Regional Air-Sea Interactions (RASI) Climatology for Central America Coastal Gap Wind and Upwelling Events

TitleRegional Air-Sea Interactions (RASI) Climatology for Central America Coastal Gap Wind and Upwelling Events
Publication TypeConference Proceedings
Year of Publication2014
AuthorsSmith, DK, Li, X, Keiser, K, Flynn, S
Conference NameOceans 2014 MTS/IEEE Conference
Date Published09/2014
PublisherOceans 2014 MTS/IEEE Conference
Conference LocationSt Johns, Newfoundland, CA
Keywordsair-sea interactions, data mining, DISCOVER, gapwinds, ocean upwelling, RASI
AbstractCoastal gap wind jets and associated ocean upwelling events present significant regional Air-Sea interaction over the eastern Pacific warm pool. Besides the regional climate impact, the ocean upwelling events also significantly change the regional nutrient distribution over the area by bringing up deep cold water and nutrients to the ocean surface. These events are therefore of interest to both research and commercial users. In this paper, we present details on an algorithm to extract gap wind and upwelling events from satellite-derived data products. An ocean upwelling event is characterized by sudden and significant decrease in sea surface temperature (SST). This study focuses on three special locations: Gulf of Tehuantepec, Gulf of Papagayo and Gulf of Panama, where gap wind events are often observed during winter months. This research effort is conducted as part of DISCOVER (Distributed Information Services for Climate and Ocean Products and Visualizations for Earth Research), a NASA/MEaSUREs project. The wind product used for the gap wind detection is the Cross-Calibrated Multi-Platform (CCMP) ocean surface wind product. The CCMP data are created using a four-dimensional variational analysis to incorporate satellite microwave wind speeds, in situ wind observations and winds from a medium-range weather model. A number of image processing techniques, including thresholding, edge detection, region growing and morphological operations are used to extract the most intensive wind jet regions in the CCMP wind maps. Wind direction, neighboring wind information as well as shapes of wind regions are also considered to ensure proper extraction. The extracted wind region maps are then grouped into a wind jet event. The SST product used for upwelling detection is from Remote Sensing Systems OI SST data set. This product is created using SSTs from TMI, AMSR-E and WindSat measurements using an optimal interpolation technique. The onset of an upwelling event is extracted by comparing SST maps in any two consecutive time steps for a region that has significant SST decrease. Once the onset of the upwelling event is identified, it ends when the SST value over the region starts to increase. This algorithm is being used to process historical data with the goal of generating a climatology of past and current identified events. Eleven years of the CCMP and OI SST data products from 1998 to 2009 have been processed. The resulting information is collected and managed by the Global Hydrology Resource Center (GHRC), a NASA Distributed Active Archive Center (DAAC), located in Huntsville, AL, and will be made publicly available to researchers and other users, such as commercial and military interests. Although the current focus is on Central America Gulf regions, the reusable techniques will be applied to other gap wind locations around the world. A web-based application has been developed that will provide easy access of these wind and upwelling event records, including quickly navigating the historical events through a calendar interface, plotting and comparison of wind and temperature parameters over time, and downloads of the data, facilitating a variety of users for research and education. Through multi-years of results, temporal patterns of wind events can be analyzed; co-occurrence of events in the three gulf regions can be examined, and the relationship between gap wind events and ocean upwelling events can be investigated.