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Cloud-radiation interaction as simulated by the Canadian GEM model compared to ARM observations Danahé Paquin-Ricard Director: Colin Jones Codirector:

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Presentation on theme: "Cloud-radiation interaction as simulated by the Canadian GEM model compared to ARM observations Danahé Paquin-Ricard Director: Colin Jones Codirector:"— Presentation transcript:

1 Cloud-radiation interaction as simulated by the Canadian GEM model compared to ARM observations Danahé Paquin-Ricard Director: Colin Jones Codirector: Paul Vaillancourt Source:http://www.cs.pitt.edu/

2 1. Motivation MacroMicrophysicsEnvironment Cloud-Radiation Interaction Surface Radiative Budget Precipitation

3 2. GEM-LAM v.3.2.2 Diagnostic variables: Cloud fraction LWC, IWC r ei, r el Parameterization: Cloud fraction f(RH) & vertical overlap Liquid-ice separation & effective radii f(T) Radiation: Correlated-K Prognostic variables : T, q v, q c, q s, q r Shallow convection: Kuo-Transient Deep convection: Kain-Fritsch Advection Microphysics: Sundqvist

4 3. Simulations Simulations:  53 vertical levels  Horizontal resolution: 0,5°  Time step: 30 min  Prescribed SSTs & ice fraction  LBCs: ERA40 & ECMWF  7/8 years: 1998-2004/05 Source: Ayrton Zadra & Paul Vaillancourt

5 Source: http://www.arm.gov NSA SGP 4. Observations ARM (Atmospheric Radiation Measurement Program)  SGP (Southern Great Plains)  NSA (North Slope of Alaska) Observations:  SWD and LWD  LWP and IWV  Cloud fraction  Precipitation  Surface T & p

6 5. Results  3 hourly-mean (except for precip.: 3 hourly accumulation)  Radiation fluxes: function of cloud fraction  Clear-sky: CF<10%  Overcast: CF>90%  All-sky  LWP & IWV: only when precipitation ≤ 0,25mm/3h

7 5. Cloud fraction, IWV & LWP

8

9

10 5. SWD vs. IWV: clear sky (≤10 %)

11 C Local Time (h)

12 5. LWD vs. IWV: clear sky (≤10 %)

13

14 5. SWD vs. LWP: overcast (≥90%)

15 Local Time (h)

16 5. LWD vs. LWP: overcast (≥90%)

17

18 5. SWD + CF underestimated

19 5. LWD + CF underestimated

20 6. Conclusion  Cloud-radiation interaction can modify surface radiative fluxes by different ways  Verification of individual components is important

21 Thank you for your attention… Questions ?

22 6. A feedback example Drier Surface Less evaporation Overestimate near surf. Temperature Underestimate Cloud fraction Overestimate SWD Underestimate IWV

23 5. Résultats D

24 5. LWP


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