Department of Climate and Space Sciences and Engineering in the College of Engineering at the University of Michigan

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An IR story about cloud and snow

Posted: September 23, 2014

An IR story about cloud and snow

In a recent paper, AOSS researchers quantitatively showed the non-negligible contributions to polar radiation budget by two physical mechanisms ignored by most state-of-the-art global climate models (GCMs).

Associate Professor Xianglei Huang’s research group conducted the study in collaboration with Assistant Professor Mark Flanner. The abstract states that in current climate models, both clouds and surface are usually assumed to be non-reflective for the infrared radiation. Only a couple of GCMs used in the most recent IPCC assessment have included treatments of cloud scattering in the infrared and no GCM has taken the non-blackbody surface into account.

By first-principle modeling of snow surface spectral emissivity and utilizing actual atmospheric observations acquired by CloudSat (a cloud profiling radar), this study shows that the scattering of clouds and reflection of snow surface can lead to discernible impact on the monthly-mean polar radiation budget averaged over the Antarctic Plateau.

Moreover, such impact is dominantly resulted from the far infrared, a spectrum region that so far still has never been directly observed from the space yet. This study will motivate both the improvement of GCM modeling on this issue and the future observation of far infrared radiation from the space.

The paper is published in Geophysical Research Letters.

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