Tropical cyclone characteristics in the MERRA-2 reanalysis and AMIP simulations

These data sets use the same atmospheric model, the Goddard Earth Observing System Model, Version 5 (GEOS-5) during the same period. However, while MERRA-2 AMIP is a free-running atmospheric simulation forced only with sea surface temperature (SST), MERRA-2 Reanalysis uses an advanced data assimilation system to include a large variety of data sets.

Thus, we analyze (1) the sensitivity of TC activity to the model forcing, (2) how well the TCs in both data sets replicate observed TC characteristics, (3) the sensitivity of these results to tracking schemes and thresholds. Standard diagnostics such as the number of tropical cyclones and their intensity distribution are very similar in the AMIP model and the reanalysis. TCs in both data sets are weaker than observed, as is typical for the spatial resolution of these global models.