Evaluation of Cloud-Radiation Evaluation of Cloud-Radiation Interaction in the Canadian Interaction in the Canadian

GEM Model Using ARM GEM Model Using ARM Observations 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 BudgetSurface 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

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 *10

*10

*10

LWP (without precip.), SGP

LWP (without precip.), NSA

Underestimate of LWP LWD & SWDSGP NSA

JJA S

ON

DJF

MA

M

SGP NSA

Summary for SGPOverestimate 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! Thank you!

Source:http://www.cs.pitt.edu/

More SGP LWD

More SGP SWD

More NSA LWD

More NSA SWD

Cloud Fraction & Integrated Water Vapor