Transcript GOES-SST RDAC - Bureau of Meteorology
Geostationary-Sea Surface Temperature (SST) NOAA/NESDIS Regional Data Assembly Center
Eileen Maturi Andy Harris Jonathan Mittaz
The Eighth Science Team Meeting of the Global Ocean Data Assimilation Experiment High Resolution Sea Surface Temperature Pilot Project (GHRSST-PP) Bureau of Meteorology Head Office , 700 Collins St, Docklands, Melbourne, Australia -Monday 14 May to Friday 18 May, 2007
GOES-SST L2P FORMAT
•
Level 2P (L2P – “P” stands for preprocessed) for the operational GOES-SST .
•
The L2P format requires the appending of a number of ancillary data records to the standard SST value at each pixel
–
latitude, longitude, time, cloud proximity, aerosol optical depth, wind speed, surface solar irradiance, sea ice fraction, single-sensor error statistics (SSES
)
Single Center Error Statistics (SSES) Estimation
Using SSES to provide
additional information that cannot be calculated from L2P ancillary data
Assumption is that retrieval bias depends on
Clear-sky transmittance (calculated from NCEP → CRTM)
Air-sea temperature difference (currently
NCEP only
) Assume that sensitivity to Air-Sea Temperature Difference (ASTD) increases with decreasing transmittance
Derive bias = offset + gradient
ASTD for different
11 Post-corrected σ is estimated as a function of transmittance
only
Different for sensor/day/night
NOAA GOES-SST L2P
• • • • • • • • • • The full L2P data set has been implemented.
Products are derived from ½-hourly GOES-East & West North & South sectors in native satellite projection. Dataset includes the full L2P ancillary field.
Aerosol field is derived from the NESDIS operational daily aerosol optical depth analysis, and values are sampled to each GOES retrieval on a nearest-neighbor basis. The “age of observation” value that is available with the analysis is also included – in this case the range may extend to several days rather than the 24 hours. Meteorological fields are derived from the NCEP Global Forecast System forecast fields and bi-linearly interpolated to the SST retrieval location . Surface solar irradiance is derived from the 3-hr average for the period in which the SST observation was made.
Wind speeds are interpolated in time “proximity confidence” is actually the Bayesian probability of clear-sky, with a range from 0.95 to 1 in steps of 0.0002. Product generates 24 Gb /day uncompressed~8Gb/day compressed
GOES L2P Product
– – – – – – – A GOES L2P
net
CDF product file has
22 parameters
for each pixel: – – – – – – –
SST
Time, Latitude, Longitude Satellite Zenith Angle
Aerosol Optical Depth* Surface Solar Irradiance* Wind Speed* Uncertainty estimates (bias and S.D.) Proximity Confidence Value
QC flags (including cloud and land) Ice concentration* Deviation from analysis SST Temporal coincidences of ancillary data* c.f. SST observation Source codes for ancillary data*
Probability of clear-sky (optional field)
Example fields
shown on next slide
GOES-12 Level 2P N. Hem Mar 28 15:15
SST clear )
Future Work
• Correct for Radiance Bias
– Improve the GOES calibration – Dynamic cloudy priors