Envisat Symposium 2007 kicks off in Switzerland   More than 900 scientists from around the world have gathered in Montreux, Switzerland, for a five-day symposium to discuss, present and review their findings on the state of our world’s land, oceans, ice and atmosphere using data from ESA Earth observation satellites, in particular Envisat – the largest environmental satellite ever built.   ESA Director of Earth Observation (EO) programmes Dr Volker Liebig opening the 2007 Envisat Symposium   Director Daniel Fürst of the Swiss Space Office speaking at the opening of the Envisat Symposium 2007 held in Montreux, Switzerland.   Envisat demonstrates the power of two, with combined optical MERIS and radar ASAR views of the eye of Hurricane Katrina acquired 28 August 2005 over the Gulf of Mexico. The MERIS imagery shows the swirling cloud-tops of the storm, while the ASAR image pierces through the clouds to show the shape of the wind-driven sea surface.   Mean nitrogen dioxide (NO2) pollution map for 2006, measured by Envisat's Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument, which records the spectrum of sunlight shining through the atmosphere. NO2, a mainly man-made gas, can cause lung damage and respiratory problems in the case of excess exposure. It also plays an important role in atmospheric chemistry, because it leads to the production of ozone in the lowest part of the atmosphere – the troposphere.   Using a technique called Synthetic Aperture Radar (SAR) Interferometry, or InSAR for short, scientists are able to measure surface deformations before and after earthquakes and to detect surface deformations in volcanoes. SAR has advanced the fields of tectonics and volcanology by allowing scientists to monitor the changes anywhere in the world at any time.   Release date: 28 February 2012