Ocean salinity
Introduction
Soil moisture and sea surface salinity are directly linked to the global water cycle that governs the exchange of water between land, oceans and the atmosphere. High and low seasurface salinity patches can be directly linked to evaporation and precipitation respectively and with knowledge of the soil moisture it is possible to gain a deeper insight into the water cycle budget. Furthermore ocean salinity is a key variable in ocean circulation by effecting water density and thus density driven currents.
The European Space Agency ESA is planning to launch a soil moisture and ocean salinity (SMOS) remote sensing mission in September 2007 to measure these two parameters. SMOS is part of the Earth Explorer Opportunities as part of ESA$B!G(Bs Living Planet programme and as a requisite for opportunity missions will demonstrate a new sensor technology not previously used in space. The payload is a 2-dimensional interferometric passive microwave sensor measuring the incoming blackbody radiation at L-band frequency of 1.4 GHz which at this frequency is correlated to soil moisture and salinity that affect the dielectric constant of the radiating material and thus the radiation. Interferometry to simulate a synthetic aperture has been used extensively on active sensors but the simulation of a synthetic aperture for a passive radiometer is a novel approach in space.
Before the launch will go ahead, an international consortium of scientists in cooperation with ESA is setting up a plan of action to calibrate and validate the data that SMOS will measure against simultaneous measurements on the ground. The scientific analysis as well as the logistical effort that needs to go into these so-called Cal/Val exercises needs to be planned well in advance so that everything is functional at launch time when SMOS will enter a 6 months commissioning phase during which the sensor is to be calibrated to deliver the data during the actual operational phase with the accuracy that has been aimed for.
The remote sensing group at the Institute of Oceanography in Hamburg is part of that international Calibration and Validation team and has set up national SMOS project office that is to coordinate the German Cal/Val efforts as well as to promote the use of the SMOS data within German Earth Science groups.
The following link will take you directly to the SMOS office website: