VARIABILITY IN THE TROPICAL UPPER TROPOSPHERE/LOWER STRATOSPHERE FROM SUB-SEASONAL TO INTER-ANNUAL TIMESCALES

THIS PROJECT UTILIZES NASA SATELLITE DATASETS REANALYSIS PRODUCTS AND A NASA GENERAL CIRCULATION MODEL TO BETTER UNDERSTAND VARIABILITY IN THE TROPICAL UPPER TROPOSPHERE/LOWER STRATOSPHERE (UTLS) AND ITS INFLUENCE ON TROPICAL DEEP CONVECTION. RECENT OBSERVATIONAL RESULTS HAVE DEMONSTRATED A STRONG CORRELATION BETWEEN THE MADDEN JULIAN OSCILLATION (MJO) AND THE STRATOSPHERIC QUASI-BIENNIAL OSCILLATION (QBO) IN BOREAL WINTER WITH ENHANCED MJO ACTIVITY AND INCREASED PREDICTABILITY DURING THE EASTERLY PHASE OF THE QBO. DESPITE THE REMARKABLE ROBUSTNESS OF THE OBSERVATIONAL RESULT THE PHYSICAL PROCESSES THROUGH WHICH THE MJO AND QBO INTERACT ARE UNKNOWN THOUGH PRELIMINARY STUDIES SUGGESTS THAT QBO MODULATION OF THE UTLS MAY DRIVE CHANGES IN MJORELATED CONVECTION. WE WILL EXAMINE UTLS VARIABILITY IN NASA DATASETS ATTRIBUTABLE TO THE MJO AND THE QBO IN WIND TEMPERATURE HUMIDITY CLOUDS AND RADIATIVE PROPERTIES FROM SUB-SEASONAL TO INTER-ANNUAL TIMESCALES TAKING INTO ACCOUNT ADDITIONAL MODULATION OF THESE SIGNALS BY ONE ANOTHER AND BY ENSO AND THE SEASONAL CYCLE. AFTER CHARACTERIZING THE STRUCTURES OF VARIABILITY IN THE UTLS IN OBSERVATIONS WE WILL EXAMINE THE ABILITY OF A NASA GENERAL CIRCULATION MODEL TO REPRODUCE THE OBSERVED RESULTS BEFORE CONDUCTING EXPERIMENTS IN WHICH THE MODEL UTLS IS RELAXED TOWARDS VARIOUS OBSERVED UTLS STATES TO EXAMINE PARTICULAR HYPOTHESES REGARDING THE MJO-QBO INTERACTION AND THE ABILITY OF THE UTLS TO MODULATE DEEP CONVECTION. THE WORK HAS BROAD SCIENTIFIC AND SOCIETAL IMPACT: IT AIMS TO IMPROVE THEORETICAL UNDERSTANDING OF TWO KEY MODES OF VARIABILITY IN THE TROPICS TO INFORM MODEL DEVELOPMENT TO CATEGORIZE UTLS VARIABILITY ON A BROAD SPECTRUM OF TIMESCALES IN NASA DATA SETS AND ULTIMATELY HAS POTENTIAL TO IMPROVE FORECAST SKILL ON SUB-SEASONAL TO SEASONAL TIMESCALES