1. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 1 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 Bordeaux Université Bordeaux 1, Observatoire Aquitain Sciences de l’Univers, Floirac, France

2. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 2 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

3. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 3 1. General introduction: the middle atmosphere

4. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 4 1. General introduction: composition of the atmosphere Ozone (O 3 ) 0,001020 min. 10 20 10 6 yr 3 yr 5-10 yr Lifetime

5. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 5 1. General introduction: role of stratospheric ozone Stratospheric 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 Earth If not: Average temperature at the Earth surface ≈ - 18°C

6. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 6 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: passiveColumn densities: ozone, NO 2, OClO 4.Ozone sondes: passiveVertical profiles: ozone 5.Dobson and Brewer spectrophotometers: passiveColumn densities: ozone 5.Microwave radiometry: passive Vertical profiles: stratospheric ozone, water vapour, ClO, HCN, HNO 3, N 2 O, etc.

7. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 7 2. Remote sensing of the atmosphere: world-wide Network for the detection of Stratospheric Change Measurements: Ground-based but also Balloon-borne Airborne Satellite-borne

8. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 8 2. Remote sensing of the atmosphere: ground-based used frequencies Range 10 to 280 GHz 22 GHzH 2 O 110 GHzO 3 142 GHzO 3 183 GHzH 2 O 200-210 GHz O 3, ClO, HNO 3, N 2 O, HO 2 H 2 18 O, HO 2 265-280 GHz O 3, ClO, HCN, HNO 3, N 2 O

9. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 9 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

10. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 10 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, 2005 in the Qpack environment (Eriksson et al., JQSRT, 2005)

11. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 11 3. Some ground-based microwave radiometers University of Bern MIAWARA: Middle Atmospheric Water Vapor Radiometer 22 GHz, H 2 0 line

12. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 12 3. Some ground-based microwave radiometers University Bordeaux 1/OASU Floirac => Pic du Midi Ozone microwave radiometer 110.836 GHz, O 3 line

13. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 13 3. Some ground-based microwave radiometers University of Bern GROMOS: Radiometer 142 GHz, O 3 line

14. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 14 3. Some ground-based microwave radiometers University of Bremen, University Bordeaux 1 Danish Meteorology Institute, University of Leeds Radiometer for Atmospheric Measurements At Summit: RAMAS SIS junction, cooled to 4 K 265 to 281 GHz O 3, ClO, HCN, HNO 3, N 2 O lines

15. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 15 4. Satellite-borne microwave radiometers Range 300 GHz to 2.5 THz Some bandsSome molecules of interestobservable in these bands 315-327 GHzO 3, ClO, 335-349 GHzH 2 O, H 2 18 O, 487-495 GHzH 2 17 O, HDO, 497-505 GHzH 2 O 2, HO 2, 544-557 GHzHCN, HNO 3, 566-580 GHz N 2 O, NO 2, 624-638 GHzCO, HCl, 650-652 GHzH 2 CO, HOCl,...CH 3 Cl, SO 2,... 1 000 GHz 1.5 THzHBr 2.5 THzOH

16. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 16 4. Satellite-borne microwave radiometers The Upper Atmosphere Research Satellite (UARS) launched in 1991. Microwave Limb Sounder (MLS) 63 GHz O 2 lines for T and P profiles 183 GHz O 3, H 2 O 205 GHz O 3, ClO, HNO 3, SO 2

17. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 17 4. Satellite-borne microwave radiometers The Odin satellite: Sweden-France-Finland-Canada launched in February 2001 Sub-Millimeter Radiometer (SMR) 4 sub-millimeter receivers in 486 – 506 GHz O 3, ClO, N 2 O, H 2 O, H 2 18 O, HDO, HNO 3 541 – 560 GHz O 3, HNO 3, H 2 O, H 2 18 O, H 2 17 O, N 2 O 546 – 564 GHz O 3, H 2 O, H 2 O 2, NO, H 2 17 O 566 – 581 GHz O 3, CO, HO 2, N 2 O

18. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 18 4. Satellite-borne microwave radiometers The Microwave Limb Sounder (MLS) on Aura: a NASA satellite launched on 15 July 2004 118 GHz primarily T and P profiles 190 GHz primarily H 2 O & HNO 3 240 GHz primarily O 3 and CO 640 GHz primarily HCl, ClO, BrO, HO 2, N 2 O 2.5 THz primarily OH

19. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 19 5. Some results of the Odin satellite measurements The Antarctic ozone hole evolution in September-October 2002

20. ESF-sponsored Workshop, Cagliari, Sardinia, Italia, 28-29 October 2004 20 6. Conclusions Ground-based, airborne and satellite microwave measurements of the middle atmosphere employ frequencies also used by astronomers 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 Conference in 2010. The preparatory work is going to start now. Microwave aeronomers should be involved in such a task.