THERE IS A COMPELLING NEED FOR INTENSIVE STUDY OF CONVECTIVE IMPACTS ON THE SUMMER STRATOSPHERE OVER NORTH AMERICA. EACH SUMMER THE NORTH AMERICAN MONSOON ANTICYCLONE (NAMA) DOMINATES THE CIRCULATION OF THE NORTH-WESTERN HEMISPHERE AND ACTS TO PARTIALLY CONFINE AND ISOLATE AIR FROM THE SURROUNDING ATMOSPHERE. STRONG CONVECTIVE STORMS IN THE NAMA REGULARLY PENETRATE DEEP INTO THE LOWER STRATOSPHERE (LS) WITH SOME ASCENDING ABOVE 20 KM (~450 K POTENTIAL TEMPERATURE). THE UNIQUENESS OF THE NAMA REGION IS MOST EASILY SEEN IN SATELLITE MEASUREMENTS OF WATER VAPOR WHICH SHOW A LARGE ENHANCEMENT IN THE LS OVER NORTH AMERICA NOT SEEN EITHER IN MAGNITUDE OR AT SUCH HIGH LATITUDES ELSEWHERE AROUND THE GLOBE. BUT THE COUPLING OF TROPOPAUSE-PENETRATING CONVECTION WITH LARGE-SCALE MONSOONAL MOTION IS POORLY UNDERSTOOD AS IS THE IMPACT OF CONVECTION ON THE CHEMICAL COMPOSITION OF THE LS BOTH IN MONSOON REGIONS AND IN THE GLOBAL STRATOSPHERE WHICH RECEIVES INPUTS OF MOIST AND POLLUTED MONSOON AIR FROM THE NAMA. THE DYNAMICS AND CHEMISTRY OF THE SUMMER STRATOSPHERE (DCOTSS) PROPOSAL DIRECTLY ADDRESSES THIS KNOWLEDGE GAP. DCOTSS ADDRESSES SEVERAL MAIN (THRESHOLD) SCIENCE OBJECTIVES TO UNDERSTAND HOW MUCH TROPOSPHERIC AIR AND WATER IS IRREVERSIBLY INJECTED INTO THE STRATOSPHERE BY CONVECTION AND WHICH CONVECTIVE SOURCE REGIONS IMPACT THE NAMA? CONVECTION CAN BRING UP POLLUTANTS IN THE FORM OF AEROSOLS AND TRACE GASES. DCOTSS WILL EXAMINE AS A FUNCTION OF TIME FOLLOWING CONVECTIVE INJECTION WHAT CHEMICAL CHANGES TAKE PLACE IN THE STRATOSPHERE DUE TO CONVECTION IN THE NAMA? MEASUREMENTS FROM MULTIPLE SATELLITES SHOW THAT O3 IN THE LS HAS CONTINUED TO DECLINE SINCE 1998; THE REASONS FOR THIS ARE UNCLEAR AND ATMOSPHERIC MODELS CANNOT REPRODUCE THE MEASURED TRENDS. DCOTSS AIMS TO UNDERSTAND HOW IMPORTANT QUANTITATIVELY IS INORGANIC/VERY SHORT-LIVED BROMINE IN LOWER STRATOSPHERIC OZONE LOSS? DCOTSS ALSO ADDRESSES SEVERAL IMPORTANT (BASELINE) SCIENCE QUESTIONS SUCH AS WHAT IS THE RESIDENCE TIME FOR CONVECTIVELY INJECTED AIR IN THE NAMA HOW IS AIR FROM THE NAMA EXPORTED TO THE GLOBAL STRATOSPHERE AND WHAT DYNAMICAL MECHANISMS LEAD TO THE IRREVERSIBLE INJECTION OF MATERIAL INTO THE STRATOSPHERE BY CONVECTIVE STORMS? IN ADDITION WHAT ARE THE COMPOSITION AND POTENTIAL SOURCES OF AEROSOL IN THE LOWER STRATOSPHERE OVER NORTH AMERICA? IN THE EVENT OF A MAJOR VOLCANIC ERUPTION THE DCOTSS SCIENCE TEAM IS WELL SITUATED TO MAKE MEASUREMENTS TO UNDERSTAND WHAT WILL BE THE STRATOSPHERIC CHEMICAL RESPONSE TO A VOLCANIC ERUPTION?