Change Detection In Satellite Observed Change Detection In Satellite Observed Nightime LightsNightime Lights

Chris Elvidge, Earth Observation GroupNOAA National Geophysical Data Center (NGDC). Boulder, Coloradochris.elvidge@noaa.gov

September 28, 2011

The U.S. Air ForceDefense Meteorological Satellite Program (DMSP)Operational Linescan System (OLS) has aUnique capability to collect low-light imagery.

Polar orbiting3000 km swath2.7 km ground sample

distance (GSD)Two spectral bands:

visible and thermalNightly global coverageFlown since 1972Will continue till ~2012

Visible

Thermal

Originally designed Originally designed for the detection for the detection of moonlit clouds, of moonlit clouds, the OLS detects the OLS detects lights from cities, lights from cities, towns, villages, towns, villages, gas flares, fires, gas flares, fires, and heavily lit and heavily lit fishing boats.fishing boats.

Fires in Africa

Gas flares – Persian Gulf

Fishing boats & city lights - Japan

Changes in LightingChanges in Lighting

Growth in lighting associated with growth Growth in lighting associated with growth in developmentin development

Losses in lighting areas of conflict or Losses in lighting areas of conflict or economic collapseeconomic collapse

Temporary lights (construction, holidays)Temporary lights (construction, holidays) Changes in lighting sources (e.g. Changes in lighting sources (e.g.

conversion from mercury vapor to sodium conversion from mercury vapor to sodium vapor lamps)vapor lamps)

Changes in the efficiency of lighting Changes in the efficiency of lighting fixturesfixtures

OutlineOutline

Brief history of DMSP nighttime Brief history of DMSP nighttime lightslights

The version 2 time series: 1992-2003The version 2 time series: 1992-2003 Review of changes in lighting 1992-Review of changes in lighting 1992-

20032003 Limitations of this data sourceLimitations of this data source Review of application areasReview of application areas Conclusion - future possibilitiesConclusion - future possibilities

The ability to detect nighttime lights with DMSP-OLS has been known since the early 1970's. Early OLS data were only available on film, which limited the product quality.

Early DMSP Nighttime Lights Products – From Film

NGDC’s earliest nighttime lights product was NGDC’s earliest nighttime lights product was made for the USA using lights detected in 29 made for the USA using lights detected in 29

orbits of nighttime DMSP data.orbits of nighttime DMSP data.

Adding more data – more lights were found. Adding more data – more lights were found. NGDC’s second nighttime lights product of the NGDC’s second nighttime lights product of the USA used 236 orbits of OLS data.USA used 236 orbits of OLS data.

Nighttime Lights of the Nighttime Lights of the WorldWorld

The algorithms were then applied The algorithms were then applied to ~1000 orbits of data covering to ~1000 orbits of data covering the same time period to the same time period to generate the first digitally generate the first digitally derived global map of nighttime derived global map of nighttime lights. Four different types of lights. Four different types of lights were distinguished: 1) lights were distinguished: 1) human settlements, 2) gas human settlements, 2) gas flares, 3) fires, and 4) heavily lit flares, 3) fires, and 4) heavily lit fishing boats. The initial product fishing boats. The initial product was completed in 1997. The was completed in 1997. The data were reprocessed in 1999 data were reprocessed in 1999 with an improved light detection with an improved light detection algorithm. algorithm.

Original

Reprocessed

Nighttime Lights of the World Nighttime Lights of the World PosterPoster

Global Radiance Calibrated Nighttime Global Radiance Calibrated Nighttime Lights: 1996-97Lights: 1996-97

In 1995, NGDC researched the In 1995, NGDC researched the calibration of the OLS low light calibration of the OLS low light imaging data and in 1996 imaging data and in 1996 conducted experiments with the conducted experiments with the gain settings on the OLS and found gain settings on the OLS and found that it would be possible to that it would be possible to generate a radiance calibrated generate a radiance calibrated nighttime lights product. It was nighttime lights product. It was found that three gain settings are found that three gain settings are required to cover the full dynamic required to cover the full dynamic range of observable light from range of observable light from human settlements. A preliminary human settlements. A preliminary global product was made using 28 global product was made using 28 nights of data from 1996-97. nights of data from 1996-97.

Global Radiance Calibrated Nighttime Global Radiance Calibrated Nighttime Lights: Lights:

2000-01 and 2005-06?2000-01 and 2005-06?

Dallas, Texas 2001

NGDC is producing a second global radiance calibrated nighttime lights product (2000-2001) for use in a NASAcarbon cycle study. Data fora third (2005-06) are being collected.

Eighteen Annual Cloud-Free Composites Eighteen Annual Cloud-Free Composites

Available By FTPAvailable By FTP http://www.ngdc.noaa.gov/dmsp/global_compohttp://www.ngdc.noaa.gov/dmsp/global_compo

sites_v2.htmlsites_v2.html

A Large Number of Imaginative Ideas A Large Number of Imaginative Ideas For For

Using the Lights Have Been ExpressedUsing the Lights Have Been Expressed“Thanks, Chris.Here's the USA at night image, with two rings highlighted. Looking for clues beyond the "settled" eastern half and the sparse western half of the USA, which is pretty apparent, I see rings and arcs which don't follow state boundaries, or rivers, or even the major topography. I didn't highlight the arc that is centered on North Carolina, for example, which goes from New York to the Great Lakes, through Indiana and all the way down to the Florida Panhandle, regardless of the Appalachians or the various river valleys.”

Ancient Craters?

Can Ancient Craters be Can Ancient Craters be Located Based on Rings of Located Based on Rings of

Lights?Lights?

Review by Review by ColleagueColleague“Chris,  the circles are

clearly the rims of the glasses of a giant cat that perished long ago and has since turned to dust.  I was able to deduce this after careful examination of several other, all too obvious, nighttime light features similar to these, such as the great ‘Nighttime cat of Africa.‘”

Another Set of Unusual Another Set of Unusual Lights….Lights….

Version 2 Annual Version 2 Annual CompositesComposites1992-20031992-2003

Center half of swathCenter half of swath No moonlightNo moonlight No sunlightNo sunlight No glareNo glare No “low-gain” dataNo “low-gain” data No cloudsNo clouds -65 to 65 latitude-65 to 65 latitude

Total Number of Coverages

Satellite F10 - Year 1992

Total Number of Cloud-Free Coverages

Satellite F10 - Year 1992

Average Visible Band Digital Number

Satellite F10 - Year 1992

Stable Lights Average Visible Band Digital NumberWith Background Noise and Fires Removed

Satellite F10 - Year 1992

Average Visible Band DN Color Composite (2003, 1998, 1992 as r,g,b)

Georgia Georgia FloridaFlorida1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = 2003 = redred

SpainSpainPortugalPortugal1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = 2003 = redred

MoldovaMoldovaRomaniaRomania1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = 2003 = redred

Cote Cote d’Ivoired’IvoireGhanaGhana1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = 2003 = redred

JohannesbuJohannesburgrg1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = red2003 = red

SyriaSyriaLebanonLebanon1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = 2003 = redred

EgyptEgypt1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = 2003 = redred

BeijingBeijing1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = 2003 = redred

ShanghaiShanghai1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = 2003 = redred

KoreaKorea1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = 2003 = redred

MalaysiaMalaysiaIndonesiaIndonesia1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = 2003 = redred

IndiaIndia1992 = 1992 = blueblue1998 = 1998 = greengreen2003 = 2003 = redred

OverglowOverglow

LA – line drawn fortransect.

Digital number values acrosstransect.

Interesting Features in Interesting Features in Transects Hong Kong Transects Hong Kong

The Hong Kong region1992 = blue1998 = green2003 = red

Transect across Hong Kong 1992 = blue1998 = green2003 = red

Can global trends in Can global trends in lighting change be lighting change be

observed? observed?

This is the 2003 lights minus 1992. Notice losses in the brightness of lights in the USA northeast, upper midwest, and west coast. Other places where the brightness of lighting declined include the UK, Belgium, former Soviet Union and Japan. Lighting grew in South Asia, China, Middle East, and Southern Europe.

Shortcomings of DMSP LightsShortcomings of DMSP Lights• Coarse spatial resolution 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 quantitization• Urban centers saturate in operational data• No 3-5 um band for fires• No spectral information on the type of lighting or changes in lighting type.

Contrast enhanced to show dim lighting

The Human Footprint Dataset The Human Footprint Dataset Uses Nighttime Lights and Other Uses Nighttime Lights and Other

Data SourcesData Sources

Available at http://www.ciesin.columbia.edu/wild_areas/Available at http://www.ciesin.columbia.edu/wild_areas/

Global Rural Urban Mapping Project Global Rural Urban Mapping Project (GRUMP)(GRUMP)

Global Population Density ProductGlobal Population Density Product

Available at http://sedac.ciesin.org/gpw/global.jsp#

Global Map Of Poverty Number Global Map Of Poverty Number EstimatesEstimates

Based on Nighttime Lights and DOE Landscan Based on Nighttime Lights and DOE Landscan

Population DensityPopulation Density

Available at http://www.ngdc.noaa.gov/dmsp/download_poverty.html

Gridded Estimates for Constructed Surface Gridded Estimates for Constructed Surface

Area Density: 2000Area Density: 2000 Based on Nighttime Lights and DOE Landscan Based on Nighttime Lights and DOE Landscan

Population DensityPopulation Density

Available at http://www.ngdc.noaa.gov/dmsp/download.html

Detection of Detection of Power Power

OutagesOutagesFrom From

Hurricane Hurricane KatrinaKatrina

http://dmsp.ngdc.noaa.gov/interest/katrina.html

What do high resolution What do high resolution nighttime lights look nighttime lights look

like?like?

1.5 meter resolution nighttime 1.5 meter resolution nighttime lights from Cirrus DCS lights from Cirrus DCS camera acquired from the camera acquired from the NASA ER-2 over Las Vegas, NASA ER-2 over Las Vegas, Nevada on September 30, Nevada on September 30, 2004.2004.

FUTURE POSSIBILITIESFUTURE POSSIBILITIES

Concept for a moderate resolution satellite Concept for a moderate resolution satellite sensor for global mapping of nighttime sensor for global mapping of nighttime lights (Nightsat) has been developed and lights (Nightsat) has been developed and will be published soon in IJRS.will be published soon in IJRS.

Satellite mapping of electrical and radio Satellite mapping of electrical and radio frequency emissions is an untapped area frequency emissions is an untapped area for our community. for our community.

The biggest advances in improved The biggest advances in improved high resolution urban data sources high resolution urban data sources and open access are coming from and open access are coming from the commercial sector. the commercial sector. The The scientific community should scientific community should ride this wave!ride this wave!