Influence of SAL on Tropical Cyclogenesis: Comparative Studies of Helene (2006) and Julia (2010)

The impact of the Saharan air layer (SAL) over tropical cyclogenesis of Helene (2006) and Julia (2010) is investigated in relation to the interactions of the dust particles with the systems and their environment. The main objective of this study is to find a threshold value for the density of the dust content. The study is based on the use of data from the 2006 NASA African Monsoon Multidisciplinary Analysis (NAMMA) project and the 2010 Genesis and Rapid Intensification Processes (GRIP) project. Hurricanes Helene 2006 and Julia 2010 were selected for this study, since both systems developed around the same time frame and spatial location (September 12, 2006 and September 12, 2010 respectively). The pre, during and post conditions of these two systems were analyzed to quantify a threshold for the density of the dust particles. The amount of dust content could influence a hurricane by altering other parameters such as temperature, relative humidity and mixing ratio. Satellite observations from the GOES, METEOSAT and Moderate Resolution Imaging Spectroradiometer (MODIS) - Terra Aerosol Optical Depth (AOD) were also employed for the study of the dust content. Lightning activity data from the Met Office Arrival Time Difference (ATD) system is used as another parameter to track any convection and sign of cyclone formation. The combination of remote sensing data, ground observations, airborne and aircraft-deployed data may help improve or advance our understanding of the interactions between the tropical cyclones and the dust particles.