Use of TCI-15 Datasets to Demonstrate New-Generation Satellite Atmospheric Motion Vectors for Improved Tropical Cyclone Predictions

A dynamic initialization utilizing rapid-scan Atmospheric Motion Vectors (AMVs) that have been reprocessed at 15-minute intervals to simulate the capability of opportunity that now exists from the new generation of geostationary meteorological satellites such as the Japanese Himawari-8 and the United States GOES-16 has been carried out in the Atlantic so that validations can be made with special datasets obtained during the ONR Tropical Cyclone Intensity (TCI-15) field experiment. The focus is the 15-minute AMVs from 1200 UTC to 1800 UTC 4 October leading up to a NASA WB-57 aircraft eyewall crossing of Hurricane Joaquin (2015) during which High Definition Sounding System (HDSS) dropwindsondes were deployed at a spacing of 4.5 km. Zonal and meridional wind increments relative to a background COAMPS-TC wind field forecast from 1200 UTC to 1800 UTC are calculated on the 45 km, 15 km, and 5 km grids with a novel SAMURAI-COAMPS Dynamic Initialization (SCDI) technique. There are 10, 30, and 90 timesteps during which the mass fields are adjusted to these AMV-based wind increments during each 15-minute period. The SCDI analysis of the three-dimensional vortex structure of Joaquin at 18 UTC replicates the vortex tilt analyzed from the HDSS dropwindsondes. Utilizing this SCDI analysis as the initial conditions for a 72-h COAMPS-TC model forecast results in an accurate track prediction, and the interruption of a rapid decay followed by a period of constant intensity is well predicted. Upscaling a similar SCDI analysis on the 15 km grid based on 15-minute interval AMVs between 1800 UTC 29 September to 0000 UTC 30 September provides a more realistic intensity and structure of Tropical Storm Joaquin for the initial conditions of the NAVGEM global model than the synthetic TC vortex used operationally. Although this is only a first demonstration, improving the parent global model forecast is then anticipated to produce better initial and lateral boundary conditions for the next SCDI analysis, and thus impact the end-to-end cycling through the next COAMPS-TC forecast and NAVGEM forecast.