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Accueil du site → Doctorat → Hong Kong → Heterogeneous changes in hydrologic system of the Tibetan Plateau in response to climate variability : application of multi-source satellite data

The Chinese University of Hong Kong (2014)

Heterogeneous changes in hydrologic system of the Tibetan Plateau in response to climate variability : application of multi-source satellite data

SONG, Chunqiao

Titre : Heterogeneous changes in hydrologic system of the Tibetan Plateau in response to climate variability : application of multi-source satellite data

Auteur : SONG, Chunqiao

Université de soutenance : The Chinese University of Hong Kong

Grade : Doctor of Philosophy (PhD) 2014

Résumé
he Tibetan Plateau (TP) and surrounding mountains are known as the Third Pole, with an average elevation of 4,000 meters above sea level. It holds the largest reserves of glacier ice outside of Antarctica, Greenland, and Canada. It is thus referred as Asian water towers, which form the source of more than ten major rivers in Asia. In the broad basins of the inner plateau, there are more than one thousand lakes, mostly featured by closed watersheds. In the context of climate change and variability, regional terrestrial water storage (TWS) budgets of the TP are critical terms in the global water balance, yet they are poorly observed at high altitude. Thus new strategies are required to investigate changes of mountain glaciers and lakes in the high-altitude hydrologic system. Multiple remote sensing techniques are deployed here to address questions in high-latitude hydrology.

The temperature of the TP has risen rapidly since the 1980s, but spatio-temporal variability of precipitation remains unclear partly due to more spatial incoherence in precipitation variation. Eight gridded precipitation datasets are inter-compared with each other and evaluated by gauge-based data over the TP and surroundings between 1979 and 2011. The results show that the GPCP, CMAP-1/2 andPREC/L precipitation data agreebetter with gauge-based precipitation. The two reanalysis data havethe weakest correlations with gauge-based data, and the APHRODITE and TRMM data arein between. Analyses of precipitation trends based on the GPCP, CMAP-1, PREC/L and APHRODITE datasets consistently reveal that an obvious increase isobserved in the inner TP since the mid-1990s and insignificant decreasing trends areobserved in the southeastern TP. In the Himalayas, the precipitation trends are rather inconsistent among the four datasets. Comparisons of the GRACE TWS changes and precipitation variability between 2003 and 2011 show that increasing precipitation in the central and northeastern TP and decreasing precipitation in the Tienshan Mountainsaretightly associated with the TWS variations in the two regions. However, there arerelatively lower correlations between TWS changes and precipitation in the Himalayas and southeastern TP. It implies that there areprobably other factors(such as glacier meltwater loss induced by warming climate)which are also correlated with the GRACE-observed mass changes

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