190 likes | 299 Views
Evaluation of Cloud-Radiation Interaction in the Canadian GEM Model Using ARM Observations. Danahé Paquin-Ricard 1 Colin Jones 1 , Paul Vaillancourt 2 1. CRCMD, UQAM 2. Environment Canada. Source: http://www.cs.pitt.edu/. Why the cloud-radiation interaction ?. Cloud-Radiation Interaction
E N D
Evaluation of Cloud-Radiation Interaction in the Canadian GEM Model Using ARM Observations Danahé Paquin-Ricard1 Colin Jones1, Paul Vaillancourt2 1. CRCMD, UQAM 2. Environment Canada Source:http://www.cs.pitt.edu/
Why the cloud-radiation interaction ? Cloud-Radiation Interaction Microphysics Macrophysics Environment Precipitation Surface Radiation Budget • Diurnal cycle of SWD & LWD, for summer & winter (SGP) • LWP, winter (SGP) • LWP at SGP vs. NSA
Model & Observations • GEM: • Prognostic total cloud water • Lateral boundary conditions: ERA40 • Prescribed SSTs and ice fraction • Horizontal resolution ≈ 42km • time step 30 min • Observations: • ARM-SGP site: 37°N, 97°W, 318 m • ARM-NSA site: 71°N, 157°W • Microwave radiometer, tipping bucket, radiometers … • Average over 3h period for all variables (except precipitation: 3h accumulation) over 7 years (1998-2004) • LWP & IWV: removed when precipitation ≥ 0,25mm/3h NSA SGP
SZA≤30° 30°<SZA≤60° Shortwave Down, Summer (SGP)
Longwave Down, Summer (SGP) Source: Bernard Dugas
*10 *10 *10 *10 *10 LWP (without precip.), Winter (SGP) • Overestimate of clear-sky occurrences • Precipitation too frequently triggered at too low LWP • Incorrect separation of cloud water between liquid & ice
SGP NSA Underestimate of LWP LWD & SWD SGP NSA JJA SON DJF MAM
Summary for SGP Overestimate of light precipitation Underestimate of LWP, IWV & cloud fraction Underestimate of Overestimate of LWD SWD Warm & dry bias Overestimate of Underestimate of LWD for JJA convection Possible corrections to the microphysics scheme (autocon-version) to reduce light precipitation…
Thank you! Source:http://www.cs.pitt.edu/