SENSITIVITIES OF BIOMASS BURNING AND LAND USE CHANGE ON THE NUMBER OF PRECIPITATION DAYS IN THE MARITIME CONTINENTRECENT ECONOMIC DEVELOPMENT OF THE MARITIME CONTINENT HAS INCLUDED SIGNIFICANT LAND USE CONVERSION WITH ASSOCIATED DEFORESTATION AND AGRICULTURAL MAINTENANCE BIOMASS BURNING. IN DROUGHT YEARS SUCH AS EL NINO PERIODS MASSIVE BURNING AND SMOKE EVENTS GARNER WORLD-WIDE ATTENTION. BUT STRONG AEROSOL SOURCES FROM BIOMASS BURNING FOSSIL FUEL CONSUMPTION AND INDUSTRIAL EMISSIONS AFFECT THE REGION'S ATMOSPHERE IN BOTH WET AND DRY YEARS. BOTH THE LAND USE CONVERSION AND ITS ASSOCIATED BURNING EVENTS HAVE POSSIBLEIMPACTS ON REGIONAL PRECIPITATION. THIS POSSIBILITY HAS BEEN STUDIED FROM SEVERAL ANGLES BY THE SCIENTIFIC COMMUNITY INCLUDING ANTHROPOGENICALLY FORCED CHANGES IN LOCAL PRECIPITATION PATTERNS AND POTENTIAL POSITIVE FEEDBACKS BETWEEN BURNING AND DROUGHT SEVERITY. OF PARTICULAR NOTE ARE REPORTS OF AN INCREASE IN THE NUMBER OF ZERO RAIN DAYS OVER RECENT DECADES. BUT MODELED ANDOBSERVATIONAL ESTIMATES OF PRECIPITATION TRENDS VARY CONSIDERABLY AND PREVIOUS RESEARCH HAS SHOWN THAT THE MARITIME CONTINENT HOSTS SOME OF THE MOST SIGNIFICANT OBSERVABILITY CHALLENGES IN THE WORLD FOR AEROSOL CLOUDS AND PRECIPITATION. FURTHER BIOMASS BURNING BEHAVIOR AND REGIONAL METEOROLOGY CO-VARY TO SUCH A STRONG DEGREE THAT CAUSE AND EFFECT STUDIES CAN EASILY BE CONFOUNDED.THE CURRENT SATELLITE DATA RECORD AND COMMON MODELS IN AND OF THEMSELVES ARE PROBABLY INCAPABLE OF DIRECTLY CONSTRAINING PRECIPITATION IMPACTS OF BIOMASS BURNING AT THE CLIMATE LEVEL IN REGIONS AS COMPLEX AS THE MARITIME CONTINENT. HOWEVER THEY CAN IDENTIFY THE LIKELY CANDIDATE MECHANISMS OF PRECIPITATION IMPACTS FOR USE IN GUIDING FUTURE OBSERVATIONS TO QUANTIFY REGIONAL CLIMATECHANGE. IN THIS PROPOSED GRANT WE WILL SPOTLIGHT THREE HYPOTHESES THROUGH WHICH BIOMASS BURNING AND LAND SURFACE CHANGE MAY AFFECT PRECIPITATION DURING THE TRADITIONAL BURNING SEASON USING THE NUMBER OF PRECIPITATION FREE DAYS AS A METRIC:1) BOTH LAND SURFACE CHANGE AND BIOMASS BURNING EQUALLY REDUCE THE FREQUENCY OF LIGHT PRECIPITATION FROM SMALL WARM CONVECTION LEADING TO THE OBSERVED INCREASE IN THE NUMBER OF ZERO RAIN DAYS AT SURFACE STATIONS.2) DETRAINMENT OF SMOKE PARTICLES AT MID-TROPOSPHERIC LEVELS IN DEEP CONVECTION WILL INHIBIT PRECIPITATION IN TROPICAL MID-LEVEL STRATIFORM CLOUDS FURTHER INCREASING THE NUMBER OF ZERO RAIN DAYS.3) THE PRESENCE OF SMOKE LEADS TO MORE ISOLATED BUT MORE INVIGORATED THUNDERSTORMS ALONG THE NW COAST OF SARAWAK BORNEO. THE NULL HYPOTHESIS FOR THESE IS THAT BULK METEOROLOGY ALONE WITHOUT ANY AEROSOL OR LAND SURFACE EFFECTS CAN EXPLAIN THE NATURE OFZERO RAIN DAYS IN OUR AREA OF INTEREST. USING THE ABOVE HYPOTHESES AS FOCAL POINTS WE WILL EMPLOY A COMPREHENSIVE OBSERVATION AND MODELING FRAMEWORK. FIRST BOTH IN SITU AND SATELLITE OBSERVATIONS OF AEROSOL PARTICLES CLOUDS AND PRECIPITATION WILL BE USED TO DEVELOP A BASELINE CONCEPTUAL MODEL OF CONVECTION CHARACTERISTICS IN OUR TARGET AREAS IN THE CONTEXT OF BIOMASS BURNING METEOROLOGY. SECOND THE MODEL SENSITIVITIES OF BOTH SHALLOW AND DEEP CONVECTION TO LAND COVER CHANGE AND BIOMASS BURNING WILL BE EXPLORED USING MARKOV CHAIN MONTE CARLO METHODOLOGY AND A SEPARATE LES STUDY FOR SEVERAL IDEALIZED CASES OF SHALLOW CONVECTION. THIRD BASED ON THE SENSITIVITY ANALYSIS DETERMINISTIC WRF RUNS WILL BE CONFIGURED TO HELP UNDERSTAND THE IMPACT OF LAND COVER CHANGE AND BIOMASSBURNING SMOKE IN EL NINO AND NEUTRAL CASES. FINALLY BASED ON THE PREVIOUS THREE COMPONENTS OUR HYPOTHESES WILL BE EVALUATED AND AN ASSESSMENT WILL BE MADE AS TO OBSERVATIONAL REQUIREMENTS TO MONITOR REGIONAL CLIMATE CHANGE.