Radiosonde vs Rawisonde (difference)
Dennis Shea
>What is the difference between a Radiosonde and a Rawisonde?
==============================================================
``Upper air'' observations began in the 1940s. However, large
numbers of these observations only became available
starting with the International Geophysical Year (IGY; 1957--58).
Today a small number of stations make
upper air observations up to four times per day
at internationally agreed--upon times.
These upper air observations are made by radiosondes
or rawinsondes. A radiosonde (invented in 1927) is an
expendable balloon--borne instrument
which measures pressure, temperature and humidity
and relays the information to an observing station
where the data are recorded after corrections are
made for instrument response time.
A rawinsonde is a radiosonde whose three dimensional
position is measured by one of several position
tracking methods. In the past, a reflector was tracked by
radar or radio--theodolite to estimate wind speed and direction.
These days, rawinsondes are tracked using the Omega or Loran
location finding systems. In the future, they may be
tracked by the GPS. These upper air observations
are referred to as ``raob'' data, regardless of which
instrument was actually used.
The wind speeds and directions at the
pressure levels are estimated from the horizontal
displacement of the balloon using: (i) the balloon altitude,
(ii) measured azimuth and elevation angles of the balloon or other
location indicators, and (iii) trigonometric relationships.
The words ``height'' and ``geopotential height''
are sometimes carelessly interchanged. However, they are
subtly different. Height (or altitude) refers to the
absolute distance above sea--level.
Geopotential height is what is actually reported in
raob observations. The geopotential height is closely related
to altitude but accounts for variations of gravity
within latitude and height.
Regards,
Dennis Shea
sh...@ncar.ucar.edu
ZAMORA ROBERT JOSEPH
Dennis Shea <sh8...@isis.cgd.ucar.edu> wrote:
><al...@dtint.dtint.com> writes
>
>>What is the difference between a Radiosonde and a Rawisonde?
>==============================================================
>
>``Upper air'' observations began in the 1940s. However, large
>numbers of these observations only became available
>starting with the International Geophysical Year (IGY; 1957--58).
>Today a small number of stations make
>upper air observations up to four times per day
>at internationally agreed--upon times.
>These upper air observations are made by radiosondes
>or rawinsondes. A radiosonde (invented in 1927) is an
>expendable balloon--borne instrument
>which measures pressure, temperature and humidity
>and relays the information to an observing station
>where the data are recorded after corrections are
>made for instrument response time.
>A rawinsonde is a radiosonde whose three dimensional
>position is measured by one of several position
>tracking methods. In the past, a reflector was tracked by
>radar or radio--theodolite to estimate wind speed and direction.
The radio-theodolite does not track a reflector. It homes on the
carrier wave transmitted by the radiosonde.
>These days, rawinsondes are tracked using the Omega or Loran
>location finding systems.
This is true in the NCAR CLASS system and some other commercial
system. However, the U.S. Weather Service uses radio-theodolites
at upper-air stations using the 1680 Mhz radiosondes. The modernized
system in use (ART) still uses the WBRT and GMD radiotheodolite trackers
with solid state replacements for the vaccumn tube technology that was
originally used.
>In the future, they may be tracked by the GPS. These upper air observations
>are referred to as ``raob'' data, regardless of which
>instrument was actually used.
>
>
>The wind speeds and directions at the
>pressure levels are estimated from the horizontal
>displacement of the balloon using: (i) the balloon altitude,
>(ii) measured azimuth and elevation angles of the balloon or other
>location indicators, and (iii) trigonometric relationships.
>
>The words ``height'' and ``geopotential height''
>are sometimes carelessly interchanged. However, they are
>subtly different. Height (or altitude) refers to the
>absolute distance above sea--level.
>Geopotential height is what is actually reported in
>raob observations. The geopotential height is closely related
>to altitude but accounts for variations of gravity
>within latitude and height.
>
>Regards,
>Dennis Shea
>sh...@ncar.ucar.edu
>
Bob Zamora
NOAA/ETL Boulder, CO
r...@etl.noaa.gov
David J. Schneider
:
: What goes up, must come down. If a ballon has to come down faster than
: expected, it is tagged as a UFO or vice-versa :-). I guess it would be
: a good idea if there is a mechanism to deploy a small parachute from the
: instrument package, in case of a failure. Perhaps the chance of a
: catastrophic ballon failure is very small to account for such devices.
:
Well, I new that the thing has to come down, and that there is probably
something like a parachute that is deployed, but since these things are
launched at airports around the world, this seems like a bit of a hazard
to me. Even if the thing doesn't get hit by an aircraft, the parachute
has to land somewhere.
My orignal question still goes unanswered.....
Dave
David J. Schneider
(edited)
: A radiosonde (invented in 1927) is an
: expendable balloon--borne instrument
: which measures pressure, temperature and humidity
: and relays the information to an observing station
: where the data are recorded after corrections are
: made for instrument response time.
I have a related question which has been bugging me for years...what
happens to the instrument package once the balloon breaks?? I can't
picture these things plummeting to earth like blue ice from aircraft.
Dave Schneider
Zaphiris Christidis
writes:
>
> I have a related question which has been bugging me for years...what
> happens to the instrument package once the balloon breaks?? I can't
> picture these things plummeting to earth like blue ice from aircraft.
What goes up, must come down. If a ballon has to come down faster than
expected, it is tagged as a UFO or vice-versa :-). I guess it would be
a good idea if there is a mechanism to deploy a small parachute from the
instrument package, in case of a failure. Perhaps the chance of a
catastrophic ballon failure is very small to account for such devices.
--
Zaphiris Christidis email: zap...@watson.ibm.com, zaphiri@yktvmv
Phone: (914) 945-2887 snail: IBM TJ Watson Research Ctr, PO Box 218
Fax: (914) 945-4469 Yorktown Heights, NY 10598, USA.
Dennis J. Boccippio
writes:
>I have a related question which has been bugging me for years...what
>happens to the instrument package once the balloon breaks?? I can't
It does, indeed, come down. :-) Most sondes have a "return to NWS" label
on them.
No parachutes that I'm aware of, but I'm not a sonde expert.
Incidentally, sonde packages that continue transmitting on the way down
are often useful for special purposes. Sondes which make it up through
the very dry (in an absolute sense) tropopause and into the stratosphere
are often contaminated by carrying along water molecules from lower
levels, at least temporarily. At the low mixing ratios that exist up
there, this contamination can be severe in terms of relative humidity.
However, on the way down, the sonde is usually falling from drier to
moister air, and thus may give more reliable humidity measurements.
Such "dropsondes" are often used in field programs.
-Dennis
David J. Low
>happens to the instrument package once the balloon breaks?? I can't
>picture these things plummeting to earth like blue ice from aircraft.
They do :-) A standard Vaisala RS-80 is about 200-250 grams, and AFAIK
none of the standard launches employ any sort of landing control.
People do return them to the Regional Offices, despite notices on them
explaining what they are, and not to bother :-)
A campaign I was involved in a couple of years back involved
launching about 150 sondes, at 3-hour intervals. We didn't get any
reported incidents of damage, even though about 75% of flights would
have terminated over land.
Question set to atmospheric physics class, after they've done he
"terminal velocity of a raindrop" problem: what is the terminal velocity
of a sonde package? :-)
Regards,
David.
--
___ ~~ | David J. Low, Atmospheric Group, Dept. Physics
/ /-----^-/~~~ | University of Adelaide, South Australia 5005
/ /-------/~ "I'll be back"|
<__/ ' --- Arnie | E-Mail : dl...@physics.adelaide.edu.au
Grant W. Petty
>In article <36hol8$5...@ashcloud.geo>, djsc...@mtu.edu (David J. Schneider)
>writes:
>>
>> I have a related question which has been bugging me for years...what
>> happens to the instrument package once the balloon breaks?? I can't
>> picture these things plummeting to earth like blue ice from aircraft.
>
>What goes up, must come down. If a ballon has to come down faster than
>expected, it is tagged as a UFO or vice-versa :-). I guess it would be
>a good idea if there is a mechanism to deploy a small parachute from the
Almost every radiosonde I ever launched while doing upper air
soundings with the Navy had cone-shaped paper parachutes between the
balloon and the sonde package. The only occasional exception was when
we were getting low on parachutes AND we far enough from land (several
100 km or more) that there was no chance the package would come down
on a populated area. I have always assumed (though I can't verify it
from personal experience) that the NWS uses parachutes routinely on
their sondes. Catalogs for radiosonde equipment always list
parachutes along with all the other expendables.
>instrument package, in case of a failure. Perhaps the chance of a
>catastrophic ballon failure is very small to account for such devices.
>
Catastrophic balloon failure is the usual way a balloon sounding ends.
The balloon rises until it has expanded to the bursting point (usually
somewhere around ~10 mb or less), then the sonde falls back to earth.
You can usually monitor the temperature and humidity data as it falls
and see that it essentially retraces the previously measured profile
in reverse, but over a much shorter period of time. I even once
watched the signal abruptly disappear at the point in the reverse
trace where the ocean surface should be (it had just passed back
through the boundary layer inversion). Most often, the signal was
gradually lost as the sonde descended below the horizon many miles
downwind, or else we simply got tired of watching it and shut off the
receiver.
--
Grant W. Petty gpe...@rain.atms.purdue.edu
Asst. Prof. of Atmospheric Science
Dept. of Earth & Atmospheric Sciences (317) 494-2544
Purdue University, West Lafayette IN 47907-1397 FAX:(317) 496-1210
Bob Zamora
Dennis J. Boccippio <djbo...@graupel.mit.edu> wrote:
>In article <36hol8$5...@ashcloud.geo> David J. Schneider, djsc...@mtu.edu
>writes:
>>I have a related question which has been bugging me for years...what
>>happens to the instrument package once the balloon breaks?? I can't
>
>It does, indeed, come down. :-) Most sondes have a "return to NWS" label
>on them.
>No parachutes that I'm aware of, but I'm not a sonde expert.
>
It depends on the radiosonde used. The VIZ(tm) radiosonde used by the
NWS is launched with an orange paper parachute in the train that deploys
when the balloon breaks and the package starts down. Some NWS upper air
sites were supposed to begin using Vaisala(tm) sondes this year. I don't know
if those sites are using parachutes. The Vaisala sonde used with the
NCAR CLASS system and the AIR (tm) sondes are light and don't use a parachute.
Bob Zamora (r...@etl.noaa.gov)
John Berger
D>: A radiosonde (invented in 1927) is an
D>: expendable balloon--borne instrument
D>: which measures pressure, temperature and humidity
D>: and relays the information to an observing station
D>: where the data are recorded after corrections are
D>: made for instrument response time.
D>I have a related question which has been bugging me for years...what
D>happens to the instrument package once the balloon breaks?? I can't
D>picture these things plummeting to earth like blue ice from aircraft.
D>Dave Schneider
D>
The baloon package should have a paper parachute on it to assist in it's
fall. Out over the ocean, parachutes are not done...
This message writen at 02:44 10/02/94
John Berger Virginia Beach, VA, USA
Internet: John....@sourcebbs.com
---
þ CMPQwk #1.4þ UNREGISTERED EVALUATION COPY