# Product Tutorial on Land Surface Temperature (LST)

## Print Version

## Chapter I: Introduction

### Table of Contents

- Chapter I: Introduction
- Introduction

### Introduction

Is the Earth in thermal equilibrium? Is vegetation in danger? Is the climate actually changing?

To answer questions like these it is essential to know with a high degree of accuracy one of the key parameters of weather and climate: the surface temperature of the Earth. However, the term "Earth surface temperature" is vague; it may refer to distinct physical definitions (thermodynamic temperature, kinetic, radiometric) depending on the different measuring instruments (as illustrated in Figure 1), and it pertains to different domains of the Earth's surface: ground, air, sea, land, lakes, ice, soil. In other words, there is no single temperature for the Earth but a wide variety of local temperatures that span the range from the frozen Antarctic to the tropical jungles and arid deserts of Africa (read more).

Fig. 1: This image illustrates the wide variety of temperatures on Earth: air temperature, ground, soil, urban, sub-urban, ice, lakes... (source: https://www.acs.org, Credit: David Simonds).

Earth temperatures from different surfaces actually correspond to distinct variables that play different roles, though commonly inter-connected, in the earth-atmosphere system (Merchant, C. J. et al., 2013)

In this module we focus on one of the aforementioned domains - the land - and clarify the meaning of Land Surface Temperature (LST), a parameter often confused with air temperature, aerodynamic temperature or soil temperature. The term "Land Surface Temperature" is widely used by distinct research communities such as those of climate, numerical modelling or boundary layer studies while referring to different physical meanings (Menglin and Dickinson, 2010). We take a deep look at LST by considering how this temperature can be obtained from satellite measurements and how it compares to other temperatures.

Different techniques to measure this variable are presented, including local and remote observations. Special emphasis is given to the retrieval of LST from satellites, in particular from the thermal infrared radiances measured by sensors onboard different platforms, like the SEVIRI sensor onboard the Meteosat Second Generation geostationary satellite and AVHRR onboard the Metop series of polar orbiting satellites.

Information about LST is required in a wide variety of applications, as described in last section: as a climate change indicator, for modelling studies, for burnt area mapping, to study interactions in the land-biosphere-atmosphere system, accounting for urban islands and monitoring of heat waves and cold surges, among others.

Acknowledgements

This product tutorial has been scientifically revised by professor Carlos daCamara from the University of Lisbon, and has benefited from his valuable advice and suggestions.