Percent frequency of light detections (pct_lights) in cloud-free observations. The number of light detections is not provided but can be calculated by multiplying pct_lights by the number of cloud-free observations (cf_cvg). Data values range from 0-100.
This composite set is a component of the DMSP-OLS nighttime lights imagery for the years 1992-2013. The individual images are cloud-free composites made using all the available archived DMSP-OLS (Defense Meteorological Satellite Program - Operational Linescan System) 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. Each composite set is named with the satellite and the year (F121995 is from DMSP satellite number F12 for the year 1995). Five ArcGIS image services are available, each containing images from 1992-2013.
Data creation: 2016-01-01
Contact points:
Metadata Contact: National Geophysical Data Center
Resource Contact: NOAA's National Geophysical Data Center NOAA
Resource Contact: NOAA National Centers for Environmental Information (NCEI)
Data lineage:
The products are 30 arc second grids, spanning -180 to 180 degrees
longitude and -65 to 75 degrees latitude. A number of constraints are
used to select the highest quality data for entry into the composites:
* Data are from the center half of the 3000 km wide OLS swaths.
Lights in the center half have better geolocation, are smaller,
and have more consistent radiometry.
* Sunlit data are excluded based on the solar elevation angle.
* Glare is excluded based on solar elevation angle.
* Moonlit data are excluded based on a calculation of lunar
illuminance.
* Observations with clouds are excluded based on clouds
identified with the OLS thermal band data and NCEP surface
temperature grids.
* Lighting features from the aurora have been excluded in the
northern hemisphere on an orbit-by-orbit manner using visual
inspection.
More information on the attached file (gcv4_readme.txt) in the Distribution info section of this metadata.
Resource constraints:
Terms of Use: Whenever using or distributing DMSP data or derived images, please credit NOAA's National Centers for Environmental Information (NCEI). In details:
Image and data processing by NOAA's National Geophysical Data Center.
DMSP data collected by US Air Force Weather Agency.
Online resources:
NOAA National Centers for Environmental Information (NCEI) DMSP Data Download