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SMOS – The Science Perspective. Matthias Drusch Hamburg, Germany 30/10/2009. OVERVIEW. What will be observed? – Geophysical parameters and accuracies. What is the measurement principle? – Passive microwave radiative transfer. What is the measurement technique? – Interferometry.
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SMOS – The Science Perspective Matthias Drusch Hamburg, Germany 30/10/2009
OVERVIEW • What will be observed? – Geophysical parameters and accuracies. • What is the measurement principle? – Passive microwave radiative transfer. • What is the measurement technique? – Interferometry. • Why are soil moisture and ocean salinity important? – Turbulent surface – atmosphere exchange processes. • What are the main challenges?– Horizontal and vertical scaling. • How will the data be used? – Applications, multi-scale analyses, data fusion and data assimilation.
Surface Soil Moisture 4 % accuracy(at 50 50 km2) SMOS observed range 10 % 20 % 30 % 40 % 50 % Ocean Salinity 0.01 – 0.02 % accuracy(monthly mean at 200 200 km2) ~ 0 % 3 % 3.5 % 33 % WHAT WILL BE OBSERVED?
WHAT IS THE MEASUREMENT PRINCIPLE? • SMOS measures radiation theoretical relationship atmosphere soil and roughness / roughness and waves vegetation / foam 21 cm dry L-band Soil Moisture wet warm cold Radiation fresh Ocean Salinity salty
Image courtesy of NRAO/AUI and NRAO 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.
WHY ARE SOIL MOISTURE AND OCEAN SALINITY IMPORTANT? Soil Moisture … Ocean Salinity … Bureau of Meteorology … 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. … is one key variable describing the waterand heat exchange between the land surface and the atmosphere.
WHAT ARE THE MAIN CHALLENGES? • 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 NASA ECMWF • SMOS observations are “snapshots” in space and time providing information on the surface layer
HOW WILL THE DATA BE USED? Forecast System = + initial (current) conditions predictive model forecast oceanography ocean currents, shiprouting, ice damage, storm surge numericalweatherprediction weather forecast, droughts, precipitation, heat waves agriculture &water management crop yield forecasts,water availability climate climate change time hydrology floods, river runoff
THANK YOU Matthias Drusch Land Surfaces Principal Scientist ESTEC, The Netherlands Matthias.Drusch@esa.int