| Popis: |
Air-sea moisture, heat and momentum exchanges that govern hurricane intensification occur within the hurricane boundary layer (HBL). However, the HBL is under-sampled due to the dangers of flying crewed aircraft within this turbulent region. In 2017, a novel instrument called the Coyote, a small uncrewed aircraft system (sUAS), was deployed in Atlantic Hurricane Maria after the storm weakened following its traverse of Puerto Rico. Flights 1 and 3 from this dataset, in conjunction with 9 dropsondes from the surrounding times, were used to compare observed boundary layer characteristics with the current theoretical understanding of the boundary layer above a hurricane's cold wake. The cold wake is an area of anomalously low sea surface temperatures created by the upwelling and mixing of colder water up to the ocean's surface by the hurricane. In atmosphere-ocean coupled models, the cold wake creates a stable boundary layer in the storm's right-rear quadrant. In the observational analysis of Maria, thermodynamic stability, thermodynamic hurricane boundary layer (THBL) height, and dynamic hurricane boundary layer (DHBL) height were calculated in a storm-relative framework. The lower virtual potential temperatures in the right quadrants showed evidence of the cold wake. The boundary layer heights decreased toward the eye of the storm and the DHBL heights were higher than the THBL heights, which agreed with previous findings. The THBL also showed the stable layer was the shallowest in the right-rear quadrant. Due to the small sample size, the methods should be repeated with a larger dataset to see if the conclusions hold. |
