Eliashiv, J., A. Subramanian and A. J. Miller, 2018:

Tropical climate variability in the Community Earth System Model Data Assimilation Research Testbed


Climate Dynamics, sub judice.

Abstract. This study evaluates the tropical climate variability of a 12-year coupled data assimilation experiment. The Community Earth System Model using the Data Assimilation Research Testbed (CESM-DART), a coupled data assimilation system, is used to produce a 12-year state estimate of the ocean and atmosphere by assimilating conventional oceanic and atmospheric observations. This study assesses the surface uxes in this reanalysis product compared to observational estimates as well as two other renalysis products. The models mean state, variance, and wavenumberfrequency characteristics of the intraseasonal variability in zonal winds at 850 hPa (U850) and 200 hPa (U200), and velocity potential at 200 hPa (VP200) are evaluated. The study finds improvements in the variability of surface uxes compared to observational datasets and in contrast to other data assimilated products. Additionally, the study shows increased intraseasonal variability and energy in tropical waves in the CESM-DART 12-year assimilated product. The MJO spectral response with CESM-DART shows higher power in the MJO band region compared to CESM runs with no assimilation. The MJO events simulated during the 12-year period agree with the events identified in other reanalyses products and the amplitude of CESM-DART ensemble mean agrees with those of the NCAR/NCEP reanalysis MJO events.

Preprint (pdf)