Inserting ECV definition and in-situ observations info

Author: justbia

observations/intro.md

@@ -2,7 +2,7 @@
 
 # Tutorials on C3S climate observations datasets
 
-Earth observation plays a crucial role in monitoring various aspects of the Earth’s atmosphere, and the surfaces of our land, oceans, and cryosphere. Observation systems can be based upon satellite-based sensors, as with the majority of datasets we explore in these tutorials. However, it is important to note they can also be based on ground-based, or airborne sensors. These are not necessarily used in isolation, and can often complement each other to provide a more holistic, and comprehensive insight into Earth’s systems. Within C3S, our collection of observations of Earth’ systems are grouped into six main domains: atmospheric chemistry, atmospheric physics, land biosphere, land hydrology, oceans, and cryosphere. Note that occasionally, observation parameters such as surface temperature, can contribute to multiple domains such as oceans (sea surface temperature), land biosphere (land surface temperature) and cryosphere (sea and ice surface temperature). In these tutorials, we help you explore and use some of these observation datasets, providing a collection of useful pathways into key climate-relevant datasets available on the C3S.
+Earth observation (EO) plays a crucial role in monitoring various aspects of the Earth’s atmosphere, and the surfaces of our land, oceans, and cryosphere. Through EO, we can gather data on various Essential Climate Variables (ECVs). These are physical, chemical, or biological aspects of the Earth, that when monitored and measured contribute to understanding and characterizing Earth's climate. Observation systems can be based upon satellite-based sensors, as with the majority of datasets we explore in these tutorials. However, it is important to note they can also be based on ground-based, or airborne sensors. C3S provides in-situ as well as satellite observations, recognising that both types of data are not necessarily used in isolation. They can often complement each other to provide a more holistic, and comprehensive insight into Earth’s systems. Within C3S, our collection of observations of Earth’ systems are grouped into six main domains: atmospheric chemistry, atmospheric physics, land biosphere, land hydrology, oceans, and cryosphere. Note that occasionally, observation parameters such as surface temperature, can contribute to multiple domains such as oceans (sea surface temperature), land biosphere (land surface temperature) and cryosphere (sea and ice surface temperature). In these tutorials, we help you explore and use some of these observation datasets, providing a collection of useful pathways into key climate-relevant datasets available on the C3S.
 
 
 ## Satellite observations of atmospheric physics ECVs