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Sea surface temperature (SST) basics

Sea surface temperature (SST) basics. NASA Ocean Biology Processing Group Goddard Space Flight Center, Greenbelt, Maryland, USA SeaDAS Training Material. MODIS sea surface temperature (SST). thermal band suite:. longwave SST (11-12  m), day and night

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Sea surface temperature (SST) basics

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  1. Sea surface temperature (SST) basics NASA Ocean Biology Processing Group Goddard Space Flight Center, Greenbelt, Maryland, USA SeaDAS Training Material SeaDAS Training ~ NASA Ocean Biology Processing Group

  2. MODIS sea surface temperature (SST) thermal band suite: • longwave SST (11-12 m), day and night • shortwave SST (3.9 - 4.0 m), night only • SST quality level (0-4) • brightness temperatures (all thermal ) related ocean products: SeaDAS Training ~ NASA Ocean Biology Processing Group

  3. MODIS data acquisition http://oceancolor.gsfc.nasa.gov/cgi/browse.pl SeaDAS Training ~ NASA Ocean Biology Processing Group

  4. Level-2 SST processing (1) convert observed radiances to brightness temperatures (BTs) (2) apply empirical algorithm to relate brightness temperature in 2 wavelengths to SST sst = a0 + a1*BT1 + a2*(BT2-BT1) + a3*(1.0/-1.0) (3) assess quality (0=best, 4=not computed) * e.g., cloud or residual water vapor contamination * no specific “cloud mask” SeaDAS Training ~ NASA Ocean Biology Processing Group

  5. Daytime SST products longwave SST shortwave SST cloud Sun glint SeaDAS Training ~ NASA Ocean Biology Processing Group

  6. Nighttime SST products shortwave SST longwave SST Cloud cloud SeaDAS Training ~ NASA Ocean Biology Processing Group

  7. SST quality levels shortwave SST shortwave SST QL QL=0 QL=1 QL=2 QL=3 QL=4 SeaDAS Training ~ NASA Ocean Biology Processing Group

  8. SST quality tests SST quality tests SST quality levels SeaDAS Training ~ NASA Ocean Biology Processing Group

  9. SST validation buoy measurements SeaDAS Training ~ NASA Ocean Biology Processing Group

  10. References http://oceancolor.gsfc.nasa.gov/DOCS/modis_sst/ K.A. Kilpatrick et al., J. Geophys. Res. 106, 9179-9197 (2001) SeaDAS Training ~ NASA Ocean Biology Processing Group

  11. Shortwave SST sst4 = a0 + a1*BT39 + a2*dBT + a3*(1.0/-1.0) where: BT39 = brightness temperature at 3.959 um, in deg-C BT40 = brightness temperature at 4.050 um, in deg-C = cosine of sensor zenith angle dBT = BT39 - BT40 a0, a1, a2, a3 - fit coefficients derived derived by regression of MODIS BTs with in situ buoys vary seasonally (probably due to residual water-vapor effects) determined by science team PI (Peter Minnett and Univ. Miami staff) SeaDAS Training ~ NASA Ocean Biology Processing Group

  12. Longwave SST dBT <= 0.5 sst = a00 + a01*BT11 + a02*dBT*bsst + a03*dBT*(1.0/-1.0) dBT >= 0.9 sst = a10 + a11*BT11 + a12*dBT*bsst + a13*dBT*(1.0/-1.0) 0.5 < dBt < 0.9 sstlo = a00 + a01*BT11 + a02*dBT*bsst + a03*dBT*(1.0/-1.0) ssthi = a10 + a11*BT11 + a12*dBT*bsst + a13*dBT*(1.0/-1.0) sst = sstlo + (dBT-0.5)/(0.9-0.5)*(ssthi-sstlo) where: BT11 = brightness temperature at 11 um, in deg-C BT12 = brightness temperature at 12 um, in deg-C bsst = baseline SST, which is either sst4 (if valid) or sstref (from oisst) dBT = BT11 - BT12  = cosine of sensor zenith angle SeaDAS Training ~ NASA Ocean Biology Processing Group

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