at different altitudes than that of PG ms. Summer precipitation in the study catchments was influenced more by valley-scale convection than by large-scale monsoon circulation.

Characterizing basin-scale precipitation gradients in the Third Pole region using a high-resolution atmospheric simulation-based dataset

“…3b and Table 2, a large positive APG mainly occurs in the inner TP, with an average value of 0.07 mm d −1 × 100 m −1 , followed by the eastern TP (covering the Yellow, Yangtze, Lancang and Nu River basins) (0.06 mm d −1 × 100 m −1 ), the Yarlung Tsangpo River basin and the Qaidam basin (0.05 mm d −1 × 100 m −1 ), and the upper Indus has the smallest APG of 0.04 mm d −1 × 100 m −1 . In some specific regions, such as the Qilian Mountains (Wang et al, 2009;Han et al, 2020) and some small basins in the southern TP (Wang et al, 2018b;Zeng et al, 2021;Zhang et al, 2015), where the observed precipitation generally increases with altitude, our study reports consistent results. Notably, most sub-basins along the Himalayas show large negative APGs.…”

Influences of Summer Precipitation Occurrence Time on Raindrop Spectrum Characteristics over the Northeastern Tibetan Plateau

“…During the summer monsoon season, the TP is intruded on by a warm humid southerly airflow, which may induce active moist convection over the TP [12][13][14][15]. The formation and development of convective clouds and the diurnal cycle of convection are strongly influenced by the topography of the TP [16,17].…”