This study aims to evaluate the performances of two latest released GPM-era satellite precipitation final run products (IMERG-V06B and GSMaP-V07) and one TRMM-era product (TMPA-3B42-V07) at hourly, daily and monthly scale over the TP, with special focus on the performances at different rain intensities, sub-basins, and elevations at daily scales. Besides, hourly scale evaluations were carried out for one grid box value of IMERG-V06B and GSMaP-V07 versus 15 rain gauges on the rainy season, 2019. Results indicated that (1) GSMaP-V07 outperformed TMPA-3B42-V07 and IMERG-V06B with higher CC and lower RBias, MAE, and RMSE values at daily and monthly scale. (2) Satellite products showed overestimation during light rain and underestimation throughout moderate rain, heavy rain and rainstorm; (3) Satellite products have performed relatively better in lower elevation (4000 m). (4) Satellite precipitation products performed better in the source region of the Yellow River (SRYR), Yangtze Rivers (SRYZR), Lancang River (SRLCR), and Nujiang River (SRNR) basins, while the products greatly overestimated the precipitation in the source region of the Yarlung zangbo River (SRYLZB) basin. In arid climate regions (Qiangtang Basin and Qaidam Basin), GSMaP-V07 had better performances than other products; (5) Although GSMaP-V07 showed higher overestimation than IMERG-V06B product at hourly scale, it has better consistency with rain-gauge observations. For satellite precipitation data application within the TP, we recommend the GSMaP-V07 over the IMERG-V06B. Furthermore, improvement on the multi-satellite rainfall retrieval algorithm is required.
4 February 2022 in Paleoceanography and Paleoclimatology
Loess sequences in the eastern Tibetan Plateau (TP) are valuable paleoenvironmental archives for reconstructing the environmental history related to the Indian summer monsoon (ISM). We conducted a detailed environmental magnetism analysis of the Ganzi loess sequence that developed since the Last Interglacial (LIG) and reconstructed the paleo‐precipitation history by analyzing multiple magnetic parameters. Our results are as follows: (a) Magnetic minerals of the Ganzi loess are mainly maghemite and magnetite, with high concentrations of magnetic minerals in the paleosol layer. The pedogenic ferrimagnetic particles dominated the magnetic enhancement, and magnetic parameters can be used to reconstruct precipitation history. (b) Precipitation reconstructed by using the multiple magnetic parameters of the Ganzi loess shows that rainfall in the eastern TP has varied dramatically, and the wettest periods over the last glacial cycle were the LIG and the Holocene. (c) The ISM has influenced precipitation changes since the LIG in the eastern TP. The ISM and precipitation in the eastern TP were mainly driven by the combined effect of orbital changes, global ice volume, atmospheric CO2 concentration, and internal climate forcing on the glacial‐interglacial timescale.
23 June 2022 in Journal of Geophysical Research: Atmospheres
This article characterized the linear trends and interannual signals of terrestrial water storage (TWS) and meteorological variables including precipitation (P) and evapotranspiration (ET) over the arid Northwestern China (NWC). The relative impaction of P, ET, and human water utilization (HU) on TWS variation among the 10 watersheds of NWC (i.e., 5 watersheds in Xinjiang, 3 watersheds in Hexi Corridor, and 2 watersheds in Qinghai) were then investigated. The result indicated that groundwater storage (GWS) was the main contributor to the TWS variation and matched well with TWS in spatial features or watershed-scale variations. The entire NWC presented growth trends for P (0.05 cm/year) and ET (0.22 cm/year) and decline trends for TWS (−0.19 cm/year) and GWS (−0.20 cm/year). The watersheds in Qinghai province where mainly affected by natural factors showed the increasing TWS/GWS trend. The watersheds in Xinjiang and Hexi Corridor, which had strong impact from human activities generally showed the declining TWS/GWS trends, but Xinjiang showed more intensive declining trend than Hexi Corridor. The analysis of HU indicated that water sustainable management and water-saving technologies had effectively kept down the tendency of TWS/GWS declining in the watersheds in Hexi Corridor, however, they were not sufficient to address the water shortage caused by farmland expansion, slight P growth, and high ET growth in Xinjiang. Groundwater use, as the main source to compensate for the increase in HU (especially agricultural water use), exacerbated TWS/GWS loss in Xinjiang. This article provides valuable information for the water management over the arid NWC.
Aeolian sediments hold key information on aeolian history and past environmental changes. Aeolian desertification and extensive land degradation have seriously affected the eco-environment in the Gannan region on the eastern Tibetan Plateau. Understanding the history of aeolian activities can deepen our understanding of the impacts of climatic changes on aeolian activities in the future. This study uses a detailed chronology and multiple proxy analyses of a typical aeolian section in Maqu to reconstruct aeolian activities in the region during the Holocene. Our results showed that aeolian activities have occurred in the eastern Tibetan Plateau since the early Holocene. Magnetic susceptibility, grain size records, and paleosols formation indicated a trend of stepwise weakening in aeolian activities from the early Holocene to the present. The weakening of aeolian activities was divided into three stages: ∼10.0–8.0 ka BP, ∼8.0–4.0 ka BP, and ∼4.0 ka BP to the present. Paleosols were primarily formed after ∼8.0 ka BP, and episodically interrupted aeolian activities processes in the Gannan region. Aeolian activity may increase in the Gannan region as the climate gradually warms. Climatic changes and local hydrological conditions have jointly affected the history of aeolian activities in this region.