Major Moisture Pathways and Their Importance to Rainy Season Precipitation over the Sanjiangyuan Region of the Tibetan Plateau

Abstract

Knowledge of the quantitative importance of moisture transport pathways of the Sanjiangyuan region (known as the “water tower” of China) can provide insights into the regional atmospheric branch of the hydrological cycle over the Sanjiangyuan region. A combined method with a clustering algorithm [Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN)] and a Lagrangian moisture source diagnostic is developed to identify the major moisture transport pathways and quantify their importance to three types of consecutive precipitation events—extreme precipitation (EP) events, moderate precipitation (MP) events, and extreme aridity (EA) events—for the Sanjiangyuan region during the rainy season (June–September 1960–2017). The results indicate that moisture paths from the northwest covering northwest China and central Asia (the N.W. pathway) and moisture paths from southern and southeastern China (the S.S. pathway) are stable moisture transport pathways during EP and MP events [importance (precipitation contribution in percentage): N.W. pathway, 18.4% (EP), 32.2% (MP); S.S. pathway, 25.9% (EP), 28.5% (MP)]. Affected by the western edge of a significant anticyclone anomaly centered around 35°N, 115°E, the moisture paths via the Bay of Bengal (the B.B. pathway) can reach the target region and become a supplementary moisture contributor (14.9%) to EP events. Moisture paths via the Arabian Sea and Indian peninsula (the A.I. pathway) are also active but the contributions are limited [4.9% (EP) and 5.6% (MP)]. For EA events, the fast-moving trajectories from farther western Asia (the F.W. pathway) play a dominant role and all major moisture pathways (F.W., N.W., and S.S. pathways) carry limited moisture to the target region.

Surface Heating Over the Tibetan Plateau Associated With the Antarctic Oscillation

“…In addition, due to the steep slope of the southern TP, a large amount of water vapor accumulates here (Figure 8c). All of these results are consistent with previous results (C. Zhang, 2020;Y. Zhang et al, 2019).…”

Intensified Moisture Sources of Heavy Precipitation Events Contributed to Interannual Trend in Precipitation Over the Three-Rivers-Headwater Region in China

“…Studies have further pointed out that the enhancement of the westerlies over the mid-latitude may be one reason for the continuous increase in moisture around the northwestern side of the plateau ( Liao et al, 2018). Thus, we can deduce that the neighboring west-northeastern region supplies a large amount of extra moisture for increased precipitation, with the increased moisture contribution from the ocean playing a secondary role, although the water vapor from this region has a strong correlation with the interannual variation of precipitation in the TRHR (Chen et al, 2012;Zhang et al, 2019).…”

Atmospheric Basins: Identification of Quasi‐Independent Spatial Patterns in the Global Atmospheric Hydrological Cycle Via a Complex Network Approach

“…Daily‐ or weekly‐scale moisture links may be controlled by different meso‐ and small‐scale atmospheric processes (e.g., Bohlinger et al, 2017; Huang et al, 2018; Zhang et al, 2019). To obtain relatively stable and representative moisture links, the daily moisture links of a 3° × 3° grid cell were aggregated seasonally, and the seasonal moisture links for that 3° × 3° grid cell were obtained.…”