Wind speed effect on L-band brightness temperature inferred from EuroSTARRS and WISE 2001 field experiments

The results from two field experiments in the Mediterranean Sea are used to study the wind speed dependence of brightness temperature at L-band. During the EuroSTARRS airborne experiment, an L-band radiometer made measurements across a large wind speed gradient, enabling us to study this dependence at high wind speed. We compare our results with a two-scale emissivity model using several representations of the sea state spectrum. While the results are encouraging, unfortunately the accuracy of the measurements does not permit us to distinguish between the so-called twice Durden and Vesecky spectrum and the Elfouhaily spectrum above 7 m/spl middot/s/sup -1/. The effect of foam is certainly small. During the WISE 2001 field experiment carried on an oil rig, we studied this dependence at low wind speed, finding an abrupt decrease of the wind speed effect on the brightness temperature below 3 m/spl middot/s/sup -1/.

[1]  D. E. Evans,et al.  An airborne measurement of the salinity variations of the Mississippi River outflow , 1970 .

[2]  Jacques Verron,et al.  Can we improve the representation of modeled ocean mixed layer by assimilating surface-only satellite-derived data? A case study for the tropical Pacific during the 1997-1998 El Nino , 2003 .

[3]  Ramon Villarino,et al.  Sea surface emissivity observations at L-band: first results of the Wind and Salinity Experiment WISE 2000 , 2002, IEEE Trans. Geosci. Remote. Sens..

[4]  A. Stogryn,et al.  The emissivity of sea foam at microwave frequencies , 1971 .

[5]  W. Reich,et al.  A radio continuum survey of the northern sky at 1420 MHz. II , 1986 .

[6]  Jacqueline Boutin,et al.  Influence of sea surface emissivity model parameters at L-band for the estimation of salinity , 2002 .

[7]  K. Katsaros,et al.  A Unified Directional Spectrum for Long and Short Wind-Driven Waves , 1997 .

[8]  Hans J. Liebe,et al.  Propagation Modeling of Moist Air and Suspended Water/Ice Particles at Frequencies Below 1000 GHz , 1993 .

[9]  C. Swift,et al.  An improved model for the dielectric constant of sea water at microwave frequencies , 1977, IEEE Journal of Oceanic Engineering.

[10]  Luis Enrique,et al.  The WISE 2000 and 2001 field experiments in support of the SMOS mission: sea surface L-band brightness temperature observations and their application to sea surface salinity retrieval , 2004, IEEE Transactions on Geoscience and Remote Sensing.

[11]  J. Arenas,et al.  Sea foam effects on the brightness temperature at L-band , 2003, IGARSS 2003. 2003 IEEE International Geoscience and Remote Sensing Symposium. Proceedings (IEEE Cat. No.03CH37477).

[12]  Philippe Waldteufel,et al.  Calibration error of L-band sky-looking ground-based radiometers , 2002 .

[13]  R. Murtugudde,et al.  On the potential impact of sea surface salinity observations on ENSO predictions , 2002 .

[14]  Stephan D. Howden,et al.  Sea surface salinity measurements in the historical database : The role of surface salinity on upper ocean dynamics, air-sea interaction, and climate (SURFSAL) , 2002 .

[15]  Y. Kerr,et al.  EuroSTARRS: campaign description , 2003 .

[16]  W. W. Ho,et al.  Radiometric observations of sea temperature at 2.65 GHZ over the chesapeake bay , 1977 .

[17]  S. Durden,et al.  A physical radar cross-section model for a wind-driven sea with swell , 1985, IEEE Journal of Oceanic Engineering.

[18]  Edward C. Monahan,et al.  Acoustically relevant bubble assemblages and their dependence on meteorological parameters , 1990 .

[19]  David G. Long,et al.  High resolution wind retrieval from SeaWinds , 2001, IEEE International Geoscience and Remote Sensing Symposium.

[20]  Adriano Camps,et al.  WISE 2000 and 2001: campaign description and executive summary , 2003 .

[21]  Frank J. Kerr,et al.  Atlas of Galactic Neutral Hydrogen , 1997 .

[22]  Stuart D. Smith.  Coefficients for sea surface wind stress, heat flux, and wind profiles as a function of wind speed and temperature , 1988 .

[23]  Jacqueline Boutin,et al.  Issues concerning the sea emissivity modeling at L band for retrieving surface salinity , 2003 .