1 Houser P R. Remote-sensing soil moisture using four-dimensional data assimilation. Doctor Dissertation. Arizona: University of Arizona,1996
[2]
2 Houser P R, Shuttleworth W J, Famiglietti J S, et al. Integration of soil moisture remote sensing and hydrologic modeling using dataassimilation. Water Resour Res, 1998, 34: 3405–4320？？
[3]
3 Evensen G. Sequential data assimilation with a non-linear geostrophic model using Monte Carlo methods to forecast error statistics. JGeophys Res, 1994, 99: 10143–10162？？
6 Yang K, Takahiro W, Toshio K, et al. Auto-calibration system developed to assimilate AMSR-E data into a land surface model forestimating soil moisture and the surface energy budget. J Meteorol Soc Japan, 2007, 85A: 229–242
9 Tian X J, Xie Z H, Dai A G. An ensemble-based explicit four-dimensional variational assimilation method. J Geophys Res, 2008, 113:D21124？？
[10]
10 Tian X J, Xie Z H, Dai A G. A land surface soil moisture data assimilation system based on the dual-UKF method and the Community LandModel. J Geophys Res, 2008, 113: D14127？？
[11]
11 Tian X J, Xie Z H. An ensemble-based three-dimensional variational assimilation method for land data assimilation. Atmos Ocean Sci Lett,2009, 2: 125–129
13 Tian X Z, Xie Z H, Dai A G, et al. A dual-pass variational data assimilation framework for estimating soil moisture profiles from AMSR-Emicrowave brightness temperature. J Geophys Res, 2009, 114: D16102？？
19 Qian T T, Dai A G, Trenberth K, et al. Simulation of global land surface conditions from 1948 to 2004, part I: Forcing data and evaluations.J Hydrometeorol, 2006, 7: 953–975？？
22 Stamnes K, Tsay S C, Wiscombe W, et al. Numerically stable algorithm for discrete ordinate method radiative transfer in multiple scatteringand emitting layered media. Appl Optics, 1988, 27: 2502–2509？？
[23]
23 Stuhlmann R, Rieland M, Paschke E. An improvement of the IGMK model to derive total and diffuse solar radiation at the surface fromsatellite data. J Appl Meteor, 1990, 29: 596–603
[24]
24 Evensen G. The Ensemble Kalman Filter: Theoretical formulation and practical implementation. Ocean Dyn, 2003, 53: 343–367？？
[25]
25 Evensen G. Sampling strategies and square root analysis schemes for the EnKF. Ocean Dyn, 2004, 54: 539–560？？
[26]
26 Njoku E G, Jackson T J, Lakshmi V, et al. Soil moisture retrieval from AMSR-E. IEEE Trans Geosci Remote Sensing, 2003, 41: 215–229？？
