Russell L. Elsberry

A View of Tropical Cyclones from Above: The Tropical Cyclone Intensity Experiment

AbstractTropical cyclone (TC) outflow and its relationship to TC intensity change and structure were investigated in the Office of Naval Research Tropical Cyclone Intensity (TCI) field program during 2015 using dropsondes deployed from the innovative new High-Definition Sounding System (HDSS) and remotely sensed observations from the Hurricane Imaging Radiometer (HIRAD), both on board the NASA WB-57 that flew in the lower stratosphere. Three noteworthy hurricanes were intensively observed with unprecedented horizontal resolution: Joaquin in the Atlantic and Marty and Patricia in the eastern North Pacific. Nearly 800 dropsondes were deployed from the WB-57 flight level of ∼60,000 ft (∼18 km), recording atmospheric conditions from the lower stratosphere to the surface, while HIRAD measured the surface winds in a 50-km-wide swath with a horizontal resolution of 2 km. Dropsonde transects with 4–10-km spacing through the inner cores of Hurricanes Patricia, Joaquin, and Marty depict the large horizontal and ver...

Environmental Factors and Internal Processes Contributing to the Interrupted Rapid Decay of Hurricane Joaquin (2015)

AbstractThe objective in this study is to demonstrate how two unique datasets from the Tropical Cyclone Intensity (TCI-15) field experiment can be used to diagnose the environmental and internal fa...

Seven-Day Intensity and Intensity Spread Predictions in Bifurcation Situations with Guidance-On-Guidance for Western North Pacific Tropical Cyclones

An objective technique to detect and predict intensity bifurcation situations in a five-day Weighted Analog Intensity forecast technique for the western North Pacific (WAIP) has been extended to seven days. A hierarchical cluster analysis is applied to the N analog intensities to separate them into two clusters, which are considered to represent a substantial intensity bifurcation if a threshold maximum velocity difference of 15 kt is satisfied. Two important modifications have been made to develop the bifurcation version for seven-day WAIP forecasts. First, the number of track analogs has been increased from 10 analogs to 16 analogs, which results in larger sample sizes and better performance. Second, separate intensity bias corrections are calculated for the two cluster WAIP forecasts rather than using the same 16-analog intensity bias correction. If an always perfect selection of the correct cluster WAIP forecast of each bifurcation situation is made, a substantial improvement in the intensity mean absolute errors is achieved relative to the original WAIP forecasts based on all 16 of the best analogs. These perfect-cluster selection WAIP forecasts have smaller bias errors and are more highly correlated with the verifying intensities at all forecast intervals through 168xa0h. Furthermore, the Probability of Detection is improved for the perfect-cluster selection and more realistic intensity spreads are specified. A simple guidance-on-guidance technique is demonstrated to assist the forecasters in selecting the correct WAIP cluster forecast in bifurcation situations.