Variability in Upper-Ocean Thermal Structure beneath Tropical Cyclones as Observed by Air-Deployed Profiling Floats

During the 2014 and 2015 hurricane seasons, a new air-deployed profiling float was used to record observations of upper-ocean thermal structure beneath eight Atlantic and Central Pacific tropical cyclones (TCs). These Argo-type Air-Launched Autonomous Micro Observer (ALAMO) floats were deployed for the first time from Air Force Hurricane Hunter WC-130J aircraft during operational missions and recorded observations at 2-hourly intervals prior to, during, and after the passage of multiple TCs at locations ranging from beneath the eyewall to several hundred km from the TC center. Data from the floats were subsampled to 1-m bins then reported via the Iridium satellite phone network, processed, and submitted to the GTS. Sequential temperature observations of the upper 300 m of the ocean at sub-inertial frequencies facilitated the collection of this unique data set and provided insight into temporal and spatial scales of the impact of wind stress on the upper ocean.

Several observations are highlighted and observed changes in the mixed layer are compared to theoretical results obtained using the Price-Weller-Pinkel ocean mixed layer model. In addition, the ALAMO observations are assimilated into the Coupled Ocean/Atmosphere Mesoscale Prediction System for Tropical Cyclones (COAMPS-TC) using the Navy Coupled Ocean Data Assimilation (NCODA) system. The impact of ALAMO data on the ocean prediction in COAMPS-TC using the NCODA adjoint model will be presented.