Meteorological Observations from Offshore Installations on the Norwegian Continental shelf

Pursuant to the Norwegian Regulation on Aviation Meteorological Services (FOR-2008-01-28-81, BSL G 7-1) an improved observations system will be implemented by Statoil ASA, where a combination of METAR (manually prepared) and AUTOMETAR will be provided. The implementation date will be published by NOTAM.

METAR and/or AUTOMETAR will be prepared for these areas: Norne HTZ, Heidrun HPZ, Tampen HPZ, Oseberg HPZ, Heimdal HPZ, Sleipner HPZ and Ekofisk HPZ.

Every METAR issued from at least one installation or ship within a HPZ shall contain observation of sea surface temperature and sea state.

At no significant weather there is generally no major difference between the METAR and AUTOMETAR.

At significant weather there usually can be found differences in visual parameters like visibility horizontally/vertically, clouds and present weather.

AUTOMETAR gives exact meteorological values at a specific point. By presentation of visibility and cloud base the instruments will only provide data at the point they are located. Sensors are installed in the area that is most representative for the meteorological conditions at the installation.

The following are well known differences between AUTOMETAR and METAR:

1. Generally AUTOMETAR presents lower visibility and cloud base than METAR
2. Differences can increase when the air mass is unstable
3. AUTOMETAR does not provide the cloud types CB and TCU
4. NCD (No Clouds Detected) is only used in AUTOMETAR
5. NDV (No Directional Variations) is only used in AUTOMETAR
6. UP (Unidentified Precipitation) is only used in AUTOMETAR
7. AUTOMETAR will always start with the term AUTO, stated after date/time in the string

The new system of using AUTOMETAR in combination with METAR on the Norwegian continental shelf will be evaluated after a period of approximately one year. The CAA-N sees the need for as complete data as possible to ensure improvement of the meteorological services offshore. The CAA-N would like to encourage all users of meteorological observations to provide feedback to the offshore installation on meteorological conditions considered to be of value for flight safety. The feedback will be a part of an evaluation of the meteorological services on the Norwegian continental shelf.

Overview of offshore installations with METAR/AUTOMETAR

Some installations with METAR will issue AUTOMETAR when the HFIS-services are shut down.