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, UQAM2. Environment Canada Source:
Why the cloud-radiation interaction ? Cloud-Radiation Interaction Microphysics Macrophysics Environment Surface Radiation Budget 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 ( ) LWP & IWV: removed when precipitation ≥ 0,25mm/3h SGP NSA
Shortwave Down, Summer (SGP) SZA≤30° 30°<SZA≤60°
Longwave Down, Summer (SGP) Source: Bernard Dugas
Shortwave Down, Winter (SGP)
Longwave Down, Winter (SGP)
Overestimate of clear-sky occurrences Precipitation too frequently triggered at too low LWP Incorrect separation of cloud water between liquid & ice *10 LWP (without precip.), Winter (SGP) *10
LWP (without precip.), SGP
LWP (without precip.), NSA
Underestimate of LWP LWD & SWD SGP NSA JJA SON DJF MAM SGP NSA
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 JJAconvection Possible corrections to the microphysics scheme (autocon- version) to reduce light precipitation…
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Cloud Fraction & Integrated Water Vapor