On the Importance of a Geostationary View for Tropical Cloud Feedback

• Published in: Geophysical research letters Vol. 51; no. 4
• Main Authors: Lee, Yoon‐Kyoung, Choi, Yong‐Sang, Hwang, Jiwon, Hu, Xiaoming, Yang, Song
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.02.2024; Wiley
• Subjects: Climate models; Cloud cover; cloud feedback; Cloudiness; Coefficients; Earth orbit; Earth orbits; Feedback; geostationary satellite; Geostationary satellites; Low earth orbits; Regression coefficients; Satellites; Sea surface; Sea surface temperature; SST; Strength; sun‐synchronous satellite; Surface temperature; Synchronous satellites; Tropical clouds; tropical western Pacific; Visual field
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL106897

This study shows that geostationary satellites are critical to estimate the accurate cloud feedback strength over the tropical western Pacific (TWP). Cloud feedback strength was calculated by the simultaneous relation between cloud cover and sea surface temperature (SST) over the TWP [120°E–170°E, 20°S–20°N]. During 2011–2018, the cloud cover was obtained by geostationary earth orbit satellite (GEO) and low‐level earth orbit satellite (LEO) (AGEO, ALEO), and the NOAA's all‐sky SST (To) was weighted with the clear‐sky fraction observed by GEO and LEO (TwGEO; TwLEO). The linear regression coefficients between clouds and SST are very different: −7.93%K−1 (AGEO/TwGEO), −6.94%K−1 (ALEO/TwGEO), −1.35%K−1 (AGEO/TwLEO), −0.69%K−1 (ALEO/TwLEO), −0.02 %K−1 (AGEO/To), and −0.50 %K−1 (ALEO/To). Among these, only the TwGEO values provided a valid cloud feedback signal. This is because GEO's field of view is large enough to simultaneously capture cloud cover over the entire TWP. Plain Language Summary Geostationary satellites are essential for accurately estimating cloud feedback strength over the tropical western Pacific (TWP). Cloud feedback strength is the change in cloudiness that results from a change in sea surface temperature (SST). When using data from both geostationary and low‐earth orbit satellites, the resulting cloud feedback signals are very different. This is because geostationary satellites have a large enough field of view to capture cloud cover over the entire TWP, while low‐earth orbit satellites do not. Therefore, geostationary satellites are the only reliable source of data for estimating cloud feedback strength over the TWP. This is important because cloud feedback is a major uncertainty in climate models. Key Points In the tropical western Pacific (TWP), the cloud‐sea surface temperature (SST) relation has been subject to the analysis methods with satellite observations The negative relationship is revealed only when the daily SST is weighted with the clear‐sky fraction from a geostationary satellite This disparity arises from the capability of geostationary satellites to simultaneously capture a snapshot of the entire TWP area