THIS PAGE

CIRCULAR
DECEMBER 1949
AUTOMATIC WEATHER STATIONS
P r e p a r e d i n the A i r N a v i g a t i o n Bureau
a n d published by authority of t h e Secretary G e n e r a l
INTERNATIONAL
CIVIL AVIATION
O R G A N I Z A T I O N
CANADA
MONTREAL
This Publication is issued i n English, Frsnch and Spanish
Published i n Montri. 2, Canada, by t h e
I n t e r n a t i o n a l CiviJ A i9.5iorX Organization.
Correspondence colcerning publications
should be addressed t o tts S e c r r t q General
of IGAO, I n t e r n a t i o n a l Aviation Building,
2080 University S t r e e t , Hontredl, Canada.
Orders f o r ICAO pub1ication.s should be sent, on p ~ ~ l e n t :
~n ~anadjlanc u r r e r ~ y($1, t o
Secretary General, ICAG,
I n t e r n a t i o n a l Avf a t i o n Building,
1080 University S t r e e t ,
Montreal, Canada.
(Cable address : ICAO MONTREAL);
I n French currency
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In S-t --e s l ,-.--. o r I r i s h curremy ( ~ / d l , t o
H i s >5ajesty9s Stationery Office,
P,O, Box 569,
London, S.E. 1,
England.
(Cable address : HEMSTO-rJERY LONDON) ;
-I n E ~ r ~ p t S acurrency
n
(dm), t o
I C A O Representative,
European & African Office,
6obis,avenue d f I b a ,
P a r i s (16&me), France.
(Cable address : ICAOREP PARIS) ;
ICAO Representative,
Middle East Office,
10 Sharia Lotfallah, Apartment 7,
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Cairo, Egypt,
(Cable address : ICAOREP CAIRO) ;
I n Peruvian e u r r e n a ( s o l e s ) , t o
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ICAO Representative,
ICAO Representative,
Far East & P a c i f i c Office,
17 Robe S t r e e t , St. Kilda,
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( C ~ b i eaddress : ICAOREP MELBOURNE)
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Page 3
ICAO Circular 13-AN/ll
TABLE OF CONTENTS
Foreword
..........................................................
AUTOMATIC WEATHER STATIONS
1.. Introduction
2
.
.
..................................................
..............
S t a t i o n s established by t h e United S t a t e s .............
Types of Automatic Weather Stations i n operation
2.1..
2.1.1.2.1.2.-
U.S. Automatic Weather S t a t i o n
(Model TDM.~ )
Automatic Weather Stations operated on
islands by the United S t a t e s Weather
Bureau
. ............................
....................................
2.2.2.3..
Buoy Type operated by the Canadian Heteorological
Service
.............................................
French Stations .......................................
2.3.1.-
...........
.....................................
Automatic Weather Stations i n the U.S.S.R.
............
German Automatic Weather Stations .....................
2.3.2.-
2.4.2.5..
3..
Automatic Weather Stations of the French
National Meteorological Service
A u t o i t i c Weather Station on the E i f f e l
Tower
Conclusions
4.. Bibliography
...................................................
..................................................
5
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ICAO Circular 13-~~/11.
Page 5
I n t h e progressive establishmen% of a world-wide network of meteorological observing stations,one outstanding d i f f i c u l t y has been t h e provision
of observations from sparsely populated or d e s e r t a r e a s and a l s o from ocean
a r e a s devoid of i s l a n d s or remote from regular shipping lanes. It was i n
recognition of t h i s d i f f i c u l t y t h a t the Meteorological Division a t i t s Second
Session and t h e Meteorological Committees a t several Regional A i r Navigation
Meetinga recommended that the progress made i n t h e d m d o p n e n t of a u h m a t i c
w e a t h e s t a t i o n s be given continuing study by t h e ICAO Meteorological
Secretariat.
The S e c r e t a r i a t study h s resulted i n t h e comp&lation of t h e present
ICAO C i r c u l a r which includes a review of the automatic weather s t a t i o n s
developed by c e r t a i n s t a t e s and now i n use i n d i f f e r e n t p a r t s of the world.
k number of i l l u s t r a t i o n s i s a l s o included together with a s h o r t bibliography.
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AUTOMATIC WEATHER STATIONS
1.- INTRODUCTION
The development of automatic weather s t a t i o n s appears t o have received
i t s f i r s t important impetus during the years immediately preceding World
War I1 when experiments were carried out i n Europe and North America. Automatic s t a t i o n s have been developed by both c i v i l and military organizations
and seem t o have conformed t o a generally similar pattern, although d i f f e r i n g
i n the methods used i n recording and transmitting observations.
I n Section 2, which represents the principal p a r t of t h i s c i r c u l a r , a
f u l l description, including a summary of specifications, i s given f o r each of
the types of s t a t i o n i n operation on which information has been received by
I C A0
.
2.- TYPES OF AUTOMATIC WEATHER STATIONS NOW I N OPEaiATION
One of t h e most successful types now i n use, which has been employed by
the United S t a t e s Navy and the United S t a t e s Army i s based on the Modified
Molchanoff System, d e t a i l s of which a r e given below:
The meteorological elements measured by t h i s automatic s t a t i o n a r e
atmospheric pressure, humidity, wind speed and d i r e c t i o n and precipitation.
The indications of the values of the meteorological elements being observed
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I C A O Circular
Page 8
13-mh1
are converted i n t o two-letter Morse code signals, t h e speed of transmission
of which i s approximately 1 2 words per minute, The transmission cycle i s
rapid and accurate. I n p r a c t i c e each cycle of observation i s repeated two
or three times t o ensure accurate reception. There i s a d i s t i n c t and d i f f e r e n t Morse Code s i g n a l f o r each increment i n t h e data f o r each p a r t i c u l a r
element being measured.
The observations a r e transmitted every t h r e e hours according t o a pres e t twenty-four-hour sequence and each 'observation i s preceded by a s t a t i o n
c a l l - s i g n f o r i d e n t i f i c a t i o n purposes, follokred by t h e meteorological readings,
repeated a s necessary, and l a s t i n g approximitely 15 minutes.
The long experiments c a r r i e d out i n connection with various types of
automatic wgather s t a t i o n s have resulted i n t h e achievement of a high degree
of accuraoy 5n
, t h e observations a s demonstrated by t h e following s t a t i s t i c s
i n respect .of Dhe MoJchanoff System:
a) Atmospheric pressure i s measured t o an accuracy witbin one
miLl$bar af a standard mercurial barometer;
b) Humidity readings a r e found t o be within 5 percent of the
a c t u a l humidity a s obtained by a psychrometer;
c) The temperature unit i s within one degree F , of t h e temperature obtained from t h e dry bulb thermometer;
d) P r e c i p i t a t i o n readings cause some d i f f i c u l t y on account of
occasional freezing of rain-water i n t h e funnel shaped opening. The
average degree o f accuracy has, however, been found t o be within one
hundredth of an inch;
e) On checking the accuracy of t h e wind u n i t with a hand anemometer, t h e wind direction was found t o be exact and t h e v e l o c i t y t o be
accurate within one to two knots in winds between f i f t e e n and twenty
knots, ,
Range
The e f f e c t i v e reception range of t h e s t a t i o n s i s c l e a r l y dependent upon
t h e puwer of' t h e t r a n s m i t t e r but t h e average appears to be of t h e order of
4.00 miles, The location of t h e s t a t i o n i s espeoially important and the effective range is influenced very g r e a t l y by the topography of the country between
t h e s t a t i o n and t h e receiving paint.
Pagc 9
ICAO Circular 1 3 - ~ ~ / l l
Power Suualy
Both primary b a t t e r i e s and a i r o r liquid-cooled gas engines have been
used i n experiments with t r i a l s t a t i o n s but maintenance of such power u n i t s
apparently r e q u i r e s t h e attendance of operating personnel a t . l e a s t every
six months.
The b e s t solution t o t h i s problem would be a wind-driven e l e c t r i c genera t o r charging a bank of lead-acid storage b a t t e r i e s which gives promise of
unattended operation f o r a period of one year o r more i f s u i t a b l e storage batt e r i e s a r e used.
Costs
R e l i a b l e estimates of t h e c o s t s of automatic weather s t a t i o n s a r e very
d i f f i c u l t t o obtain s i n c e they a r e s t i l l i n t h e experimental s t a g e and, where
development work has been done by m i l i t a r y organizations, c o s t s a r e obviously
not e a s i l y estimated. From d a t a s o f a r made a v a i l a b l e , however, c o s t per u n i t
of a s t a t i o n of t h e Molchanoff type would appear t o be between $12,000 t o
$15,000.
House and Instrument S h e l t e r
A few instruments of t h i s type have been manufactured f o r use by t h e
United S t a t e s Army and Navy. The compact recording and power u n i t s a r e
s h e l t e r e d i n a well-insulated house on top of which i s mounted a standard
instrument s h e l t e r , The house i s of t h e pre-fabricated type, e a s i l y erected
on a s u i t a b l e concrete foundation. The f l o o r s e c t i o n i s attached t o t h e foundat i o n by anchored b o l t s and i s surrounded by a p r o t e c t i v e metal s h i e l d which
prevents t e r m i t e s from e n t e r i n g t h e house. Four guy wires provide a d d i t i o n a l
support f o r t h e instrument s h e l t e r . Screened v e n t i l a t o r openings with approp r i a t e s h i e l d s a r e located i n t h e f r o n t and r e a r s e c t i o n s , The roof i s made
up of two copper covered s e c t i o n s joined i n t h e centre. Two i n s u l a t e d antenna
lead-in connectors a r e placed i n t h e r e a r wall. An opening i s a l s o provided i n
t h e r e a r w a l l t o admit t h e conduit f o r connecting t h e e x t e r n a l instruments.
Figures I , I1 and I11 a r e photographs showing both t h e e x t e r i o r and i n t e r i o r
views.
Descriution of Meteoroloaical Recording A ~ ~ a r a t u s
P r e s s u r e Unit.- The u n i t generally employed i n automatic weather s t a t i o n s
f o r t h e recording of pressure changes i s a microbarograph, which has been
ICA 0 C i r c u l a r 13-~2;/13
Page 1 0
-
modified by t h e removal of t h e clock mechanism and i n which t h e c h a r t drum i s
replaced by a r e s i s t a n c e u n i t , The pressure s e n s i t i v e element a c t u a t e s a
c o n t a c t arm, t h e l a t t e r being moved t o t h a t c o n t a c t of t h e r e s i s t a n c e element
which corresponds t o t h e p r e v a i l i n g barometric pressure. The r e s i s t a n c e e l e ment c o n s i s t s of a s e r i e s of 1 0 1 r e s i s t o r s which a r e d i r e c t l y connected t o
t h e c o n t a c t p o i n t s . Therefore,the amount of r e s i s t a n c e introduced depends
upon t h e p o s i t i o n of t h e c o n t a c t arm. During transmission t h e c o n t a c t arm i s
clamped s e c u r e l y t o t h e c o n t a c t p o i n t over which i t was l o c a t s d a t t h e beginning of t h e transmission. The instrument h ~ as p r e s s u r e range of 100 mbs, t h e
maximum and minimum readings depending on t h e a l t i t u d e of t h e instrument, i,e,
from 850 t o 950 mbs. o r from 950 t o 1050 mbs, e t c . A photograph of t h e pressu r e u n i t i s shown i n Figure I V ,
Temnerature Unit.- The temperature u n i t c o n s f s t s o f f o u r small r e s i s t o r s
connected i n s e r i e s . The r e s i s t o r s have a high negative temperature c o e f f i c i e n t s o t h a t t h e r e s i s t a n c e of t h e u n i t i n c r e a s e s a s t h e temperature drops
and v i c e versa. This instrument i s protected by a small louvred s c r e e n , Teml O O O F can be measured. A photograph of t h e temperature
p e r a t u r e s from -60° t o
u n i t i s shown i n Figure V.
+
Humidity Unit,- Normally using s t r a n d s of human h a i r , t h e humidity u n i t
i s a hypograph, which has been modified by r e p l a c i n g t h e recording drum and
clock mechanism w i t h a s u i t a b l e r e s i s t a n c e element. The changes i n l e n g t h of
t h e h a i r d e f l e c t a c o n t a c t arm over t h e c o n t a c t s connected t o f i f t y r e s i s t o r s
and t h e v a r i a t i o n s a r e transmitted I n exactly t h e same way a s t h e pressure
changes described i n Paragra?h a ) , R e l a t i v e humidities from 1 5 percent t o 100 p e ~
c e n t can be measured. A photograph of the humidity u n i t i s shown i n Figure VT.
Wind Unit,- The wind d i r e c t i o n t r a n s m i t t e r c o n s i s t s of s i x t e e n cam- ,
operated switches connected t o s i x t e e n r e s i s t o r s s o t h a t any motion of t h e
wind vane w i l l be followed e x a c t l y by t h e cam. Wind d i r e c t i o n can t h e r e f o r e
be measured t o t h e s i x t e e n p o i n t s of t h e compass, Figures V I I and V I I I are
photographs of t h e wind u n i t ,
Wind v e l o c i t y i s recorded by means of a t r a n s m i t t e q w h i c h c o n s i s t s of a
set of c o n t a c t p o i n t s operated by means of a gear and cam arrangement through
t h e r o t a t i o n of t h e anemometer cups. The c o n t a c t p o i n t s a r e closed once f o r
each one hundred and t w e n t i e t h p a r t of a n a u t i c a l mile of wind thaZ, passes t h e
anemometer, Thus, t h e number of p u l s e s c o u n t ~ dduring one h a l f minute w a l l
give t h e wind v e l o c i t y reading d i r e c t l y i n knots.
P r e c i p i t a t i o n Recorder.- The instruments used f o r measurement of prec i p i t a t i o n vary considerably b u t a common type i n use i s the tipping-bucket
r a i n gauge which i s s o arranged t h a t each time t h e bucket t i p s a c o n t a c t i s
Circulaire
~ - ~ / 1 1
House and Instrument Shelter
Cabine et abri des i n s t m n t s
Cabina y abrigo de instrumentos
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Fia. I1
--
I n t e r i o r View of House showing Engine and Control Unit
Cabine Vue i n t e r i e u r e m n t r a n t l e moteur e t l e tableau de c o m n d e
Cabina Vista d e l i n t e r i o r con motor y mandos
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Cir c a l a r
13-L~v/ll
Circulaire
.orloge
Fig. I11
Interior View of House showing Transmitter
Cabine Vue interieure montrant ll6metteur
Cabina Vista interior con e l transmisor
-
-
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Circular
Circulaire
13-ANhl
Plots de contact
Resistance units
R6sistances ohmiques
Resistencias
Pressure adjusting nut
V i s de reglage de l a pression
Tuerca de ajuste de presibn
Latch release lever
Levier dlouverture
Palanca de desenganche
d e l trinquete
Contact arm
Levier contacteur
Brazo de contac
Barre de verrouilla
Barra de fijaci6n
Clamping relay
Relais de verrouillage
Relevador d e fijacidn
Pressure Unit
E16ment barometrique
Elemento barometrico
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Circulaire
13-~J/ll
Temperature sensitive resistors
Resistances ohmlques fonctions de la temperature
Resistencias sensibles a la temperatura
Fia. V
Temperature Unit
El6ment thermodtrique
Elemento termom6trioo
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Circular
Circulaire 13-AN/ll
Fia. VI
Humidity U n i t
Eldment hygrometrique
Elemento higromdtrico
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Circular
13-~~/ll
Circulaire
Anemometer cup assembly
Cupules de l~an6mom8tre
Cucharas del anemdmetro
Upper anermmeter bearing shield
Ecran protecteur du roulement
supbrieur de llan6nom8tre
Tornillo de fija
sup4rieur de la girouette
Cubierta del rodamiento superior
de la veleta
North orientation indicator
Indicateur d'orientation Nord
Contact mechanism housing
Boltier de &canisme contacteur
Caja del mecanism de contact0
Cover plate
Plaque protectrice
Fig. V I I
Vind Unit, Masthead Assernbly
Element an6momktrique, assemblage place en haut du m8t
Elemento anemom6tric0, conjunto colocado en l a parte superior d e l poste
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Circular
U-A N / ~ I
Circulaire
Mercury seal container
Rgservoir d'btanch6it6, B mercure
Depdsito estanco por mercurio
contact points
\ Velocity
Yitease: plots dde contact
Contacto de velocidad
Vis de r6glage de but60 de laaxe
Tornillo de reglaje d e l empuje d e l eje
Fig. VIII
-
Wind Unit Recording Mechanism
Eldment andmm4trique M4canisme enregistreur
Elemento anemodtrico Mecanism registrador
--
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Page 27
ICAO C i r c u l a r 13-~~/ll
made and a r a d i o s i g n a l transmitted. R a i n f a l l can be measured from 0 t o 1 2
inches, A photograph of t h e p r e c i p i t a t i o n u n i t i s shown i n Figure IX.
2.1.2,-
Automatic Weather S t a t i o n s h e r a t e d on I s l a n d s
by t h e United S t a t e s Weather Bureau
A s an a d d i t i o n t o t h e hurricane observation network, t h e United S t a t e s
Meather Bureau has had considerable success i n t h e operation of automatic
weather s t a t i o n s on small i s l a n d s off t h e c o a s t of F l o r i d a s i n c e 1945. If
t h e a d d i t i o n of a wind-driven generator can extend t h e l e n g t h of time between
s e r v i c i n g s , it would appear t h a t t h e i n s t a l l a t i o n of s i m i l a r s t a t i o n s could
be considered f o r more remote i s l a n d s . Each i n s t a l l a t i o n i s housed i n a
"hurricane-proof" type of construction and i s equipped with a t r a n s m i t t e r
c o n s i s t i n g e s s e n t i a l l y of two u n i t s , each operating on a staggered schedule
and producing a l t e r n a t e transmissions. I n c a s e of f a i l u r e of one u n i t , t r a n s missions w i l l s t i l l occur, b u t a t double t h e r e g u l a r (3-hourly) time i n t e r v a l ,
The antenna f o r t h e t r a n s m i t t e r s i s of t h e non-directional shunt f e d type,
c o n s i s t i n g of a 65-foot self-supporting t u b u l a r s t e e l mast designed t o withstand wind speeds of 130 knots. Each transmission includes t h e s t a t i o n ident i f i c a t i o n , barometric pressure, wind d i r e c t i o n and wind speed, The i d e n t i f y i n g l e t t e r s assigned t o each s t a t i o n a r e t r a n s m i t t e d i n I n t e r n a t i o n a l Morse
Code by a u t o m a t i c a l l y keying t h e unmodulated c a r r i e r , Transmissions from a l l
t h e s t a t i o n s a r e on 3352-5 kc b u t a r e scheduled s o t h a t t h e transmissions a r e
not concurrent.
D e s c r i ~ t i o nof Meteoroloaical A ~ p a r a t u s
P r e s s u r e Unit,- Aneroid c e l l s with 100 mb, p r e s s t r e range from 930 t o
1030 mb. i n d i c a t e t h e p r e s s u r e within an accuracy of 41 mb. P r e s s u r e d a t a
a r e t r a n s m i t t e d between two reference pulses which occur approximately
30 seconds a p a r t . For example, i f t h e v a r i a b l e pulse occurs 20 seconds a f t e r
t h e f i r s t r e f e r e n c e p u l s e and t h e time between t h e f i r s t and second reference
pulse i s 30 seconds, t h e p r e s s u r e i s 20/30 x 100 930 mb. = 997 mb.
+
Wind Unit.- The wind d i r e c t i o n i s a s c e r t a i n e d by a s i m i l a r method. If
a pulse i s assumed t o occur 1 5 seconds a f t e r t h e f i r s t reference p u l s e and
t h e time between reference p u l s e s i s again 30 seconds, t h e wind d i r e c t i o n would
be 15/30 x 360° = 180°, Wind speed i s t r a n s m i t t e d by keying t h e t r a n s m i t t e r
d i r e c t l y from t h e 60th mile contact of a standard'deather i3ureau anemometer.
The speed i s then i n d i c a t e d by t h e number of p u l s e s transmitted p e r minute.
Page 28
I C A O C i r c u l a r 13-~li//ll
Power S u ~ ~ l g Primary
,power i s supplied from s t o r a g e c e l l s hevinp, s i l f F i c i e n t c a p a c i t y t o l a s t f o u r months without recharging. Wind g e n e r a t o r s a r e
now being used experimentally f o r b a t t e r y recharging t o i n c r e a s e f u r t h e r t h e
l e n g t h of time between t r i p s f o r servicing. A power i n p u t of 50 w a t t s produces s u f f i c i e n t l y high s i g n a l s t r e n g t h t o g i v e s a t i s f a c t o r y r e c o r d i n g s a t
t h e r e c e i v i n g terminals,
Receiving Eaui.pment.- The main r e c e i v e r i s placed a t a beach l o c a t i o n
favourable f o r r a d i o r e c e p t i o n and i t s output i s c a r r i e d by land l i n e s t o a
recorder i n t h e Weather Bureau Office. An a u x i l i a r y r e c e i v e r , l o c a t e d i n t h e
Weather Bureau O f f i c e , provides a simultaneous recording i n t h e event t h a t t h e
primary f a i l s . The recording equipment i s turned on a u t o m a t i c a l l y by a time
clock and t h e complete record i s made without t h e presence of an operator.
The r e c o r d e r s a r e of t h e v i b r a t i n g s t y l u s type which produce r e c o r d s of t h e
p u l s a t i o n s on a waxed t a p e moving a t constant speed. The record i s d i r e c t l y
evaluated by measuring t h e d i s t a n c e s between t h e s i g n a l p u l s e and r e f e r e n c e
pulses. An a u x i l i a r y b a t t e r y power supply hes been provided f o r operation of
t h e r e c e i v e r s a t each t e r m i n a l i n case of power f a i l u r e ,
E f f e c t i v e Range of Transmitters,- The t h r e e automatic weather s t a t i o n s
a r e l o c a t e d a t Orange Xey, Cape S a b l e and Dog Rock o f f t h e south c o a s t of
F l o r i d a . The broadcasts from t h e t h r e e t r a n s m i t t e r s a r e received a t Miami
and Key West. The g r e a t e s t d i s t a n c e of transmission i s 170 m i l e s and t h e
s h o r t e s t d i s t a n c e i s 62 miles.
--
Cost,- No information i s a v a i l a b l e concerning t h e c o s t of c o n s t r u c t i o n ,
i n s t a l l a t i o n and maintenance of t h i s type of automatic weather s t a t i o n .
a,Buoy T m e
of Automatic Weather S t a t i o n Operated
Lake Ont-o
by t h e Canadian Meteor~$p&cal S e r v i c e on
I n o r d e r t o obtain more r e p r e s e n t a t i v e information of meteorological
elements t o f a c i l i t a t e f o g f o r e c a s t i n g on t h e n o r t h shore of Lake Ontario,
an automatic weather s t a t i o n was e s t a b l i s h e d on t h e l a k e by t h e Canadian
Government i n 1942. S i n c e t h e r e were upwelling e f f e c t s near t h e shore, temp e r a t u r e measurements i n t h i s a r e a were u n r e p r e s e n t a t i v e and misleading f o r
purposes of f o g f o r e c a s t i n g . Accordingly, t h i s automatic weather s t a t i o n was
c o n s t r u c t e d and i n s t a l l e d i n a l a r g e navigation buoy and anchored some d i s t a n c e
from t h e shore (see F i g u r e x ) ,
Circulaire
13-~~/=
Conn
Born
Born
Precipitation Recorder
Pluviodtre enregistreur
Pluvi6grafo
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-
I
Aerial
Antenne
Antena
Anemometer
An4mombtre
Anemdmetro
le
Air thermometer
Thermomhtre place dans 1fair
Term6metro para tenperatura
del aire
Navigation light
Feu de navigation
Luz de posici6n
11 1
1
Transmitter
lketteur
Water thermometer
Thermoclatre place dans l'eau
Tendmetro sumergido en el agua
Boude
Flotteur
Flotador
--
Battery compartment
Accumulateurs
Acudadores
0
I
I
2
4
6
Scale in feet
Echelle en pieds
Escala en pies
General arrangement of buoy
Disposition d'ensemble de la bou6e
Disposici6n general de la boya
8
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Page 33
ICAO C i r c u l a r 13-AN/ll
..
----
Meteoroloaical Elements Measured
I n d i c a t i o n s of a i r temperature, water temperature and wind speed a r e
transmitted t o t h e meteorological o f f i c e .
Meteorological Instruments
A i r Thermometer.- The thermometer c o n s i s t s of seven r e s i s t o r s i n s e r i e s .
These r e s i s t o r s have a negative temperature c o e f f i c i e n t . For exarqle they
have a r e s i s t a n c e of about 70,000 ohms a t 860F and about 154,000 ohms a t 32OF.
Each r e s i s t o r i s about 3 inches long and about 0.07 inch i n diameter so t h a t
t h e s e v e r a l r e s i s t o r s can e a s i l y be mountcd i n a tube of
inch diameter. The
assembly i s properly i n s u l a t e d and enclosed i n a t h i n coppcr tube. The thermometer i s bolted t o t h e s a f e t y r i n g on t h e t a l l superstructure of t h e buoy.
Water Thermometer.- The water thermometer i s of t h e same type a s t h e
a i r thermometer except f o r heavier i n s u l a t i o n t o prevent s h o r t c i r c u i t i n g . I t
i s mounted on a separate buoy 2 f e e t i n diameter and 18 inches high connected
t o t h e main buoy by a hinged frame. This arrangement keeps t h e thermometer a t
approximately constant depth below t h e surface. If it were mounted on t h e
buoy t h e r o l l i n g of t h e l a t t e r would often submerge it deeply or r a i s e i t out
of t h e water.
Anemometer.- The anemometer i s an ordinary three-cup instr.urnent making
I t i s mounted on t h e uppermost
p a r t of t h e buoy.
150 contacts f o r a run of one mile of wind.
Transmitter.- A f i v e tube t r a n s m i t t e r with an output of about 3 watts,
t r a n s m i t t i n g a t a frequency of 62.4 megacycles, i s mounted i n a watertight
comgartment on t h e s u p e r s t r u c t u r e of t h e buoy. The antenna extends t o a
height of about 24 f t . above t h e waterline.
Receiver.. The transmissions from t h e buoy e r e received by a communicat i o n s r e c e i v e r with i t s output fed t o an e l e c t r o n i c frequency meter, which
i n d i c a t e s d i r e c t l y on a meter d i a l the frequency of t h e pulses received from
t h e buoy (100 t o 500 cycles per second).
Power Sunply.- The e n t i r e apparatus, including a f l a s h i n g red navigat i o n l i g h t , i s powered by 3 l o w discharge type DHB-5-1 c e l l s f o r t h e filament
power and f i v e L a y e r b i l t "B" S a t t e r i e s i n s e r i e s f o r t h e p l a t e supply. The
ICAO Circu!
Page 34
ZT
13-iG,'X-
t,
o r replecel i f e of t h e b a t t e r i e s i s t e n t o twelve months, i v F t h ~ ~recl?.rging
If
t
h
e
cup
anemometer
could
b
e
used
t
o
r
e
c
h
a
r
g
e
t
h
e
b
a
t
t
e
r
i
e
s , the
ment.
p e r i o d of t i n e between s e r v i c i n g s co:~.ld be extended t o w e l l over a y e a r .
-Operation.- Every 3 hours an e l e c t r i c c l l y uo:md c l o c k ~13'zcsc o n t a c t ,
s t a r t i n g a motor which d r i v e s 5 t i m i n g cans 2nd t u r n i n g on t h e f i l a m e n t s and
h e a t e r s of' t h e t r a n s m i t t e r , The r e l a y s t o t h e v a r i o u s r e s i s t a n c e elements a r e
completed i n t u r n which t h u s a l t t r t h e f r e q ~ e n c j rof t h e b r o a d c a s t s i g n a l i n
r e l a t i o n t o t h e v a l u e of t h e element b e i n g measured.
-
Accu-.A f t e r two s e a s o n s of o-?er,;tioyl, t h e i n s t r t u n e n t s were r e c a l i ' ~ r a t e d . The a i r thermometer s t i l l had i t s c r i g i n a l r e l a t i o r i s h i p between
r e s i s t e n c e and temperature. However, t h e water thermometer was r e p d i n g
3 . 5 9 t o o h i g h a t '72'3' and 2.5%' t o o Sigh a t 3 2 9 . T h l s i n d i c a t e d a l o t ~ e r i n g
of r e s i s t a n c e , s u g q e s t i n g t h e e n t r y of w s t e r . Hocsever, t h i s d i s c r e ? a n c y h a s
been c o r r e c t e d . The anemometer sho\:cd no v a r i a t i o n .
-
No s p e c i f i c i n f o r m a t i o n i s a v a i l a 5 l e concerning a c t u a l c o s t of
-*C o s t
t h e i n s t r u m e n t o r i t s maintenance. With the e x c e ? t i o n nf t h e r e s i s t o r s , a l l
t h e components of t h e programxe c i r c u i t z r c com5iercial ? r o d u c t s , I t i s worthy
of n o t e t h a t t h e e n t i r e development was c e r r i e d olut t i i t h d e p a r t m e n t a l f a c i l i t i e s , i n c l u d i n g t h e c o n s t r u c t i o n of a l l a p p a r a t u s n o t commercially a v a i l a b l e ,
--2.3,-
French S t a t i o n s
-
2.3.1,- Automatic Keather S t a t i o n
of t h e French N a t i o n a l M e t e o r o l o a i c n l S e r v i c e
The a u t o m a t i c w e s t h e r s t a t i o n , of t h e t y y e developed by t h e M6t6oroloaie
i s designed t o t r a n s m i t by r c d i o - t e l e g r a p h y , over a r a n g c of more
,et h a n 1500 kms, s i g n a l s c o r r e s 2 o n d i n g t o t h e v a l u e s of p e s s u r t , t e m p e r a t u r e ,
l i m i d i t j . , wind ( d i r c c t i o n and speed) and amount of p r e c i p i t a t i o n . P r o v i s i o n
h a s been made t o add an a p p a r a t u s which w i l l p e r m i t t h e s t ~ t i o nt o t r a n s m i t
t h e t e m p e r a t u r e a t t h e c l o u d b ~ s e ,which wo~rld e n a b l e one t o make a good
approximation of t h e t p e of clotid and t h e h e i g h t of t h e b a s e , a s w e l l a s
a n o t h e r a 2 p a r a t u s t o i n d i c a t e t h 3 t E s t o r r n o c c u t r c , d i n 5he v i c i n i t y c f t h e
s t a t i o n a t a yiven hour o r d u r i n g t h t~h r e e hours p r e c e d i n g t h e t i n e of trmsmission.
Page 35
ICAO C i r c u l a r 13-&3/ll
The s t a t i o n includes?
a)
A p r e c i s i o n clock equipped with e l e c t r i c a l rewinding apparatus;
b)
S p e c i a l l y equipped meteorological instruments;
c)
An apparatus f o r remote c o n t r o l and f o r telemetering;
d)
A double short-wave pulse t r a n s m i t t e r ( 2 weve l e n g t h s ) ;
e ) A power supply comprising a bank of accumulators and a windd r i v e n generator.
General P r i n c i p l e s of O ~ e r a t i o n
The clock mechanism i n t h e s t a t i o n a c t u a t e s a t given hours t h e c l o s i n g
of a c i r c u i t which c o n t r o l s r e l a y of t h e remote c o n t r o l apparatus which i n
t u r n a p p l i e s v o l t a g e t o t h e tube filaments of one of t h e t r a n s m i t t e r s .
After a s u f f i c i e n t time i n t e r v a l , high t e n s i o n i s applied t o t h e anodes
and t o t h e screen g r i d s of t h e t r a n s m i t t e r which, a s from t h i s moment, i s
ready t o function.
The telemetering apparatus c o n t r o l s t h e successive sending by t h e t r a n s m i t t e r of s e v e r a l s e r i e s of d i s t i n c t s i g n a l s , t h e number of s i g n a l s i n a
s e r i e s being between 1 and 10:
1) The f i r s t s e r i e s of s i g n a l s corresponds t o t h e s t a t i o n
indicator;
2) S e v e r a l s e r i e s of s i g n a l s correspond to:
t h e barometer r e a d i n g
- 2 figures
t h e thermometer
-
lt
theraingauge
t h e hygrometer
t h e anemometer
t h e windvane
t h e measurement of
( u n i t s and t e n s )
2 f i g u r e s ( u n i t s and t e n s )
- 1 f i g u r e (unitsonly)
- 2 f i g u r e s ( u n i t s and t e n s )
- 1 f i g u r e ( u n i t s only)
- 1f i g u r e ( u n i t s only)
cloud base - 2 f i g u r e s ( u n i t s and t e n s )
t h e storm i n d i c : ~ t o r
- 1figure
( u n i t s only).
ICAO C i r c u l a r 1 3 - ~ , / 1 l
Page 36
-.
When t h i s c y c l e has been t r a n s m i t t e d t h r e e stlccessive t i m e s t h e a p p a r a t u s
reassumes i t s standby c o n d i t i o n a f t e r , having c u t t h e high and low t e n s i o n
current supplying t h e transmitter.
A wind-driven g e n e r a t o r p r o v i d e s f o r t h e c h a r g i n g of t h e accumulators
supplying t h e t r a n s m i t t e r u n i t . Radio r e c e p t i o n i s obtained by means of a
r e c e i v e r s p e c i a l l y adapted f o r t h e r e c e p t i o n of t h e impulses and which cont r o l s a n o s c i l l o g r a p h f o r r e g i s t e r i n g on a s t r i p of paper t h e s i g n a l s s e n t o u t
by t h e t r a n s m i t t e r :
Description
-
E l e c t r i c Clock.- The e l e c t r i c pendulum c l o c k u t i l i z e d i s of t h e w a l l
t y p e , which has a r e s e r v e p e r i o d of o p e r a t i o n ensured by means of a s m a l l
e l e c t r i c motor f o r t h e rewinding of t h e clock.
Two s e r i e s of s t u d s a r r a n g e d on a mobile d i s c operated by t h e c l o c k
e n a b l e two d i s t i n c t c o n t a c t s t o be e s t a b l i s h e d a t t h e proposed hours of t r a n s mission, t h e s e c o n t a c t s b e i n g r e l a t e d e l e c t r i c a l l y t o t h e remote c o n t r o l s e t .
One of t h e s e c o n t a c t s corresponds t o t h e daytime high frequency, t h e o t h e r t o
the n i g h t - t i m e high frequency, t h u s p e r m i t t i n g t r a n s m i s s i o n s t o be made under
t h e most f a v o u r a b l e p r o p a g a t i o n c o n d i t i o n s .
M e t e o r o l o ~ i c a lInstruments.- The s e n s i t i v e elements of t h e i n s t r u m e n t s
a r e i d e n t i c a l w i t h t h o s e of t h e r e c o r d i n g i n s t r u m e n t s which a r e used i n meteoro l o g i c a l s t a t i o n s . The s t y l u s of each a p p a r a t u s i s provided a t i t s e x t r e m i t y
w i t h two c o n t a c t p o i n t s and moves w i t h o u t f r i c t i o n i n f r o n t of a v e r t i c a l c o l l e c t o r c a r r y i n g two s e r i e s of c o n t a c t s , t h e f i r s t corresponding t o t h e u n i t s ,
t h e second t o t h e t e n s ( t h e r a i n gauge, anemometer and t h e windvane a r e o n l y
provided w i t h a simple c o l l e c t o r corresponding t o t h e sending of a s i g n a l
having o n l y one f i g u r e ) .
The w i r e s f o r t h e t e n s of t h e same v a l u e a r e a l l i n t e r c o n n e c t e d on t h e
c o l l e c t o r s and t h e n l e d t o t h e t e n s c o n t r o l j a c k s of t h e switchboard; t h e
same a p p l i e s a s r e g a r d s t h e u n i t s w i r e s .
A t t h e time of t h e o b s e r v a t i o n , a " f e e l e r t 1 e n s u r e s t h e c o n t a c t of t h e
s t y l u s on one o r more s t u d s corresponding t o t h e v a l u e of t h e r e a d i n g provided
by t h e s e n s i t i v e element.
Remote C o n t r o l and Telemetering Apparatus.- T h i s a p p a r a t u s c o n t r o l l e d
by t h e c l o c k and t h e m e t e o r o l o g i c a l i n s t r u m e n t s has a s i t s f u n c t i o n :
Page 37
ICAO C i r c u l a r 1 3 - ~ d / l l
'
1 ) S e t t i n g t h e t r a n s m i t t e r i n o p e r & t i o n a l order a f t e r a ?rearranged tirne i n t e r v a l ;
2) Connecting t h r e e times t h e v a r i o u s meteorological instruments
and t h e s t a t i o n i n d i c a t o r i n suczession;
3) Ensuring t h e t r a n s n ~ i s s i o nof a c e r t a i n number of s i ~ n n l scorrespondicg s n c c e s s i v e l y Lo t h e f i g u r e s f o r t e n s and mits;
4 ) C u t t i n g t h e power supply t o t h e t r a n s m i t t e r when t h e t h i r d
sweep of t h e instruraent c o n t s c t o r has been e f f e c t e d .
Arrangement of t h e Signals.- The transmission of each f i g u r e (unit o r
tens) corresponds t o a s many transmissions of f o u r I F p.dses of' a d u r a t i o n cf
40 microseconds
t r a n s d t t e d a t a frequency of a hmdred ?er second
as there
,me u n i t s i n t h e f i g u r e s t o be transmitted. These d i s t i n c t t r z n s n i s s i o n s each
j e i n g t h e r e f o r e of a d u r a t i o n cf 40-milliseconds a r e separated one froin t h e
s t h e r by 3 c o n s t a n t time i n t e r v a l .
-
-
T!le r e c e i v e r i n t e p a t e s t h e s e r i e s of f o u r s h o r t p u l s e s (40 microseconds) and t h e pen of the recording o s c i l l o g r s p h marks a t i c k on each recept i o n of a group of f o u r p u l s e s ,
P u l s e Transmitter.- The apparatus used i s a pulse t r a n s a i t t e r , The
transmission can b e made on t w o d i s t i n c t IiF channels, each one connected t o
t v o d i f f e r e n t antennae:
Channel 1. 20 t o 11.1 MC/S.
Channel 2.
(15-27 metres);
11,7 t o 6.5 ~ c / s . (25.6-46 metres).
The p u l s e transmissions permit one t o o b t a i n a peak antenna 7ower g r e c t s r
?hnn 1-Kw s i n c e t h e average power does n o t exceed 4-watts, whereby an import a n t economy of e l e c t r i c n l energy f o r a given range i s obtained.
Two tuSes i n p a r a l l ~ l a r ei n use a t each s t a y e of t h e t r a n s m i t t e r s , i n
:such a way t h a t Lhe f u n c t i o n i n g i s maintained i f a f i l a m e n t i s broken. The
antennae used a r c of t h e Conrad type,
Power Suoulv A ~ ~ a r z t u s .The
power consumption of t h e s t a t i o n (converter,
r e l a y , h e z t i n g of t h e r z d i o tubes) i s 20C w a t t s f o r t h e t v o minutes taken by
each transmission. The c u r r e n t necessary i s supplied by a converter 24 v o l t s
1>c/I10 v o l t s A C / ~ O ps. The sup;Ay t o t h e c o n v e r t e r i s assured by a bank of
accumulators of 24 v o l t s , t h e charging of which i s obtained by means of a winddriven &;enerator s p e c i a l l y ada2ted f o r t h i s purpose.
Page 38
are
the
for
180
ICAO Circular 13-~l\;hl
The accumulators of a s p e c i a l type with a l a r g e r e s e r v e of e l e c t r o l y t e
equipped w i t h an a u x i l i a r y apparatus which ensures a w n s t a n t l e v e l i n
c e l l s by means of an automatic supply of d i s t i l l e d water t o compensate
t h e evaporating e l e c t r o l y t e . The capacity of t h e b a t t e r y i s normally
ampere hours.
The wind-driven generator has a nominal power of 150 watts/24 v o l t s ,
i t s tapered form and t h e s p e c i a l arrangement of t h e p r o p e l l e r p e r m i t t i n g i t t o
r e s i s t s t r o n g g u s t s of wind, Thc compactness of t h e streamlining ensures
e f f e c t i v e p r o t e c t i o n f o r t h e i n t e r n a l mechanisms a g a i n s t inclement weather. A
d i f f e r e n t i a l make-break c o n t a c t permits t h e u s e of t h e apparatus even during
periods of l i g h t winds and i n a d d i t i o n avoids supplying c u r r e n t t o t h e accwnul a t o r s when t h e l a t t e r a r e s u f f i c i e n t l y charged, The wind g e n e r a t c r i s f i x e d
a t t h e t o p of a t u b u l a r mast 8 metres i n height and i s made secure by means
of t h r e e guy wires.
Installation
The enclosure (See Figure X I ) should be s e l e c t e d i n a s i t e a s open a s
p o s s i b l e , t h i s preliminary c o n d i t i o n being favourable both f o r t h e t a k i n g of
meteorolcgical observations and f o r t h e good propagation of r a d i o e l e c t r i c
transmissions.
A s f a r a s p o s s i b l e a s i t e immediately a d j o i n i n g t h e seacoast should be
avoided, s i n c e t h e s a l t and i o d i z e d a i r causes p a r t i c u l a r l y a c t i v e chemical
corrosion of t h e d i f f e r e n t metals which a r e used i n t h e c o n s t r u c t i o n of t h e
automatic s t a t i o n . I n t h e same way one should avoid very humid l o c a t i o n s ,
Whenever p o s s i b l e one should avoid making an i n s t a l l a t i o n on a rocky s u r f a c e
which w i l l i n c r e a s e t h e d i f f i c u l t i e s of f i x i n g t h e guy wires and, i n a d d i t i o n ,
p r e s e n t s some d i f f i c u l t y i n t h e e a r t h i n g of t h e r a d i o equipment,
The ground necessary f o r t h e i n s t a l l a t i o n of t h e s t a t i o n should have
t h e following dimensions: 25 x 35 metres, t a k i n g i n t o account t h e i n s u l a t e d
antenna w i r e s and t h e guying of t h e pylon f o r t h e wind-driven generator.
Weight of t h e Eauipment
A l l t h e equipment, meteorological instruments, r a d i o t r a n s m i t t e r s and
a c c e s s o r i e s weigh 2,500 kilograms. To t h i s t o t a l should be added t h e hut
(constructed a t t h e s e l e c t e d l o c a t i o n ) and t h e v a r i o u s m a t e r i a l s r e q u i r e d i n
t h e p r e p a r a t i o n of t h e concrete used f o r t h e mounting of t h e pylons, f o r t h e
instrument s h e l t e r and f o r t h e enclosure.
Fig. X I
-
French automatic weather s t a t i o n S i t e
Station m6t6orologique frangaise
Implantation
Estaci6n meteorol6gica a u t o d t i c a francesa
Instalacidn
-
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ICAO Circular 13-AX/ll
Page LJ
T r i a l s of t h e S t a t i o n
I n s t a l l e d a t Trappes during t h e month of December 1948 t h e a u t o m t i c
weather s t a t i o n has been i n continuous operation. Recordings made a t 3 r e s t
snd a t Acnccy have ziven every s a t i s f n c t i o n .
2.3,2,- Automatic Weather S t a t i o n Mlintained by t h e French
M e t ~ o r o l o ~ i c Ss el r v i c e on t h e t o 3 of t h e E i f f e l Tower
A t t h e present time t h e r e i s an automatic weather s t a t i o n i n s t a l l e d a t
the top of t h e E i f f e l Tower i n P a r i s . Since t h e time of i t s i n s t a l l a t i o n i n
1942, t h e transmissions t o t h e headquarters of t h e Meteorologicel Service
hsve been by l a n d - l i n e communications. However, a r a d i o t r a n s m i t t e r of low
:20wer consumption !ias r e c e n t l y been u t i l i z e d . The r e s ~ r l t sof t h i s l a t e s t
i n s t a l l a t i o n h ~ v enot, a s y e t , been received.
M e t e o r o l o ~ i c a lElements Measured
Continuous observations of temperature, humidity and pressure a r c made
The number of records made
cnch d ~ j i' s 1,IAO f o r each element observed, a r e l a t i v e l y Iiigh f i g u r e which
,3ermits a c c u r s t e determination of the mean meteorological data.
n t one minute i n t e r v a l s throughout t h e . 2 4 hours.
Meteorological Instruments
-
Thermometer.- The s e n s i t i v e element, based on t h e Wheatstone bridge
system, i s contained i n an a i r - t i g h t metal tube, and two wires a r c used f o r
t h e tr?nsrnission. Each increment of 3.2% i s transmitted from t h e Tower 3nd
rcmotsly recorded.
Hy.~rometer.- A hygrometric instrument i s employed. I t i s exposed t o t h e
oien a i r a f a i r d i s t c n c e from t h e Tower with very l i t t l e protection a g a i n s t
the westher. Transmissions of r e l a t i v e humidity take place by a succession
of d i s c r e t e s t e p s , each s t e p averaging 3 t o 4 percent of s a t u r a t i o n .
-3arorneter
*
- A Richcrd W l - t w e s e n s i t i v e barometer i s used.
l;ior, concerning successive incrsments transmitted i s not a v a i l a b l e .
Informa-
Page
@
ICAO Circular 13-Al~/ll
Transmitter.- An i n t e r e s t i n g type of t r a n s m i t t e r , designed and produced
e n t i r e l y i n t h e workshops of t h e National Meteorological Office, h s s proved
t o be very successful. No f a i l u r e ascribable t o t h e a c t u a l p r i n c i p l e of t h e
device has been noted over s e v e r a l years of operation.
Receiver.- A permanent record of a l l observations i s m d e on a revolving
drum-tyse recorder. Each contact on the r o t a t i n g d i s c causes an e l e c t r o magnetic armature t o operate and t h e pen attached t o the l a t t e r marks a dot o r
g i p on t h e recording drum. Thus, t h e observer may take frequent readings from
the recording device located i n t h e instrument room, o considerzble d i s t z n c e
from t h e place of recording.
-
Maintenance,- The only normal servicing required i s a l u b r i c a t i o n of
t h e e l e c t r i c motor and o t h e r moving p n r t s a t i n t e r v a l s of s i x months,
Power S U X ) P ~ ~The
. - power supply, apparently from the municipal u t i l i t i e s ,
i s an a l t e r n a t i n g c u r r e n t r e c t i f i e d by copper oxide c e l l s cind f i l t e l - e d by a
condenser of about 1 0 microfarads.
Cost.- Since t h i s instrument was produced and i s maintained e n t i r e l y
by t h e National Meteorological Office, no s p e c i f i c information i s a v a i l a b l e
concerning a c t u a l cost.
Comments.- Continuous observations of l a p s e r a t e of temperature, humidity
and pressure from t h e surfoce t o t h e top of t h e E i f f e l Tower heve yielded
valuable information f o r purposes of s t r a t u s cloud and temperature f o r e c a s t i n g
and three-dimensional research.
2.4.-
Automatic Weather S t a t i o n s i n t h e U.S.S.R
I t i s understood t h a t t h e r e i s a network of automstic weather s t a t i o n s
a l r e a d y established i n t h e U.S,S,R, which transmit observations on t h e average
l+times a day. The elements measured a r e pressure, temperature, wind speed
and d i r e c t i o n and, i n some cases, p r e c i p i t a t i o n . S t a t i o n s have already been
established on t h e Plurmansk c o a s t , i n t h e Kara Kum d e s e r t and on one of t h e
i s l a n d s i n t h e Aral Sea. The s t a t i o n s have a range of 375 miles and a r e
designed f o r a y e a r ' s operation without any servicing.
Page 43
ICAO C i r c u l a r 1 3 - ~ ~ / l l
2.5
.-
German Automatic g e a t h e r S t a t i o n s
Two types of automatic s t a t i o n s were developed and u t i l i z e d i n Germany
during t h e 1939-1945 war: a marine type, mounted on a buoy and a type f o r
use on land. The d e t a i l s of t h e s e instruments a r e summarized below.
A)
Marine Type
The buoy has more o r l e s s t h e same shape and s i z e a s a torpedo. A
system of anchorage, made up of a cable and a heavy weight maintains t h e buoy
i n a f i x e d p o s i t i o n (experiments have shown t h s t during s t r o n g winds and a t a
depth of 2,000 metres, t h e s t a b i l i t y t h u s obtained i s s a t i s f a c t o r y , and t h e
d r i f t does n o t exceed more than a f e w n a u t i c a l miles over a period of s e v e r a l
months). Moreover t h e c e n t r e of g r a v i t y of t h e buoy has been placed low
enough t o make i t s r o l l i n g n e g l i g i b l e . The t e n s i o n plaque b a t t e r y i s of t h e
d r y type of 900 v o l t s maximum, mounted i n a c y l i n d e r i n t h e i n t e r i o r of which
s l i d e s a second f l o a t i n g c y l i n d e r carrying t h e heating b a t t e r y adapted f o r
t h r e e months operation, t h e t r a n s m i t t e r and t h e clock mechanism f o r t h e
purpose of s t a r t i n g t h e functioning of t h e s t a t i o n ,
The t r a n s m i t t e r i s a Lorentz with a 100-150 w a t t antenna, mounted on
7,000 kcs. (about
s p r i n g s 8nd covering a range of frequencies from 3,800
43 metres). The clock mechanism which, f o u r times a day, a t t h e required
79
i n t e r v a l s , provides f o r t h e operation of t r a n s m i t t e r c i r c u i t s and t h e operat i o n of t h e measuring instruments i s a Siemens s p r i n g model, having a reserve
period of operation of s e v e r a l hours and i s rewound a t r e g u l a r i n t e r v a l s by
an e l e c t r i c a u x i l i a r y motor. A meticulous s e t t i n g of t h e frequency of t h e
c o n t r o l l i n g mechanisms appears t o ensure t h a t the clock s h a l l have an adequate
operating precision.
-
-
The antenna i s t e l e s c o p i c and has a v e r t i c a l extension of 8 metres. A t
i t s base a r e arranged t h e instruments f o r measuring t h e meteorological e l e ments. The telemetering system of t h i s apparatus f u n c t i o n s i n t h e following
nanner:
A c e r t a i n number of m e t a l l i c d i s c s , each one bearing i n r e l i e f
one o r more morse code l e t t e r s i n such a way t h a t each d i s c c o n s t i t u t e s
a d i f f e r e n t s i g n a l , a r e s e t up one above t h e o t h e r , each one of them
being separated from i t s neighbour by a s i m i l a r d i s c made of nonconducting material. I n t h i s way a revolving c y l i n d e r i s provided which
has a uniform movement. The stylus-arms of t h e meteorological measuring
instruments move over t h e e x t e r i o r s u r f a c e of t h i s c y l i n d e r with which
theyvare i n contact, one a f t e r t h e o t h e r a t t h e time of t h e observation;
when t h e m e t e o r o l o g i c ~ lelement corresponding t o one of t h e s t y l u s
r e c o r d e r s v a r i e s , t h i s s t y l u s moves along t h e g e n e r a t r i x of t h e c y l i n d e r
Page 44
ICAO C i r c u l a r 13-Al~/ll
and a t t h e time of t h e observation makes contact with one or t h e other
of t h e d i s c s bearing t h e Morse l e t t e r s i n such a way t h a t t h e s i g n a l
corresponds t o a value of t h e element being measured.
Ivloreover, t o d i s t i n g u i s h unlllrstakably t o which element t h e transmitted
s i g n z l corresponds, t h e stylus-arms a r e arranged asymmetrically on t h e
e x t e r i o r surface of t h e c y l i n d e r , I t i s simple t o transmit a s p e c i a l s i g n a l
or "pip" a t t h e beginning of each revolution of t h e cylinder i n order t o rnark
t h e beginning of t h e measurem~nt,
F i n a l l y , t h e cylinder-stylns mechanism comprises a morse manipulator f o r
t h e t r a n s m i t t e r s o t h a t each observation transmitted by t h e buoy i s composed
of a c e r t a i n number of l e t t e r s (as many l e t 5 e r s a s t h e number of elements
measured) each group of l e t t e r s corresponding t o t h e value of one of t h e s e
elements a t t h e time of observation, The measuring instruments used were two
barometers having Vidi capsules, t h e f i r s t giving an approximate value of
pressure, t h e second supplementing t h e first value t o give t h e exact pressure;
a Bourdon tube thermometer f o r t h e a i r temperature and a bi-metallic thermometer
f o r t h e water tem?erature,
An apparatus f o r measuring t h e d i r e c t i o n and speed of t h e wind has been
studied but was not used on t h e buoys,
The accuracy obtained was within plus or minus one milibar, and within
p l u s o r minus one degree centigrade. The messages were given i n t h e following
form: A: B: C: D: T t A being t h e approximate pressure reading, B being
t h e complementary pressure reading i n order t o obtain t h e pressure reading t o
t h e n e a r e s t m i l l i b a r , C being t h e water temperature, D t h e a i r temperature,
and T t h e s t a t i o n i n d i c a t o r , The duration of t h e broadcast was one minute,
and during t h i s minute t h e measurement group was repeated twelve times, which
r e p r e s e n t s a very acceptable standard of operation.
Buoys of thSs t.ype were i n s t a l l e d i n t h e following regions:
a)
Atlantic
b)
Baltic
Gulf of Bothnia
c)
Mediterranean
43'~
9OE
d)
Black Sea
4.4'~
37'~
42'~
31'~
Page 45
ICAO C i r c u l a r 13-AN/ll
____1
The broadcast frequencies were s e l e c t e d t o secure t h e
t h e Germans, it seems, r e c e i v e d 80 905 of t h e messages a t
1,000 and 2,000 Kilometres i n middle l a t i t u d e s and 50
603
l a t i t u d e s . S e v e r a l l i s t e n i n g s t a t i o n s were responsible f o r
inessages i n order t o improve t h e chances of success.
-
-
best results.
a d i s t a n c e of
i n northern
picking up t h e
B) Tme f o r Use on Land
The c o n s t r u c t i o n of t h e s t a t i o n s f o r use on land i s of t h e same type
a s t h e buoy and only t h e antenna is d i f f e r e n t . I t i s mounted on a t r i p o d
mast, each l e g of which houses one of t h e t h r e e main instruments. The t o t a l
weight of t h e s t a t i o n i s two and a h a l f tons, and t h e b a t t e r i e s ensnre operat i o n f o r a period of s i x o r nine months. An anemometer and a wind vane could
e a s i l y be added, t h e question of weight being q u i t e secondary. F i n a l l y , a
clock-work operated system permits t h e s t a t i o n t o transmit two s e r i e s of
l e t t e r s i n s t e a d of one: t h e second s e r i e s giving, f i r s t l y , t h e wind d i r e c t i o n
i n two l e t t c r s ; secondly,the wind speed i n two l e t t e r s ; and t h i r d l y , a repet i t i o n of t h e s t a t i o n i n d i c a t o r .
S t a t i o n s of t h i s type were established p r i n c i p a l l y i n t h e following
l o c a t i o n s : Bear I s l a n d , Spitzbergen, J a n Mayen, Novaja Zemlya, i n t h e Aaland
I s l a n d s and i n Labrador, According t o t h e Germans, t h e instruments gave
s a t i s f a c t o r y r e s u l t s even i n t h e extremely severe c l i m a t i c c o n d i t i o n s t o which
t h e y were subjected.
A f t e r almost 1 0 y e a r s of experiments, t h e S t a t e s which have undertaken
r e s e a r c h on automatic weather s t a t i o n s have modified and improved them t o
such an e x t e n t t h a t a high degree o f accuracy and r e l i a b i l i t y i s now obtaina b l e i n t h e i r operation. Moreover, with t h e a d d i t i o n of t h e wind-driven
e l e c t r i c generator t o chnrge t h e lead-acid s t o r a g e b a t t e r i e s , t h e l e n g t h of
time between s e r v i c i n g s can probably be extended t o a year o r more.
The examples given above of e x i s t i n g and s u c c e s s f u l l y o p e r a t i n g automatic wsather s t a t i o n s c l e a r l y i n d i c a t e t h a t t h e y can be used t o o b t a i n weather
information from i s o l a t e d p l a c e s on a r o u t i n e b a s i s and a r e adaptable- t o varyi n g c o n d i t i o n s of climate and l o c a t i o n . Thus f a r , no information has been
received concerning t h e performance of automatic weather s t a t i o n s i n d e s e r t
regions although t h e r e i s no reason t o suppose t h a t they cannot r e a d i l y be
adapted f o r use i n such a r e a s .
d ' a ~ e46
ICAO C i r c u l a r 13-&:/ll
P r a c t i c a l recognition of the importance of automatic weather s t a t i o n s
has been evidenced i n t h e r e p o r t s of t h r e e ICkO Regional A i r Navigation
Heetings, v i z . , Middle East, South P a c i f i c and South A t l a n t i c and i n t h e ICAO
luIissionls t e c h n i c a l r e p o r t on A i r Navigation f a c i l i t i e s i n Iceland.
S t a t e s , i n whose a r e a s s p a r s e and inadequate weather r e p o r t i n g networks
a x i s t may, t h e r e f o r e , f i n d i n t h i s p u b l i c a t i o n s u f f i c i e n t j u s t i f i c a t i o n f o r
re-considering t h e p o s s i b i l i t y of supplementing such networks by a s e r i e s of
i 3 u t o ~ t i cweather s t a t i o n s l o c a t e d a t t h e most s i g n i f i c a n t p o i n t s .
The establishment of automatic s t a t i o n s i s a l r e a d y recommended f o r t h e
following locations:
1)
J a r v i s Island
- Approximotely 1200 miles
o.~OS,
2)
south of Hawaii,
160%.
-
a r e e f i n the South A t l a n t i c approximately
Rochedos Sao Paulo
half-way between Dakar, French West Africa and
Natal, B r a z i l .
3) Fjordungsvatn, Iceland
-
A small l a k e approximately i n t h e c e n t r e
of Iceland.
L,- BIBLIOGRAPHY
1) Automatic Weather S t a t i o n , Navy Model TDM-1, Navships 900,832,
Bendix Aviation Corporation, F r i e z Instrument Division, Baltimore 4,
Maryland, U.S.A,
2)
A Buoy Automatic Weather S t a t i o n , !.i.E, Knowles Middleton, Meteoro l o g i s t , Department of Transport, Toronto, Ontario and LoEo ' C o f f e ~ ,
Radio Engineer, Department of Transport, Ottawa, Ontario, P. 122-129,
Vol. 2, Number 2, June 1945, *'The J o u r n a l of Meteorologyn.
3)
Automatic Weather S t a t i o n s , JeS.Fo
p. 197-198 "Weather".
- Vole 22 b ~ . ~ ~ b7,e rJ u l y 19479
4 ) T&16m&t60rographeR, S t r u t z , Modble O,NoM, e t int6graphe m6t6orologique par R. S t r u t z , E.E,R,M,
S e r v i c e , Instruments 9M6thodes
dlObservation. Etudes instrumentales.
ICAO Circqlar 13-AN/=
Page 47
5) Autornatic meteorological s t c t i o n network i n the U.S.S.R,
Anon.
Journal of S c i e n t i f i c Instruments, London 23, 1946, p. 192.
Pear, Radio equipment f o r an un-manned weather s t a t i o n .
B. Amer. Met. S. 21, 1940, pp. 107-110,
6) C.B.
-
7)
Diamond & Hinman. An automatic weather s t a t i o n Washington,
J. Res. Bar. Stand. 25, 1940, pp. 113-148. (Scj-0 Abs. 1882 B,
October 1940). See J. Sc. Instru., London, 18, 1941, p. 16; Abs.
S c i , 8 Tech. P r e s s , 25321, November, 1940; Milan, Geof Pma
Appl. 2, 1940, pp, 220-223.
8)
Diamond & Hinman. Remote automatic weather observations.
Met. S. 21, 1940, pp. 343-349.
9)
11. Diamond,
B. Amer.
Recent application of radio t o the remote indication
of meteorological elements. Repr. from: New York, N,Y,
Elect,
Engin. April, 1 9 U , pp. 163-167.
,
10) Wood. Automatic weather stations.
1946, pp. 115-121.
J. met. Amer, Met. Soc. 3,
Washington P.U.S.
11)
Coates. The Automatic weather s t a t i o n .
I n s t . 73, 1947, pp. 1096-1103.
12)
A. P e r l a t . Les S t a t i o n s a$t60rologiques automatiques.
~ r o l o g i e ,July September, 1948, p. 196.
13)
A, Perlat. La S t a t i o n in6t60rologique automtique de l a Mgt6oroJan-Mars 1949
l o g i e nationale, "La M6t60rologien
-
Naval
La Gt6-
-
I t i s desired t o acknowledge the kind cooperation of the following i n
making avai'lable the i l l u s t r a t i o n s contained i n t h i s Circular:
Pa.:le 42
I C A O Circular 1 3 - ~ 1 t ' / ~
-
F i g ~ e sI, 11, 111, I V , V, V I , V I I , V I I I and I X
The Bendix Aviation
Corporation, Briez Instrument Division, Towson, Baltimore 4, Maryland,
U.S.A.
-
Figure X
Journal of Meteorology, American ~ e tbrological
e
Society,
Vol. 2, No. 2, June 1945.
-
Figure X I
La M&t&orologie,Annuaire de l a Societd rn6t6orologique de
France, Janvier
Mars, 1949.
-
- END -