Expansion of the All-Sky Radiance Assimilation to ATMS at NCEP

Abstract

Since the implementation of all-sky radiance assimilation of the Advanced Microwave Sounding Unit-A (AMSU-A) in the operational hybrid 4D ensemble–variational Global Forecast System at NCEP in 2016, the all-sky approach has been tested to expand to the radiances of Advanced Technology Microwave Sounder (ATMS) in the Gridpoint Statistical Interpolation analysis system (GSI). Following the all-sky framework implemented for the AMSU-A radiances, ATMS radiance assimilation adopts similar procedures in quality control, bias correction, and model of observation error. Efforts have been focused on special considerations that are necessary because of the unique features of the ATMS radiances and water vapor channels, including surface properties based on fields of view size and shape, and taking care of large departures from the first guess (OmF) along coastlines and radiances affected by strong scattering. More importantly, it is shown that this work makes microwave radiance OmFs become more consistent among different sensors, and provides indications of the deficiencies in quality control procedures of the original ATMS and Microwave Humidity Sounder (MHS) clear-sky radiance assimilation. While the generalized tracer effect is noticed, the overall impact on the forecast skill is neutral. This work is included in the upcoming operational implementation in 2019.

All‐sky microwave humidity sounder assimilation in the Korean Integrated Model forecast system

“…However, the later results of Zhu et al . (2019) are based on 4DEnVar with a 10 K O‐B screening threshold, even including ATMS water vapour channel assimilation, enabling better comparison with this study.…”

Multiple Hydrometeors All-Sky Microwave Radiance Assimilation in FV3GFS

“…Nonprecipitating cloudy radiances from the Advanced Microwave Sounding Unit-A (AMSU-A) microwave radiometer have been assimilated into NCEP's Global Forecast System (GFS) since 2016 (Zhu et al 2016). More recently, the all-sky approach has been expanded to the assimilation of the nonprecipitating cloudy radiances from the Advanced Technology Microwave Sounder (ATMS) (Zhu et al 2019).…”

“…Nonprecipitating cloudy radiances from the Advanced Microwave Sounding Unit-A (AMSU-A) microwave radiometer have been assimilated into NCEP's Global Forecast System (GFS) since 2016 (Zhu et al 2016). More recently, the all-sky approach has been expanded to the assimilation of the nonprecipitating cloudy radiances from the Advanced Technology Microwave Sounder (ATMS) (Zhu et al 2019). Precipitationaffected radiances have not been assimilated in the operational GFS Global Data Assimilation System (GDAS), mainly because the cloud microphysics parameterization scheme (Zhao and Carr 1997;Moorthi et al 2001) used in the original Global Spectral Model (GSM)-based GFS does not provide precipitation information in the model output.…”

“…Cloud water, which covers cloud liquid water and cloud ice, is the only cloud-related prognostic variable in the GSM-based GFS. Cloud water is a control variable in the all-sky radiance assimilation framework of GFS (Zhu et al 2016).…”

Assimilation of GPM Rain Rate Products With GSI Data Assimilation System for Heavy and Light Precipitation Events

“…In the past decade, progresses have been made to overcome the issues related to cloudy radiances including bias correction strategy, quality control, the observation operator in radiation model to project radiance into microphysics properties, and observational errors. Many recent studies have stepped into assimilating all‐sky radiances under both cloud‐free and cloudy conditions (Geer et al, , ; Pangaud et al, ; Zhu et al, , ). The direct assimilation of radiance data seems appealing as it avoids dealing with uncertainties and errors related to the retrieval process including the sampling errors, the beam‐filling effect, retrieval errors, and the biases in background fields that were used to constrain the satellite radiance data (Fisher & Wolff, ; Migliorini, ).…”