28-29 October 2004 ESF Workshop, Cagliari 1

Future Programmes on Earth Observation

World Radiocommunication Conference 2007 Agenda Item 1.20 on unwanted emissions

- protection of the EESS (passive) -

Björn Rommen

28-29 October 2004 ESF Workshop, Cagliari 2

Future Programmes on Earth Observation

* Introduction ** The use of the EESS (passive) ** Scope of agenda item 1.20 *

* Regulatory measures ** Summary *

Content

28-29 October 2004 ESF Workshop, Cagliari 3

Future Programmes on Earth Observation

Within WRC-07 Agenda Item 1.20 covered by Resolution 738, a total of five EESS (passive) bands (5.340) need to be addressed, i.e.

}•         1400 – 1427 MHz

•         23.6 – 24.0 GHz•         31.3 – 31.5 GHz•         50.2 – 50.4 GHz •         52.6 – 54.25 GHz

Operational radiometerssuch as AMSU-A, SSM/I, CMIS

Pre-operational:SMOS, HYDROS, AQUARIUS

Introduction

“to consider the results of studies, and proposals for regulatory measures, if appropriate, regarding the protection of the Earth exploration-satellite service (passive) from unwanted emissions of active services in accordance with Resolution 738 (WRC 03)”

28-29 October 2004 ESF Workshop, Cagliari 4

Future Programmes on Earth Observation

Use of EESS (passive)• important tool widely used for meteorological, climatological, and environmental monitoring and survey (operational and scientific applications) • frequency and the strength of natural emissions characterize the type and the status of a number of important geophysical atmospheric and surface parameters (land, sea, and ice caps), which describe the status of the Earth/atmosphere/oceans system, and its mechanisms:

     Earth surface parameters such as soil moisture, sea surface temperature, ocean wind stress, ice extension and age, snow cover, rainfall over land, etc; Three-dimensional atmospheric parameters such as

temperature profiles, humidity profiles, total water vapour content and concentration profiles of radiatively and chemically important trace gases (for instance ozone and chlorine monoxide)

• all-weather capability 60% of the Earth is overcast with clouds

28-29 October 2004 ESF Workshop, Cagliari 5

Future Programmes on Earth Observation

1400 – 1427 MHzESA’s SMOS mission (launch 2007) Soil Moisture and Ocean Salinity

new measuring technique: SMOS will carry the first-ever polar-orbiting satellite-borne 2-D interferometric radiometer

Pre-operational: feasibility of measuring soil moisture (key variable in the hydrologic cycle) and ocean salinity (thermohaline circulation, variations in salinity influence the near surface dynamics of tropical oceans)

Protection of this passive band is essential: no capability to measure soil moisture and sea surface salinity directly on a global basis

Airborne campaigns in Europe and US have already identified occasional strong levels of unwanted emissions in this band

28-29 October 2004 ESF Workshop, Cagliari 6

Future Programmes on Earth Observation

23.6 – 24.0 GHz• covers the flank of the water vapour spectral line (located at 22.235 GHz)

• measurements made at 24 GHz directly lead to the total column water vapour content in the atmosphere

• potential loss of these data that are assimilated in Numerical Weather Prediction (NWP) models will severely affect the quality of weather forecasting

• also used for correcting temperature measurements (made between 50-60 GHz) for attenuation due to water vapour:

Without correct measurements at 24 GHz, temperature measurements at 50- 60 GHz cannot be corrected for attenuation due to water vapour

content in the atmosphere and thus have severely increased errors that feed back in the NWP models and potentially result in wrong interpretation and in degraded weather forecasts

28-29 October 2004 ESF Workshop, Cagliari 7

Future Programmes on Earth Observation

31.3 – 31.5 GHz• above 26 GHz the opacity of the atmosphere due to water vapour declines to a minimum close to 30 GHz, before slowly rising again

• sensitivity to cloud liquid water continues to rise such that at 30 GHz sensitivity to cloud is greater than sensitivity to water vapour

• this channel is therefore used as a window channel to correct at other frequencies for cloud liquid water as well as surface contributions

• also used for carrying out polarimetric sea surface observations to derive wind speed and direction:

these wind observations are extremely vulnerable to contamination due to their very low signal intensity

28-29 October 2004 ESF Workshop, Cagliari 8

Future Programmes on Earth Observation

50.2 – 50.4 & 52.6 – 54.25 GHz• used for temperature profile observation using the O2 absorption spectrum

in the vicinity of 60 GHz: volume-mixing ratio of oxygen in the atmosphere up to approximately 90 km stays constant while the atmosphere pressure becomes larger towards the Earth surface according to a known exponential law by making use of these two effects, the atmospheric temperature can be calculated

• proven very large positive impact on NWP equating to 1-2 days in forecast period

• channels further away from the oxygen absorption spectrum (e.g. 52.6 – 54.25 GHz) are sensitive to lower altitudes than those channels closer to 60 GHz

28-29 October 2004 ESF Workshop, Cagliari 9

Future Programmes on Earth Observation

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 flank 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

28-29 October 2004 ESF Workshop, Cagliari 10

Future Programmes on Earth Observation

Compatibility analyses/ Resolution 738 (1)EESS (passive) band Active service band Active service

1 400-1 427 MHz 1 350-1 400 MHz Fixed service (FS)Mobile service (MS)

Radiolocation

1 400-1 427 MHz 1 427-1 429 MHz FS, MS and space operation service (Earth-to-space)

1 400-1 427 MHz 1 429-1 452 MHz FS and MS

23.6-24 GHz 22.55-23.55 GHz Inter-satellite service

31.3-31.5 GHz 30-31 GHz FSS (Earth-to-space)

50.2-50.4 GHz 50.4-51.4 GHz FSS (Earth-to-space)

50.2-50.4 GHz 47.2-50.2 GHz (Region 2+3)49.44-50.2 GHz (Region 1)

FSS

28-29 October 2004 ESF Workshop, Cagliari 11

Future Programmes on Earth Observation

f) that according to Recommendation ITU‑R SM.1633, the EESS (passive) in the band 31.3-31.5 GHz can be protected if the unwanted emissions of fixed-service systems (except high-altitude platform stations (HAPS)) operating in the band 31.0-31.3 GHz do not exceed –38 dBW in a 100 MHz reference bandwidth in the band 31.3-31.5 GHz;g) that according to Recommendation ITU‑R SM.1633, the EESS (passive) in the band 52.6-54.25 GHz can be protected if the unwanted emissions of fixed-service systems operating in the band 51.4-52.6 GHz do not exceed –33 dBW in a 100 MHz reference bandwidth in the band 52.6-54.25 GHz;

2 to invite ITU‑R to further study the impact of implementing the values provided in considering f) and g) for unwanted emissions of fixed-service systems operating in Regions 2 and 3, taking into account that the impact on fixed-service systems in Region 1 has already been investigated;

considering f + g:

resolves 2:

Compatibility analyses/ Resolution 738 (2)

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Future Programmes on Earth Observation

Regulatory measures

• to be based on numerical limits on unwanted emissions: limits need to be technology-neutral

• on the long-term benificial for both active and passive systems: better use of the spectrum

• to be applied to systems deployed after a certain date in the future so as to enable a smooth transition of systems to the changed regulatory environment (e.g. beyond 2010)

• worldwide applicability so as to avoid different regional regulations that could lead to:

unfair competition between different operators or manufacturers interference to EESS (passive) in some parts of the world

28-29 October 2004 ESF Workshop, Cagliari 13

Future Programmes on Earth Observation

Summary •4 out of 5 bands are used for operational meteorology and are channels on a single radiometer instrument:

signal strength on a given frequency may depend on several variables, making the use of several frequencies at the same time necessary to match the multiple unknowns

interference in one of these bands will lead to misinterpretation or deletion of data

• unique global coverage needed for climatology and NWP

• regulations needed to ensure these products in the future worldwide applicability