Sea ice knowledge

Sea ice has global relevance. It is an important element of the cryosphere and therefore of our climate system. The optical and thermodynamic characteristics of sea ice differ considerably from open water. Therefore, the spatial extent of sea ice and its overlying snow cover is of great importance for the global energy budget. Vice versa, due to its interactions with atmosphere and ocean, sea ice is a sensitive indicator for changes in the global climate system and can be used as a diagnostic parameter for climate change observations. The occurence of sea ice shows a distinct seasonality and spatially comprehensive measurements of the seasonal and annual changes of sea ice are therefore very important for earth system and climate science. Additionally, sea ice is an important habitat for various organisms.
After the initital freezing of sea water, sea ice is strongly altered through physical, biological and chemical processes and forms an extremely heterogenous, semi-solid matrix. Ocean, atmosphere and continents determine the formation, solidification and stabilisation of sea ice and the subsequent melting, when ice turns back into water. One of the most important properties of sea ice is its lesser density compared to sea water, forcing it to float on the ocean surface. In doing so, the ice displaces as much of the water volume as it would take on in its liquid state. Therefore, melting and freezing of sea ice have next to no effect on sea level.
But what is sea ice exactly? What do we know about the formation of sea ice? How does the freezing process take place and how does the desalination of sea ice work? What does the crystal structure of sea ice look like and which factors determine its growth? Sea ice is further more an unique inhabitat for many species.