Digital elevation model (DEM) generation from NOAA–AVHRR night‐time data and its comparison with USGS‐DEM

Abstract

The advent of Earth Resources Technology has added a new dimension to observing, studying and interpreting the ground objects of an area. Since the inception of operational remote sensing researchers have made continuous efforts to generate elevation data from satellite images, thus producing a digital elevation model (DEM). A DEM is a surface generated from the elevation data which is used for various geospatial analyses. However, high spatial resolution and an accurate DEM of the entire globe is still not available to the user community. Furthermore, requirements of DEMs of rugged terrain are very high since other DEM generation approaches have severe limitations in highly rugged terrains like the Himalayas. Several studies have been carried out in this direction, but have mainly focused on stereo pair data of the same sensor, deriving the DEM from these datasets. In recent years Synthetic Aperture Radar (SAR) interferometry technique has been developed to generate DEM, but without any success in highly rugged terrains like the Himalayas.

There is a general understanding that elevation and temperature values are inversely related. The present study attempts to exploit this inverse relationship between elevation and temperature values, generating a relatively coarse resolution DEM from National Oceanic & Atmospheric Administration Advanced Very High Resolution Radiometer (NOAA‐AVHRR) night‐time thermal infrared data. A visual and statistical comparison between NOAA‐AVHRR night‐time thermal infrared data and US Geological Survey (USGS)‐DEM clearly illustrates the existence of this inverse relationship. It indicates that the temperature of an area decreases with an increase in elevation. NOAA‐AVHRR night‐time thermal infrared data were used so as to avoid the effects of differential solar heating, which is very common during daytime in a highly rugged terrain like the Himalayas. Furthermore, the main advantages of using USGS DEM for this comparative analysis are: (a) its spatial resolution (1 km), which is very close to the spatial resolution of the NOAA‐AVHRR thermal data (1.1 km); and (b) its availability through the Internet. This technique of generating DEM from NOAA‐AVHRR night‐time thermal infrared data is most applicable to hilly terrain where human interference is less. Applicability of the present approach is enormous and can be highly efficacious when using relatively high spatial resolution (60 m) Landsat ETM+ night‐time thermal infrared data of highly rugged terrains.