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Influence of the Saharan Air Layer on Hurricane Nadine

NASA's Terra satellite captured this true-color image of Hurricane Nadine in the Atlantic Ocean on Sept. 16 at 1345 UTC (9:45 a.m. EDT) while NASA's Global Hawk was flying around the storm.

Toshihisa Matsui, ESSIC Associate Research Scientist, is credited on a new paper in Monthly Weather Review titled, “Influence of the Saharan Air Layer on Hurricane Nadine (2012). Part I: Observations from the Hurricane and Severe Storm Sentinel (HS3) Investigation and Modeling Results”. Matsui’s co-authors include NASA scientists Jainn Shi, Scott Braun, and Zhining Tao.

The study uses a model with aerosol-cloud-radiation coupling to examine the impact of Saharan dust and other aerosols on Hurricane Nadine (2012). Eight different NASA-Unified Weather Research and Forecasting (NU-WRF) simulations were conducted in order to study aerosol direct (radiation) and indirect (cloud microphysics) effects from all aerosol species. 

In several simulations, aerosols led to storm strengthening, followed by weakening relative to the control simulation. This variability of the aerosol impact may be related to whether aerosols are ingested into clouds within the outer rainbands or the eyewall. Upper tropospheric aerosol concentrations indicate vertical transport of all aerosol types in the outer bands but only vertical transport of sea salt in the inner core. The results suggest that aerosols, particularly sea salt, may have contributed to a stronger initial intensification, but that aerosols ingestion into the outer bands at later times may have weakened the storm in the longer term. In most aerosol experiments, aerosols led to a reduction in cloud and precipitation hydrometeors, the exception being the dust-only case that produced periods of enhanced hydrometeor growth. The Saharan Air Layer (SAL) also impacted Nadine by causing a region of strong easterlies impinging on the eastern side of the storm. 

[Matsui bio]

To access the article, click here: “Influence of the Saharan Air Layer on Hurricane Nadine (2012). Part I: Observations from the Hurricane and Severe Storm Sentinel (HS3) Investigation and Modeling Results”.

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