1. Yanjun Jiao and Colin Jones University of Quebec at Montreal September 20, 2006 The Performance of the Canadian Regional Climate Model in the Pacific Ocean

2. OUTLINE: 1.Experiment configurations 2.Results from original CRCM (precipitation, cloud and relative humidity) 3.Modification to the CRCM model physics 4.Results of CRCMM 5.Summary

3. CRCM4 domain in cylindrical projection CRCM4 domain in PS projection 180km (60ºN) resolution 115  75 grid points 29 Gal-Chen levels 15-min time step Output every 3hrs 1. Experiment configurations Sponge zone (9 grid points) GPCI 2D domain (5ºS-45ºN,160ºE-120ºW) GPCI cross-section (13 points) ISCCP cloud cover (JJA 1998)

4. CRCM4 0.25º TRMM Stratiform precipitation Convective precipitation Total precipitation

5. ISCCP CRCM4 Total cloud

6. Siebesma et al. (2004)

8. 1)The eddy diffusivities calculation of the ECMWF. 2)A switch to turn off the shallow convection. 3)The trigger function of shallow convection (DTRH). 4)The cloud base mass flux closure=f (w*). 5)Variable cloud radius of the deep convection=f(w LCL ). 6)Variable minimum cloud-depth=f(T LCL ). 7)A dilute updraft ascent. 8)Xu-Randall cloud scheme. 9)Evaporation of falling large scale precipitation. 3. Modification to the model physics of CRCM4

9. zpbl 0.1zpbl buofxs < 0 buofxs > 0 3.1 Modification to vertical diffusion (ECMWF documentation CY28r1) Revised Louis scheme Troen and Mahrt (1986) Non-local diffusion when eddies have a similar size as the PBL Explicit entrainment parameterization in the PBL top

10. 2) The trigger function of shallow convection 1) A switch to turn off the shallow convection once deep convection has been detected on the same grid point 3.2 Modification to shallow convection (BKF) 3) The closure of cloud base mass flux (Grant 2001 and Neggers et al. 2004) free convective vertical velocity scale CAPE adjustment closure: mass flux at cloud base is totally controlled by the conditions in the cloud layer Subcloud convective velocity scaling closure: links the mass flux at cloud base to the TKE in subcloud layer. Based on the observation that shallow cumulus clouds (visible part because of condensation) often root deeply into the subcloud mixed layer (invisible dry thermal) CTL LCL Deep convection is driven by latent heat release in the convective cloud

11. 2) The minimum cloud-depth threshold has been parameterized according to the cloud-base temperature rather than remaining constant. 1) Cloud radius of the deep convection vary with the vertical velocity at lifting condensation level (LCL) 3.3 Modification to deep convection Kain (2004)

12. 3) A dilute updraft ascent has been used to calculate CAPE, which provides a more accurate calculation in convection rainfall and mass flux 3.3 Modification to deep convection Equivalent potential temperature in undilute updraft (produces a significant larger CAPE than actual one) Equivalent potential temperature in dilute updraft Reduces the CAPE value in highly unstable regimes (especially for dry condition) Reduces the precipitation and the degree of stabilization

13. 3.4 Modification to cloud scheme Xu and Randall (1996) is cloud liquid water

14. 3.5 Modification to large scale precipitation (evaporation of falling precipitation from ECMWF) Kessler (1969)

15. CRCM4 CRCMM 0.25º TRMM JJA 1998 precipitation over GPCI 2D domain

16. CRCM4 CRCMM

17. ISCCP CRCMM CRCM4 JJA 1998 total cloud over GPCI 2D domain

18. CRCMM CRCM4

19. Vertical profile of the relative humidity

20. Siebesma et al. (2004) Vertical profile of the cloud cover

21. Vertical profile of vertical velocity (Pa/s)

22. Thanks to the GPCI, some deficiencies in the CRCM4 have been found. The CRCMM is better than CRCM4 in the field of: 1)Precipitation 2)Total cloud cover (shallow cumulus region). 3)Vertical profiles of relative humidity, cloud and vertical velocity. 4)Still have some space to improve in convective precipitation (too strong), PBL (too moist and sharp), and LWP (too low in stratocumulus region) …… Testing the sensitivities to horizontal and vertical resolutions (180km ~ 90km ~ 45km and L29 ~ L47) Testing over the North America (AMNO domain) (CLASS, winter and summer) 5. Summary