1. Tartu, Estonia, 24-26 January 2005
LITHUANIAN HYDROMETEOROGICAL SERVICE under the Ministry of Environment VILNIUS UNIVERSITY Division of Hydrology & Climatology
Case study based on one dimensional model with Kain-Fritsch convection parameterization scheme
Paulius Jalinskas
Tartu, Estonia, January 2005

2. The role of the different trigger functions
MAIN GOALS
To test:
Downdraft effect
The role of the different trigger functions

3. RCA1D (SMHI Rossby Centre Regional Climate Model) Physical parameterizations in the model follow closely those in the operational version of the HIRLAM at SMHI
Deep convection case
2330 UTC June 1997

4. Fig. 1: Precipitation (ppt) in mm/day and total cloud cover (%) from RCA1D simulations with no downdrafts (NODD), with downdrafts (norm) and timeseries of observations (OBS)

5. Fig. 2: Outgoing longwave radiation (OLR) in Wm-2 and total cloud water path in kg/m2 from RCA1D simulations with no downdrafts (NODD), with downdrafts (norm) and timeseries of observations (OBS)

6. Fig. 3: Precipitation (ppt) in mm/day and total cloud cover (%) from RCA1D simulations with precipitation fall-out rate equal to 0.02 (Lrate02), 0.09 (Lrate09) and timeseries of observations (OBS)

7. Fig. 4: Outgoing longwave radiation (OLR) in Wm-2 and total cloud water path in kg/m2 from RCA1D simulations with precipitation fall-out rate equal to 0.02 (Lrate02), 0.09 (Lrate09) and timeseries of observations (OBS)

8. Fig. 5: Precipitation (ppt) in mm/day and total cloud cover (%) from RCA1D simulations with only relative humidity (rh trig), only temperature (t trig) and both trigger functions (norm); timeseries of observations (OBS)

9. Fig. 6: Outgoing longwave radiation (OLR) in Wm-2 and total cloud water path in kg/m2 from RCA1D simulations with only relative humidity (rh trig), only temperature (t trig) and both trigger functions (norm); timeseries of observations (OBS)

10. Conclusions:
Downdrafts act as drying factor and indirectly affect surface radiation budget
Precipitation fall-out rate isn’t a crucial factor for deep convection event
Both relative humidity and temperature trigger function resulted increase of total cloud cover just before heavy rainfall event

11. Thank you for your attention !