CMA Working Papers for CGMS-43 China Meteorological Administration National Satellite Meteorological Center Training Course on Satellite Meteorology 2012 ）Oct.22-Nov.2 Beijing China

CMA’s Concern for New Allocation of Band 13.25-13.75GHz to FSS CGMS-43, CMA-WP-04 Prepared by CMA Agenda Item: I/3 Discussed in WGI

Motivation The frequency band 13.25-13.75 GHz is important for the earth remote sensing of spaceborne active sensors. There are three kinds of space-borne instruments operating in this band: a) Altimeters, such as SSALT onboard JASON series, HY-2 and SRAL onboard Sentinel-3 satellites; b) Scatterometers, such as HY-2 , SeaWinds on ADEOS-II and QuickScat; c)Precipitation radars, such as DPR on the GPM satellite.

CMA planning on active sensor using 13.25-13.75 GHz A scatterometer —WindRadar on FY-3E meteorological satellite; A precipitation measuring Radar on Fengyun Rain Measurement (FY-RM, 2020) satellite. These two radars each have one channel operating in the band 13.25-13.75GHz.

Interference scenario 120 FSS satellites are assumed at 3° spacing in GSO.

As shown in Figure 4, the 120 FSS satellites cause 48 As shown in Figure 4, the 120 FSS satellites cause 48.66% of data loss for the PR interference criterion, which is much larger than the 0.2% of permissible data loss. In another word, the 120 FSS satellites create an interference level of –135.1dBW/MHz for 0.2% of the time in PR, therefore exceeding the protection criterion of –147.8 dBW/MHz with a margin of about –13dB.

As shown in Figure, the 120 FSS earth stations create an interference level of –131.3 dBW for 0.2% of the time in PMR2, therefore exceeding the protection criterion of –141.3 dBW with a margin of –10 dB.

CMA analyzed the compatibility between FSS with(both directions) and PMR2 in detail. Just as the result shows, FSS services would cause harmful interference in PMR2 in uplink and downlink respectively, and PMR2 would also create harmful interference in FSS earth stations. CMA also noted that there are many insufficient places in the current sharing studies between FSS and space borne radars in WP 4A. CMA thought that some improper conclusion was drawn in WP 4A. For example, there is no any dynamic analysis of the interference from FSS downlink to space-borne radars in current studies. The only one analysis of interference from space- borne radars to FSS earth stations in current studies shows that space-borne radars should not affect the quality of the FSS. This analysis adopted 100% interfering time of any month as the protection criterion of FSS ES, but the time flying over one FSS ES by one space-borne radar is very limited because of its orbit character of the Non-GSO satellites.

Recommendation CMA expressed concern for the undue constraints on future EESS (active) systems imposed by a new FSS (space-to-Earth) allocation, that would incur unacceptable measurement degradation if such allocation is made by WRC-15, Considering the current status of WP 4A sharing studies between FSS and space-borne active sensors, and in view of the importance of band 13.25-13.75 GHz to the existing and future EESS systems, particularly to the space-borne active sensors, CMA invites CGMS members to give attention to the conclusion and concern expressed in CMA study over the issue. Annex_1: “Compatibility Assessment between EESS and Potential New FSS Allocation in the 13.25-13.75GHz Band for WRC-15 Agenda Item 1.6”, CGMS43-CMA-WP04-Annex_1 Annex_2: “Typical technical and operational characteristics of Earth exploration-satellite service (active) systems using allocations between 432 MHz and 238 GHz”, CGMS43-CMAWP04-Annex_2

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