The global distribution of clouds and cloud top temperatures is monitored via imagery provided by the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). The visible and infrared (OLS) sensors collect images globally across a 3000 km swath, twice per day. The archived dataset consists of low resolution global and high resolution regional imagery, satellite ephemeris, and solar and lunar information.
Products
These files are cloud-free composites made using all the available archived DMSP-OLS smooth resolution data for calendar years. In cases where two satellites were collecting data - two composites were produced. The products are 30 arc second grids, spanning -180 to 180 degrees longitude and -65 to 75 degrees latitude.
Average Visible, Stable Lights, & Cloud Free Coverages
- Disk space required for compressed data is ~300 MB and uncompressed data is ~3 GB.
- These files are gzipped and added to tar files under linux. Winzip and some other windows utilities may convert newlines in the data into a windows linefeed. To avoid this in WinZip go to -> Options -> Configuration -> Miscellaneous and uncheck the 'TAR file smart CR/LF conversion'.
| Average Visible, Stable Lights, & Cloud Free Coverages | ||||||
|---|---|---|---|---|---|---|
| Year\Sat. | F10 | F12 | F14 | F15 | F16 | F18 |
| 1992 | F101992 | |||||
| 1993 | F101993 | |||||
| 1994 | F101994 | F121994 | ||||
| 1995 | F121995 | |||||
| 1996 | F121996 | |||||
| 1997 | F121997 | F141997 | ||||
| 1998 | F121998 | F141998 | ||||
| 1999 | F121999 | F141999 | ||||
| 2000 | F142000 | F152000 | ||||
| 2001 | F142001 | F152001 | ||||
| 2002 | F142002 | F152002 | ||||
| 2003 | F142003 | F152003 | ||||
| 2004 | F152004 | F162004 | ||||
| 2005 | F152005 | F162005 | ||||
| 2006 | F152006 | F162006 | ||||
| 2007 | F152007 | F162007 | ||||
| 2008 | F162008 | |||||
| 2009 | F162009 | |||||
| 2010 | F182010 | |||||
| 2011 | F182011 | |||||
| 2012 | F182012 | |||||
| 2013 | F182013 | |||||
The OLS visible band detector observes radiances about one million times dimmer than most other Earth observing satellites. The sensor is typically operated in a high gain setting to detect moonlit clouds. However, with six bit quantization and limited dynamic range, the recorded data sets are saturated in the bright cores of urban centers.
A limited set of observations at low lunar illumination were obtained while the gain of the detector was set significantly lower than its typical operational setting (sometimes by a factor of 100). By combining these sparse data acquired at low gain settings with the operational data acquired at high gain settings, we have produced a set of global nighttime lights products with no sensor saturation. This product can be related to radiances based on the pre-flights sensor calibration.
Data Access
Note: The files are compressed with tar/gzip
Calibrated Nighttime Global Radiance
Last update: 2/20/2014
| File Name | Data |
|---|---|
| F16_20100111-20110731_rad_v4 | |
| F16_20100111-20101209_rad_v4 | |
| F16_20051128-20061224_rad_v4 | |
| F14_20040118-20041216_rad_v4 | |
| F14-F15_20021230-20031127_rad_v4 | |
| F12-F15_20000103-20001229_rad_v4 | |
| F12_19990119-19991211_rad_v4 | |
| F12_19960316-19970212_rad_v4 |
This product is a global inventory of the spatial distribution and density of constructed Impervious Surface Area (ISA). Examples of ISA include roads, parking lots, buildings, driveways, sidewalks and other manmade surfaces. While high spatial resolution is required to observe these features, this product is at one kilometer (km)2 resolution and is based on two coarse resolution indicators of ISA.
Inputs into the product include the brightness of satellite observed nighttime lights and population count. The reference data used in the calibration were derived from 30 meter resolution ISA estimates of the USA from the U.S. Geological Survey. Nominally, the product is for the years 2000-2001 since both the nighttime lights and reference data are from those two years.
When this product was developed, 1.05% of the United States land area was impervious surface (83,337 km2 ) and 0.43% of the world's land surface (579,703 km2 ) was constructed impervious surface. China had more ISA than any other country (87,182 km2 ), but had only 67 m2 of ISA per person, compared to 297 m2 per person in the USA.
ISA can cause hydrologic and environmental impacts when it occupies 10% of land surface in a given area. An examination of the areas with 10% or more ISA in watersheds finds that with the exception of Europe, the majority of watershed areas have less than 0.4% of their area at or above the 10% ISA threshold. The authors believe the next step for improving the product is to include reference ISA data from more areas around the world.
Global Distribution and Density of Constructed Impervious Surfaces
ISA in Geographic Coordinates
2010 January-June GeoTiff image (Compressed with gzip 165MB)
ISA in GCS (WGS84)
- ENVI (2000-2001) (Compressed with tar/gzip)
- GeoTiff (2000-2001)
ISA in Mollweide (WGS84)
ENVI (2000-2001) (Compressed with tar/gzip)
Other ISA Data
The data is in GeoTiff format (Compressed using tar/gzip.)
Collecting data on economic variables, especially sub-national income levels can be problematic due to shortcomings in the data collection process. Additionally, the informal economy is often excluded from official statistics.
Nighttime lights satellite imagery and the LandScan population grid provide an alternative way to measure economic activity. A model was developed creating a disaggregated map of estimated total (formal plus informal) economic activity for countries and states of the world.
Regression models were developed to calibrate the sum of lights to official measures of economic activity at the sub-national level for China, India, Mexico, and the United States and at the national level for other countries of the world. Subsequently, unique coefficients were derived. Multiplying the unique coefficients with the sum of lights provided estimates of total economic activity, which were spatially distributed to generate a spatially disaggregated 1 km2 map of total economic activity.
- Download Data: The data is in GeoTiff format and has been compressed using tar/gzip.
- Ghosh, T., Powell, R., Elvidge, C. D., Baugh, K. E., Sutton, P. C., & Anderson, S. (2010). Shedding light on the global distribution of economic activity. The Open Geography Journal (3), 148-161.
Analysis of a time series of global annual satellite maps of nighttime lights spanning 21 years and six satellite reports reveals several distinct patterns linked to population changes, economic development and improvements in lighting efficiency. The results indicate that there are national level differences in the behavior of nighttime lights over time.
National Lighting Trend Categories
- Rapid Growth
- Moderate Growth
- Population Centric Lighting
- Economic Centric Lighting
- Stable Lighting
- Erratic Lighting
- Antipole lighting
Recognition of these patterns may lead to improved spatial modeling of socioeconomic processes based on satellite observed nighttime lights.
Data and Documentation
Specifications
Infrared pixel values correspond to a temperature range of 190 to 310 Kelvins in 256 equally spaced steps. Onboard calibration is performed during each scan. Visible pixels are relative values ranging from 0 to 63 rather than absolute values in Watts per m^2. Instrumental gain levels are adjusted to maintain constant cloud reference values under varying conditions of solar and lunar illumination. Telescope pixel values are replaced by Photo Multiplier Tube (PMT) values at night. A telescope pixel is 0.55 km at high resolution (fine mode) and 2.7 km at low resolution(smooth mode). Low resolution values are the mean of the appropriate 25 high resolution values.
Instrument Description
The OLS instrument consists of two telescopes and a photomultiplier tube (PMT). The visible telescope is sensitive to radiation from 0.40 - 1.10 um (0.58 - 0.91 um FWHM) and 10-3 - 10-5 Watts per cm2 per steradian. The infrared telescope is sensitive to radiation from 10.0 - 13.4 um (10.3 - 12.9 um FWHM) and 190 to 310 Kelvins. The PMT is sensitive to radiation from 0.47 - 0.95 um (0.51 - 0.86 um FWHM) at 10-5 - 10-9 Watts per cm2 per steradian. The detectors sweep back and forth in a "whisk broom" or pendulum-type motion. The continuous analog signal is sampled at a constant rate so the Earth-located centers of each pixel are roughly equidistant, i.e., 0.5 km apart. 7,325 pixels are digitized across the 1080 swath from limb to limb. The instruments are built by Westinghouse Corporation. DMSP satellites are in a sun-synchronous, low altitude polar orbit.
Processing
OLS data are decompressed, reordered, restructured and deinterleaved. Satellite ephemeris are computed using a four body orbital mechanics program with observed, rather than predicted, orbital elements used as input. Missing scan lines are correctly positioned. Quality assessments are made of each pixel and characterized for each complete scan line.
NGDC has archived analog images of the aurora from DMSP OLS sensors since 1972. The National Snow and Ice Data Center (NSIDC) maintained the archives of other analog OLS data 1979 - 1992. An archive file contains an orbit header, and data records organized by scan line. A "smooth" resolution scan line consists of 1,465 visible pixels, 1,465 IR pixels, satellite ephemeris, a quality assessment and other satellite and astronomical parameters. A high resolution scan line contains 7,325 pixels and the same supporting information.
Applications
OLS visible data records visible and near-Infrared emissions from the sun or the moon reflected off clouds and other features. Ground-based sources such as fires and upper atmospheric sources like the northern lights are also seen. OLS thermal infrared data record thermal emissions by the Earth's surface and atmosphere. OLS imagery is the primary input to the Air Force Weather Agency’s (AFWA) cloud analysis program. In addition, nighttime imagery records the aurora [Snyder et al., 1973], city lights [Akasofu et al., 1975], manmade and natural fires [Cahoon et al., 1993], and natural gas flaring [Croft, 1975]
