Performances between the <scp>FY‐4A</scp>/<scp>GIIRS</scp> and <scp>FY‐4B</scp>/<scp>GIIRS</scp> Long‐Wave InfraRed (<scp>LWIR</scp>) channels under clear‐sky and all‐sky conditions

Niu, Zeyi; Zhang, Lei; Yang, Han; Dong, Peng; Huang, Wei

doi:10.1002/qj.4473

Cited by 15 publications

(6 citation statements)

References 26 publications

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“…However, there are two spectral regions where the standard deviations are unrealistically larger than 2 K: 725–740 and 1075–1150 cm −1 . These large standard deviations are attributed to the low quality of observed GIIRS radiances in these spectral regions, as reported by other studies (Niu et al., 2023), those channels are excluded data assimilation and sounding retrieval. Overall, Figure 4 demonstrates that the CCRs have similar statistics to clear radiances, indicating that the cloud‐clearing process effectively removes the cloud impact and generates clear equivalent radiances with quality comparable to clear radiances, especially for those channels that have been assimilated operationally (Yin et al., 2020).…”

Section: Results and Analysismentioning

confidence: 65%

Enhancing Clear Radiance Generation for Geostationary Hyperspectral Infrared Sounder Using High Temporal Resolution Information

Di,

Li,

et al. 2024

Geophysical Research Letters

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With high spatio‐temporal resolution geostationary hyperspectral infrared sounder (GeoHIS) observations, monitoring, and predicting rapidly changing weather events are expected to be improved with continuous information of 3D weather cube. However, due to the nature of radiation, clouds prevent an adequate retrieval of atmospheric thermodynamic information under clear‐sky conditions due to large uncertainties in the current radiative transfer model. Removing cloud effects from GeoHIS sub‐footprint is an alternative approach for enhancing clear radiance generation. Such cloud removal can be achieved through the optimal cloud‐clearing (OCC) method, which usually relies on the assumption of atmospheric spatial homogeneity. With high temporal resolution observations from GeoHIS, cloud removal can also be achieved through OCC but using the assumption of temporal homogeneity. This concept was demonstrated using 15‐min Geostationary Interferometric Infrared Sounder (GIIRS) observations. The longwave GIIRS clear radiances under partially cloud cover can be effectively produced with observation errors less than 0.02 ± 0.86 K and 0.04 ± 0.77 K for 11 and 12 μm, respectively.

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Section: Results and Analysismentioning

confidence: 65%

Enhancing Clear Radiance Generation for Geostationary Hyperspectral Infrared Sounder Using High Temporal Resolution Information

Di,

Li,

et al. 2024

Geophysical Research Letters

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“…On December 11, 2016, the Fengyun (FY)-4A was successfully launched in China, which has been extensively utilized for the assimilation of clear-sky radiances (CSR) in NWP models (Niu et al, 2022;Niu, Zhang, et al, 2023;Xu, Cheng, et al, 2023). Kumar et al (2022) employed hydrometeors as control variables in assimilating all-sky infrared WV radiance.…”

Section: Introductionmentioning

confidence: 99%

All‐sky assimilation of FY‐4A AGRI water vapor channels: An observing system experiment study for south Asian monsoon prediction

Niu,

Tang,

Wang

2024

Quart J Royal Meteoro Soc

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In this study, a month‐long parallel experiment is conducted to assess the assimilation effects of all‐sky radiance (ASR) versus clear‐sky radiance (CSR) in the single and multiple water vapor (WV) channels provided by the Advanced Geostationary Radiation Imager (AGRI) onboard the Fengyun‐4A (FY‐4A) satellite. The Weather Research and Forecasting model data assimilation system (WRFDA) is utilized for assimilating the FY‐4A AGRI WV observations. Compared with the CSR, the assimilated data of the ASR increases by ~1.7 times in WV channel 9 and around 2.4 times in the multiple WV channels (channels 9 and 10). Both the CSR and ASR assimilation results demonstrate that the simulated brightness temperature (TB) from the WRF analyses is closer to the TB observations from Sondeur Atmospherique du Profil d'Humidite Intertropicale par Radiometrie (SAPHIR) channels 1–2 and Microwave Humidity Sounder (MHS) channel 3, as compared with the control experiment where only conventional data are assimilated. Furthermore, a larger improvement is noted in assimilation of multiple WV channel against assimilation of a single WV channel for both CSR and ASR runs. Overall, the analyses and forecasts generated from the ASR run exhibit superior performance compared with the CSR run when verified against SAPHIR and MHS measurements, as well as the National Centers for Environmental Prediction (NCEP) Global Data Assimilation System (GDAS) analyses. The verification of the rainfall predicted by the WRF against the Global Satellite Mapping of Precipitation (GSMaP) products over India indicates that the assimilation of the ASR in multiple WV channels has the largest impact on rainfall prediction. Moreover, the ASR run demonstrates an accurate prediction of heavy rainfall events that are missed in the control experiment and underestimated in the CSR run.

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“…The Geostationary Interferometric Infrared Sounder (GIIRS) carried on FY-4A is the first high-spectral-resolution advanced infrared sounder on board a geostationary weather satellite [6,9,10]. It has 1650 spectral channels, significantly improving its atmospheric vertical detection capability [11,12].…”

Section: Introductionmentioning

confidence: 99%

Error Analysis and Correction of FENGYUN-4A GIIRS Temperature Profile Products in Summer over the Qinghai–Tibet Plateau

Jiang,

Wang,

Niu

2024

Remote Sensing

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To understand the applicability of the temperature profile product of the FENGYUN-4A (FY-4A) geostationary interferometric infrared detector (GIIRS) in summer over the Qinghai–Tibet Plateau and to improve product quality, the error of GIIRS temperature products was analyzed based on radiosonde data. A long short-term memory network model (LSTM) was used to correct the GIIRS temperature profile product in summer over the plateau at a high altitude (above 500 hPa), and further evaluation of the corrected product was conducted. The results show that summertime GIIRS temperature retrievals over the Qinghai–Tibet Plateau had a positive bias above 150 hPa and a negative bias below 150 hPa, resulting in an overall negative bias. The root mean square error was between 2 and 2.9 K, and the root mean square error was relatively large at 100 hPa and above. The LSTM established in this study could effectively correct the GIIRS temperature over the plateau. The correlation and root mean square error of the corrected GIIRS temperature and the radiosonde observation temperature were significantly improved. Using a trained LSTM correction model to correct the hourly GIIRS temperature can improve the accuracy and usability of the product. After correction, the average bias of the GIIRS temperature compared to the ERA5 temperature product was reduced from −0.26 K to 0.06 K, and the root mean square error was reduced from 2.25 K to 1.25 K. The correction model can be applied to different seasons, and it can also correct the GIIRS temperature in larger areas based on other high-precision and high-resolution data, achieving good results, thus indicating that the correction model has universal applicability.

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Performances between the FY‐4A/GIIRS and FY‐4B/GIIRS Long‐Wave InfraRed (LWIR) channels under clear‐sky and all‐sky conditions

Cited by 15 publications

References 26 publications

Enhancing Clear Radiance Generation for Geostationary Hyperspectral Infrared Sounder Using High Temporal Resolution Information

Enhancing Clear Radiance Generation for Geostationary Hyperspectral Infrared Sounder Using High Temporal Resolution Information

All‐sky assimilation of FY‐4A AGRI water vapor channels: An observing system experiment study for south Asian monsoon prediction

Error Analysis and Correction of FENGYUN-4A GIIRS Temperature Profile Products in Summer over the Qinghai–Tibet Plateau

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