An investigation of microphysics and sub-grid scale variability in warm rain clouds using the A-train observations and a multi-scale modeling framework

Details

• Journal Title:
  Journal of Geophysical Research: Atmospheres
• Personal Author:
  Takahashi, Hanii ; Lebsock, Matthew ; Suzuki, Kentaroh ; Stephens, Graeme ; Wang, Minghuai
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; CPO (Climate Program Office)
• Description:
  A common problem in climate models is that they are likely to produce rain at a faster rate than is observed and therefore produce too much light rain (e.g., drizzle). Interestingly, the Pacific Northwest National Laboratory (PNNL) multiscale modeling framework (MMF), whose warm‐rain formation process is more realistic than other global models, has the opposite problem: the rain formation process in PNNL‐MMF is less efficient than the real world. To better understand the microphysical processes in warm cloud, this study documents the model biases in PNNL‐MMF and evaluates warm cloud properties, subgrid variability, and microphysics, using A‐Train satellite observations to identify sources of model biases in PNNL‐MMF. Like other models PNNL‐MMF underpredicts the warm cloud fraction with compensating large optical depths. Associated with these compensating errors in cloudiness are compensating errors in the precipitation process. For a given liquid water path, clouds in the PNNL‐MMF are less likely to produce rain than are real‐world clouds. However, when the model does produce rain it is able to produce stronger precipitation than reality. As a result PNNL‐MMF produces about the correct mean rain rate with an incorrect distribution of rates. The subgrid variability in PNNL‐MMF is also tested, and results are fairly consistent with observations, suggesting that the possible sources of model biases are likely to be due to errors in its microphysics or dynamics rather than errors in the subgrid‐scale variability produced by the embedded cloud resolving model.
• Keywords:
  • Warm‐rain clouds
  • Subgrid‐scale variability
  • Multiscale modeling framework
• Source:
  J. Geophys. Res. Atmos., 122, 7493– 7504
• DOI:
  https://doi.org/10.1002/2016JD026404
• Document Type:
  Journal Article
• Funding:
  Grant no. NA15OAR4310153
• Rights Information:
  Other
• Compliance:
  Submitted
• Download URL:
  https://repository.library.noaa.gov/view/noaa/28416/noaa_28416_DS1.pdf
• File Type:
  [PDF - 7.05 MB]
• Collection(s):
  Office of Oceanic and Atmospheric Research (OAR)
• Main Document Checksum:
  urn:sha256:9d401b5879b1353d4067b11d1d66c3b3d4a6db71cce1a7be74d48a71777996c0