______
COMMISSION FOR BASIC SYSTEMS
STEERING GROUP ON RADIO FREQUENCY COORDINATION
GENEVA, 6-8 February 2002 / CBS/SG-RFC 2002/Doc. 4(3)
(31.I.2002)
______
ITEMS 4
ENGLISH only
Updated Preliminary Draft Revision to ITU-R Recommendation SA.1028
(Submitted By David Franc, National Weather Service
Prepared by John Zuzek, NASA and David McGinnis NESDIS)
Summary and Purpose of Document
This document is the U.S. proposal to Working Party 7C for revisions to ITU-R Recommendation SA. 1028.
Action Proposed
This document is for information to the SG-RFC.
United States
Updated Preliminary Draft Revision to ITU-R Recommendations SA.1028
Introduction
At the May 2001 meeting of Working Party 7C, several documents were considered in producing three Preliminary Draft Revised Recommendations of SA.515, 1028 and 1029. Although the revisions to SA.515 were largely accepted, the revisions to the radiometric sensitivities or DTe values were not in agreement with all of the input documents. Based on information collected by NOAA and NASA in the United States as well as inputs from other members of the user community, a new version of Preliminary Draft Revised Recommendation for SA.1028 has been produced.
The ANNEX to this document provides an updated version of the Preliminary Draft Revision to ITU-R Recommendation SA.1028 containing the radiometric sensitivity values agreed to by participants at the Space Frequency Coordination Group meeting in held in September 2001 in Cayenne, French Guiana, as well as several updated/corrected pieces of information that were used to further revise and correct the existing PDRR from the WP 7C Chairman’s Report.
Methodology
With respect to the scientific requirements, there are at least three types of radiometric measurements that can be linked to the characteristics of the emissions to be measured:
· The measurements performed integrating across relatively wide bandwidth channels, typical of the low frequency emissions often observed for meteorological or climatological applications;
· The atmospheric vertical sounding measurements for meteorological applications that are performed by measuring multiple channels inside the allocated bandwidth to characterize the curve of the emission and derive three-dimensional information including vertical distribution;
· The atmospheric limb sounding with radiometers to characterize weak emissions by atmospheric gases, which are generally above 100 GHz.
The technical feasibility in achieving the scientifically required sensitivity has to also be considered and is linked to the system noise temperature, the integration time, and the instrument bandwidth. That is, some sensitivities are not technically feasible given a certain integration time and instrument bandwidth unless the radiometer is cryogenically cooled. Finally, it is not wise to revise the Recommendations in such a way that may indicate that passive sensing user community wishes to revisit all previous sharing studies since that is not the case. There can be no retroactive effect from these revisions. Therefore, existing sharing conditions must be taken into account in revising the temperature sensitivities for each passive sensing band.
Based on these considerations, the following information is given for each allocation used for passive remote sensing in the Table: the allocations in GHz; the total bandwidth required in MHz; the required DTe in Kelvin; the minimum required data availability percentage; and, the sensor instrument’s scan mode (i.e., nadir or limb). It is important to note that the required sensor sensitivities and data availability percentages are given for both the scientific requirements and for the reality of the existing sharing situations, where applicable. This is to highlight the fact that the proposed changes to these recommendations will not be applied retroactively to situations where sharing has already been studied and various parameters for sharing have been agreed to and observed.
The Recommendation itself was updated to correct or clarify some information in the considerings. The existing three recommends were rewritten and recast into two recommends to improve the Recommendation and clarify the data availability criteria.
annex
Preliminary DRAFT REVISION oF RECOMMENDATION ITU-R SA.1028-1
PERFORMANCE CRITERIA FOR SATELLITE PASSIVE REMOTE SENSING
(Question ITU-R 140/7)
(1994-1997-2002)
Rec. ITU-R SA.1028-1
The ITU Radiocommunication Assembly,
considering
a) that certain frequency bands, including some absorption bands of atmospheric gases(e.g., O2 (oxygen) andH2O (water vapour)), have been allocated for spaceborne passive microwave remote sensing;
b) that some of these bands are also allocated to other radio services;
c) that performance criteria are a necessary prerequisite to the establishment of interference and sharing criteria;
d) that surface brightness temperature, the atmospheric temperature at points along a path, and absorption coefficients can be determined from measurements of the sensor antenna temperature, TA;
e) that the surface brightness temperature and the absorption coefficients, in turn, depend upon the physical properties of the surface or atmosphere that are to be sensed;
f) that studies have established measurement sensitivity requirements;
g) that studies have established that measurements in absorption bands are extremely vulnerable to interference because, in general, there is no possibility to detect and to reject data that are contaminated by interference, and because propagation of undetected contaminated data into numerical weather prediction (NWP) models may have a destructive impact on the reliability/quality of weather forecasting;
h) that passive microwave remote sensing is performed in absorption bands to obtain important three-dimensional atmospheric data that are used in particular to initialize NWP models;
j) that performance requirements for passive sensors can be stated in terms of measurement sensitivity, DTe, and availability, measured at the satellite, assuming that degradation from other elements in the system will be small;
k) that three-dimensional measurements of atmospheric temperature or gas concentration are performed in the absorption bands including those in the range 50.26159.3GHz and bands near 118GHz and183GHz,
recommends
1 that the measurement sensitivities suitable for passive remote sensing of the Earth’s land, oceans and atmosphere are as indicated in Table 1;
2 that in shared frequency bands used for passive remote sensing(except absorption bands), the required minimum availability of passive sensor data for each band as enumerated above shall be as specified in Table 1. exceed 95% from all locations in the sensor service area in the case where the loss occurs randomly, and shall exceed 99% from all locations in the case where the loss occurs systematically at the same locations;
3 that the availability of passive sensor data shall be 99.99% from all locations in the sensor service area for three-dimensional measurements of atmospheric temperature or gas concentration, as noted in §k).
TABLE 1
(GHz) / Necessary bandwidth
(MHz) / Measurements / Required DTe
(K)
Near 1.4 / 100 / Soil moisture, salinity, sea temperature, vegetation index / 0.1
Near 2.7 / 60 / Salinity, soil moisture / 0.1
Near 4 / 200 / Ocean surface temperature / 0.3
Near 6 / 400 / Ocean surface temperature / 0.3
Near 11 / 100 / Rain, snow, ice, sea state, ocean wind / 1.0
Near 15 / 200 / Water vapour, rain / 0.2
Near 18 / 200 / Rain, sea state, ocean ice, water vapour / 1.0
Near 21 / 200 / Water vapour, liquid water / 0.2
22.235 / 300 / Water vapour, liquid water / 0.4
Near 24 / 400 / Water vapour, liquid water / 0.2
Near 31 / 500 / Ocean ice, water vapour, oil spills, clouds, liquid water / 0.2
Near 37 / 1000 / Rain, snow, ocean ice, water vapour / 1.0
50.2-50.4 / 200 / Temperature profiling / 0.3/0.1(1)
52.6-59.0 / 6400(2) / Temperature profiling / 0.3/0.1(1)
60.3-61.3 / 1000(2) / Temperature profiling (upper atmosphere) / 0.3/0.1(1)
Near 90 / 6000 / Clouds, oil spills, ice, snow / 1.0
100.49 / 2000 / Nitrous oxide / 0.2
110.80 / 2000 / Ozone / 0.2
115-122 / 7000(2) / Temperature, carbon monoxide / 0.2
125.61 / 2000 / Nitrous oxide / 0.2
150.74 / 2000 / Nitrous oxide / 0.2
155.5-158.5 / 3000 / Earth and cloud parameters / 0.2
164-168 / 4000 / Cloud water and ice, rain / 0.2
167.20 / 2000 / Chlorine oxide / 0.2
175-192 / 17000(2) / Water vapour, nitrous oxide, ozone / 0.2
200.98 / 2000 / Nitrous oxide / 0.2
217-231 / 2000 / Clouds, humidity, nitrous oxide / 0.2
230.54 / 2000 / Carbon monoxide / 0.2
235.71 / 2000 / Ozone / 0.2
237.15 / 2000 / Ozone / 0.2
251.21 / 2000 / Nitrous oxide / 0.2
276.33 / 2000 / Nitrous oxide / 0.2
301.44 / 2000 / Nitrous oxide / 0.2
325.10 / 2000 / Water vapor / 0.2
345.80 / 2000 / Carbon monoxide / 0.2
364.32 / 2000 / Ozone / 0.2
380.20 / 2000 / Water vapour / 0.2
(1) Second number for pushbroom sensors.
(2) This bandwidth is occupied by multiple channels.
TABLE 1
Performance Criteria for Passive Remote Sensing of Environmental Data
Frequency Band(s)(1) (GHz) / Total BW required (MHz) / Required DTe (K) / Data availability (%) / ScanMode (N, L)(4) /
1.37-1.4s,
1.4-1.427P / 100 / 0.05 / 99.9 / N
2.64-2.655s,
2.655-2.69s,
2.69-2.7P / 45 / 0.1 / 99.9 / N
4.2-4.4s,
4.950-4.990s / 200 / 0.3/0.05(6) / 99.9 / N
6.425-7.25 / 200 / 0.3/0.05(6) / 99.9 / N
10.6-10.68p,
10.68-10.7P / 100 / 1.0/0.1(6) / 99.9 / N
15.2-15.35s,
15.35-15.4P / 200 / 0.1 / 99.9 / N
18.6-18.8p / 200 / 1.0/0.1(6) / 95/99.9(6) / N
21.2-21.4p / 200 / 0.2/0.05(6) / 99/99.9(6) / N
22.21-22.5p / 300 / 0.4/0.05(6) / 99/99.9(6) / N
23.6-24.0P / 400 / 0.05 / 99.99 / N
31.3-31.5P,
31.5-31.8p / 500 / 0.2/0.05(6) / 99.99 / N
36.0-37.0p / 1000 / 1.0/0.1(6) / 99.9 / N
50.2-50.4P / 200 / 0.05 / 99.99 / N
52.6-54.25P,
54.25-59.3p / 6700(2) / 0.3/0.05(6) / 99.99 / N
86.0-92.0P / 6000 / 0.05 / 99.99 / N
100.0-102.0P / 2000 / 0.005 / 99 / L
109.5-111.8P / 2000 / 0.005 / 99 / L
114.25-116.0P / 1750 / 0.005 / 99 / L
115.25-116.0P,
116.0-122.25p / 7 000 (2) / 0.05/0.005(5) / 99.99/99(5) / N, L
148.5-151.5P / 3000 / 0.1/0.005(5) / 99.99/99(5) / N, L
155.5-158.5(3)p / 3000 / 0.1 / 99.99 / N
164.0-167.0P / 3000(2) / 0.1/0.005(5) / 99.99/99(5) / N, L
174.8-182.0p, 182.0-185.0P, 185.0-190.0p, 190.0-191.8P / 17000(2) / 0.1/0.005(5) / 99.99/99(5) / N, L
200.0-209.0P / 9000(2) / 0.005 / 99 / L
226.0-231.5P / 5500 / 0.2/0.005(5) / 99.99/99(5) / N, L
235.0-238.0p / 3000 / 0.005 / 99 / L
250.0-252.0P / 2000 / 0.005 / 99 / L
275.0-277.0 / 2000(2) / 0.005 / 99 / L
294.0-306.0 / 12000(2) / 0.2/0.005(5) / 99.99/99(5) / N, L
316.0-334.0 / 18000(2) / 0.3/0.005(5) / 99.99/99(5) / N, L
342.0-349.0 / 7000(2) / 0.3/0.005(5) / 99.99/99(5) / N, L
363.0-365.0 / 2000 / 0.005 / 99 / L
371.0-389.0 / 18000(2) / 0.3 / 99.99 / N
416.0-434.0 / 18000(2) / 0.4 / 99.99 / N
442.0-444.0 / 2000(2) / 0.4/0.005(5) / 99.99/99(5) / N, L
496.0-506.0 / 10000(2) / 0.5/0.005(5) / 99.99/99(5) / N, L
546.0-568.0 / 22000(2) / 0.5/0.005(5) / 99.99/99(5) / N, L
624.0-629.0 / 5000(2) / 0.005 / 99 / L
634.0-654.0 / 20000(2) / 0.5/0.005(5) / 99.99/99(5) / N, L
659.0-661.0 / 2000 / 0.005 / 99 / L
684.0-692.0 / 8000(2) / 0.005 / 99 / L
730.0-732.0 / 2000(2) / 0.005 / 99 / L
851.0-853.0 / 2000 / 0.005 / 99 / L
951.0-956.0 / 5000(2) / 0.005 / 99 / L
NOTES:
(1) P = Primary Allocation, shared only with passive services (S5.340); p = primary allocation, shared with active services; s = secondary allocation.
(2) This bandwidth is occupied by multiple channels.
(3) This band is needed until 2018 to accommodate existing and planned sensors.
(4) N = Nadir, Nadir scan modes concentrate on sounding or viewing the Earth's surface at angles of nearly perpendicular incidence. The scan terminates at the surface or at various levels in the atmosphere according to the weighting functions. L = Limb, Limb scan modes view the atmosphere "on edge" and terminate in space rather than at the surface, and accordingly are weighted zero at the surface and maximum at the tangent point height.
(5) Second number for microwave limb sounding applications
(6) First number for current sharing conditions; second number for scientific requirement
8