ICT AND CLIMATE CHANGE MONITORING OF CLIMATE CHANGE AND MICROWAVE - - PowerPoint PPT Presentation

QUESTION Q24/2 ICT AND CLIMATE CHANGE MONITORING OF CLIMATE CHANGE AND MICROWAVE SATELLITE REMOTE SENSING

Satellite altimetry Passive remote sensing Earth Exploration Satellite frequencies

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

Monitoring of climate change

• Today, climatology relies increasingly on space
• technology. Earth observation delivers series of

precise, global measurements matching the scale of planetary climate phenomena.

• Remote sensing is the acquisition of physical data

without touch or contact.

• Focus on the usage of the electromagnetic

spectrum and of Earth Observation satellites to monitor some aspects of climate change.

• Importance of the ITU-R Radio

Regulations to protect the Earth Exploration Satellite frequencies.

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

SATELLITE ALTIMETRY

• Seventy-one per cent of the planet’s surface is

covered by water: key parameter for understanding the forces

behind changing weather patterns.

• Combining oceanic and atmospheric models  accurate

forecasts on both a short- and long-term basis.

• Coupling of oceanic and atmospheric models

needed to take the mesoscale (medium- distance) dynamics of the oceans  weather forecasting beyond two weeks.

• The oceans are also an important part of the process of climate

change: rise in sea levels all over the world is widely recognized as potentially one of the most devastating consequences of global warming.

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

SATELLITE ALTIMETRY: Hydrology and Land

• The earliest altimetry missions were dedicated to studying the open
• cean and some ice measurements. Every stretch of water

(enclosed seas, lakes, rivers, flooding areas...) or even flat surfaces

• ver lands can give valid data.
• Altimetry: global, homogeneous, repeated measurements (thus

enabling systematic monitoring to be carried out over several years), unhindered by clouds, night or even vegetation. Measured surface heights referenced to the same frame.

• Technique is mainly optimized for the ocean (but although

specific land re-tracking can be applied): measurements only at the nadir (i.e. just under below the satellite), with a rather narrow footprint -- and averaging everything in that footprint.

• Over non-ocean surfaces (wet or dry), the accuracy of the

altimetry measurements can be degraded to by several centimetres or tens of centimetres, mainly because of the heterogeneity of the reflecting surface (a mix of water and emerged land surfaces).

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

SATELLITE ALTIMETRY

JASON 1, 2 SATELLITES: CNES, NASA, NOAA and EUMETSAT Measurements:

• Distance between the

Satellite and the sea

• wave height
• wind speeds

Accuracy:

• Range to surface (cm,

corrected) : 2.3

• Radial orbit height (cm) : 1.0
• Sea-surface height (cm) : 2.5
• Wind speed (m/s) : 1.5

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

• Jason-1 satellite was launched on

December 7, 2001.

• Jason-2 satellite was launched on June

20, 2008.

• Jason-3 in preparation
• Orbit :

 Altitude 1336 km, circular, non-sun-synchronous  66° inclination, global data coverage between 66°N

and 66°S latitude

 10-day repeat of ground track (±1-km accuracy)  coverage of 95% of ice-free oceans every 10-days

SATELLITE ALTIMETRY

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

SATELLITE ALTIMETRY TECHNOLOGY:

Estimates of wind and waves from altimeter: analysis of the return from the sea surface: peak backscattered power and shape of the waveforms.

 Back scatter, σo, from the sea surface: sensitive to small scale

surface roughness (short ocean waves).

 σo is the primary variable used in estimating wind speed.  σo sensitive to much larger waves that are only related weakly to

the local wind  recent algorithms for wind speed also include the altimeter estimate of significant wave height.

 Significant wave height (SWH) can be estimated using the return

pulse by large waves, since the radar signal can be reflected from both the troughs and peaks of waves. The sea surface height is usually estimated from the centre point of the leading edge.

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

MEAN SEA LEVEL RISE

• Global mean Sea Level rise is one of the consequences of global
• warming. Monitoring this level is an application of altimetry, and one of the

main issue in Environmental sciences of the 21st century.

• It is quite difficult to separate the natural variability of the climate from

the warming effects. The measurements of the mean sea levels are derived from a period of time of 19 years of satellite earth observation:

such a period of time is short. In addition to that, it is necessary to

indicate that human induced peturbation is added to the natural climate variability.

• Climate change signals can be detected only if they are greater than the

background natural variability. Detecting global climate change is much more demanding than monitoring regional impacts.

• Need to have a stable environnment and time series must be stable and

accurate.

• The rise of the sea level is mainly a consequence of past climatic events.

The following figure shows that the rise is about 3,2 mm per year,

roughly 5.8 cm within 19 years.

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

MEAN SEA LEVEL RISE

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

MAP OF SEA LEVELS VARIATION TRENDS SINCE 1992: REGIONAL TRENDS

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

MEAN SEA LEVEL AS SEEN BY OTHER TECHNIQUES

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

MEAN SEA LEVEL

• Since the beginning of the 1990s, altimetry is the main

tool for continuous, precise and nearly-global mean sea level monitoring, with moreover regular measurements (every 10 or 35 days). However, other techniques existing a long time before, new ones have appeared that enable to validate altimetry results, and above all to better understand why mean sea level is varying.

• The longest sea level time series are provided by tide

gauges (« Marégraphes »). Some of them (not many) measured the sea level for more than a century. However, they support the effects of the movements of continents, and are very unevenly distributed around the globe: necessarily close to shore, but many more, and the oldest in Europe and the United States

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

MEAN SEA LEVEL: TIDE GAUGES (« marégraphes »)

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

MEAN SEA LEVEL (MSL): VALIDATION

Sources of error in the Error in the MSL calculation slope of MSL Orbit determination +/-0.15 mm/year Wet troposphere +/-0.30 mm/year Corrections from weather data fields +/-0.10 mm/year Altimetry parameters +/-0.10 mm/year Sea Surface Height bias model +/-0.25 mm/year

Total error +/-0.6 mm/year

Confidence interval= 90%

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

MSL VARIATIONS CAUSES

• water mass variations:

water can be added to the ocean, either by increased rain over the ocean,

• r run-off from the rivers; glaciers melting can also add water

Increased evaporation can also decrease the water mass (as well as glaciation, as it happened during last Ice age, when sea level was about 100 m below the nowadays level)

• temperature variations:

water dilates when it warms, which leads to higher sea level. Among other things, it leads to sea level seasonal variations, and also year-to-year variations linked to climate events (e.g. El Niño).

• salinity variations:

the saltier the water, the denser it is; thus saltier water will have a lower

• level. Salinity variations can occur by fresh water addition (increased run-
• ff, rain, or ice melting), which decreases salinity, or by increased

evaporation, or by glaciation, which increase salinity.

• ocean circulation changes:

changes in sea level can be due to changes in the ocean circulation.

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

WHAT IS MAKING THE OCEANS RISE?

Thermal expansion 1.6 +/- 0.5 mm/yr Glaciers and ice caps 0.77 +/- 0.22 mm/yr Greenland ice sheet 0.21 +/- 0.07 mm/yr Antarctic ice sheet 0.21 +/- 0.35 mm/yr Sum 2.8 +/- 0.7 mm/yr Observed 3.2 +/- 0.6 mm/yr

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

El nino event

http://www.aviso.oceanobs.com/en/newsstand/altimetry-and-doris-applications- in-videos/el-nino/index.html

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

Latest plot of El Nino situation in the Pacific ocean

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

Latest plot of El Nino situation: mean sea anomaly

La Niña may be back again this year: temperatures in the Pacific are hinting at a continued pattern

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

Monitoring of the level of the East Africa’s Lakes in connection with El nino events

Monitoring the rising of the lake levels in East Africa in late 1997: consequence of heavy rainfall caused by El Niño conditions over the Pacific on the watershed

• f these lakes.

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

Frequencies for satellite active remote sensing Frequencies for satellite active remote sensing

• For most of the Eearth Exploration Satellite Service (active)

sensors, the operating frequency range is linked to the geophysical parameters to be observed. For instance, to enable measurement of clouds and precipitation, the wavelength needs to be small enough to reach the required sensitivity.

• For radar altimeters, the main frequencies

used are at 5.3 GHz, 13.65 GHz and also at 35.4-36 GHz. It is essential to keep protecting these frequencies which are shared with other radio services.

• In addition to active remote sensing frequencies, passive

frequencies are needed for an accurate estimate of all the

• utput products.

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

PASSIVE SATELLITE REMOTE SENSING

• Soil Moisture and Ocean Salinity

SMOS: mission: to observe soil moisture and ocean salinity, two

crucial variables for modelling our weather and climate.

• Salinity is fundamental in determining ocean density and hence

thermohaline circulation. SMOS instrument launched 2 November 2009: to provide temperature brightness (TB) data for 3–5 years. First time that salinity is measured from space.

• Soil moisture: first time that soil moisture is measured from

space.

• Microwave radiometer at 1.4 GHz.
• Accuracy requirment of salinity: 0.1 practical salinity

units (1 psu= 1g salt in 1kg of seawater),

every 10 days at 200 km spatial resolution.

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

Microwave frequencies used for Earth Exploration Satellite: passive at 1.4 GHz (21 cm): soil moisture and sea salinity (SMOS)

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

SMOS SATELLITE

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

SMOS satellite: Mean altitude of 758 km and inclination of 98.44°; low-Earth, polar, Sun- synchronous, quasi-circular, 23-day repeat cycle

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

SMOS results: SOIL MOISTURE

• April 2011, the second hottest month since 1900 for

FRANCE

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

SMOS results: SOIL MOISTURE for UK

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

Floodings (April-May 2011) in the Mississippi Basin: SOIL MOISTURE

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

SMOS results: SEA SURFACE SALINITY (SSS)

The strong salinity (psu) gradient of the Amazon plume measured by SMOS in August 2010

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

Field of SMOS SSS anomaly (psu) with respect to World Ocean Atlas 2005 climatology for the period 6 to 16 February 2011

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

AQUARIUS: NASA MISSION (launch 10 June 2011) for SSS

NASA Credits, see http://aquarius.nasa.gov/index.html

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

1400-1427 MHz: Exclusive passive frequency band: ALL EMISSIONS ARE PROHIBITED

• Frequency band also used by radio astronomy (the

famous redshift).

• Recommended regulation (WRC Resolution,

November 2007) to protect the frequency band 1400- 1427 MHz from out of band emission derived from adjacent frequency bands below 1400 MHz and above 1427 MHz: mainly radars (Radiolocation), fixed, mobile.

• Compulsory regulation in many european countries

since March 2011

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

SWITCH ON OF SMOS instrument

Areas affected more than 10 % of the time by strong RFI for ascending orbits (CESBIO Credits)

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

Radio frequency interference situation in Europe

Map of Europe showing the probability of SMOS sustained RFI occurrences beginning 2010 (Credits CESBIO)

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

Current situation RFI in Europe for the 1400-1427 MHz frequency band

Map of Europe showing the probability of SMOS sustained RFI occurrences from 14th October to 14th December 2010 (Credits CESBIO)

ITU-D SG2 13 September 2011 Jean PLA Q24/2 ICT and climate change

Any questions?