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

Abstract

Abstract. Altitudinal precipitation gradient plays an important role in the interpolation of precipitation in the Third Pole (TP) region, where the topography is very complex but in situ data are very sparse. This study proves that the altitude dependence of precipitation in the TP can be reasonably reproduced by a high-resolution atmospheric simulation-based dataset called ERA5_CNN. The precipitation gradients, including both absolute (APGs) and relative gradients (RPGs), for 388 sub-basins of the TP above 2500 m a.s.l. are calculated based on the ERA5_CNN. Results show that most sub-basins have positive precipitation gradients, and negative gradients are mainly found along the Himalayas, the Hengduan Mountains and the western Kunlun. The annual APG and RPG averaged across all sub-basins of the TP are 0.05 mm d−1 × 100 m−1 and 4.25 % × 100 m−1, respectively. The values of the APG are large in wet seasons but small in dry seasons, while the RPG shows opposite variations. Further analyses demonstrate that the RPGs have negative correlations with relative humidity but positive correlations with wind speed, likely because dry air tends to reach saturation at high altitudes, while stronger wind can bring more humid air to high altitudes. In addition, we find that precipitation gradients tend to be positive at small spatial scales compared to those at large scales, mainly because local topography plays a vital role in determining precipitation distribution at small scales. These findings on the spatiotemporal variations of precipitation gradients provide useful information for interpolating precipitation in the TP region.

Understanding the Asian water tower requires a redesigned precipitation observation strategy

“…Meteorological stations across the AWT are usually located in valleys or low-elevation locations for the convenience of data reading and instrument maintenance as a result, precipitation gauges at lower elevations tend to miss precipitation occurring at higher elevations which leads to underestimations of precipitation within grid cells ( 11 ). These errors are further amplified due to the existence of a considerable vertical precipitation gradient (up to a certain elevation) found in the majority of AWT regions, particularly during the prevalent snowfall months of winter and spring ( 12 ), and the gradient for the increase in precipitation with elevation was estimated typically in the range of 0.05 to 0.5% m −1 ( 13 ). A comparison of the elevation of the meteorological station and the corresponding elevation of the grid cell where the station site is located revealed that the median elevation of existing meteorological stations across the AWT is ~1 km lower than the average elevation of the corresponding grid cells (0.5° × 0.5°) ( Fig.…”

Temporal Scaling Characteristics of Sub‐Daily Precipitation in Qinghai‐Tibet Plateau

“…Besides, due to the limitation of available weather stations, some related issues such as the effects of altitudinal precipitation gradient (Jiang et al., 2022) and diurnal characteristics of sub‐daily precipitation (Li, 2018; Zipser & Xu, 2011), cannot be fully taken into account in this study. Future studies considering these could further improve the quality of the parameters data set generated.…”

The spatiotemporal variability in precipitation gradients based on meteorological station observations in mountainous areas of Northwest China

“…Previous research on the Qinghai-Tibet Plateau has shown that the relative precipitation gradient (RPG) generally decreases with increasing relative humidity, while there is a high positive correlation between wind speed and RPG (Jiang et al 2022). In this study, we investigated the impact of these two meteorological factors on PGs.…”

“…However, there are few studies on the vertical gradient of precipitation based on the Tianshan and Qilian Mountains in the arid northwest region. Large-scale changes in precipitation at the spatial scale are mainly affected by atmospheric circulation mechanisms, while relatively small-scale regional and local precipitation changes mainly rely on local terrain (Jiang et al 2022). Using yearly or monthly time scales to study the precipitation-altitude relationship is more effective (Guo et al 2022), which highlights the importance of studying the spatial and temporal changes in PG at yearly and monthly scales after regional division and is conducive to a deeper understanding of the characteristics of mountain precipitation changes in the northwestern region of China.…”