International Journal of Environmental Sciences

Volume 2 Issue 4 2012           Pages:2203- 2211

Relative Percentage Difference between Ground Based and Satellite Estimation of Solar UV Index in Four Seasons at the Measurement Sites of Nepal

Author Information:

Sharma N.P  Department of Engineering Science and Humanities, Pulchowk Campus, Institute of Engineering,  Tribhuvan University, Kathmandu, Nepal

Bhattarai B.K  Department of Engineering Science and Humanities, Pulchowk Campus, Institute of Engineering,  Tribhuvan University, Kathmandu, Nepal

Sapkota B  Department of Engineering Science and Humanities, Pulchowk Campus, Institute of Engineering,  Tribhuvan University, Kathmandu, Nepal

Kjeldstad. B  Department of Physics, Norwegian University of Science and Technology, (NTNU), N-7491 Trondheim, Norway

ABSTRACT

The main objective of this study is to analyze the relative percentage difference between ground based and satellite estimation of solar UV index in four different seasons at four sites of Nepal namely, Kathmandu (KTM), Pokhara (PKR), Biratnagar (BRT), and Lukla (LUKL). Kathmandu (27.720N, 85.320E), Pokhara (28.220N, 83.320E), Biratnagar (26.450N, 87.270 E) and Lukla (27.690N, 86.730E) are located at an elevation of 1350m, 800m, 72m and 2850m respectively from the sea level. The study is based on UV data from January to December 2010. The Ground Based (GB) measurements and satellite estimation were performed by the NILU-UV irradiance meter and the EOS Aura OMI satellite respectively. The NILU-UV irradiance meter is a six channel radiometer designed to measure hemispherical irradiance on a flat surface. Meanwhile, the Ozone Monitoring Instrument (OMI) on board, the NASA EOS Aura space craft, is a nadir viewing spectrometer that measures solar reflected and back scattered light in ultraviolet and visible spectrum. The relative percentage difference between GB and OMI UV Index (UVI) in pre-monsoon season was found to be 91.7% at KTM, 97.3% at PKR, 73.9% at BRT and 119.5% at LUKL. During monsoon season the relative percentage difference decreased to 83.3% at KTM, 75.4% at PKR and 46.1% at BRT while in Lukla it increased to 294 %.  From the analysis it is found that:

  • The relative percentage difference between GB and OMI UVI are found to be higher in pre-monsoon season except in Lukla where the fluctuation in UVI is higher in the monsoon season.
  • During winter season the relative percentage difference between GB and OMI UVI was higher in Biratnagar in comparison to other sites.

Keywords: OMI, NILU-UV, Ultraviolet Radiation, Clouds, UV Index

DOI: 10.6088/ijes.00202030103


© 2012 Copyright Sharma N.P et al, licensee IPA.This is an open access article distributed under the Creative Commons Attribution License (2.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The electronic version of the article can be downloaded below.

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