THE ABUNDANCE OF MICROORGANISMS IN THE MID-TO-UPPER TROPOSPHERE CAN BE HIGH BUT VERY LITTLE IS KNOWN ABOUT THEIR ATMOSPHERIC ABUNDANCE AND SPECIATION. THIS PROJECT AIMS AT ACQUIRING THE APPROPRIATE DATA TO ADDRESS THIS GAPS IN KNOWLEDGE AND DEVELOP METHODS AND INSTRUMENTATION PIPELINES TO EFFICIENTLY STUDY CELLS IN ATMOSPHERIC SAMPLES COLLECTED DURING NASA-LEAD (AND OTHER) MISSIONS. WE WILL EVALUATE PORTABLE OPTICAL (FLUORESCENCE) TECHNOLOGIES USED TO DETECT AND MONITOR THE ABUNDANCE OF MICROBIAL CELLS IN AIR SAMPLES INSITU AND REAL-TIME. CURRENTLY WE DEVELOPED THE METHODOLOGY AND APPLIED FLOW CYTOMETRY TO QUANTIFY SPECIATED BIOAEROSOLS WITH DATASETS COLLECTED IN URBAN AND MARINE ENVIRONMENTS. THIS DATASET WILL BE USED TO EVALUATE AND IMPROVE BIOAEROSOLS DETECTION/SPECIATION WITH THE NASA BIOAEROSOL DETECTION INSTRUMENTATION. IN ADDITION THE DATA ANALYSIS WILL UNRAVEL THE RESPONSE OF AIRBORNE BIOLOGICAL PARTICLES TO ATMOSPHERIC STRESSORS AND STUDY ITS POSSIBLE CLOUD LIFECYCLE. OPTIMUM BIOAEROSOLS DETECTION AND QUANTIFICATION IS IMPORTANT TO: (1) UNDERSTAND ITS POSSIBLE EFFECT IN THE RADIATION BUDGET OF THE EARTH (2) ASSESS THE IMPACT OF MICROBES ON THE REDISTRIBUTION OF PRECIPITATION PATTERNS AND (3) UNDERSTAND ITS GLOBAL TRANSPORT AND ROLE SUPPLYING NUTRIENTS TO SUSTAIN LIFE IN THE EARTH. THIS PROJECT IS DIRECTLY LINKED TO NASA SECOND STRATEGIC GOAL (OBJECTIVE 2.2): AIMING TO ADVANCE KNOWLEDGE ABOUT THE EARTH SYSTEM AND IMPROVE DETECTION OF AIRBORNE MICROORGANISM TO MEET THE ENVIRONMENTAL CHALLENGES CAUSED BY ANTHROPOGENIC POLLUTION.