Question

How to estimate land surface temperature using landsat 8 in arcgis?

Answer 1

The Land Surface Temperature can be estimated or calculated using the Landsat 8 thermal bands. It simply requires applying a set of equations through a raster image calculator (ArcMap, ArcGIS Pro, QGIS).

The first step is to download a Landsat 8 image from a particular location, unzip it, and check certain information needed (within the metadata) to execute this procedure.

This tutorial shows how to calculate Land Surface Temperature (LST) using the Landsat 8 bands. In particular, band 10 as the thermal band, and bands 4 and 5 to calculate the Normal Difference Vegetation Index (NVDI).

The process is synthesized in six steps below:

1. Calculation of TOA (Top of Atmospheric) spectral radiance  :

TOA (L) = M_L * Q_cal + A_L

where:

M_L = Band-specific multiplicative rescaling factor from the metadata (RADIANCE_MULT_BAND_x, where x is the band number).

Q_cal = corresponds to band 10.
A_L = Band-specific additive rescaling factor from the metadata (RADIANCE_ADD_BAND_x, where x is the band number).

TOA = 0.0003342 * “Band 10” + 0.1

Therefore the equation must be solved using the Raster Calculator tool in ArcMap.

2. TOA to Brightness Temperature conversion :

BT = (K₂ / (ln (K₁ / L) + 1)) − 273.15

where:

K₁ = Band-specific thermal conversion constant from the metadata (K1_CONSTANT_BAND_x, where x is the thermal band number).
K₂ = Band-specific thermal conversion constant from the metadata (K2_CONSTANT_BAND_x, where x is the thermal band number).

L = TOA

Therefore, to obtain the results in Celsius, the radiant temperature is adjusted by adding the absolute zero (approx. -273.15°C).

BT = (1321.0789 / Ln ((774.8853 / “%TOA%”) + 1)) – 273.15

3. Calculate the NDVI :

NDVI = (Band 5 – Band 4) / (Band 5 + Band 4)

Note that the calculation of the NDVI is important because, subsequently, the proportion of vegetation (P_v), which is highly related to the NDVI, and emissivity (ε), which is related to the P_v, must be calculated.

NDVI = Float(Band 5 – Band 4) / Float(Band 5 + Band 4)

4. Calculate the proportion of vegetation P_v :

P_v = Square ((NDVI – NDVI_min) / (NDVI_max – NDVI_min))

Usually the minimum and maximum values of the NDVI image can be displayed directly in the image (both in ArcGIS, QGIS, ENVI, Erdas Imagine), otherwise you must open the properties of the raster to get those values.

P_v = Square((“NDVI” – 0.216901) / (0.632267 – 0.216901))

5. Calculate Emissivity ε :

ε = 0.004 * P_v + 0.986

Simply apply the formula in the raster calculator, the value of 0.986 corresponds to a correction value of the equation.

6. Calculate the Land Surface Temperature :

LST = (BT / (1 + (0.00115 * BT / 1.4388) * Ln(ε)))

Finally apply the LST equation to obtain the surface temperature map.

As a result of the process developed, there is a map of the Land Surface Temperature, it should be noted that it is not equal to the air temperature.