Assimilation of the AMSU-A radiances using the CESM (v2.1.0) and the DART (v9.11.13)–RTTOV (v12.3)
<p>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 Assim...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-09-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://gmd.copernicus.org/articles/16/5365/2023/gmd-16-5365-2023.pdf |
| Summary: | <p>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, spatial thinning, and bias correction
processes. In the quality control, two sub-processes are included, outlier
test and channel selection, depending on the cloud condition and surface
type. The bias correction process is divided into scan-bias correction and
air-mass-bias correction. Like 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.</p> |
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| ISSN: | 1991-959X 1991-9603 |