An Analysis of the African Easterly Jet and the African Monsoon and their possible impact on the 2024 Atlantic Hurricane Season during the ORCESTRA Campaign 2024

The ORCESTRA Campaign took place in an 8-week period from August 10^th to September 30^th, 2024, across the tropical Atlantic basin from Cape Verde to the Lesser Antilles. As part of ORCESTRA, extensive atmospheric soundings were performed and these included about 1,000 dropsondes launched from the German HALO aircraft; and about 700 radiosondes from the ship METEOR, the Barbados Cloud Observatory (BCO), and ground-based operations on Sal (Cape Verde). The culmination of this field campaign is that a great deal of data that covers this usually data sparse region of the world is now available for analysis. This period of the campaign coincided with what should have been the most active period of the 2024 Atlantic Hurricane Season which was projected to be hyperactive by every agency due to the anomalously high sea surface temperatures (SSTs) and the projected transitioning of the ENSO phase from El Nino to La Nina. However, other than Hurricane Beryl in June/July before the campaign, the hurricane season remained unexpectedly quiet during the campaign. This coincided with a peculiar westward extension of the African Monsoon as far west as Barbados. Furthermore, the area of elevated precipitable water in the Trade Wind Trough was observed to be much more spatially extensive than usual. Another unusual observation during this period was that the African Easterly Jet was offset from its climatological mean position. Furthermore, there was also anomalous rainfall over northern Africa and more rapid dissipation of easterly waves upon entry into the Atlantic Ocean. Using the extensive observations collected during ORCESTRA, the structure of the monsoon trough, and the African Easterly Jet are analyzed and compared to their climatology and their conceptual models using the ERA5 Reanalysis.