Q32 · UPSC Prelims 2019 · Set A · Science and Technology

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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 location2.Greenhouse gas emissions from rice paddies of a specific location3.Land surface temperatures of a specific locationSelect the correct answer using the code given below

A 1 only
B 2 and 3 only
C 3 only
D 1, 2 and 3

Correct answer: (d) 1, 2 and 3

Explanation

  1. A

    1 only

    (a) 1 only. Chlorophyll/vegetation indices from satellites are real, but greenhouse-gas sensing over rice paddies and land-surface temperature are also established remote-sensing products, so 1 only is not the key.

  2. B

    2 and 3 only

    (b) 2 and 3 only. Those two are valid uses, but dropping chlorophyll is incomplete, so this is not the key.

  3. C

    3 only

    (c) 3 only. LST is only one of the three listed applications, so 3 only is not the key.

  4. D

    1, 2 and 3

    (d) 1, 2 and 3. Optical indices estimate chlorophyll/vegetation greenness; microwave and other missions constrain methane and related fluxes from rice; thermal infrared gives land-surface temperature. All three uses are live, so this is the official key.

Summary. Official key is (d) 1, 2 and 3. Remote sensing is not only pretty pictures: vegetation chlorophyll, paddy-related greenhouse gases, and surface temperature are all retrieved from satellite sensors. Honour the stored letter (d).