A microwave land data assimilation system: Scheme and preliminary evaluation over China

نویسندگان

  • Xiangjun Tian
  • Zhenghui Xie
  • Aiguo Dai
  • Binghao Jia
  • Chunxiang Shi
چکیده

[1] To make use of satellite microwave observations for estimating soil moisture, a dual‐pass land data assimilation system (DLDAS) is developed in this paper by incorporating a dual‐pass assimilation framework into the Community Land Model version 3 (CLM3). In the DLDAS, the model state (volumetric soil moisture content) and model parameters are jointly optimized using the gridded Advanced Microwave Scanning Radiometer–EOS (AMSR‐E) satellite brightness temperature (Tb) data through a radiative transfer model (RTM), which acts as an observation operator to provide a link between the model states and the observational variable (i.e., Tb). The DLDAS embeds a state assimilation pass and a parameter calibration pass. In the assimilation pass, the whole soil moisture profiles are assimilated from the Tb data using an ensemble‐based four‐dimensional variational assimilation method (En4DVar). Simultaneously, several key parameters in the RTM are also optimized using the ensemble Proper Orthogonal Decomposition‐based parameter calibration approach (EnPOD_P) in the parameter optimization pass to account for their high variability or uncertainty. To quantify the impacts of the Tb assimilation on CLM3‐calculated soil moisture, the original CLM3 (Sim) and the DLDAS (Ass) were run separately over China on a 0.5° grid forced with identical, observation‐based atmospheric forcing from 2004 to 2008. Soil moisture data from 226 stations over China are averaged over seven different climate divisions and compared with the soil moisture from the Sim and Ass runs. It is found that the assimilation of the AMSR‐E Tb data through the DLDAS greatly improves the soil moisture content within the top 10 cm with reduced mean biases and enhanced correlations with the station data in all divisions except for southwest China, where the current satellite sensors may have difficulties in measuring soil moisture due to the dense vegetation and complex terrain over this region. The results suggest that the AMSR‐E Tb data can be used to improve soil moisture simulations over many regions and the DLDAS is a promising new tool for estimating soil moisture content from satellite Tb data.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Assimilation of microwave brightness temperature in a land data assimilation system with multiobservation operators

[1] A radiative transfer model (RTM) that provides a link between model states and satellite observations (e.g., brightness temperature) can act as an observation operator in land data assimilation to directly assimilate brightness temperatures. In this study, a microwave Land Data Assimilation System (LDAS) was developed with three RTMs (The radiative transfer model for bare field (QH), land e...

متن کامل

Evaluation of AMSR-E-Derived Soil Moisture Retrievals Using Ground-Based and PSR Airborne Data during SMEX02

A Land Surface Microwave Emission Model (LSMEM) is used to derive soil moisture estimates over Iowa during the Soil Moisture Experiment 2002 (SMEX02) field campaign, using brightness temperature data from the Advanced Microwave Sounding Radiometer (AMSR)-E satellite. Spatial distributions of the near-surface soil moisture are produced using the LSMEM, with data from the North American Land Data...

متن کامل

Exploitation of microwave sounder/imager data over land surfaces in the presence of clouds and precipitation SAF-HYDROLOGY, Final Report

Observations from SSMI/S are still not as intensively used in NWP as are observations from other microwave sensors. Despite their large information content, these observations are still insufficiently used. Some feasibility studies have been conducted within the ECMWF assimilation system as preliminary steps to use SSMI/S observations over land and under cloudy/rainy situations. New development...

متن کامل

The Ecmwf Surface Analysis: Use of Active and Passive Microwave Data for Soil Moisture Analysis

This paper presents the European Centre for Medium-Range Weather Forecasts (ECMWF) soil moisture (SM) analysis system and its recent developments which enables the assimilation of active and passive microwave data. The current operational SM analysis used in the Integrated Forecast System (IFS), is based on an Optimal Interpolation (OI) scheme using proxy observations (2 m air temperature and r...

متن کامل

Development of a coupled land–atmosphere satellite data assimilation system for improved local atmospheric simulations

This study developed a coupled land–atmosphere satellite data assimilation system as a new physical downscaling approach, by coupling a mesoscale atmospheric model with a land data assimilation system (LDAS). The LDAS consists of a land surface scheme as the model operator, a radiative transfer model as the observation operator, and the simulated annealing method for minimizing the difference b...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2010