Download Space-borne sensing

Essential role of radio-frequencies for Earth
observations and meteorology
Philippe TRISTANT
Météo France Frequency Manager
EUMETNET Frequency Manager
([email protected])
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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• Most people know that Meteorology and Earth
observations are important …
• … but much less are aware that these activities are
fully dependent on radio-frequencies
“No spectrum, no global observations!”
(ITU Statement in a side event during Cancun UNFCCC)
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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WMO Global Observing System (GOS)
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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Radio applications for meteorology
• Meteorological aids :
– Radiosondes : about 900 stations worldwide in the 400 MHz band
(core) and 1675 MHz band (roughly 1 000 000 launches per year)
• Radiolocation :
– Precipitation and Doppler radars : about 1000 radars worldwide in
the 2.8, 5.6 and 9.4 GHz bands
– Wind profiler radars (WPR) : about 200 radars in the 50, 900 and
1270 MHz bands
• Miscellaneous :
– Lightning detection
– Terrestrial data collection
• Satellites …
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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Constellation of METSAT
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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Satellite Applications
• Space-Borne sensing (Earth Exploration Satellite Service (EESS)):
– Passive sensors (radiometers)
– Active sensors (scatterometers, altimeters, cloud and precipitation radars)
• Data Transmissions, mainly in the 1.7, 2.2 and 7.8 GHz bands
• Communication satellites, broadcasting data or forecasts
• A number of METSAT receiving stations and several METSAT centers
in a large number of countries
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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Importance of Satellite Applications
•
Space-borne sensing of the Earth’s surface and atmosphere has an essential and
increasing importance for mitigating the impact of weather and climate-related
disasters
•
Space-borne sensing allows for consistent observations all around the globe
•
The impressive progress made in the recent years in weather and climate analysis and
forecasts, including warnings for dangerous weather phenomena (heavy rain, storms,
cyclones) that affect all populations and economies, is to a great extent attributable to
spaceborne observations and their assimilation in numerical models.
•
One key element : although the satellites are operated by a limited number of space
agencies, the data, products and/or forecasts based on these data are shared among all
countries (via WMO or GEO)
•
It is therefore a global and common responsibility to ensure protection and
availability of the corresponding frequency bands
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
7
Activities in ITU-R on environmental
satellite applications
• Meteorological/Earth observations activities are considered in ITU-R
Study Group 7 (science services)
• All World Radiocommunication Conferences (WRC) include several
related agenda items
• Over long period of time, environmental and meteorological
applications suffered from a lack of understanding and support
• This was mainly under the fake argument, mainly economical, that it’s
only science and hence represent less importance compared to
telecommunication applications
• The situation is improving but a lot is still to do through Radio
Administrations to ensure relevant understanding of the importance of
these activities.
• WRC-07 adopted Resolution 673 to study possible means to improve
the recognition of the essential role and global importance of Earth
observation radiocommunications applications
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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Activities in ITU-R on environmental
satellite applications
• WRC-12 will have to consider the results of these studies
to propose that this recognition be included in the Radio
Regulations, and a broad support will be necessary.
• In particular, during the preparation process, ITU-R
adopted :
– The Joint WMO/ITU Handbook on “Use of Radio Spectrum for
Meteorology: Weather, Water and Climate Monitoring and
Prediction”
– Recommendation ITU-R RS.1859 on “disasters”
– Recommendation ITU-R RS.1883 on “climate”
– Report ITU-R RS.2178 on “The essential role and global
importance of radio spectrum use for Earth observations and
for related applications”
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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Activities in ITU-R on environmental
satellite applications
• All these documents stress the role of Earth Observations
radio applications:
– “The considerable societal value of Earth observation can directly
be translated into terms of societal weight and economic value of
the radio-spectrum which is used for these Earth observation
activities”
– “Most of the data retrieved from the use of this spectrum are
directly dedicated to the benefit of every citizen”
– “Most of this societal value is incommensurable in financial terms,
as it relates to preventing large losses of lives or threats to sociopolitical stability and security”
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
10
Space-borne passive sensing
• By far, space-borne passive sensing that involve the
measurement of naturally-occurring terrestrial and
atmospheric radiations is the most sensitive to interference
• The radiations occur at very low power levels and contain
essential information on the physical process under
investigation
• The relevant frequency bands are mainly determined by
fixed physical properties (e.g., molecular resonance), so
these bands cannot be changed
• These “passive bands” are, therefore, an essential and
unique natural resource
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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Space-borne passive sensing
•
•
•
the passive sensors are in general unable to discriminate between these natural
radiations and man-made radiations
bands below 100 GHz are of particular importance, as they provide an “allweather” observation capability
In this respect Provision No. 5.340 of the Radio Regulations (RR) states that
“all emissions are prohibited”, meaning by principle that:
– no in-band emissions are authorised
– only unwanted emissions from adjacent bands can be experienced
•
•
•
Unfortunately, in may cases, such unwanted emissions can be high enough
to interfere the sensors, in particular when aggregated from multiple sources
of interference (Mobile phones, Short-Range devices, …)
the scientific community is working hard to convince Radio administrations
to adopt limits in the RR to ensure protection of the “passive bands”
This is not always successful, in particular since we are said of being overconservative and unduly constrain other radiocommunication service
BUT …
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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Example of interference on passive sensors
RFI at 1.4 GHz
RFI at 10.6 GHz
RFI at 6.8 GHz
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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“No spectrum, no global observations!”
It is a global and common responsibility for worldwide
countries to ensure protection and availability of
essential frequency bands used for
meteorology and Earth observations
Thank you for your attention
ITU Symposium on ICTs and the
Environment & Climate Change
Accra, 7-8 June 2011
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