Abstract
The aerosol vertical distribution in the tropical cyclone (TC) main development region (MDR) during the recent active hurricane seasons (2015–2018) was investigated using observations from NASA’s Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) Satellite. The Total Attenuated Backscatter (TAB) at 532 nm was measured by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP Lidar) onboard CALIPSO which is a polar orbiting satellite that evaluates the role clouds and atmospheric aerosols play in Earth’s weather, climate and air quality. The TAB was used to illustrate the dispersion and magnitude of the aerosol vertical distribution in the TC-genesis region. A combination of extinction quality flag, cloud fraction, and cloud-aerosol discrimination (CAD) scores were used to filter out the impact of clouds. To better describe the qualitative and quantitative difference of aerosol along the paths of African Easterly Waves (AEWs), the MDR was further divided into two domains from 18° W to 30° W (Domain 1) and 30° W to 45° W (Domain 2), respectively. The distribution of average aerosol concentration from the time of active cyclogenesis was compared and quantified between each case. The resulting observations suggest that there are two distinct layers of aerosols in the vertical profile, a near surface layer from 0.5–1.75 km and an upper layer at 1.75–5 km in altitude. A quantification of the total aerosol concentration values indicate domain 2 cases were associated with higher aerosol concentrations than domain 1 cases. The environmental variables such as sea surface temperature (SST), vertical windshear (VWS), and relative humidity (RH) tended to be favorable for genesis to occur. Among all cases in this study, the results suggested tropical cyclone genesis and further development occurred under dust-loaded conditions while the environmental variables were favorable, indicating that dust aerosols may not play a significant role in inhibiting the genesis process of TCs.
Highlights
It is imperative to improve our observational understanding of tropical cyclone (TC)activities and to further develop accurate TC forecasting models
The perspective events are each shown with TERRA/MODIS visual satellite imagery with its selected Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) pass in order to assess the vertical profile (Figure 2)
The importance of evaluating the dust aerosol concentration ahead of the developing TC before genesis takes place exemplifies the interaction that is bound to occur as the TC moves into the air mass
Summary
It is imperative to improve our observational understanding of tropical cyclone (TC)activities and to further develop accurate TC forecasting models. As African Easterly Waves (AEW) propagate westward off the coast of West. Africa, they begin to decrease in sea level pressure if the environmental conditions are favorable (e.g., mesoscale convective systems) forming a closed surface circulation leading to TC genesis (e.g., Gray 1968; Tompkins and Chiao 2011) [1,2]. The environmental factors that influence the development of TCs can influence the duration of an individual storm and the length of the season. The upper-level atmosphere can provide supplementary support for the development of a TC due to an upper-level trough being present in the path of the tropical wave (Montgomery and Farrell 1993) [6]. In synoptic conditions, mid to upper-level wind speeds tend to be stronger than the surface causing unfavorable shearing to occur on convection that is assembling for TCs
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