Intercalibration of DMSP-OLS and NPP-VIIRS to Develop Enhanced
Night-time Light Time-series for Evaluating the Urban Development
Pattern of Major Indian Metropolitan cities
Abstract
Defense Meteorological Satellite Program-Operational Line scan System
(DMSP-OLS) and Suomi National Polar-orbiting Partnership-Visible
Infrared Imaging Radiometer Suite (NPP-VIIRS) night-time light (NTL)
datasets portraying nocturnal lit pixels have been widely applied to
effectively monitor anthropogenic activities, temporal variation in
urbanization, and assessment of the dynamics of socio-economic
activities and development. Among the various challenges in conventional
NTL remote sensing studies, one has been the development of a consistent
and long-term NTL time series dataset, indispensable for extended
duration analysis. Lack of onboard-calibration, low spatial and
radiometric resolution causing saturation for dense urban built up and
blooming effect exaggerating the urban extent; pose challenges in the
efficient use of DMSP-OLS (2.7 km) data for urban development studies
despite its availability since 1992. Therefore, this study attempts to
generate high resolution enhanced DMSP-OLS dataset which could generate
long-term and consistent NTL time series (1992-2021), intercalibrating
with NPP-VIIRS (500 m) products considering invariant pixels.
Considering NPP-VIIRS data as base, enhanced DMSP-OLS data are simulated
for the period 2012-2013 (common to both retrieved datasets).
Calibration of remaining DMSP-OLS datasets is performed utilizing the
simulated products (for 2012, 2013) and taking advantage of neighborhood
layers. Consequently, a consistent and more accurate NPP-VIIRS like NTL
time series is achieved for the entire period overcoming the issue of
saturation and blooming effects for DMSP-OLS products. The developed NTL
time series is then used to study the urbanization patterns for major
Indian metropolitan cities of Delhi, Mumbai, Chennai, and Kolkata. A
significant increase in urbanization has been observed with decadal
growth rate ranging from 20 to about 40 percent in the 30-year study
period, depicting maximum growth proportion during the second decade,
for majority of the cities. Further, adopting machine learning approach,
Landsat 5 and 8 images have been classified to extract urban extent for
the designated period and validate the intensity of urban development
derived through NTL products. Keywords: Night-time lights, DMSP-OLS,
NPP-VIIRS, urban growth