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Tropical anvil cirrus are highly sensitive to ice microphysics within a nudged global storm-resolving model
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  • Rachel Atlas,
  • Christopher S. Bretherton,
  • Adam B Sokol,
  • Peter N. Blossey,
  • Marat Khairoutdinov
Rachel Atlas
University of Washington

Corresponding Author:[email protected]

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Christopher S. Bretherton
Allen Institute for Artificial Intelligence
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Adam B Sokol
University of Washington
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Peter N. Blossey
University of Washington
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Marat Khairoutdinov
Stony Brook University
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Cirrus dominate the longwave radiative budget of the tropics. For the first time, we quantify the variability in cirrus properties and longwave cloud radiative effects (CREs) that arises from differences in microphysics within nudged global storm-resolving simulations from a single model. Nudging allows us to compute radiative biases precisely using coincident satellite measurements and to fix the large-scale dynamics across our set of simulations and isolate the influence of microphysics. We run five-day simulations with four commonly-used microphysics schemes of varying complexity (SAM1MOM, Thompson, M2005 and P3) and find that the tropical average longwave CRE varies over 20 W m$^{-2}$ between schemes. P3 best reproduces observed longwave CRE. M2005 and P3 simulate cirrus with realistic frozen water path but unrealistically high ice crystal number concentrations which commonly hit limiters and lack the variability and dependence on frozen water content seen in aircraft observations. Thompson and SAM1MOM have too little cirrus.
27 Aug 2023Submitted to ESS Open Archive
11 Sep 2023Published in ESS Open Archive