Preprints
https://doi.org/10.5194/amtd-8-11753-2015
https://doi.org/10.5194/amtd-8-11753-2015

  12 Nov 2015

12 Nov 2015

Review status: this preprint has been withdrawn by the authors.

Simulating the effects of mid- to upper-tropospheric clouds on microwave emissions in EC-Earth using COSP

M. S. Johnston1, G. Holl2, J. Hocking3, S. J. Cooper4, and D. Chen1 M. S. Johnston et al.
  • 1Department of Earth Sciences, University of Gothenburg, Gothenburg, Sweden
  • 2Department of Meteorology, University of Reading, Reading, UK
  • 3Satellite Applications, Met Office, Fitzroy Road, Exeter, UK
  • 4Department Atmospheric Sciences, University of Utah, Salt Lake City, Utah, USA

Abstract. In this work, the Cloud Feedback Model Intercomparison (CFMIP) Observation Simulation Package (COSP) is expanded to include scattering and emission effects of clouds and precipitation at passive microwave frequencies. This represents an advancement over the official version of COSP (version 1.4.0) in which only clear-sky brightness temperatures are simulated. To highlight the potential utility of this new microwave simulator, COSP results generated using the climate model EC-Earth's version 3 atmosphere as input are compared with Microwave Humidity Sounder (MHS) channel (190.311 GHz) observations. Specifically, simulated seasonal brightness temperatures (TB) are contrasted with MHS observations for the period December 2005 to November 2006 to identify possible biases in EC-Earth's cloud and atmosphere fields.

The EC-Earth's atmosphere closely reproduces the microwave signature of many of the major large-scale and regional scale features of the atmosphere and surface. Moreover, greater than 60 % of the simulated TB are within 3 K of the NOAA-18 observations. However, COSP is unable to simulate sufficiently low TB in areas of frequent deep convection. Within the Tropics, the model's atmosphere can yield an underestimation of TB by nearly 30 K for cloudy areas in the ITCZ. Possible reasons for this discrepancy include both incorrect amount of cloud ice water in the model simulations and incorrect ice particle scattering assumptions used in the COSP microwave forward model. These multiple sources of error highlight the non-unique nature of the simulated satellite measurements, a problem exacerbated by the fact that EC-Earth lacks detailed micro-physical parameters necessary for accurate forward model calculations. Such issues limit the robustness of our evaluation and suggest a general note of caution when making COSP-satellite observation evaluations.

This preprint has been withdrawn.

M. S. Johnston et al.

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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

M. S. Johnston et al.

M. S. Johnston et al.

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This preprint has been withdrawn.