WE PROPOSE AN OBSERVATIONAL STUDY OF SOLAR ECLIPSE PRODUCED CONTINENTAL US IONOSPHERE AND THERMOSPHERE PERTURBATIONS DURING THE AUGUST 21 2017 TOTAL ECLIPSE. ECLIPSE EFFECTS HAVE BEEN STUDIED FOR MORE THAN 50 YEARS BUT MODERN RADIO SOUNDING OBSERVATIONAL ADVANCES IN SENSITIVITY AND SPATIAL/TEMPORAL RESOLUTION CAN ADVANCE INFORMATION ON ITM SYSTEM RESPONSE AND SOLAR-TERRESTRIAL COUPLING DURING ECLIPSE EVENTS. PROJECT OBJECTIVES: WE WILL TARGET LARGE SCALE IONOSPHERIC DISTURBANCES OVER THE ENTIRE CONTINENTAL US TRIGGERED BY THE ECLIPSE AND SPANNING BOTH TOTALITY AND PARTIAL ECLIPSE ZONES. THE DISTURBANCES INCLUDE IONOSPHERIC VARIATIONS ASSOCIATED WITH PHOTOIONIZATION RATE REDUCTION AND RECOVERY AND TRAVELING IONOSPHERIC DISTURBANCES (TIDS) ASSOCIATED WITH ATMOSPHERIC GRAVITY WAVES (AGWS) EXCITED DURING TOTAL AND PARTIAL ECLIPSE PARTICULARLY TID/AGW GENERATION AND PROPAGATION CHARACTERISTICS. UNDERSTANDING THESE SIGNATURES ALSO REQUIRES STUDY OF THERMOSPHERE ECLIPSE RESPONSE AND WE WILL CONDUCT AN OBSERVATIONAL PROGRAM DIRECTLY MEASURING PLASMA AND NEUTRAL THERMAL STATE AS WELL AS NEUTRAL WIND VARIATION DURING RAPIDLY EVOLVING SOLAR HEATING. IN ADDITION TO CLASSICAL THERMODYNAMIC PROCESSES VARIATIONS OF PHOTOELECTRON ENERGETICS DURING THE ECLIPSE HAVE STRONG IMPACTS ON IONOSPHERIC PLASMA WAVES AND OUR STUDIES WILL ACCORDINGLY INCLUDE OBSERVATIONS AND ANALYSIS OF THESE IMPACTS. DATA TO BE USED INCLUDE A DENSE GLOBAL NETWORK OF ~6000 GNSS TOTAL ELECTRON CONTENT (TEC) RECEIVERS (100 MILLION MEASUREMENTS PER DAY; SECONDS-MINUTES TEMPORAL RESOLUTION; 1X1 DEGREE SPATIAL GRID); INCOHERENT SCATTER RADAR (ISR) OBSERVATIONS OF PLASMA PARAMETER FULL ALTITUDE PROFILES IN PARTIAL ECLIPSE ZONES (MILLSTONE HILL AND ARECIBO; 70+% ECLIPSE MAGNITUDE); AND NASA TIMED GUVI AND SEE DATA FOR SPATIAL VARIATIONS OF NEUTRAL COMPOSITION AND TEMPERATURE AS WELL AS SOLAR UV FLUX. ANALYSIS METHODOLOGY: 1. GNSS TEC DATA ANALYSIS AT MIT HAYSTACK WILL PRODUCE (1) ABSOLUTE VALUES OF CONTINENTAL US TEC; (2) DIFFERENTIAL TEC FOR TID STUDIES AFTER SUBTRACTING BACKGROUND TEC VALUES (ACCURACY = ~0.1 TEC UNITS). MULTIPLE METHODS OF BACKGROUND TEC SUBTRACTION WILL BE USED (E.G. AVERAGE TEC FROM PRIOR DAYS) AND TID PROPAGATION CHARACTERISTICS WILL BE DERIVED. 2. ISR DATA WILL BE COLLECTED FOR 5 DAYS (CONTROL: 2 DAYS BEFORE/AFTER ECLIPSE). AT MILLSTONE HILL THE ZENITH AND FULLY-STEERABLE ANTENNAS WILL BE USED FOR ESTIMATES OF TID PROPAGATION DIRECTION SPEED AND WAVELENGTH. AT ARECIBO HIGH PRECISION PLASMA DENSITY PROFILES FROM LANGMUIR (PLASMA) LINE DATA WILL BE USED TO EXAMINE VERTICAL PROPAGATION OF TIDS. BOTH MILLSTONE HILL AND ARECIBO RADAR DATA WILL BE ALSO USED FOR MAGNETICALLY ALIGNED NEUTRAL WIND ESTIMATES. PLASMA LINE DATA WILL PROVIDE PHOTOELECTRON IMPACT MONITORS. 3. NASA MISSION DATA INCLUDING TIMED/GUVI WILL PROVIDE SPATIAL VARIATIONS OF NEUTRAL COMPOSITION AND TEMPERATURE ALONG ECLIPSE AFFECTED ORBITS. THESE WILL BE COMPARED TO IONOSPHERIC DENSITY AND TEMPERATURE MEASUREMENTS. TIMED/SEE DATA WILL CORRELATE IONOSPHERIC VARIATIONS TO SOLAR EUV CHANGES ALONG THE SOLAR ECLIPSE AFFECTED SATELLITE ORBITS. MULTIPLE TIMED CONTROL DAY OBSERVATIONS ALLOW REMOVAL OF BACKGROUND SPATIAL VARIATIONS. CHANGES IN COMPOSITION AND THERMOSPHERIC WIND FUSION OF SPACE-BASED AND GROUND-BASED THERMOSPHERIC AND IONOSPHERIC DATA WILL EXAMINE THE INTERPLAY OF CHANGING SOLAR RADIATION COOLING PHOTOCHEMISTRY AND TRANSPORT PROCESSES. RELEVANCE OF THE APPROACH TO PROGRAM GOALS OF CONNECTING ECLIPSE EFFECTS TO ITM SYSTEM STUDIES: CHANGES IN IRRADIATION DURING THE SOLAR ECLIPSE INFLUENCES NOT ONLY PHOTOIONIZATION BUT ALSO THE GENERATION OF ATMOSPHERIC AND IONOSPHERIC WAVES. BOTH HELIOPHYSICS DECADAL SURVEY GOALS AND NASA S STRATEGIC GOALS TO EXPLORE THE FUNDAMENTAL RELATIONSHIP BETWEEN EARTHS IONOSPHERE AND SUN ARE ADDRESSED. THE RESEARCH USES DATA FROM THE NASA TIMED MISSION.