smos – the science perspective matthias drusch hamburg, germany 30/10/2009
Post on 20-Dec-2015
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TRANSCRIPT
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
WHAT WILL BE OBSERVED?
Surface Soil Moisture
SMOS observed range
10 % 20 % 30 % 40 % 50 %
4 % accuracy(at 50 50 km2)
Ocean Salinity
~ 0 % 3 % 3.5 % 33 %
0.01 – 0.02 % accuracy(monthly mean at 200 200 km2)
WHAT IS THE MEASUREMENT PRINCIPLE?
• SMOS measures radiation
21
cm
L-b
an
d
Soil M
ois
ture
Radiationcold warm
wet
dry
theoretical relationshipatmospheresoil and roughnessvegetation
/ roughness and waves/ foam
Ocean
Salin
ity
salty
fresh
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
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.
WHAT ARE THE MAIN CHALLENGES?
• SMOS observations are “snapshots” in space and time providing information on the surface layer
NASAECMWF
• 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
HOW WILL THE DATA BE USED?
predictive model forecast=+Forecast System
initial (current) conditions
hydrology floods, river runoff
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
THANK YOU
Matthias Drusch
Land Surfaces Principal Scientist
ESTEC, The Netherlands