Prospects for Improved Global Mapping of Development Using VIIRS Data

Chris ElvidgeEarth Observation Group

NOAA-NESDIS National Geophysical Data Center325 Broadway, Boulder, Colorado 80305 USA

Tel. 1-303-497-6121Email: chris.elvidge@noaa.gov

Kimberly BaughCooperative Institute for Research in Environmental Sciences

University of Colorado, Boulder, Colorado USA

June 10, 2012

Cities

Industrial Sites

Boats

Gas Flares Fires

Lights AtNight!

Artificial lighting is a excellent remote sensing observable!

Two Satellite Systems Collect Low Two Satellite Systems Collect Low Light Imaging Data at Nights Light Imaging Data at Nights

U.S. Air Force Defense Meteorological U.S. Air Force Defense Meteorological Satellite Program (DMSP) Operational Satellite Program (DMSP) Operational Linescan System (OLS). 1972 to present.Linescan System (OLS). 1972 to present.

NASA-NOAA Suomi NPP Visible Infrared NASA-NOAA Suomi NPP Visible Infrared Imaging Radiometer Suite (VIIRS). Imaging Radiometer Suite (VIIRS). Launched October 28, 2011.Launched October 28, 2011.

In both cases the purpose of the low light In both cases the purpose of the low light imaging is the detection of moonlit clouds imaging is the detection of moonlit clouds

Comparing DMSP and VIIRSComparing DMSP and VIIRSDMSPDMSP U.S. Air ForceU.S. Air Force Polar orbitingPolar orbiting 07:30 and 19:30 overpasses07:30 and 19:30 overpasses 3000 km swath3000 km swath Two spectral bands (vis and TIR)Two spectral bands (vis and TIR) Panchromatic low light imagingPanchromatic low light imaging 2.7 km ground sample distance2.7 km ground sample distance 5 km+ ground instantaneous field of 5 km+ ground instantaneous field of

viewview 6 bit quantization (vis)6 bit quantization (vis) No inflight calibrationNo inflight calibration Saturation on bright lights in Saturation on bright lights in

operational collectionsoperational collections Direct broadcast encryptedDirect broadcast encrypted Archive at NGDCArchive at NGDC Flown since 1972Flown since 1972 May continue another three years?May continue another three years?

VIIRSVIIRS NASA-NOAA Joint Polar Satellite System NASA-NOAA Joint Polar Satellite System

(JPSS)(JPSS) Polar orbitingPolar orbiting 01:30 and 13:30 overpasses01:30 and 13:30 overpasses 3000 km swath3000 km swath 22 spectral bands22 spectral bands DNB panchromatic low light imagingDNB panchromatic low light imaging 742 meter GSD742 meter GSD 750 meter GIFOV750 meter GIFOV 14 bit quantization in DNB14 bit quantization in DNB In flight calibration In flight calibration No saturationNo saturation Direct broadcast not encryptedDirect broadcast not encrypted Archives at NCDC and NGDCArchives at NCDC and NGDC Launched in 2011Launched in 2011 Series expected to continue for several Series expected to continue for several

decadesdecades

DMSP Nighttime VisibleDMSP Nighttime VisibleMay 21, 2012 at ~19:30 local timeMay 21, 2012 at ~19:30 local time

NGDC has produced a time series of DMSP NGDC has produced a time series of DMSP annual cloud-free nighttime lights annual cloud-free nighttime lights

composites (1992-2011)composites (1992-2011)

• Coarse spatial resolution of the OLS

2.7 km GSD 5+ km GIFOV• OLS lights are larger

than sources on the ground

• “Overglow” surrounds bright sources

• No visible band calibration

• 6 bit quantization• Urban centers saturate

in operational data• No 3-5 um band for fires

Shortcomings of DMSP Nighttime Lights

Contrast enhanced to show dim lighting

VIIRS - Visible Infrared Imaging Radiometer SuiteVIIRS - Visible Infrared Imaging Radiometer Suite

VIIRS Nighttime Day / Night Band (DNB)VIIRS Nighttime Day / Night Band (DNB)May 21, 2012 at ~ 01:30 local timeMay 21, 2012 at ~ 01:30 local time

VIIRS versus DMSP VIIRS versus DMSP May 21, 2012 May 21, 2012

VIIRS OLS

Detection of Villages in VIIRS Nighttime Visible (DNB)Detection of Villages in VIIRS Nighttime Visible (DNB)May 21, 2012 at ~ 01:30 local timeMay 21, 2012 at ~ 01:30 local time

VIIRSOLS

Aerosol daytime only

Clouds day and night

Fires day and night

What Else VIIRS Has To OfferFire detections - discriminate lights from combustion sources.Cloud optical thickness and snow cover to rate the quality of light detections.

Snow Cover

What needs to be developedWhat needs to be developed

Light detection algorithm Light detection algorithm Terrain correction – DNB data are Terrain correction – DNB data are

not terrain corrected since the not terrain corrected since the primary mission is detection of primary mission is detection of moonlit clouds.moonlit clouds.

Atmospheric correction – to estimate Atmospheric correction – to estimate upwelling radiances at the earth upwelling radiances at the earth surface.surface.

The Way ForwardThe Way Forward

Reuse portions of NGDC algorithm Reuse portions of NGDC algorithm base for processing DMSP nighttime base for processing DMSP nighttime lights:lights:• Terrain correctionTerrain correction• Light detectionLight detection• Cloud-free compositingCloud-free compositing

MODTRAN atmospheric correctionMODTRAN atmospheric correction

VIIRS Stray Light VIIRS Stray Light The DMSP light detection algorithm operates with overlapping square tiles to The DMSP light detection algorithm operates with overlapping square tiles to define detection thresholds and assumes that the majority of tile pixels are define detection thresholds and assumes that the majority of tile pixels are background. The square tile approach does not appear to be appropriate for background. The square tile approach does not appear to be appropriate for VIIRS due to stray light problem.VIIRS due to stray light problem.

Light DetectionLight DetectionRather than square tiles – it may be more appropriate to analyze individual Rather than square tiles – it may be more appropriate to analyze individual scanlines – defining a background and noise level that varies from left to right.scanlines – defining a background and noise level that varies from left to right.

NGDC’s plan for a 2012 global NGDC’s plan for a 2012 global map of developmentmap of development

Initial product will be a mosaic made Initial product will be a mosaic made with a relatively low number of with a relatively low number of repeat observation. October 2012.repeat observation. October 2012.

Subsequently a full year product will Subsequently a full year product will be processed to characterize the be processed to characterize the variability in lighting. March 2013.variability in lighting. March 2013.

Participate in GEO SB-04 Participate in GEO SB-04 collaborations.collaborations.