1. Sensitivity of Simulated Philippine Rainfall to Model Resolution and Convective Closure Scheme JOSEFINA ARGETE Institute of Environmental Science and Meteorology University of the Philippines ELLA CECILIA CASTILLO Climate Studies Division Manila Observatory ANA LIZA SOLIS Climatology & Agrometeorology Branch PAGASA, Weather Bureau

2. Objectives To test the sensitivity of RegCM3 to different domain resolutions on Philippine rainfall To test the sensitivity of the model to 2 convective closure schemes To validate the model output with observed values (station data, CRU and XA)

3. Brief Climatology Northeast Monsoon Season – (Oct-Mar) brings relatively warm & humid air masses e.g. much rainfall in northern and eastern part of the country. Southwest Monsoon Season – (May-September) peak in August, deep current up to 10,000m high Almost all parts of the island receive high rainfall, max. at coasts and slopes directly exposed to the monsoon. North Pacific Trades – (Mar-Apr) NE monsoon weakens, islands under influence of trades, easterlies bring warmest air in the Phils. NCEP REANALYSIS

4. Input data: ET42, L15 (ECWCRP) GTOPO30_10MIN GLCC10MIN_BATS OISST Start date=1997052500 End date=1997070100 clat = 14 clon= 120 iproj=“ROTMER”Methodology

5. 60 km45 km20 km No. of grids55 x 4563 x 53163 x 133 ds604520 nspgx6(12)8(16)18(36) dt20010060 igccFC/ASFC

6. Validation data CRU monthly precip Xie-Arkin monthly precip rate Observed daily/monthly station rainfall

7. RESULTS:

8. 60

9. 45

10. 20

11. PRCC at different Resolutions (FC)

12. Convective Closure Scheme

13. Domain for averaging daily rainfall

16. CONCLUSIONS: 60 & 45km res. runs captured the spatial pattern of rr ; details are more evident in 20km res.run The run using Arakawa-Schubert Scheme simulated the Philippine rainfall better than the Fritsch-Chappel Scheme In general, the model’s prca compared relatively well with the observed rainfall values but tended to overestimate The same is true for convective precip (prcc)