[mmaimcal] location of terahertz array

[Steven T. Myers]

I would be very careful interpreting a few radiosonde measurements in 
this regard.  Our best info would be obtained by contemporaneous weather
measurements at the higher sites with CBI, NRAO and Japanese station data
over a long time with minimal cost.  You can tell from the temperature and
Rel Humidity data when the inversion layer has dropped past a given site.
My guess is the incremental improvement over a slighly lower ALMA site
is minimal - when observing with CBI over 3 weeks I saw at most one night
where the layer might have been just above the NRAO site but below one of
the adjacent peaks.

As Simon said, more careful study will be needed, but I doubt that
radiosonde will the long-term solution (let alone cost-effective).

   -steve

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On Tue, 20 Jun 2000, Simon Radford wrote:

> 
> Should nearby mountain tops be condsidered for the location of a
> teraherz/super-terahertz array?
> 
> Radiosonde profiles show the bulk of the water vapor is trapped below an
> inversion layer fairly close to the ground at least some of the time (e.
> g., flight 85, 1999 November 7 UT 4). Putting a high frequency array
> 400-700 m higher, i. e., on Cordon Honar (5400 m), Cerro Chascon (5650
> m), or Cerro Sairecabur (5750 m), would lift it above the inversion
> layer and dramatically improve the observing conditions. This is not a
> novel idea -- it was suggested at the Cornell workshop last week, among
> other places -- but it should be considered seriously and carefully. 
> 
> At the very least, we should determine from the existing radiosonde data
> the expected improvement in observing time. And more radiosonde launches
> certainly would help.
>   
> Simon
>