Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site ames.UUCP
Path: utzoo!linus!philabs!cmcl2!seismo!ut-sally!mordor!lll-crg!lll-lcc!dual!ames!eugene
From: eugene@ames.UUCP (Eugene Miya)
Newsgroups: net.space
Subject: Re: Spacecraft emissions
Message-ID: <1323@ames.UUCP>
Date: Wed, 8-Jan-86 04:01:09 EST
Article-I.D.: ames.1323
Posted: Wed Jan  8 04:01:09 1986
Date-Received: Sat, 11-Jan-86 06:17:07 EST
References: <8601071745.AA14637@s1-b.arpa>
Organization: NASA-Ames Research Center, Mtn. View, CA
Lines: 57

[I tell myself that I'm going the read this group less.... oh well.]

I did not see the original posting.

> >> scientific community has spent a huge amount of effort studying the
> >> upper atmosphere and devising various models of chemical
> >> transformations, the precise answer should be relatively easy to
> >> obtain.  

The atmosphere about 70,000 feet to 250,000 feet is relatively poorly
understood.  We have a building full of physicists and chemists working
on a Cyber 205 around the clock spending $millions trying to understand the
chemistry of this regime.

> >You have a lot more faith in those models and research than I do.
> >The accuracy
> >of weather prediction should give you an idea of how good such models really
> >are - not very (maybe in a few decades ...).
> 
> Actually, atmospheric chemical models and weather forecasting are not
> closely related.

There is very little "chemical" with the weather: maybe ozone and small
things.  Weather is basically the state change of one compound (water).
Very interesting.

> Current chemical models have proven inaccurate
> for this reason: there are thousands of chemical reactions going
> on in the atmosphere at various rates, and not all are well understood.
> In contrast, the physical processes in weather are reasonably well
> understood, but lack of fine grained measurements cripples forecasting.

This is correct.  The people at NCAR could tell you better, but the
spatial resolution of the GASP [Global AtmoSPheric circulation] model
is about 2.5 degrees of latitude and longitude [over-simplication in my
figures, but close enough 100 by 100 miles, which in turn barely fits
on a Cray-1].  Consider 1 datapoint representing a 10,000 square mile area:
say 1 temperature.  Another problem is this the lack of adequate
data from satellites: consider cloud cover.  Typical weather images show
cloud patterns over the NA continent [BTW: these were unknown before
the space program].  But 70% of the world is covered by water which is
NOT watched by satellites, so there is a major sampling problem.
Nothing like running a weather program and then looking outside a window!
Several radar-based instruments for measuring wind have been sent up
on an experimental basis.

> interesting uses two polar-orbiting satellites with CO2-laser radar
> to get global wind measurements.

There is an interesting story about CO2 measurements by a fellow at Scripps
Inst. of Oceanography, but too long for this message.

From the Rock of Ages Home for Retired Hackers:
--eugene miya
  NASA Ames Research Center
  {hplabs,ihnp4,dual,hao,decwrl,allegra}!ames!aurora!eugene
  emiya@ames-vmsb.ARPA