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StevenFrost / AviationWeather

A C++ library for formatting and parsing various meteorology-related data structures
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Report modifier #37

Open ollyau opened 9 years ago

ollyau commented 9 years ago

From AC 00-45G page 3-6:

3.1.3.4 Report Modifier (As Required) METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT +TSRA BR OVC010CB 18/16 A2992 RMK AO2 TSB25 TS OHD MOV E SLP132 The report modifier, AUTO, identifies the METAR/SPECI as a fully automated report with no human intervention or oversight. In the event of a corrected METAR or SPECI, the report modifier, COR, is substituted for AUTO.

This suggests that the report modifier is optional and METARs lacking report modifiers have been reviewed by people (and that METARs reviewed by people and were found to be wrong, then corrected get COR). The current code defaults to modifier_type::automatic, which seems to conflict with what AC 00-45G implies for METARs without report modifers.

Can we add a new modifier_type (maybe modifier_type::reviewed or modifier_type::none?) and make that the default?

ollyau commented 8 years ago

Was reviewing AC 00-45G as well as the AIM while adding additional integration tests and it appears my previous conclusion was incorrect:

AIM 7−1−31. International Civil Aviation Organization (ICAO) Weather Formats (page 7−1−63) notes the following:

4. Modifier (As Required). “AUTO” identifies a METAR/SPECI report as an automated weather report with no human intervention. If “AUTO” is shown in the body of the report, the type of sensor equipment used at the station will be encoded in the remarks section of the report. The absence of “AUTO” indicates that a report was made manually by an observer or that an automated report had human augmentation/backup. The modifier “COR” indicates a corrected report that is sent out to replace an earlier report with an error.

NOTE− There are two types of automated stations, AO1 for automated weather reporting stations without a precipitation discriminator, and AO2 for automated stations with a precipitation discriminator. (A precipitation discriminator can determine the difference between liquid and frozen/freezing precipitation). This information appears in the remarks section of an automated report.

AC 00-45G 3.1.4 METAR/SPECI Examples (Page 3-29) also denotes report modifier omitted as "Either a manual or an augmented observation".

Although the modifier_type::none is applicable, the comment next to the enum entry is incorrect.