Applications
A Cross-Calibrated Multi-Platform Ocean Surface Wind Velocity Product for Meteorological and Oceanographic Applications
Figure 1: Annual mean (July 1998 - June 1999) streamline and vector magnitudes in the El Nino 4 region (click to enlarge)
Consistent oceanic surface wind data of high quality and high temporal and spatial resolution are required to understand and predict the large scale air-sea interactions which influence both the atmosphere and ocean. Such observations are needed to drive ocean models and surface wave models, calculate surface fluxes of heat, moisture and momentum, provide initial data and verification data for atmospheric models, and construct surface climatologies.
Surface wind stress provides the most important forcing of the ocean circulation, while the fluxes of heat, moisture and momentum across the air-sea boundary are important factors in the formation, movement, and modification of water masses and the intensification of storms near coasts and over the open oceans (Atlas, 1987). In addition, air-sea interaction plays a major role in theories of ENSO (Figure 1) and the 50-day oscillation, as well as in the initiation and maintenance of heat waves and drought and other persistent anomalies (Wolfson et al., 1987; Atlas et al., 1993).
Figure 2: Annual mean (July 1997 - June 1998) streamline and vector magnitudes in the El Nino 4 region (click to enlarge)
Figure 1 shows annual mean SSM/I streamline and vector magnitudes in the El Nino 4 region, as an illustration of inter-annual variability. In this region, the annual displacement of the oceanic warm pool is accompanied by a low-level atmospheric circulation pattern usually associated with cyclonic vorticity centers near the equator, and located on the western extreme of the warm pool. Although there exists a suggestive analogy between the association "western pool / cyclonic circulations" and the theory of Gill (1982), the SSM/I wind fields are more complex than in Gill's model. However, the wind fields on the western side of the warm pool can be highly simplified by focusing on the singular point "C" that represents the western end of the easterly atmospheric current that prevails over the eastern and central Pacific. This feature follows the annual displacements of the warm pool. For instance, during La Nina years (1988-1990), (1995-1997) and (1999-2001), "C" was close to the "maritime continent" as shown in Figure 1., During the extreme El Nino years, 1992 and 1998, "C" was in its easternmost position, near the dateline (see Figure 2).
Applications
- NASA Official: Michael S. Seablom
- Project Manager: Joseph V. Ardizzone
- Website Manager: Lara Clemence