Examination of the Potential Impacts of Aerosols on Tropical Cyclone Nuri (2008)

In an earlier study, Cotton et al (2012) examined the potential impacts of aerosols on tropical cyclone (TC) NURI (16-23 Aug. 2008). RAMS was used in that study and aerosol concentrations were initialized inhomogeneously, but the concentrations were specified as high, low, and moderate. It was found that if the aerosols were swept into the eyewall and inner rain bands of the storm, the storm was surprisingly intensified. However, later in the simulation the aerosols mainly affected the outer rain bands and the simulated TC weakened. One problem with that study was that the intensity of the simulated TC was weaker than observed. Thus, the simulated response to aerosol might be different than if a TC of the correct intensity was simulated.

In this research we use the global model OLAM to simulate NURI with the hope that with its improved dynamical core and TC initialization procedures, the simulated intensity of NURI will be better represented. Moreover, we use GEOS-Chem to provide estimates of aerosol concentrations and chemistry using source estimates including anthropogenic sources and a run without anthropogenic sources. Using OLAM’s new TC dynamic initialization procedure, the simulations encompasses the time period starting with the mature stage (20 August) and extending to landfall (12Z 23 Aug., 2008). Our analysis consists of comparison of model predictions with observations and comparison between simulations of precipitation rates, latent heating profiles, cold-pool production and dynamics. This analysis will be discussed in relation to outer rain-band dynamics vs. eyewall dynamics and the influence of each on the evolution of the pressure and wind fields of accompanying the simulated cyclone.