EMBEDDED WITHIN THE SUN S DIFFERENTIAL ROTATION PROFILE ARE FOUR ZONAL BANDS OF FAST ROTATION. THERE ARE TWO IN EACH HEMISPHERE AND COLLECTIVELY THEY ARE OFTEN CALLED THE TORSIONAL OSCILLATIONS. THESE BANDS MIGRATE WITH THE SOLAR CYCLE AND THEIR EXISTENCE REMAINS ONE OF THE PROMINENT MYSTERIES OF SOLAR PHYSICS. THE TWO LOW-LATITUDE BANDS ARE CLEARLY CORRELATED WITH THE ACTIVE-REGION BELTS; THESE BANDS MIGRATE EQUATORWARD IN LOCKSTEP WITH THE MAGNETIC FIELD AS THE CYCLE PROGRESSES. THE SECOND PAIR THE SO-CALLED HIGH-LATITUDE BRANCH BEGINS AT MIDLATITUDES EARLY IN THE CYCLE AND SLIDES POLEWARD AS THE CYCLE CONTINUES. HOWEVER DESPITE BEING AN OBVIOUS AND WELL-KNOWN CONSEQUENCE OF THE SUN S DYNAMO CYCLE WE HAVE LITTLE UNDERSTANDING OF THE ORIGIN OF THE FAST BANDS AND WHY THEY MOVE. SO FAR ALL ATTEMPTS HAVE FAILED TO CONVINCINGLY EXPLAIN THE FAST BANDS AS A DIRECT CONSEQUENCE OF SURFACE MAGNETIC ACTIVITY EITHER THROUGH CYCLONIC CIRCULATIONS INSTIGATED BY LOCAL COOLING OR THROUGH DIRECT LORENTZ TORQUES. THIS FAILURE HAS ARISEN BECAUSE OF THE INABILITY TO RECONCILE THREE OBSERVED PROPERTIES: (1) THE LOW-LATITUDE ZONAL BANDS ARE NOT CO-LOCAL WITH THE SUN S MAGNETIC BELTS AND ARE INSTEAD CENTERED SLIGHTLY EQUATORWARD OF THE ACTIVE REGIONS; (2) GLOBAL-MODE HELIOSEISMOLOGY HAS REVEALED THAT THE FAST BANDS PENETRATE QUITE DEEPLY INTO THE CONVECTION ZONE; AND (3) THE FAST BANDS OFTEN APPEAR EARLY IN THE CYCLE AT MIDLATITUDES BEFORE ACTIVE REGIONS BEGIN TO EMERGE AT THE PHOTOSPHERE. THE EVOLUTION OF THE SUN S ROTATION RATE OVER THE SOLAR CYCLE MUST BE THE CONSEQUENCE OF A SUBTLE INTERPLAY BETWEEN A SMALL SET OF HYDRODYNAMIC AND MAGNETIC TORQUES. THE MAJOR CONTRIBUTORS ARE THE ADVECTIVE TRANSPORT OF ANGULAR MOMENTUM BY MERIDIONAL CIRCULATIONS THE TURBULENT TRANSPORT OF ANGULAR MOMENTUM BY REYNOLDS STRESSES AND MAGNETIC TORQUES ARISING FROM THE LORENTZ FORCE. PRESENTLY THE TORQUE BALANCE IN THE SUN S OUTER LAYERS IS POORLY UNDERSTOOD BOTH OBSERVATIONALLY AND THEORETICALLY. WHILE WE CANNOT DIRECTLY MEASURE THE SUBSURFACE MAGNETIC FIELD IT HAS RECENTLY BECOME POSSIBLE TO MEASURE THE SUBSURFACE CONVECTIVE FLOWS AND THEIR ASSOCIATED HYDRODYNAMIC TORQUES. HENCE FOR THE FIRST TIME AN INDIRECT ESTIMATION OF THE LORENTZ TORQUES IN THE INTERIOR CAN BE OBTAINED THROUGH APPEAL TO ROTATIONAL EQUILIBRIUM. THIS IS WHAT WE PROPOSE TO DO HERE. WE WILL DIRECTLY MEASURE THROUGH HELIOSEISMIC MEANS THE HYDRODYNAMIC TORQUES AND BY WIELDING THE REQUISITE TORQUE BALANCE WE WILL INDIRECTLY ASSESS THE COEXISTING MAGNETIC TORQUES. MEASUREMENT OF THE SUN S CONVECTIVE FLOWS THROUGHOUT THE UPPER 30 MM OF THE CONVECTION ZONE IS NOW FEASIBLE USING RECENT DEVELOPMENTS IN HELIOSEISMOLOGY. MODERN RING-ANALYSIS PROCEDURES ATTAIN HIGH RESOLUTION VIA THE DECONVOLUTION OF SEISMIC MEASUREMENTS MADE OVER A MOSAIC OF DENSELY OVERLAPPING ANALYSIS TILES. THE APPLICATION OF THESE PROCEDURES TO THE FULL-DISK DOPPLER OBSERVATIONS FROM THE HELIOSEISMIC AND MAGNETIC IMAGER (HMI) ONBOARD THE SOLAR DYNAMICS OBSERVATORY (SDO) WILL PROVIDE EXCEPTIONAL FLOW MEASUREMENTS OVER A COMPLETE SOLAR CYCLE. WE WILL SEEK TO ANSWER THE FOLLOWING QUESTIONS: (A) WHAT IS THE DYNAMIC ORIGIN OF THE TORSIONAL OSCILLATIONS AND WHAT ARE THE PRIMARY TORQUES RESPONSIBLE FOR THEIR FORMATION? (B) HOW DOES THE BALANCE BETWEEN TORQUES CHANGE AS THE SOLAR CYCLE PROCEEDS AND WHY DO THE ZONAL FAST BANDS MIGRATE? (C) CAN SUBSURFACE FLOW OBSERVATIONS BE USED TO INDIRECTLY DETECT LONG-LIVED SUBMERGED MAGNETIC FLUX THROUGH THE LORENTZ TORQUE GENERATED BY THE FIELD? THESE QUESTIONS ARE OF DIRECT RELEVANCE TO TWO OF THE DECADAL SURVEY SCIENCE GOALS. SPECIFICALLY DETERMINE THE ORIGINS OF THE SUN S ACTIVITY AND PREDICT THE VARIATIONS OF THE SPACE ENVIRONMENT AND DISCOVER AND CHARACTERIZE FUNDAMENTAL PROCESSES THAT OCCUR BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE.