Met Éireann use 4 different units for windspeed

Su Campu

One thing I find a bit bizarre and never quite understood is why Met Éireann use four different units for windspeed, all at the same time - the knot (in the online current and climatalogical observations), the km/h (on their radio and TV forecasts), m/s (in their hourly SYNOP reports), and the Beaufort Scale (in their sea-area forecasts). I know there are individual arguments for using each of the four, but I think they really should at least change their online units to km/h to coincide with what they use in the media. We have changed driving speed limits to km/h without any problem, so it can be done.

The SI unit is the metre per second (m/s), and is used in many countries (eg. Iceland, Denmark, Russia) but it is a tricky unit to get used to when you're used to the others. However the conversion from m/s to mph (yep, yet another unit, but one we grew up with) is the same factor (2.2) as converting from kg to lbs, which we're all fairly familiar with. Or to convert it to km/h the factor is a nice round 3.5. (just multiply by 7 and divide by 2). They are correct to use m/s in their SYNOP reports, but are one of the few countries to do so, most still reporting in knots.

It makes sense to use Beaufort for sea area as that is a scale developed precisely for mariners with no means of reading windspeed. The general public don't bother with it too much, though again you will hear it in forecasts alongside km/h!

Parakeets

As you probably aware, every field of science and meteorology is no exception suffers from "this is the way we've always done it" syndrome. Historical methods regularly control the present. The world was flat not because you couldn't prove that it was round but that historically it was accepted that the world was flat. Similarly cloud height and aircraft flight levels are reported in feet for no other reason than historically it is done so. Bizarrely visibility is recorded and reported in code in km or m but given in radio reports in miles with visibility values of 61 miles being reported when in fact the reported value would have been rounded to say 80 km. Sadly however I don't think it will change.

octo

Su Campu wrote: »

One thing I find a bit bizarre and never quite understood is why Met Éireann use four different units for windspeed, all at the same time - the knot (in the online current and climatalogical observations), the km/h (on their radio and TV forecasts), m/s (in their hourly SYNOP reports), and the Beaufort Scale (in their sea-area forecasts). I know there are individual arguments for using each of the four, but I think they really should at least change their online units to km/h to coincide with what they use in the media. We have changed driving speed limits to km/h without any problem, so it can be done.

The SI unit is the metre per second (m/s), and is used in many countries (eg. Iceland, Denmark, Russia) but it is a tricky unit to get used to when you're used to the others. However the conversion from m/s to mph (yep, yet another unit, but one we grew up with) is the same factor (2.2) as converting from kg to lbs, which we're all fairly familiar with. Or to convert it to km/h the factor is a nice round 3.5. (just multiply by 7 and divide by 2). They are correct to use m/s in their SYNOP reports, but are one of the few countries to do so, most still reporting in knots.

It makes sense to use Beaufort for sea area as that is a scale developed precisely for mariners with no means of reading windspeed. The general public don't bother with it too much, though again you will hear it in forecasts alongside km/h!

Su - If you're reading the synop on OGIMET, these are converted (by OGIMET? not sure) to m/s. ME's raw synops are reported in kts.

Meteorological units (along with regional variations) are stipulated by WMO and ICAO. Popular media forecasts of course, are down to the discretion of the forecaster....

Su Campu

octo wrote: »

Su - If you're reading the synop on OGIMET, these are converted (by OGIMET? not sure) to m/s. ME's raw synops are reported in kts.

Meteorological units (along with regional variations) are stipulated by WMO and ICAO. Popular media forecasts of course, are down to the discretion of the forecaster....

They're down as m/s not only in Ogimet but also others, like Wunderground, etc. The official WMO Guide allows for both m/s and knots, at the discretion of the national service, and the units used are indicated by the last digit of the date and time group of the Synop report (1 is m/s, 4 is knots). As I said, most countries report it as 4, but Ireland reports it as 1.

eg. Casement at 6am this morning.

AAXX 28061 03967 12980 02403 11021 21021 30224 40345 53009 69902
333 21030 31106 55080 92611=

octo

Su Campu wrote: »

They're down as m/s not only in Ogimet but also others, like Wunderground, etc. The official WMO Guide allows for both m/s and knots, at the discretion of the national service, and the units used are indicated by the last digit of the date and time group of the Synop report (1 is m/s, 4 is knots). As I said, most countries report it as 4, but Ireland reports it as 1.

eg. Casement at 6am this morning.

Ooops. Well looks like you're correct. I do know the observer reports knots, but somewhere in glasnevin it must be converted to m/s for international distribution.