SCIENCE GOALS AND OBJECTIVES: WE PROPOSE TO PERFORM A COMPREHENSIVE STUDY OF THE SUBSURFACE AND SURFACE FLOWS ASSOCIATED WITH ACTIVE REGIONS AND THEIR EVOLUTION USING SDO/HMI DOPPLERGRAMS AND MAGNETOGRAMS. THE EVOLUTION OF ACTIVE REGIONS IS OF FUNDAMENTAL IMPORTANCE IN SOLAR PHYSICS. SINCE ACTIVE REGIONS ARE FORMED FROM STRONG MAGNETIC FIELDS GENERATED BY A SOLAR DYNAMO LOCATED IN THE SOLAR INTERIOR THEIR EVOLUTION FROM EMERGENCE THROUGH DECAY PROVIDES CRUCIAL INFORMATION ABOUT THE SOLAR DYNAMO AND THUS ABOUT THE ORIGINS OF THE SUN S ACTIVITY. SUBSURFACE FLOW PARAMETERS CAN SERVE AS PROXIES OF THE MAGNETIC STRUCTURE IN SUBSURFACE LAYERS AND LINK THE DYNAMICS OF SUBSURFACE LAYERS WITH THE CONDITIONS OF THE MAGNETIC ACTIVITY IN THE PHOTOSPHERE AND ABOVE. STUDIES OF SUBSURFACE FLOWS HAVE FOCUSED MAINLY ON FLARE-PRODUCTIVE REGIONS OR ON THE EMERGENCE OF ACTIVE REGIONS. HOWEVER A SYSTEMATIC STUDY OF THE EVOLUTION OF SUBSURFACE FLOWS OF ACTIVE REGIONS FROM EMERGENCE TO DECAY WITH REGARD TO THEIR MORPHOLOGY HAS YET TO BE PERFORMED. ACTIVE REGIONS EVOLVE DURING THEIR LIFE TIME AND THE SUBSURFACE FLOWS ARE EXPECTED TO CHANGE AS WELL. WE PROPOSE TO STUDY THE SUBSURFACE FLOWS OF ACTIVE REGIONS OBSERVED BY SDO/HMI THROUGHOUT THE SOLAR CYCLE. WE WILL FOCUS ON FOR EXAMPLE LONG-LIVED ACTIVE REGIONS EMERGING AND DECAYING REGIONS FLARING AND NON-FLARING REGIONS AND REGIONS WITH AND WITHOUT ROTATING SUNSPOTS. THE GOAL IS TO ESTABLISH COMMON FEATURES OF THE SUBSURFACE DYNAMICS OF ACTIVE REGIONS AND DIFFERENTIATE THEM FROM CHARACTERISTICS THAT DEPEND ON THEIR MORPHOLOGY. THE RESULTING FLOW PROFILES WILL PROVIDE CRUCIAL INFORMATION ABOUT THE MAGNETIC FLUX OF ACTIVE REGIONS AND HOW IT IS SYNTHESIZED CONCENTRATED AND DISPERSED.DATA: WE WILL USE DOPPLERGRAMS AND MAGNETOGRAMS OBTAINED BY THE HMI INSTRUMENT ONBOARD THE SDO SPACECRAFT. THESE HIGHRESOLUTION OBSERVATIONS ALLOW US TO MEASURE SUBSURFACE FLOWS AT GREAT DISTANCES FROM DISK CENTER AND THUS FOLLOW THE EVOLUTION OF ACTIVE REGIONS DURING THEIR DISK PASSAGE FOR A MUCH LONGER PERIOD OF TIME THAN POSSIBLE WITH PREVIOUS OBSERVATIONS. THE AVAILABILITY OF SIMULTANEOUS VECTOR MAGNETOGRAMS WILL ALLOW US TO FOLLOW THE EVOLUTION OF ACTIVE REGIONS AT THE SOLAR SURFACE AND TO DERIVE SURFACE FLOWS AS WELL. METHODOLOGY: WE WILL PERFORM A COMPREHENSIVE STUDY OF THE SUBSURFACE AND SURFACE FLOWS OF ACTIVE REGIONS AND THEIR TEMPORAL AND SPATIAL EVOLUTION. WE WILL DERIVE THE SUBSURFACE FLOWS DURING THE DISK PASSAGE OF EACH ACTIVE REGION WITH RING-DIAGRAM AND TIMEDISTANCE ANALYSIS (TWO WELL-ESTABLISHED HELIOSEISMIC TECHNIQUES) OF HMI DOPPLERGRAMS. IN ADDITION TO USING FLOWS FROM THE HMI RING-DIAGRAM PIPELINE WE WILL CUSTOMIZE THE TECHNIQUES TO DERIVE FLOWS ON A FINER TEMPORAL AND SPATIAL GRID APPROPRIATE FOR ACTIVE REGIONS. AT THE SURFACE FLOWS AND EVOLUTION OF MAGNETIC ACTIVITY WILL BE DERIVED FROM THE CORRESPONDING HMI VECTOR MAGNETOGRAMS USING ESTABLISHED CORRELATION TRACKING TECHNIQUES TO DERIVE SURFACE FLOWS. THIS WILL ALLOW US TO MATCH THE SURFACE WITH THE SUBSURFACE EVOLUTION OF ACTIVE REGIONS. RELEVANCE: THE PROPOSED STUDY OF SUBSURFACE DYNAMICS OF ACTIVE REGIONS WILL LEAD TO A BETTER UNDERSTANDING OF THE EVOLUTION OF ACTIVE REGIONS. THE PROPOSAL IS THUS RELEVANT TO THE FOLLOWING GOAL OF THE SDO PROJECT: HOW IS ACTIVE REGION MAGNETIC FLUX SYNTHESIZED CONCENTRATED AND DISPERSED ACROSS THE SOLAR SURFACE? THE PROPOSAL ALSO ADDRESSES THE GOAL DETERMINE THE ORIGINS OF THE SUN S ACTIVITY AND PREDICT THE VARIATIONS IN THE SPACE ENVIRONMENT FROM THE HELIOPHYSICS DECADAL SURVEY.