The Entropy and Water Budgets in Tropical Cyclones Nadine and Gabrielle

The moist entropy and water budgets in a storm are important because they can give us information on the moistening or drying of the system. As a part of NASA's Hurricane and Severe Storm Sentinel (HS3) field project, the dropsonde data from tropical cyclones Nadine (2012) and Gabrielle (2013) were collected. Nadine was one of the longest-lived storms ever recorded, with 23 days between initial tropical depression stage and final decay. During that time it strengthened to a hurricane twice, with weakening to a low in between. NASA's HS3 missions captured some of the developments in the life cycle of Nadine. During the 2013 part of the HS3 project, dropsondes were deployed into Gabrielle during its early development, when the storm was struggling to become a tropical depression.

In this study, the HS3 dropsonde data were analyzed using a 3D-VAR analysis to calculate the moist entropy and wind fields on a regular 3-dimensional grid. Mixing ratio of water vapor, as a measure of a water content, was calculated as well. From those, one can calculate the inflow or the outflow of the moist entropy and water vapor as well as the surface fluxes into the storm. Those parts of the entropy and water budgets in Nadine and Gabrielle will be discussed.