The Golden Age of remote sensing and its challenges

The current era can be called the Golden Age of remote sensing. Never before has there been such an abundance of remote sensing data as it is now. In addition, most of these data are available free of charge. However, to draw reliable conclusions from the data, it is necessary to ensure that all direct and indirect remote sensing measurements are correctly calibrated and validated.

Tartu Observatory, together with 13 other parties, is participating in the H2020 project CCVS (Copernicus Calibration and Validation Solution), led by the French Space Centre ACR-ST. The aim of the project is to find a comprehensive solution to the calibration and validation of data from the entire Copernicus programme. In order to understand the problems of different areas and move towards a comprehensive solution, nearly 200 experts participated in the webinar on 13-15 October, which was held in the framework of the CCVS project.

The Copernicus programme comprises a set of satellites with an impressive number of observations every day and a global network of thousands of land, air and marine sensors, which together contribute to documenting the current state of the Earth. It is, therefore, a very large number of different devices, a huge amount of data and their measurement uncertainties, measurement protocols and data analysis.

It was repeatedly underlined during the seminar that the key to calibration/validation is the existence of accurate in-situ data. It was acknowledged that sometimes there are significant differences between remote sensing and in-situ data. To reveal these differences are one of the tasks of this project. At the same time, instruments for in-situ measurements may encounter many challenges - terrain fires, storms, instrument failures, wild animals, etc.

What are the benefits of the CCVS project for a regular user? Shortly, more reliable data and new opportunities. For example, satellites already measure air quality and atmospheric composition. However, in order to detect point source pollutions (e.g. plants) via CO2, more precise measurements are needed. One of the objectives of the CCVS project is to provide input for the upcoming CO2M project, which will be able to detect point source pollutions.

A very practical task of the CCVS project is to contribute to the creation of a ‘traffic light’ level for end-users to assess the reliability of data (red — not reliable enough; yellow — conditionally reliable; green — very reliable). The end-user does not need to go into the technical details of calibration and validation to assess the reliability of the data.

Erko Jakobson, an associate professor and CCVS project leader at Tartu Observatory, pointed out that the purpose of the webinar was to bring together the Copernicus data calibration and validation community in order to create a comprehensive solution jointly. However, the question of how to ensure long-term coordination and development in this field remained in the air.

The webinar was conducted using the Worksup platform created in 2015 by Estonians, which was also used in 2017 as an official application during the Estonian Presidency of the Council of the European Union.