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(Lei Liu, Yi Huang, John R. Gyakum)

Downwelling longwave radiation is a key component of the surface energy balance and is closely linked to surface warming. Under global warming, various atmospheric variables change simultaneously, all of which influence downwelling longwave radiation. To disentangle the impacts of these variables, we utilize long-term spectrally resolved downwelling longwave radiance (DLR) measurements from the Southern Great Plains (SGP) site. Long-term DLR trends at SGP are detected and they reveal the overall radiative impacts of DLR on the surface energy budget (Liu et al., 2022).

Using a novel spectral fingerprinting method, we attribute the total DLR changes at SGP to contributions from air temperature, carbon dioxide, water vapor, ozone, and clouds (Liu et al., 2025). Surprisingly, we identify a significant negative surface longwave cloud feedback at SGP, which partially offsets the positive effects of rising air temperatures and increasing greenhouse gas concentrations. Further analysis confirms that this negative surface longwave cloud feedback is not unique to the SGP site. Satellite observations and reanalysis datasets indicate a similar longwave cloud radiative effect over land. This consistent negative surface longwave cloud feedback over land is primarily driven by a decrease in low cloud cover.

Liu, L., Huang Y., & Gyakum R.J. (2025). Clouds reduce downwelling longwave radiation over land in a warming climate. Nature, 637, 868–874.

Liu, L., Huang, Y., Gyakum, R.J., Turner, D.D., & Gero, P.J. (2022). Trends in downwelling longwave radiance over the Southern Great Plains. Journal of Geophysical Research: Atmospheres, 127, e2021JD035949.