LARGE MONSOON LAKES MONITORING IN CHINA EXPLOITING ENVISAT, TOPEX/POSEIDON, JASON AND ALTIKA ALTIMETRY MISSIONS: YEARLY VARIATIONS AND GLOBAL TRENDS FOR POYANG AND DONGTING LAKES (P.R. CHINA)

摘要

Ability of altimetry to be a powerful tool for inlandrnwater surfaces surveys has been demonstrated overrnlarge inland seas or large reservoirs. Asian monsoonrnlakes such as Dongting and Poyang lakes have veryrnlarge and rapid fluctuations. Levels can vary of morernthan 5 meters in one month. In this case, monitoring ofrnwater height from space is challenging.rnThe goal of this work is to improve the spacernmonitoring of these fluctuations. For this, all thernaltimeter data of the ENVISAT nominal mission hasrnbeen processed (from 2002 to 2009) over Dongting andrnPoyang Lakes. Over Dongting South Lake,rnTOPEX/Poseidon data from 1992 to 2002 and JASON2rndata from 2008 to 2011 have also been analyzed. Inrnaddition, data from the recently launched ALTIKArnaltimeter over Poyang Lake have been analyzed. Afterrndiscussion of the accuracy of the altimetric solutions,rnaltimetric series are checked against in situ water levelrnmeasurements. Maximum absolute average difference isrn0.89 m.rnAltimetric series are also checked against spacernobservations of watered surfaces. The correlation is veryrnhigh with a computed coefficient of determination R2rnequal to 0.82. The relationship between water heightrnand water extent, both derived from space sensors, arernalso analyzed allowing the segmentation of the largernPoyang depression into 8 sub basins.