Submitted as: development and technical paper
26 Apr 2023
Submitted as: development and technical paper |  | 26 Apr 2023
Status: this preprint is currently under review for the journal GMD.

Assimilation of the AMSU-A radiances using the CESM (v2.1.0) and the DART (v9.11.13)/RTTOV (v12.3)

Young-Chan Noh, Yonghan Choi, Hyo-Jong Song, Kevin Raeder, Joo-Hong Kim, and Youngchae Kwon

Abstract. To improve the initial condition (“analysis”) for numerical weather prediction, we attempt to assimilate observations from the Advanced Microwave Sounding Unit-A (AMSU-A) on board the low-earth-orbiting satellites. The data assimilation system, used in this study, consists of the Data Assimilation Research Testbed (DART) and the Community Earth System Model as the global forecast model. Based on the ensemble Kalman filter scheme, DART supports the radiative transfer model that is used to simulate the satellite radiances from the model state. To make the AMSU-A data available to be assimilated in DART, preprocessing modules are developed, which consist of quality control and bias correction processes. In the quality control, three sub-processes are included: gross quality control, channel selection, and spatial thinning. The bias correction process is divided into scan-bias correction and air-mass-bias correction. As input data used in DART, the observation errors are also estimated for the AMSU-A channels. In the trial experiments, a positive analysis impact is obtained by assimilating the AMSU-A observations on top of the DART data assimilation system that already makes use of the conventional measurements. In particular, the analysis errors are significantly reduced in the whole troposphere and lower stratosphere over the Northern Hemisphere. Overall, this study demonstrates a positive impact on the analysis when the AMSU-A observations are assimilated in the DART assimilation system.

Young-Chan Noh et al.

Status: open (until 29 Jun 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2023-60', Lukas Kugler, 16 May 2023 reply
  • RC2: 'Comment on gmd-2023-60', Anonymous Referee #2, 23 May 2023 reply
  • RC3: 'Comment on gmd-2023-60', Wei Han, 01 Jun 2023 reply

Young-Chan Noh et al.

Data sets

Model outputs (CNTL & EXP) Young-Chan Noh

Model code and software

Model (CESM & DART) and preprocessing codes Young-Chan Noh

Young-Chan Noh et al.


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Short summary
This is the first attempt to assimilate the observations of microwave temperature sounders into the global climate forecast model in which the satellite observations have not been assimilated in the past. To do this, preprocessing schemes are developed to make the satellite observations suitable to be assimilated. In the assimilation experiments, the model analysis is significantly improved by assimilating the observations of microwave temperature sounders.