ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 1 Active protection of...

ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004

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Active protection of passive radio services:towards a concerted strategy

Frequency needs for remote sensing of the middle atmosphere

Jérôme de La Noë

Laboratoire d’Astrodynamique, d’Astrophysique et d’Aéronomie de BordeauxUniversité Bordeaux 1, Observatoire Aquitain Sciences de l’Univers, Floirac,

France


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Outline

1. General introduction on the middle atmosphere

2. Remote sensing of the atmosphere

3. Some ground-based microwave radiometers

4. Satellite-borne microwave radiometers

5. Some results

6. Conclusions


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1. General introduction: the middle atmosphere


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1. General introduction: composition of the atmosphere

Ozone (O3) 0,0010 20 min. 10

20 106 yr

3 yr

5-10 yr

Lifetime


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1. General introduction: role of stratospheric ozoneStratospheric ozone is essential to life on Earth

Three main functions:

1.- Blocking off solar UV-B radiation protects against• Killing human cells and microorganisms • Increasing the number of cataractes, • Decreasing the cell-mediated immunity• Increasing skin cancers, melanomae• Inhibition of vegetal reproduction and development• Inhibition of reproduction and development of marine

microorganisms.

2 - Warming of the middle atmosphere -50°C at 20 km ---> 0°C at 45 km

3 - At the troposphere, greenhouse effect allowing life on EarthIf not: Average temperature at the Earth surface ≈ - 18°C


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2. Remote sensing of the atmosphere: used techniques

Various techniques are generally employed using different wavelengths of the electromagnetic spectrum to measure either column densities and/or vertical profiles of concentration:

1. Fourier Transform InfraRed (FTIR) spectrometers in the range 700-4100 cm-1: passive. Column densities: ozone,

2. Visible: active lidars as radars but using coherent laser light retro-diffusion: active. Vertical profiles during the night: temperature, tropospheric & stratospheric ozone, water vapour, wind speed

3. UV-visible spectrometers: passive Column densities: ozone, NO2, OClO

4. Ozone sondes: passive Vertical profiles: ozone

5. Dobson and Brewer spectrophotometers: passive Column densities: ozone

5. Microwave radiometry: passiveVertical profiles: stratospheric ozone, water vapour, ClO, HCN, HNO3,

N2O, etc.


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2. Remote sensing of the atmosphere: world-wide Network for the detection of Stratospheric Change

Measurements:

Ground-basedbut alsoBalloon-borneAirborneSatellite-borne


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2. Remote sensing of the atmosphere: ground-based used frequencies

ATMOSPHERIC OPACITY IN FREQUENCY RANGE 1-275 GHz

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1 26 51 76 101 126 151 176 201 226 251

Frequency (GHz)

Vertical opacity (dB)

Minor constituents

OxygenWater vapour tropical

Water vapour sub-arctic

Range 10 to 280 GHz

22 GHz H2O110 GHz O3

142 GHz O3

183 GHz H2O

200-210 GHz O3, ClO, HNO3, N2O, HO2

H218O, HO2

265-280 GHzO3, ClO, HCN, HNO3, N2O


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2. Remote sensing of the atmosphere: microwave radiometry

• Use of the heterodyne technique in millimeter and sub-millimeter wavelength ranges

• High spectral measurements of optically thin pure rotational lines of the atmospheric emission

• Very small sensitivity to aerosol scattering

• Observations made in emission permit day and night measurements

• Determination of the time evolution from the ground-based observations

• Determination of the spatial distribution from satellite measurements


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2. Remote sensing of the atmosphere: microwave radiometry

• Pressure broadening of rotational transitions permits the retrieval of the vertical distribution of species from the shape of the line.

1- The “Forward model” integrates spectroscopic parameters of the emission line, the radiative transfer in the atmosphere, and characteristics of the instrument.

This code computes the weighting functions for the atmospheric quantity to be estimated.

2- The “Inversion code” solves the inverse problem by using the Optimal Estimation Method described by Rodgers (1976, 1990, 2000).This linear least-squares method combines statistical a priori knowledge of the

searched parameters with the information given by measuremenst, using the associated errors as weights.

Two current models used in Europe:

1) The Microwave Observation Line Estimation and Retrieval, version 5: MOLIERE (v5)Urban et al., JQSRT, 2004

2) The Atmospheric Radiative Transfer Simulator (ARTS) by Bülher et al., JQSRT, 2005in the Qpack environment (Eriksson et al., JQSRT, 2005)


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3. Some ground-based microwave radiometersUniversity of BernMIAWARA: Middle Atmospheric Water Vapor Radiometer22 GHz, H20 line


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University Bordeaux 1/OASUFloirac => Pic du MidiOzone microwave radiometer110.836 GHz, O3 line


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University of BernGROMOS: Radiometer142 GHz, O3 line


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3. Some ground-based microwave radiometersUniversity of Bremen, University Bordeaux 1Danish Meteorology Institute, University of Leeds

Radiometer for Atmospheric Measurements At Summit: RAMAS

SIS junction, cooled to 4 K265 to 281 GHzO3, ClO, HCN, HNO3, N2O lines


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ATMOSPHERIC ABSORPTION IN FREQUENCY RANGE 275-1000 GHz

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

275 325 375 425 475 525 575 625 675 725 775 825 875 925 975Frequency (GHz)

Vertical opacity (dB)

Water vapour tropical

Water vapour sub-arctic

Oxygen

Minor constituents

Range 300 GHz to 2.5 THz

Some bands Some moleculesof interest observable in

these bands

315-327 GHz O3 , ClO, 335-349 GHz H2O, H2

18O, 487-495 GHz H2

17O, HDO,497-505 GHz H2O2, HO2 ,544-557 GHz HCN, HNO3, 566-580 GHz N2O, NO2,624-638 GHz CO, HCl,

650-652 GHz H2CO, HOCl,

... CH3Cl, SO2, ...

1 000 GHz

1.5 THz HBr

2.5 THz OH


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4. Satellite-borne microwave radiometersThe Upper Atmosphere Research Satellite (UARS)

launched in 1991.Microwave Limb Sounder (MLS)

63 GHz O2 lines for T and P profiles183 GHz O3, H2O205 GHz O3, ClO, HNO3, SO2


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The Odin satellite: Sweden-France-Finland-Canadalaunched in February 2001Sub-Millimeter Radiometer (SMR)

4 sub-millimeter receivers in 486 – 506 GHz O3, ClO, N2O, H2O, H2

18O, HDO, HNO3

541 – 560 GHz O3, HNO3, H2O, H218O, H2

17O, N2O546 – 564 GHz O3, H2O, H2O2, NO, H2

17O566 – 581 GHz O3, CO, HO2, N2O


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4. Satellite-borne microwave radiometersThe Microwave Limb Sounder (MLS) on Aura:

a NASA satellite launched on 15 July 2004

118 GHz primarily T and P profiles190 GHz primarily H2O & HNO3

240 GHz primarily O3 and CO640 GHz primarily HCl, ClO, BrO, HO2, N2O2.5 THz primarily OH


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5. Some results of the Odin satellite measurementsThe Antarctic ozone hole evolution in September-October

2002


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6. Conclusions

Ground-based, airborne and satellite microwave measurementsof the middle atmosphere employ frequencies also used byastronomers in the millimeter and sub-millimeter wavelength ranges.

As technology progresses, the higher frequencies are used.

The range up to 275 GHz is already defined for protection.

The range 275-1000 GHz has to be defined for protection in the coming years for decisions to be taken at the World Radio Conferencein 2010.

The preparatory work is going to start now. Microwave aeronomers should be involved in such a task.

ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 1 Active protection of...

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