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BL Choy edited this page Jul 21, 2021 · 1 revision

--- Draft (First prepared on 20 Apr 2020. Updated on 21 Apr 2020). To be reviewed by WG-MIE and TT-AvXML members ---

Proposed changes to the Space Weather Advisory (Received on 18 Apr 2020)

The changes are proposed by the Space Weather Work Stream of the ICAO METP WG-MISD. This analysis aims at ascertaining what impact the changes may have on the XML schema and any other information exchange processes.

Comparison

Comparison is made against IWXXM version 3.0.0. Attention should be drawn to the "no change to IWXXM 3.0.0" conclusion with regard to changes to the Space Weather Advisory mentioned in Amendment 79 to ICAO Annex 3.

Details of the proposed changes

Proposal

Table A2-3. Template for advisory message for space weather information Table A2-3 (continued) Table A2-3 (continued) Examples A2-3 and A2-4 Example A2-5

Analysis

  • Name of SWXC: Correction of typo in the template. No change is required.
  • Space weather effect: As intensity is no longer mentioned, the code list iwxxm:SpaceWeatherPhenomena which describes both the effect and intensity shall be changed. No change is required for the schema.
  • Number(s) of advisory being replaced: As the number of advisory being replaced will be changed from one to one or more, the multiplicity of iwxxm:replacedAdvisoryNumber shall be changed from [0..1] to [0..*].
  • Intensity and extent of the observed for forecast effect of the space weather phenomena: Introduction of intensity will require the creation of a new code list. A new feature will be required to hold intensity and iwxxm:region together as a group and under iwxxm:SpaceWeatherAnalysis. The change of nomenclature DAYLIGHT SIDE to DAY SIDE requires a change of the corresponding item in code list iwxxm:SpaceWeatherLocation. Other changes have no effect on the schema.
  • Forecast of the phenomena (+6HR, +12HR, +18HR and +24HR): Changes to the schemas mentioned in "Intensity and extent of the observed for forecast effect of the space weather phenomena" above should already cover the needs for these entities.
  • Remarks: No change is required.

Other findings

  • Note 6: Mentioned A straight line between two points drawn on a map in the Mercator projection or a straight line between two points which crosses lines of longitude at a constant angle. This is different from the consensus arrived as mentioned in Section 2.9 of the WG-MIE/6 report. There are open discussions on this topic too.

Conclusion

  • Minor and backward incompatible changes are expected for the proposed changes to the Space Weather Advisory
  • In the advisory straight lines on Mercator projection are to be used to connect two points which is different from the consensus arrived at WG-MIE/6. As both are expected to be submitted for METP/5's consideration a resolution before submission may be necessary.

Coding challenge

As suggested by Larry Burch more details of the anticipated changes in an instance is included for comments. In the following section of the advisory:

OBS SWX: 08/0700Z SEV HNH HSH DAY SIDE / MOD HNH HSH NIGHT SIDE

Meaning: On the 8th day of the month at 0700Z severe intensity across the day light side of both northern and southern high latitude bands, in addition to, moderate intensity across the night side of both northern and southern high latitude bands.

Below is the corresponding fragment of the XML instance:

<iwxxm:SpaceWeatherAnalysis gml:id="..." timeIndicator="OBSERVATION">
    <iwxxm:phenomenonTime>
        <gml:TimeInstant gml:id="...">
            <gml:timePosition>2016-11-08T07:00:00Z</gml:timePosition>
        </gml:TimeInstant>
    </iwxxm:phenomenonTime>
    <iwxxm:newElementToBeAdded>
        <iwxxm:newCodeListToBeAdded xlink:href="http://codes.wmo.int/49-2/SpaceWxIntensity/SEV"/>
        <iwxxm:region>
            <iwxxm:SpaceWeatherRegion gml:id="...">
                <iwxxm:location>
                    <aixm:AirspaceVolume gml:id="...">
                       ...HNH...
                       ...HSH...
                    </aixm:AirspaceVolume>
                </iwxxm:location>
                <iwxxm:locationIndicator xlink:href="http://codes.wmo.int/49-2/SpaceWxLocation/DAY_SIDE"/>
            </iwxxm:SpaceWeatherRegion>
        </iwxxm:region>
    </iwxxm:newElementToBeAdded>
    <iwxxm:newElementToBeAdded>
        <iwxxm:newCodeListToBeAdded xlink:href="http://codes.wmo.int/49-2/SpaceWxIntensity/MOD"/>
        <iwxxm:region>
            <iwxxm:SpaceWeatherRegion gml:id="...">
                <iwxxm:location>
                    <aixm:AirspaceVolume gml:id="...">
                       ...HNH...
                       ...HSH...
                    </aixm:AirspaceVolume>
                </iwxxm:location>
                <iwxxm:locationIndicator xlink:href="http://codes.wmo.int/49-2/SpaceWxLocation/NIGHT_SIDE"/>
            </iwxxm:SpaceWeatherRegion>
        </iwxxm:region>
    </iwxxm:newElementToBeAdded>
</iwxxm:SpaceWeatherAnalysis>

Here the parallel listing of the new "intensity + location" blocks has the intrinsic meaning of "union"; that is all of the described "intensity + location" blocks are happening at the same time at 08/0700Z.

Larry further mentioned that both SEV HNH HSH DAY SIDE MOD HNH HSH NIGHT SIDE and SEV HNH HSH DAY SIDE HNH HSH NIGHT SIDE may happen. This means that both iwxxm:newElementToBeAdded and iwxxm:region shall have a multiplicity of [1..*]. Having said that from data model perspective whether it is more effective to represent SEV HNH HSH DAY SIDE HNH HSH NIGHT SIDE as SEV HNH HSH DAY SIDE SEV HNH HSH NIGHT SIDE can be further discussed.

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