| Intro |
The Qinghai–Tibetan Plateau (QTP), which has a unique and severe environment, suffers
from the absence of rainfall gauges in western arid land. Using different precipitation products in
this region would easily lead to contradictory results. To evaluate nine fine-resolution precipitation
products in the QTP, we propose a “down to top” methodology, based on water balance and drought
chain, by forecasting two accuracy assessment indices—multi-year precipitation bias and precipitation
correlation. We assessed the biases of all products in the Jinsha–Yalong, Yellow, Heihe, Yangtze,
Yarlung Zangbo catchments and interior drainage areas. And we assessed gauge-based correlation
of precipitation products, based on the correlations between precipitation product-based effective
drought index (EDI), Soil Moisture Active Passive (SMAP)-based soil moisture anomaly, and the
moderate-resolution imaging spectroradiometer (MODIS)-based normalized difference vegetation
index (NDVI) anomaly (R = 0.712, R = 0.36, and R = 0.785, respectively) for cross-sectional rainfall
observations on the Tibetan Plateau in 2018. The results showed that ERA5-Land and IMERG merged
precipitation dataset (EIMD) can efficiently close the water budget at the catchment scale. Moreover,
the EIMD-based EDI exhibited the best performance in correlation with both the SMAP-based
soil moisture anomaly and MODIS-based NDVI anomaly for the three main herbaceous species
areas—Kobresia pygmaea meadow, Stipa purpurea steppe, and Carex moorcroftii steppe. Overall,
we find that EIMD is the most accurate among the nine products. The annual average precipitation
(2001–2018) was determined to be 568.16 mm in the QTP. Our assessment methodology has a remote
sensing basis with low cost and can be used for other arid lands in the future. |
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