For the measurement/estimation of which of the following are satellite images/remote sensing data used? 1. Chlorophyll content in the vegetation of a specific location 2. Greenhouse gas emissions from rice paddies of a specific location 3. Land surface temperatures of a specific location Select the correct answer using the code given below.
- (a) 1 only
- (b) 2 and 3 only
- (c) 3 only
- (d) 1, 2 and 3 ✓ UPSC's answer
Why the answer is (d)
• Remote sensing measures reflected and emitted radiation from the surface and atmosphere.
• Chlorophyll content (1) is estimated from vegetation indices such as NDVI using red and near-infrared bands.
• Methane emissions from rice paddies (2) are estimated by satellites like GOSAT, Sentinel-5P and TROPOMI that sense greenhouse-gas columns, combined with paddy-area mapping.
• Land surface temperature (3) is derived from thermal-infrared bands (Landsat, MODIS).
• Hence 1, 2 and 3, option (d).
Why the other options are wrong
- (a) 1 only
- GHG emissions and surface temperature are also remotely sensed.
- (b) 2 and 3 only
- Chlorophyll is also measured via vegetation indices.
- (c) 3 only
- Chlorophyll and GHG emissions are also estimated from satellites.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2019, held on 2 June 2019. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.