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.

The correct answer is 1, 2 and 3.

Remote sensing technology and satellite imagery play a vital role in Earth observation, environmental monitoring, and climate research. Let us analyze each of the given statements step-by-step:

1. Chlorophyll content in the vegetation of a specific location:
Satellite sensors (such as MODIS, Sentinel-2, and Landsat) capture light reflected from the Earth's surface across various spectral bands. Healthy vegetation absorbing blue and red light for photosynthesis while strongly reflecting Near-Infrared (NIR) light allows scientists to calculate indices such as the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI). These spectral signatures directly correlate with the chlorophyll concentration and overall health of vegetation in a given area. Therefore, statement 1 is correct.

2. Greenhouse gas emissions from rice paddies of a specific location:
Modern high-resolution satellite instruments (such as TROPOMI aboard Sentinel-5P, GHGSat, and OCO-2) are capable of detecting atmospheric concentrations of greenhouse gases, particularly Methane (${\mathrm{CH}}_4$) and Carbon Dioxide (${\mathrm{CO}}_2$). Rice paddies are a major anthropogenic source of methane due to anaerobic decomposition in flooded soils. Remote sensing is used to monitor both the spatial extent/flooding duration of paddy fields and the resulting atmospheric methane plumes. Therefore, statement 2 is correct.

3. Land surface temperatures of a specific location:
Thermal Infrared (TIR) sensors aboard satellites measure the thermal radiation emitted from the Earth's surface. By processing this radiance data through emissivity correction algorithms, scientists can accurately measure Land Surface Temperature (LST) across local, regional, and global scales. Therefore, statement 3 is correct.

Since all three statements represent valid applications of satellite imagery and remote sensing data, the correct option code is 1, 2 and 3.