Night lights

As these data are composited monthly, there are many areas of the globe where it is impossible to get good quality data coverage for that month. This can be due to cloud cover, especially in the tropical regions, or due to solar illumination, as happens toward the poles in their respective summer months.

Cloud cover is determined using the VIIRS Cloud Mask product (VCM). In addition, data near the edges of the swath are not included in the composites (aggregation zones 29-32). Version 1 has NOT been filtered to screen out lights from aurora, fires, boats, and other temporal lights. This separation is under development and will be included in a later version of this time series. Also in development is a method to separate lights from background (non-light) values.

This product is an alternative configuration of the VIIRS DNB using a procedure to correct for stray light. The correction procedure extends visible areas closer to the poles and improves dynamic range. It should be noted some artifacts are introduced due to the procedure used in twilight regions; see reference paper for more details. This product excludes data impacted by cloud cover.