Description and validation of the Japanese algorithm for radiative flux and heating rate products with all four EarthCARE instruments: pre-launch test with A-Train

<p>This study developed an algorithm for the Level 2 (L2) atmospheric radiation flux and heating rate product by a Japanese team for Earth Cloud, Aerosol and Radiation Explorer (EarthCARE). This product offers vertical profiles of downward and upward longwave (LW) and shortwave (SW) radiative...

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Main Authors: A. Yamauchi, K. Suzuki, E. Oikawa, M. Sekiguchi, T. M. Nagao, H. Ishida
Format: Article
Language:English
Published: Copernicus Publications 2024-11-01
Series:Atmospheric Measurement Techniques
Online Access:https://amt.copernicus.org/articles/17/6751/2024/amt-17-6751-2024.pdf
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author A. Yamauchi
K. Suzuki
E. Oikawa
M. Sekiguchi
T. M. Nagao
H. Ishida
author_facet A. Yamauchi
K. Suzuki
E. Oikawa
M. Sekiguchi
T. M. Nagao
H. Ishida
author_sort A. Yamauchi
collection DOAJ
description <p>This study developed an algorithm for the Level 2 (L2) atmospheric radiation flux and heating rate product by a Japanese team for Earth Cloud, Aerosol and Radiation Explorer (EarthCARE). This product offers vertical profiles of downward and upward longwave (LW) and shortwave (SW) radiative fluxes and their atmospheric heating rates. This paper describes the algorithm developed for generating products, including the atmospheric radiative transfer model and input datasets, and its validation against measurement data of radiative fluxes. In the testing phase before the EarthCARE launch, we utilized A-Train data that provided input and output variables analogous to EarthCARE, so that the developed algorithm could be directly applied to EarthCARE after its launch. The results include comparisons of radiative fluxes between radiative transfer simulations and satellite and ground-based observations that quantify errors in computed radiative fluxes at the top of the atmosphere against Clouds and the Earth's Radiant Energy System (CERES) observations and their dependence on cloud type with varying thermodynamic phases. For SW fluxes, the bias was 24.4 W m<span class="inline-formula"><sup>−2</sup></span>, and the root mean square error (RMSE) was 36.3 W m<span class="inline-formula"><sup>−2</sup></span> relative to the CERES observations at spatial and temporal scales of 5° and 1 month, respectively. On the other hand, LW exhibits a bias of <span class="inline-formula">−</span>10.7 W m<span class="inline-formula"><sup>−2</sup></span> and an RMSE of 14.2 W m<span class="inline-formula"><sup>−2</sup></span>. When considering different cloud phases, the SW water cloud exhibited a bias of <span class="inline-formula">−</span>11.7 W m<span class="inline-formula"><sup>−2</sup></span> and an RMSE of 46.2 W m<span class="inline-formula"><sup>−2</sup></span>, while the LW showed a bias of 0.8 W m<span class="inline-formula"><sup>−2</sup></span> and an RMSE of 6.0 W m<span class="inline-formula"><sup>−2</sup></span>. When ice clouds were included, the SW bias ranged from 58.7 to 81.5 W m<span class="inline-formula"><sup>−2</sup></span> and the RMSE from 72.8 to 91.6 W m<span class="inline-formula"><sup>−2</sup></span> depending on the ice-containing cloud types, while the corresponding LW bias ranged from <span class="inline-formula">−</span>8.8 to <span class="inline-formula">−</span>28.4 W m<span class="inline-formula"><sup>−2</sup></span> and the RMSE from 25.9 to 31.8 W m<span class="inline-formula"><sup>−2</sup></span>, indicating that the primary source of error was ice-containing clouds. The comparisons were further extended to various spatiotemporal scales to investigate the scale dependency of the flux errors. The SW component of this product exhibited an RMSE of approximately 30 W m<span class="inline-formula"><sup>−2</sup></span> at spatial and temporal scales of 40° and 40 d, respectively, whereas the LW component did not show a significant decrease in RMSE with increasing spatiotemporal scale. Radiative transfer simulations were also compared with ground-based observations of the surface downward SW and LW radiative fluxes at selected locations. The results show that the bias and RMSE for SW are <span class="inline-formula">−</span>17.6 and 172.0 W m<span class="inline-formula"><sup>−2</sup></span>, respectively, which are larger than those for LW that are <span class="inline-formula">−</span>5.6 and 19.0 W m<span class="inline-formula"><sup>−2</sup></span>, respectively.</p>
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spelling doaj-art-5f47d0e4df754abaa08a6dc87dffbf7e2024-11-28T13:06:30ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482024-11-01176751676710.5194/amt-17-6751-2024Description and validation of the Japanese algorithm for radiative flux and heating rate products with all four EarthCARE instruments: pre-launch test with A-TrainA. Yamauchi0K. Suzuki1E. Oikawa2M. Sekiguchi3T. M. Nagao4H. Ishida5Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, JapanAtmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, JapanMeteorological Research Institute, Japan Meteorological Agency, Tsukuba, JapanFaculty of Marine Technology, Tokyo University of Marine Science and Technology, Tokyo, JapanAtmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, JapanMeteorological Research Institute, Japan Meteorological Agency, Tsukuba, Japan<p>This study developed an algorithm for the Level 2 (L2) atmospheric radiation flux and heating rate product by a Japanese team for Earth Cloud, Aerosol and Radiation Explorer (EarthCARE). This product offers vertical profiles of downward and upward longwave (LW) and shortwave (SW) radiative fluxes and their atmospheric heating rates. This paper describes the algorithm developed for generating products, including the atmospheric radiative transfer model and input datasets, and its validation against measurement data of radiative fluxes. In the testing phase before the EarthCARE launch, we utilized A-Train data that provided input and output variables analogous to EarthCARE, so that the developed algorithm could be directly applied to EarthCARE after its launch. The results include comparisons of radiative fluxes between radiative transfer simulations and satellite and ground-based observations that quantify errors in computed radiative fluxes at the top of the atmosphere against Clouds and the Earth's Radiant Energy System (CERES) observations and their dependence on cloud type with varying thermodynamic phases. For SW fluxes, the bias was 24.4 W m<span class="inline-formula"><sup>−2</sup></span>, and the root mean square error (RMSE) was 36.3 W m<span class="inline-formula"><sup>−2</sup></span> relative to the CERES observations at spatial and temporal scales of 5° and 1 month, respectively. On the other hand, LW exhibits a bias of <span class="inline-formula">−</span>10.7 W m<span class="inline-formula"><sup>−2</sup></span> and an RMSE of 14.2 W m<span class="inline-formula"><sup>−2</sup></span>. When considering different cloud phases, the SW water cloud exhibited a bias of <span class="inline-formula">−</span>11.7 W m<span class="inline-formula"><sup>−2</sup></span> and an RMSE of 46.2 W m<span class="inline-formula"><sup>−2</sup></span>, while the LW showed a bias of 0.8 W m<span class="inline-formula"><sup>−2</sup></span> and an RMSE of 6.0 W m<span class="inline-formula"><sup>−2</sup></span>. When ice clouds were included, the SW bias ranged from 58.7 to 81.5 W m<span class="inline-formula"><sup>−2</sup></span> and the RMSE from 72.8 to 91.6 W m<span class="inline-formula"><sup>−2</sup></span> depending on the ice-containing cloud types, while the corresponding LW bias ranged from <span class="inline-formula">−</span>8.8 to <span class="inline-formula">−</span>28.4 W m<span class="inline-formula"><sup>−2</sup></span> and the RMSE from 25.9 to 31.8 W m<span class="inline-formula"><sup>−2</sup></span>, indicating that the primary source of error was ice-containing clouds. The comparisons were further extended to various spatiotemporal scales to investigate the scale dependency of the flux errors. The SW component of this product exhibited an RMSE of approximately 30 W m<span class="inline-formula"><sup>−2</sup></span> at spatial and temporal scales of 40° and 40 d, respectively, whereas the LW component did not show a significant decrease in RMSE with increasing spatiotemporal scale. Radiative transfer simulations were also compared with ground-based observations of the surface downward SW and LW radiative fluxes at selected locations. The results show that the bias and RMSE for SW are <span class="inline-formula">−</span>17.6 and 172.0 W m<span class="inline-formula"><sup>−2</sup></span>, respectively, which are larger than those for LW that are <span class="inline-formula">−</span>5.6 and 19.0 W m<span class="inline-formula"><sup>−2</sup></span>, respectively.</p>https://amt.copernicus.org/articles/17/6751/2024/amt-17-6751-2024.pdf
spellingShingle A. Yamauchi
K. Suzuki
E. Oikawa
M. Sekiguchi
T. M. Nagao
H. Ishida
Description and validation of the Japanese algorithm for radiative flux and heating rate products with all four EarthCARE instruments: pre-launch test with A-Train
Atmospheric Measurement Techniques
title Description and validation of the Japanese algorithm for radiative flux and heating rate products with all four EarthCARE instruments: pre-launch test with A-Train
title_full Description and validation of the Japanese algorithm for radiative flux and heating rate products with all four EarthCARE instruments: pre-launch test with A-Train
title_fullStr Description and validation of the Japanese algorithm for radiative flux and heating rate products with all four EarthCARE instruments: pre-launch test with A-Train
title_full_unstemmed Description and validation of the Japanese algorithm for radiative flux and heating rate products with all four EarthCARE instruments: pre-launch test with A-Train
title_short Description and validation of the Japanese algorithm for radiative flux and heating rate products with all four EarthCARE instruments: pre-launch test with A-Train
title_sort description and validation of the japanese algorithm for radiative flux and heating rate products with all four earthcare instruments pre launch test with a train
url https://amt.copernicus.org/articles/17/6751/2024/amt-17-6751-2024.pdf
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