TWP-ICE/ACTIVE MONSOON CASE STUDY

Ice water path (IWP) measurements and ECMWF results (white lines and symbols) versus example case study simulations (colored lines):



Comments:

• VISST IWP retrievals near the Darwin ARM site are provided at 4-km pixel resolution by Pat Minnis, derived from satellite-based MTSAT measurements. We plot all retrievals centered within one degree latitude and within one degree longitude of the Darwin ARM site (results negligibly affected by reducing to a 0.5 degree margin).
• Liu IWP retrievals near the Darwin ARM site are provided at 16- to 25-km resolution (depending upon distance from satellite nadir) by Guosheng Liu, derived from satellite-based AMSU-B and ground-based MMCR measurements. We plot all retrievals centered within one degree latitude and within one degree longitude of the Darwin ARM site (results negligibly affected by reducing to a 0.5 degree margin).
• Tropical Cloud Properties and Heating Rate Profiles (TCPRHP) retrievals at Darwin are supplied by Sally McFarlane, Jim Mather, and Jennifer Comstock. Values represent instantaneous profiles over the DOE ARM site reported at 10-s and 45-m resolution.
• ECMWF supplies hourly mean data at 0.56x0.56-degree resolution, from which IWP is integrated ice condensate over all layers in each of the two grid boxes centered nearest to and immediately west of the Darwin ARM site at (130.43,-12.82) and (129.73,-12.47), both shown. The mean value is negligibly changed if a third grid box to the southeast at (131.13,-13.52) is also included (these three grid points are stored in the ARM archive for the Darwin site), bringing the total area to approximately 11,500 km².
• All measurement data have been downloaded from the DOE ARM data archive (www.arm.gov) and use in publications is subject to the policies described there. Any errors in plotting or representation shown here should be blamed on Ann Fridlind.
• Model results are instantaneous range of values at grid-scale resolution reported at 3-hr frequency and averaged over 4, 20, or 55 km over the domain size of approximately 37,000 km².

Preliminary summary:

• The mean retrievals agree to order 30% (differences in retrieval frequency from polar-orbiting versus geostationary platforms have not been accounted for and would contribute to differences). By contrast, the ECMWF model results are more than a factor of three lower and case study simulations are more than a factor of three higher.