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Improving Our Understanding Of The Water Cycle With the SMOS Earth Observation Satellite

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December 2009

Despite the water cycle being one of the most important processes operating on our planet - sustaining life and controlling our weather and climate - this fundamental system is still relatively poorly understood. Understanding if, and how, Earth's water cycle is being modified by climate change is becoming increasingly important for Canadians, not only for understanding how Earth works, but also for environmental policy and decision-making. A warmer climate is likely to lead to changes in evaporation patterns over Canadian lands and oceans, increasing the moisture content of the atmosphere - hence influencing weather patterns. This brings many concerns, especially for water consumption and agricultural needs.

By regularly and consistently mapping soil moisture and ocean salinity, the SMOS (Soil Moisture and Ocean Salinity) Earth observation (EO) satellite, launched on November 2 2009, aims to improve our understanding of the role these two key variables play in regulating the water cycle. Improving the water resource management with SMOS EO data will also give the opportunity to the Government of Canada and its partners to reduce the risks of water scaricity, floods, drought, land degradation, coastal and marine ecosystems degradation, etc.

In partnership with other Canadian departments and agencies, the Canadian Space Agency (CSA) Governmental Related Initiatives Program (GRIP) supports the research, development, demonstration and implementation of effective and efficient uses and applications of EO in multiple domains, including water. Multiple soil moisture and ocean salinity products will be developed by the Government of Canada, via GRIP, with EO information from SMOS.

Supporting Canadian Agricultural Risk Management

Managing and mitigating risk to the agriculture sector requires information and knowledge to assess risk potential implement risk reduction strategies and deliver essential responses. The availability of water, in particular the amount of moisture held in the soil, could represent a significant risk factor for this sector. EO satellites, like SMOS and RADARSAT-2, can substantially improve the information upon which effective assessment, mitigation and program delivery are based. Through CSA's GRIP, Agriculture and Agri-Food Canada (AAFC) will develop, test and evaluate methods to quantify surface soil moisture information derived from advanced satellites sensors, including SMOS and RADARSAT-2. The intent following this research and development phase will be to demonstrate the assessment of risk due to extreme soil moisture conditions using integrated active and passive microwave soil moisture products.

Volumetric Soil Moisture Estimated from AMSR-E Passive Microwave Data: NASA-VUA
(Land Parameter Retrieval Model- LPRM) - C and X band soil moisture (AAFC, 2009)

Soil moisture information derived from RADARSAT-2 data, Ottawa (Canada) (AAFC, 2009)

Implementing Canadian Environmental Prediction Systems

Soil moisture is of crucial importance in environmental prediction systems, including those used in hydrology, agriculture, forestry, air quality, meteorology, etc. Unfortunately, direct soil moisture observations are not currently available to properly initialize this important variable in environmental prediction systems. Through CSA's GRIP, Environment Canada (EC) is developing a project titled "Operational Implementation of Soil Moisture Data In EC's Prediction System" to improve the representation of soil moisture by including the SMOS mission L-band measurements in the Canadian Land Data Assimilation System (CaLDAS). In CaLDAS, either a simple variational approach or an Ensemble Kalman Filter will be used to combine SMOS information with results from a land surface modeling system in order to produce an optimal estimate of soil moisture.

Developing Canadian Ocean Products

In 1997, Canada became the first country in the world to adopt comprehensive legislation for oceans management. By passing its Oceans Act, Canada made a legal commitment to conserve, protect and develop the oceans in a sustainable manner. Understanding the three oceans that surround Canada, as well as Canada's waterways and aquatic resources, is crucial if we want to ensure their sustainability. Together with temperature, salinity determines water density, and thus is intimately linked to ocean circulation. It determines the depth to which water, cooled at the surface in winter, can sink and it thus is directly linked to the dynamics of the earth's climate. Through its effect on density, it partially controls the stability of the upper mixed layer of the ocean which has important physical and ecological consequences: it is one of the prime determinants of the environment in which fish and other marine life live, it modulates air-sea interaction including gas and heat exchange, and it allows estimation of the magnitude and fate of important freshwater sources (e.g. rivers, sea ice). Salinity is one of the most basic and important physical variables of the ocean, but has never been observable from space until now, with the successful launch of the SMOS satellite and next year's launch of Aquarius. Satellite sea surface salinity measurements need to be calibrated and validated before they can be exploited for the needs of the Government of Canada. Through CSA's GRIP, the Department of Fisheries and Oceans (DFO) is developing a project titled "2010 Sea Surface Salinity Cal/Val". The primary goals are to validate SMOS and Aquarius measurements in Canadian waters, to develop sea surface salinity (SSS) data products, and to make recommendations to CSA about participating in future operational SSS missions.

World-class Research Excellence Is Canada's Standard

In the context of the launch of the SMOS Earth Observation satellite, scientists representing the Virtual Centre for Ocean Satellite Salinity (VCOSS) are developing a project titled "Ocean surface salinity validation in Canadian waters." The collaboration involves the Department of Fisheries and Oceans (Bedford Institute of Technology; Northwest Atlantic Fisheries Centre; Institute of Ocean Sciences), Memorial University and York University. The Canadian team will evaluate the large scale structure of SMOS observation through comparison with seasonal climatology compiled from historical data archives and coincident hydrographic surveys conducted in Canadian waters. The scientists will also evaluate the time variability of SMOS observations at specific locations where more frequent in-situ measurements of surface salinity are available.

About CSA's GRIP

By providing technical guidance and support for the optimum use of Earth Observation (EO) technologies by the Government of Canada, CSA's GRIP helps derive the maximum benefit from the Government's investments in space. For more information...

About SMOS

Canada is a cooperating member of ESA and contributed to the development of SMOS. Array Systems Computing Inc. (Toronto, Canada) in collaboration with the Expert Support Labs (ESL), ESA and CSA, has successfully developed the SMOS Level 2 Soil Moisture processor. The main ESL contributors included CESBIO (France), IPSL SA (France), INRA (France), and Tor Vergata University (Italy). Array Systems has supported the Level 2 algorithm validation leading to algorithm improvements and has successfully developed and validated a large number of auxiliary data products for use in the ground segment. Array Systems and its supporting ESL are part of the SMOS commissioning team and the support team for the ground segment activities. For more information...

For more information, please contact:

• guy.aube@asc-csa.gc.ca (Canadian Space Agency)
• paul.briand@asc-csa.gc.ca (Canadian Space Agency)
• heather.mcnairn@agr.gc.ca (Agriculture and Agri-Food Canada)
• stephane.belair@ec.gc.ca (Environment Canada)
• jim.gower@dfo-mpo.gc.ca (Fisheries and Oceans)

References:

• CSA (2009) EO-Express newsletter, November 2009 / no. 39, St-Hubert
• ESA AOES Medialab (2009) SMOS
• Fisheries and Oceans (2009) Canada's Oceans Strategy: Our Oceans, Our Future. Ottawa
• Industry Canada (2009) Mobilizing Science and Technology to Canada's Advantage. Ottawa