1. SMOS – The Science Perspective Matthias Drusch Hamburg, Germany 30/10/2009

2. 1. What will be observed? – Geophysical parameters and accuracies. 2. What is the measurement principle? – Passive microwave radiative transfer. 3. What is the measurement technique? – Interferometry. 4. Why are soil moisture and ocean salinity important? – Turbulent surface – atmosphere exchange processes. 5. What are the main challenges? – Horizontal and vertical scaling. 6. How will the data be used? – Applications, multi-scale analyses, data fusion and data assimilation. OVERVIEW

3. WHAT WILL BE OBSERVED? Surface Soil Moisture SMOS observed range 10 %20 %30 %40 %50 % 4 % accuracy (at 50  50 km 2 ) Ocean Salinity ~ 0 %3 %3.5 %33 % 0.01 – 0.02 % accuracy (monthly mean at 200  200 km 2 )

4. WHAT IS THE MEASUREMENT PRINCIPLE? SMOS measures radiation 21 cm L-band Soil Moisture Radiation cold warm wet dry theoretical relationship atmosphere soil and roughness vegetation / roughness and waves / foam Ocean Salinity salty fresh

5. WHAT IS THE MEASUREMENT TECHNIQUE? L-band (21 cm) wavelength required to obtain high soil moisture sensitivity, large penetration depth and low sensitivity to atmosphere and vegetation. Long wavelength requires big antenna to obtain acceptable spatial resolution. Big antennas are difficult to operate in space Interferometry! SMOS will measure phase differences between electromagnetic waves detected at two or more receivers, which are a known distance apart. Cross correlation of observations from all possible combinations of receiver pairs provide a two dimensional image. Image courtesy of NRAO/AUI and NRAO

6. WHY ARE SOIL MOISTURE AND OCEAN SALINITY IMPORTANT? Soil Moisture … … is one key variable describing the water and heat exchange between the land surface and the atmosphere. Bureau of Meteorology Ocean Salinity … … and water temperature control the density of sea water and drive the global three-dimensional ocean circulation pattern. … is closely related to the net of evaporation minus precipitation and allows to estimate the heat exchange between the ocean and the atmosphere.

7. WHAT ARE THE MAIN CHALLENGES? SMOS observations are “snapshots” in space and time providing information on the surface layer NASA ECMWF Additional data and models have to be used to: - obtain information on the ocean mixed layer - obtain information on the root zone - generate global maps of soil moisture and ocean salinity - validate SMOS geophysical products - use the data in forecast systems

8. HOW WILL THE DATA BE USED? predictive modelforecast = + Forecast System initial (current) conditions hydrology floods, river runoff oceanographyocean currents, ship routing, ice damage, storm surge numerical weather prediction weather forecast, droughts, precipitation, heat waves agriculture & water management crop yield forecasts, water availability climateclimate change time

9. THANK YOU Matthias Drusch Land Surfaces Principal Scientist ESTEC, The Netherlands Matthias.Drusch@esa.int