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|Abstract:||The linearity of global‐mean outgoing longwave radiation (OLR) with surface temperature is a basic assumption in climate dynamics. This linearity manifests in global climate models, which robustly produce a global‐mean longwave clear‐sky (LWCS) feedback of 1.9 W/m2/K, consistent with idealized single‐column models (Koll & Cronin, 2018, https//:doi.org/10.1073/pnas.1809868115). However, there is considerable spatial variability in the LWCS feedback, including negative values over tropical oceans (known as the “super‐greenhouse effect”) which are compensated for by larger values in the subtropics/extratropics. Therefore, it is unclear how the idealized single‐column results are relevant for the global‐mean LWCS feedback in comprehensive climate models. Here we show with a simple analytical theory and model output that the compensation of this spatial variability to produce a robust global‐mean feedback can be explained by two facts: (1) When conditioned upon free‐tropospheric column relative humidity (RH), the LWCS feedback is independent of RH, and (2) the global histogram of free‐tropospheric column RH is largely invariant under warming.|
|Citation:||Zhang, Yi, Nadir Jeevanjee, and Stephan Fueglistaler. "Linearity of outgoing longwave radiation: From an atmospheric column to global climate models." Geophysical Research Letters 47, no. 17 (2020). doi:10.1029/2020GL089235.|
|Type of Material:||Journal Article|
|Journal/Proceeding Title:||Geophysical Research Letters|
|Version:||Final published version. Article is made available in OAR by the publisher's permission or policy.|
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