1. OBJECTIVE MERIDIONAL CIRCULATION PLAYS AN IMPORTANT ROLE IN THE SUNS INTERIOR DYNAMICS AND DYNAMO BUT ITS PROFILE AND HOW IT EVOLVES WITHIN ONE SOLAR CYCLE ARE NOT YET ACCURATELY DETERMINED. THE MEASUREMENT OF MERIDIONAL CIRCULATION USING HELIOSEISMIC TECHNIQUES IS COMPLICATED BY A SYSTEMATIC CENTER TO LIMB EFFECT AND DIFFERENT CIRCULATION PROFILES WERE REPORTED BY DIFFERENT AUTHORS. TO CLEAR THE OBSTACLES FOR A MORE ROBUST INFERENCE OF MERIDIONAL CIRCULATION AND TO RECONCILE DIFFERENT RESULTS BY DIFFERENT AUTHORS WE PROPOSE TO DEVELOP A NEW FREQUENCY DEPENDENT TIME DISTANCE ANALYSIS TECHNIQUE WHICH WITH A COMBINATION OF ANALYSIS ON NUMERICAL SIMULATION DATA OF BOTH LOCAL AND GLOBAL SCALES WILL ALLOW US TO DESIGN NEW WAYS OF REMOVING THE SYSTEMATIC EFFECT AND INFER THE MERIDIONAL CIRCULATION MORE ACCURATELY. THE KNOWLEDGE GAINED IN THIS PROCESS CAN ALSO BE APPLIED ON HELIOSEISMIC ANALYSES OF SUNSPOTS POTENTIALLY LEADING US TO A BETTER DETERMINATION OF SUNSPOTS SUBSURFACE FLOWS. 2. METHODOLOGY .INSPIRED BY THE RECENT DISCOVERY THAT THE CENTER TO LIMB EFFECT VARIES STRONGLY WITH FREQUENCY AND SOMETIMES SWITCHES SIGNS FROM NEGATIVE TO POSITIVE WE PLAN TO APPLY FREQUENCY DEPENDENT TIME-DISTANCE HELIOSEISMIC MEASUREMENTS ON MERIDIONAL FLOW AND DESIGN NEW APPROACHES OF REMOVING THE SYSTEMATIC EFFECT IN THE FREQUENCY DOMAIN WHICH IS A MORE SOLID APPROACH THAN THE PREVIOUS EMPIRICAL METHOD. EMPLOYING EXISTING GLOBAL WAVE FIELD SIMULATION CODE WE PLAN TO DEVELOP A NEW METHOD TO DERIVE THE FREQUENCY DEPENDENT WAVE BASED SENSITIVITY KERNELS THAT WILL BE USED IN OUR NEW INVERSIONS FOR THE MERIDIONAL CIRCULATION. THE NEW INVERSIONS WITH NEW FREQUENCY DEPENDENT MEASUREMENTS WITH NEW SENSITIVITY KERNELS ARE EXPECTED TO GIVE MORE ROBUST INFERENCE OF THE MERIDIONALCIRCULATION PROFILE. TO UNDERSTAND THE CAUSE OF THE CENTER TO LIMB EFFECT AND ITS FREQUENCY VARIATION WE PLAN TO APPLY OUR HELIOSEISMIC ANALYSIS ON DATA OBSERVED AT MULTIPLE HEIGHTS AS WELL AS DATA OF DIFFERENT HEIGHTS OBTAINED FROM LOCAL SCALE SIMULATIONS. THE BEHAVIOR OF EVANESCENT WAVES ABOVE THE PHOTOSPHERE AND HOW CONVECTIVE FLOWS AFFECT THE MEASURED TRAVEL TIMES WILL BE EXAMINED TO EXPLAIN THE MEASURED TRAVEL TIME SHIFTS IN THE CENTER TO LIMB EFFECT. THE CENTER TO LIMB EFFECT IS CONNECTED WITH THE TRAVEL TIME ASYMMETRY MEASURED IN SUNSPOT REGIONS. THEREFORE UNDERSTANDING HOW DIFFERENT ATMOSPHERIC HEIGHTS AND DIFFERENT CUTOFF FREQUENCIES AFFECT TRAVEL TIME MEASUREMENTS FOR WAVES TRAVELING IN OPPOSITE DIRECTIONS WILL HELP US REMOVE THE TRAVEL TIME SHIFTS THAT ARE NOT DIRECTLY RELATED TO SUBSURFACE FLOWS HENCE DESIGN A NEW WAY FOR A MORE RELIABLE INFERENCE OF THE SUBSURFACE DYNAMICS BENEATH SUNSPOTS. .3. PERCEIVED .SIGNIFICANCE AND RELEVANCE THE PROPOSED INVESTIGATION ARMED WITH THE NEWLY DEVELOPED FREQUENCY DEPENDENT HELIOSEISMIC ANALYSIS AS WELL AS GLOBAL AND LOCALSCALE NUMERICAL SIMULATIONS IS EXPECTED TO GIVE US A ROBUST DERIVATION OF SOLAR MERIDIONAL CIRCULATION PROFILE AND ITS TEMPORAL EVOLUTION AN IMPROVED UNDERSTANDING OF THE CENTER TO LIMB EFFECT AND A BETTER VIEW OF SUBSURFACE DYNAMICS OF SUNSPOTS. THE MERIDIONAL CIRCULATION IS DIRECTLY RELATED TO THE EVOLUTION OF SOLAR CYCLES AND SUNSPOTS ARE OFTEN ASSOCIATED WITH SOLAR ERUPTIVE EVENTS THEREFORE THIS INVESTIGATION ADDRESSES ONE OF THE HELIOPHYSICAL DECADAL SURVEY GOALS: DETERMINE THE ORIGINS OF THE SUNS ACTIVITY AND PREDICT THE VARIATIONS IN THE SPACE ENVIRONMENT. .