workshop on radio frequencies for meteorology march 20/21, 2006, geneva

WMO SG RFC: Radio Frequencies for Meteorology: Ground-based passive sensors

Hans Richner, IACETH, March 20/21, 2006, Geneva

Workshop on Radio Frequencies for MeteorologyWorkshop on Radio Frequencies for MeteorologyMarch 20/21, 2006, GenevaMarch 20/21, 2006, Geneva

Hans Richner, IACHans Richner, IACETHETH, Zurich, Zurich

WMOWMOWorld Weather WatchWorld Weather Watch

Commission on Basic SystemsCommission on Basic SystemsSteering Group Radiofrequency CoordinationSteering Group Radiofrequency Coordination

Ground-based passive sensorsGround-based passive sensors



Sources and Acknowledgments:

This presentation is primarily based in information which is freely available on the internet.

Some of the figures were presented at the Workshop "Active Protection of Passive Radio Services: towards a concerted strategy." Contributors were:

Ambrosini, Roberto IRABaan, Willem AstronCohen, Jim Jodrell Bankde La Noe, Jerome Obs. de BordeauxDeschamps, Andre Obs. de ParisFeist, Dietrich Univ. BerneFejes, Istvan FOMILazareff, Bernard IRAMMarelli, Edoardo ESAMartinelli, Massimo ESFMeens, Vincent CNESMillenaar, Rob AstronMureddu, Leonardo INAF OAC

Otter, Manfred ESAPorceddu, Ignazio INAF OACRichner, Hans WMORochard, Guy † Meteo FranceRommen, Bjorn ESARuf, Klaus DLRSpoelstra, Titus Astron/CRAFStruzak, Ryszard formerly ITU RRBUrban, Joachim Chalmers Univ.van Driel, Wim IUCAFvonDeak, Tom NASAWheeler, Bill UK Met OfficeWolf, Robert EUMETSAT

The Workshop was organized by the European Science Foundation.



1. principle of molecular spectrum

2. interference mechanisms

3. future threats

4. what should be done

Overview



principle of molecular spectra



O3,CH3Cl, HOCl, ClO, HNO3, N2O, H2O2, HCN, BrO, SO2, ...



Institute for Applied Physics, University of Bern (IAP)

ASMUWARA, the All-Sky MUlti WAvelength RAdiometer



Frequency bands and bandwidths used for passive sensing (1)

Frequency BW(GHz) (MHz) main measurements

1.4 - 1.427 100 soil moisture, salinity, ocean surface temperature, vegetation index

2.69 - 2.70 60 salinity, soil moisture4.2 - 4.4 200 ocean surface temperature6.7 - 7.1 400 ocean surface temperature (no allocation)

10.6 - 10.7 100 rain, snow, ice, sea state, ocean wind, ocean surface temperature, soil moisture

15.35 - 15.40 200 water vapour, rain18.6 - 18.8 200 rain, sea state, ocean ice, water vapour, snow 21.2 - 21.4 200 water vapour, cloud liquid water

22.21 - 22.50 300 water vapour, cloud liquid water23.6 - 24.0 400 water vapour, cloud liquid water31.3 - 31.8 500 window channel associated to temperature

measurements36 - 37 1000 rain, snow, ocean ice, water vapour,

cloud liquid water, ocean wind, soil moisture



Frequency bands and bandwidths used for passive sensing (2)Frequency BW

(GHz) (MHz) main measurements50.2 - 50.4 200 O2 (temperature profiling)52.6 - 59.3 6700 O2 (temperature profiling)

86 - 92 6000 Clouds, ice, snow, rain100 - 102 2000 N2O

109.5 - 111.8 2300 O3114.25 - 122.25 8000 O2 (temperature profiling), CO148.5 - 151.5 3000 window channel155.5 - 158.5 3000 window channel (to be terminated on 1 January 2018)

164 - 167 3000 window channel174.8 - 191.8 17000 H2O (moisture profiling), N2O, O3

200 - 209 9000 H2O, O3, N2O226 - 232 6000 clouds, CO235 - 238 3000 O3250 – 252 2000 N2O275 – 277 2000 N2O



Frequency bands and bandwidths used for passive sensing (3)Frequency BW

(GHz) (MHz) Main measurements294 – 306 12000 N2O, O3, O2, HNO3, HOCl316 – 334 10000 water vapour profiling, O3, HOCl342 – 349 7000 CO, HNO3, CH3Cl, O3, O2, HOCl, H2O363 – 365 2000 O3371 – 389 18000 water vapour profiling416 – 434 18000 temperature profiling442 – 444 2000 water vapour486 – 506 9000 O3, CH3Cl, N2O, BrO, ClO546 – 568 22000 temperature profiling624 – 629 5000 BrO, O3, HCl, SO2, H2O2, HOCl, HNO3634 – 654 20000 CH3Cl, HOCl, ClO, H2O, N2O, BrO, O3, HO2, HNO3659 – 661 2000 BrO684 – 692 8000 ClO, CO, CH3Cl730 – 732 2000 O2, HNO3851 – 853 2000 NO951 – 956 5000 O2, NO, H2O



intermediate conclusion:

evidently, the electro-magnetic spectrum is a very precious natural

resource!!!it must be protected, on the other hand reasonable use has to accepted



oxygen lines around 60 GHz



Weighting function for MSU at nadir

• Weighting function has a peak at specific altitude

• Each channel had different sensitivity to altitudes

• by measuring at several channels within the steep slope of the O2 absorption spectrum

and correcting for several factors (for which information is obtainable in the 31 GHz and 24 GHz frequency bands), an accurate temperature profile of the atmosphere results



water vapor absorption around 24 GHz



Frequency hoppingthe basics of Ultras Wide Band (UWB) systems

frequency



principle of UWB (Ultra Wide Band) systems



Jodrell Bank UK

compared to radioastronomers, meteorologists are really modest:



Measurements in the 10.6 to

10.7 GHz band with the

Effelsberg 100 m radio

telescope

… but both have the same problems:

normal

with a UWB system active



• Site control

• Jodrell Bank Consultation Zone

• Protection of particular frequency bands to agreed distances e.g. TV channel 38, 606-614 MHz



Greenbank Radio-Quiet Zone

1956 West Virginia state law puts zoning restrictions on the use of electrical equipment within 10 miles of any radio astronomy facility.

1958 National Radio Quiet Zone established by FCC: 13,000 square miles of Virginia and West Virginia.

(The laws were set up before the radio telescopes were built and before any frequency bands were allocated to the RAS.)



Network for the detection of Stratospheric Change

Measurements:

ground-basedbut alsoballoon-borneairbornesatellite-borne



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

Range10 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



Some ground-based microwave radiometers

University of BernMIAWARA: Middle Atmospheric Water Vapor Radiometer22 GHz, H20 line



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




University of BernGROMOS: Radiometer142 GHz, O3 line




University of BremenUniv. BordeauxDanish Meteorology Institute, University of Leeds

Radiometer at Summit: RAMASSIS junction, cooled to 4 K

265 to 281 GHzO3, ClO, HCN, HNO3, N2O




Mitigation methods - howadaptive cancellation using reference antennas

F. Briggs



Resultsadaptive cancellation

• WSRT example, using neighboring telescopes as reference antennas– observation at 355 MHz– crosscorrelation RT 5 and 6



GALILEO30 satellites in3 orbits

GLONASS13 satellites in3 orbits



Picture from http://www.ee.surrey.ac.uk/Personal/L.Wood/constellations/teledesic.html

• LEO satellites promised better solution + services in polar regions

• Teledesic: 840 (1994)

or 288 (1997) active satellites – suspended Oct.

2002 and died

Low-Earth-Orbit Constellations



Stratospheric radio

• Radio station at stratospheric heights, or constellations of such stations

• HAPS = High-Altitude Platform Station • The concept similar to that of LEO satellites but reduced to

stratospheric heights

• Cheaper than terrestrial or satellite radio• Satisfy “business” needs (profit), military needs,• “humanitarian” needs (“digital gap”)



Helios

On June 26, 2003, the Helios aircraft was lost

in the Pacific Ocean (Hawaii) during tests of a

new fuel cell system for

overnight flight operations in the

stratosphere



Japan’s project

• Constellation (dozens) of stations

• Operational in 2008

• Long. 250.0 m weight 32.0 t payload 1.0 tpower 10.0 kW



“Stratospheric satellites” StratoSatTM

Model of Fully-Pressurized Balloons In Flight. Picture courtesy of NASA.

• Constellation of stratospheric balloons powered by solar array

• Could be steered/ directed to fly over specific areas

• Payloads up to 2 tons at ~35 km



StratoSatTM

• 400 stations/hemisphere

• Projected life: 3 to 10 years.

• Costs: 10 to 100 times less than present space satellite or aircraft communications platforms

according to http://www.gaerospace.com/ (06.2002)

– Infrastructure: < $ 160 million

– Operation: < $ 10 million per year

– Life-cycle cost < $ 400,000 per unit



Space Data

• “Swarm” - millions (?) of low-cost “weather-type” balloons moving freely with the wind

• Reusable payload • Built from “of-the-shelf” low-cost components



Footnote to Radio Regulations:

S5.340 All emissions are prohibited in the following bands:1 400 - 1 427 MHz2 690 - 2 700 MHz except those provided for by Nos. S5.421 an S5.42210.68 - 10.7 GHz except those provided for by No. S5.483 15.35 - 15.4 GHz except those provided for by No. S5.511 23.6 - 24 GHz31.3-31.5 GHz31.5-31.8 GHz in Region 248.94-49.04 GHz from airborne stations51.4-54.25 GHz58.2-59 GHz64-65 GHz86-92 GHz105-116 GHz140.69-140.98 GHz from airborne stations and from space stations in the

space-to-Earth direction182-185 GHz except those provided for by No. S5.563217-231 GHz.




S5.340 All emissions are prohibited in the following bands:1 400 - 1 427 MHz2 690 - 2 700 MHz except those provided for by Nos. S5.421 an S5.42210.68 - 10.7 GHz except those provided for by No. S5.483 15.35 - 15.4 GHz except those provided for by No. S5.511 23.6 - 24 GHz…..…..

particularly disturbing:

unwanted emissions: consist of spurious emissions and out-of-band emissions

we all know: there are unwanted emissions!



out-of-band emissions: Emissions on a frequency or frequencies immediately outside the necessary bandwidth which results from the modulation process, but excluding spurious emissions

spurious emissions: Emissions on a frequency or frequencies which are outside the necessary bandwidth and the level of which may be reduced without affecting the corresponding transmission of information. Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products and frequencies and frequency conversion products, but exclude out-of-band emissions.




S5.340 All emissions are prohibited in the following bands:1 400 - 1 427 MHz2 690 - 2 700 MHz except those provided for by Nos. S5.421 an S5.42210.68 - 10.7 GHz except those provided for by No. S5.483 15.35 - 15.4 GHz except those provided for by No. S5.511 23.6 - 24 GHz

intentional

particularly disturbing:



Re-radiation

• Terrestrial radiations reflected by the HAPS

• Threat of nullifying terrain shadowing and direction selectivity

• Not treated in the Radio Regulations

HAPS



absorption lines between 275 GHz and 1 THz -- tomorrows resources!?



Satellite versus conventional: NH height

Sat data largest

impact ~10 hr gain

Fore

cast

skill

Roger Saunders, SFCG24



Sat data largest

impact ~ 48 hr gain

Satellite versus conventional: SH heightFore

cast

skill

Roger Saunders, SFCG24



Conclusions and recommendations (1)

Radiofrequency issues for ground-based passive systems are basically the same as for other, say, space-based passive systems.

Potential interference of active systems depends much on the siting.

Topographic shielding might prove to be not effective due to re-radiation (reflection).

Air and/or space-borne emissions are generally more problematic for ground-based passive systems than terrestrial sources.

The biggest threat for any passive sensor are ultra wide band (UWB) systems; even if they do not cause direct interference, they increase the noise level.

The number of interference sources is ever increasing; ground-based, satellites, high altitude platforms.




To a limited extent, mitigation techniques will allow observations in contami-nated bands.

Mitigation is the second choice, primarily interference must be avoided.

The dialog with the telecommunication community must be improved.

Bands currently protected by Radio Regulations must not be used by UWB systems!

The scientific community should carefully select those bands which must be protected; it will not be possible to protect all bands.

The scientific community should take all steps necessary for keeping some frequency bands free on any intentional emission - including ultra wide band.




Protection requirements in the not yet regulated frequency bands (>275 GHz)should be formulated before this band is used by active systems.

The operators of ground-based passive systems are poorly organized.

The operators of ground-based systems should compile an inventory of their instruments.

All operators of passive systems should combine their protection efforts.

As technology progresses, higher frequencies are used.

In many countries, the cooperation between telecom administrations and the scientific and meteorological community should be intensified.


Hans Richner, IACETH, March 20/21, 2006, Geneva(thanks to Guy Rochard, † Dec 05)

Mr. Telecom

some unknown scientist



TThhe e EEnndd

workshop on radio frequencies for meteorology march 20/21, 2006, geneva

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