On 19/02/2011 20:48, James Brown wrote:
In message , Jon O'Rourke
writes
"James Brown" wrote in message
...
Wouldn't it all become terribly boring? For me the uncertainty is
part of the enjoyment and fascination of our weather (and climate).
I kind of smile at the way myself and perhaps others have been drawn
into the elusive quest for certainty at longer range - but do you
know what? I'd prefer it remain an elusive hunt - just to keep us
guessing and refining our skills - or lack of it in my case!

OTOH if we ever did reach certainty at T240 I suppose we'd be
wrangling over T480!!

Just a thought to keep things in perspective ;-))


Indeed, last night it was the elusive quest for certainty at T+2.

Jon.

Wonderfully true Jon - if it all came down to perfect computer models
there would be an increase in unemployment - ooh a conspiracy theory
has come to mind - like the story of the man who invented the light
bulb that would never wear out, but was bought out by a company making
light bulbs. So to be clear, you are saying that there really isn't a
'holy grail' that has been found but squirreled away by forecasters
who rather enjoy their work.... ;-))

Very BG



As we have discussed before, the problem is not so much with the models
as with the information supplied to them - the observations. Under many
situations, the forecast outcome is extremely sensitive to these and
errors in the original conditions multiply as the forecast is run,
eventually making it no more than guesswork.

Whilst improvement in the models (or a particularly stable atmospheric
situation) may push back this "random guess" point, you can only go so
far before the limit becomes the quality of the input. AIUI, because
over much of the globe there are few observations, the forecasts are
actually started with a previous forecast output adjusted to match such
observations as we have together with satellite data such as winds
measured by radar / microwaves. This is known as "initialisation" (or
was when i was a meteorology student).

The practice of running "ensembles" is a way of determining how much the
forecasts are actually worth - the "tweaking" between the ensemble
members is intended to simulate the errors in the initial input fields.
Once the ensembles go all over the place, you know that "chaos" (in the
mathematical sense) has set in and you might as well cast the runes or
read the entrails as trust the model outputs.

--
- Yokel -

Yokel posts via a spam-trap account which is not read.