Abstract: Tropical cyclones can form over open ocean where in situ observations are limited, so forecasters rely on satellite observations to monitor their development and track. We explore the utility of an operational satellite sounding product for tropical forecasting by characterizing the products retrieval skill during research flights. Scientists from both the NOAA-Unique Combined Atmospheric Processing System (NUCAPS) research team and tropical cyclone communities collaborated to target relevant tropical cyclones during the campaign. This effort produced 130 dropsondes that are welltimed with satellite sounder overpasses over three different tropical cyclones and one Saharan Air Layer outbreak...

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The post Evaluating Satellite Sounders for Monitoring the Tropical Cyclone Environment in Operational Forecasting appeared first on NOAA's Atlantic Oceanographic and Meteorological Laboratory.

Abstract: The Jordan mean tropical sounding has provided a benchmark reference for representing the climatology of the tropical North Atlantic and Caribbean Sea atmosphere for over 50 years. However, recent observations and studies have suggested that during the months of the North Atlantic hurricane season, this region of the world is affected by multiple air masses with very distinct thermodynamic and kinematic characteristics. This study examined ;6000 rawinsonde observations from the Caribbean Sea region taken during the core months (July–October) of the 1995–2002 hurricane seasons. It was found that single mean soundings created from this new dataset were very similar to C. L. Jordan’s 1958 sounding work. However, recently developed multispectral satellite imagery that can track low- to midlevel dry air masses indicated that the 1995–2002 hurricane season dataset (and likely Jordan’s dataset as well) was dominated by three distinct air masses: moist tropical (MT), Saharan air layer (SAL), and midlatitude dry air intrusions (MLDAIs). Findings suggest that each sounding is associated with unique thermodynamic, kinematic, stability, and mean sea level pressure...
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The post Rewriting the Climatology of the Tropical North Atlantic and Caribbean Sea Atmosphere appeared first on NOAA's Atlantic Oceanographic and Meteorological Laboratory.

Abstract: A deep well-mixed, dry adiabatic layer forms over the Sahara Desert and Shale regions of North Africa during the late spring, summer, and early fall. As this air mass advances westward and emerges from the northwest African coast, it is undercut by cool, moist low-level air and becomes the Saharan air layer (SAL). The SAL contains very dry air and substantial mineral dust lifted from the arid desert surface over North Africa, and is often associated with a midlevel easterly jet. A temperature inversion occurs at the base of the SAL where very warm Saharan air overlies relatively cooler air above the ocean surface. Recently developed multispectral Geostationary Operational Environmental Satellite (GOES) infrared imagery detects the SAL's entrained dust and dry air as it moves westward over the tropical Atlantic. This imagery reveals that when the SAL engulfs tropical waves, tropical disturbances, or preexisting tropical cyclones (TCs), its dry air, temperature inversion...
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The post The Impact of the Saharan Air Layer on Atlantic Tropical Cyclone Activity appeared first on NOAA's Atlantic Oceanographic and Meteorological Laboratory.