TOYODA Eizi's blog: [WMO Codes - DRC #280] Clarification of upper-air wind reporting nearby the Poles (B/C 20, 25 and 26)

2015-11-30

[WMO Codes - DRC #280] Clarification of upper-air wind reporting nearby the Poles (B/C 20, 25 and 26)

Issue #280 has been updated by Jitsuko Hasegawa.

Final Report of IPET-DRMM-III 2015 Beijing says:

Some stations, such as drifting ice stations by Russian Federation and an upper-air station by USA, have been operated at the North or South Pole, where wind direction is reported in accordance with the Code table 0878 (True direction, in tens of degrees, from which wind is blowing (or will blow) at stations within 1° of the North Pole).

The Code table 0878 is applied to several TAC, such as SYNOP and SHIP, but not to PILOT and TEMP families. In the same way, the respective notes to Class 11 of BUFR/CREX Tables B and to B/C 01 and B/C 10 in the Manual on Codes (WMO-No.306), Vol. I.2 apply only to surface wind.

The sixteenth session of the Commission for Instruments and Methods of Observation (CIMO-XVI (2014)) has approved the Provisional 2014 Edition of the Guide to Meteorological Instruments and Methods of Observation (CIMO Guide), which states in Chapter 13 (Measurement of upper wind) upon request by Mr Alexander Kats, Roshydromet:

"Within 1° latitude of the north or south pole, surface winds are reported using a direction where the azimuth ring is aligned with its zero coinciding with the Greenwich 0° meridian. This different coordinate system should be used by all fixed and mobile upper-air stations located within 1° latitude of the north or south pole for wind direction at all levels of the entire sounding, even if the balloon moves further away in latitude greater than 1° from the pole. The reporting code for these measurements should indicate that a different coordinate system is being used in this upper-air report, in particular if encoded in traditional alphanumeric codes; location of the station in BUFR automatically indicates usage of this different coordinate system".

Mr Kats explained the background of his proposal, by which he requested the amendments to the Manual on Codes (WMO-No. 306), Vol. I.2 in compliance with the Chapter 13 above, because the Volume I.1 has been frozen except for aviation codes.

The meeting recognized that the amendment to the note to Class 11 was generally applied not only to surface-based upper-air observations but also to satellite observations. It therefore agreed the proposed amendments to B/C regulations, which are sufficient for the upper-air observations, as shown in the Annex to this paragraph in compliance with the CIMO Guide, withdrawing the amendment to the note to Class 11 of BUFR/CREX Table B.

DRC #280: Clarification of upper-air wind reporting nearby the Poles (B/C 20, 25 and 26)