Change Detection In Satellite Observed Nightime Lights Chris Elvidge, Earth Observation Group NOAA National Geophysical Data Center (NGDC). Boulder, Colorado September 28, 2011

The U.S. Air Force Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) has a Unique capability to collect low-light imagery. Polar orbiting 3000 km swath 2.7 km ground sample distance (GSD) Two spectral bands: visible and thermal Nightly global coverage Flown since 1972 Will continue till ~2012 Visible Thermal

Originally designed for the detection of moonlit clouds, the OLS detects lights from cities, towns, villages, gas flares, fires, and heavily lit fishing boats. Fires in Africa Gas flares – Persian Gulf Fishing boats & city lights - Japan

Changes in Lighting Growth in lighting associated with growth in development Growth in lighting associated with growth in development Losses in lighting areas of conflict or economic collapse Losses in lighting areas of conflict or economic collapse Temporary lights (construction, holidays) Temporary lights (construction, holidays) Changes in lighting sources (e.g. conversion from mercury vapor to sodium vapor lamps) Changes in lighting sources (e.g. conversion from mercury vapor to sodium vapor lamps) Changes in the efficiency of lighting fixtures Changes in the efficiency of lighting fixtures

Outline Brief history of DMSP nighttime lights Brief history of DMSP nighttime lights The version 2 time series: The version 2 time series: Review of changes in lighting Review of changes in lighting Limitations of this data source Limitations of this data source Review of application areas Review of application areas Conclusion - future possibilities Conclusion - 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 made for the USA using lights detected in 29 orbits of nighttime DMSP data.

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

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

Nighttime Lights of the World Poster

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

Global Radiance Calibrated Nighttime Lights: and ? Dallas, Texas 2001 NGDC is producing a second global radiance calibrated nighttime lights product ( ) for use in a NASA carbon cycle study. Data for a third ( ) are being collected.

Eighteen Annual Cloud-Free Composites Available By FTP ml

A Large Number of Imaginative Ideas For Using 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 Located Based on Rings of Lights?

Review by Colleague “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 Lights….

Version 2 Annual Composites Center half of swath Center half of swath No moonlight No moonlight No sunlight No sunlight No glare No glare No “low-gain” data No “low-gain” data No clouds No 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 Number With Background Noise and Fires Removed Satellite F10 - Year 1992

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

Georgia Florida 1992 = blue 1998 = green 2003 = red

Spain Portugal 1992 = blue 1998 = green 2003 = red

Moldova Romania 1992 = blue 1998 = green 2003 = red

Cote d’Ivoire Ghana 1992 = blue 1998 = green 2003 = red

Johannesburg 1992 = blue 1998 = green 2003 = red

Syria Lebanon 1992 = blue 1998 = green 2003 = red

Egypt 1992 = blue 1998 = green 2003 = red

Beijing 1992 = blue 1998 = green 2003 = red

Shanghai 1992 = blue 1998 = green 2003 = red

Korea 1992 = blue 1998 = green 2003 = red

Malaysia Indonesia 1992 = blue 1998 = green 2003 = red

India 1992 = blue 1998 = green 2003 = red

Overglow LA – line drawn for transect. Digital number values across transect.

Interesting Features in Transects Hong Kong The Hong Kong region 1992 = blue 1998 = green 2003 = red Transect across Hong Kong 1992 = blue 1998 = green 2003 = red

Can global trends in lighting change be observed? This is the 2003 lights minus 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 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 Uses Nighttime Lights and Other Data Sources Available at

Global Rural Urban Mapping Project (GRUMP) Global Population Density Product Available at

Global Map Of Poverty Number Estimates Based on Nighttime Lights and DOE Landscan Population Density Available at

Gridded Estimates for Constructed Surface Area Density: 2000 Based on Nighttime Lights and DOE Landscan Population Density Available at

Detection of Power Outages From Hurricane Katrina

What do high resolution nighttime lights look like? 1.5 meter resolution nighttime lights from Cirrus DCS camera acquired from the NASA ER-2 over Las Vegas, Nevada on September 30, 2004.

FUTURE POSSIBILITIES Concept for a moderate resolution satellite sensor for global mapping of nighttime lights (Nightsat) has been developed and will be published soon in IJRS. Concept for a moderate resolution satellite sensor for global mapping of nighttime lights (Nightsat) has been developed and will be published soon in IJRS. Satellite mapping of electrical and radio frequency emissions is an untapped area for our community. Satellite mapping of electrical and radio frequency emissions is an untapped area for our community. The biggest advances in improved high resolution urban data sources and open access are coming from the commercial sector. The scientific community should ride this wave! The biggest advances in improved high resolution urban data sources and open access are coming from the commercial sector. The scientific community should ride this wave!