why viirs data are superior to dmsp for mapping …...2013/01/13 · lights at night! two satellite...
TRANSCRIPT
Why VIIRS data are
superior to DMSP for mapping nocturnal lighting.
Christopher D. Elvidge, Ph.D.Earth Observation Group
NOAA National Geophysical Data CenterBoulder, Colorado [email protected]
Kimberly Baugh, Feng Chi Hsu, Tilottama Ghosh. Mikhail Zhizhin (CIRES)January 13, 2013
Cities and humansettlements
Industrial Sites
Boats
Gas Flares Fires
Lights AtNight!
Two Satellite Systems Collect Low Light Imaging Data at Nights
• U.S. Air Force Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). 1972 to present.
• NASA‐NOAA Suomi NPP Visible Infrared Imaging Radiometer Suite (VIIRS). Launched October 28, 2011.
• In both cases the purpose of the low light imaging is the detection of moonlit clouds.
• NGDC’s Earth Observation Group has worked on global mapping of nighttime lights with DMSP data for 18 years.
• NGDC recently completed a two month global cloud‐free composite of nighttime lights from VIIRS data.
Improved Spatial ResolutionBay Area to Sacramento, California
VIIRS April & October, 2012 DMSP‐OLS April & October, 2012
Note white saturation areasNote spatial features thatare missing in the DMSP image
Improved Spatial ResolutionFishing Boat Detections
VIIRS October 15, 2012 01:30 DMSP‐OLS October 14, 2012 19:30
What Makes VIIRS Better Than DMSP?• The VIIRS DNB footprint is 45 times smaller than the DMSP pixel footprint!
VIIRS Day / Night Band742 m2 footprint
DMSP OLS 5 km2 footprint
What Else Makes VIIRS Better Than DMSP?• Quantization: VIIRS 14 bit versus 6 bit for DMSP.• Dynamic Range: Due to limited dynamic range, DMSP data saturate on bright lights in operational data collections.
• Quantitative: VIIRS is well calibrated, the DMSP visible band has no in‐flight calibration.
• Multispectral: VIIRS has additional spectral bands to discriminate combustion sources from lights and to characterize the optical thickness of clouds.
Summary• The VIIRS day / night band provides substantial improvements over DMSP in spatial resolution, detection limit, dynamic range, and quantization.
• The basic processing steps developed for assembling global cloud‐free composites from DMSP data hold up for VIIRS.
• It is anticipated that the improved global nighttime lights products from VIIRS will lead to major advances in each of the application areas demonstrated with DMSP data.