Abstract
In this study, the three-dimensional (3D) warm-core structures of the Northwest Pacific typhoons Francisco, Lekima, and Krosa in August 2019 are retrieved from the Fengyun-3D (FY-3D) microwave temperature sounder-2 (MWTS-2) observations of brightness temperature. Due to the lack of two window channels at 23.8 GHz and 31.4 GHz, an empirical cloud detection algorithm based on 50.3 GHz bias-corrected observations-minus-backgrounds is applied to obtain clear-sky observations for the multiple linear regression retrieval algorithm. The MWTS-2 cloud-affected channels 3–5 are not used to retrieve temperatures under cloudy conditions to eliminate low-tropospheric cold anomalies. The multiple linear regression coefficients are obtained based on MWTS-2 brightness temperatures and the temperatures from the European Centre for Medium-Range Weather Forecasts Reanalysis-5 (ERA5) in the training period of three weeks before the month of targeted typhoons. The proposed MWTS-2 warm-core retrieval can well capture the radial and vertical temporal evolutions of the temperature anomalies of the typhoons Francisco, Lekima, and Krosa. The sizes of the warm-core anomalies of typhoons Lekima and Krosa retrieved by the MWTS-2 are horizontally and vertically similar to and stronger than those of the ERA5. Compared with the ERA5 reanalysis in August 2019, the biases for MWTS-2 temperature retrievals are smaller than ±0.25 K, with root-mean-square errors (RMSEs) smaller than and 2.0 K at all altitudes. Additionally, the location of the 250-hPa maximum temperature anomaly retrieved by the MWTS-2 is closer to the best track than that of the ERA5. A weak warm-core around 200 hPa and a cold-core anomaly in the middle troposphere are also found in the outer rain bands region due to the effect of evaporation of rainfall.
Highlights
Since the launch of the first polar-orbiting environmental operational satellite (POES), the Television Infrared Observation Satellite (TIROS), in 1960 [1], the earth’s atmosphere has been studied based on POES data
We examine the spatial distribution of the microwave temperature sounder-2 (MWTS-2) channel 6 (WFP = 250 hPa) TB
It shows that the peak warm-core intensities obtained from the European Centre for Medium-Range Weather Forecasts Reanalysis-5 (ERA5) andthat
Summary
Since the launch of the first polar-orbiting environmental operational satellite (POES), the Television Infrared Observation Satellite (TIROS), in 1960 [1], the earth’s atmosphere has been studied based on POES data. The microwave temperature sounders onboard the FY-3 series, the NOAA series, and the European Organization for the Exploitation of Meteorological Satellites Meteorological Operational (MetOp) series of POESs have become the main players of the earth’s atmosphere observation system [8]. The horizontal and vertical structures of warmcores derivable from satellite microwave temperature sounding observations is of great significance to understand and verify the warm-core height and intensity variations of any particular typhoon. The TB observations from microwave temperature sounders were used in many studies for retrieving the near-real-time (NRT) three-dimensional (3D) temperature structures of hurricanes, including MSU onboard the National Oceanic and Atmospheric Administration (NOAA)-6 to NOAA-14 satellites [25], the Advanced Microwave Sounding Unit-A (AMSU-A) onboard NOAA-15 to NOAA-19 satellites [26], and the Advanced Technology.
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