Geostationary satellite observations of Gulf Stream meanders: Infrared measurements and time series analysis

Abstract

The infrared capabilities of the Geostationary Operational Environmental Satellite (Goes) are analyzed to obtain multiyear time histories of Gulf Stream meanders. Radiative transfer calculations using monthly mean profiles of atmospheric temperature and moisture are shown to overestimate cloud‐free equivalent soundings by 2–5 K. A simple relation is derived between temperature at the satellite, sea surface temperature, and transmissivity of the atmosphere at 11.6 μm, which allows an observer to determine if a known sea surface temperature gradient is observable from Goes knowing only the precipitable water content along the slant path to the spacecraft. More than 2 years of Goes observations of Gulf Stream meanders are analyzed as a randomly spaced time series using least squares spectral analysis; the dominant periods in the spectra, based on 1976–1978 data, are 250,65, and 10 days in the Gulf of Mexico; 30 and 6 days off Onslow Bay, North Carolina; and 45 and 5 days off New England. A summary of the meanders between the Yucatan Strait and the Grand Banks shows that the largest latitudinal variability is associated with the Gulf Loop Current. Comparison of meander periods with least squares spectra of historical Florida Current transports suggests that meanders in the Gulf of Mexico are related to variability with 4‐ to 16‐day and 40‐ to 100‐day periods in the flow.

Effect of Bathymetric Curvature on Gulf Stream Instability in the Vicinity of the Charleston Bump

“…This topographic feature produces an eastward deflection in the Gulf Stream (Pietrafesa et al 1978;Rooney et al 1978;Brooks and Bane 1978), forming a quasi-permanent 10-50-km meander. It has also been reported that the lateral meanderings of the Gulf Stream undergo a dramatic "amplification" (Knauss 1969;Maul et al 1978;Bane and Brooks 1979;Hood and Bane 1983;Olson et al 1983) downstream from the CB. Accumulating evidence has suggested a regional difference in spatial scale of Gulf Stream meanders: south of the latitude of the CB cold-core frontal eddies tend to occur as smaller, elongated filaments (Lee and Mayer 1977;Lee et al 1981;Lee and Atkinson 1983) and north of CB frontal eddies tend to be considerably larger (Pietrafesa andJanowitz 1979, 1980;Bane and Brooks 1979;Pietrafesa and Janowitz 1980;Bane et al 1981;Bane 1981, 1983).…”

Estimation of the horizontal velocity of the Socotra eddy and some observations of sea surface thermal features using INSAT-1B

“…The atmospheric features have advection rates that are orders of magnitude greater than the oceanic rates. Hence Maul et al (1978) channel TIR data to minimize such misinterpretations. By this technique, the atmospheric processes disguised as oceanic ones could be eliminated.…”

Review Article Remotely-sensed tracers for hydrodynamic surface flow estimation

“…Statistical methods using boat sample calibration are common for small-scale quantification of thermal plumes and estuarine surface temperatures (Worthington 1973). Deterministic methods are quite successful for determining the exitant radiation relationship to surface temperature, but are less successful in modelling a complex atmosphere in the thermal infrared portion of the spectrum (Maul et al 1978). Such methods often must rely on radiosonde atmospheric profiles of temperature and humidity.…”