551'50~(51U)

Progress of Meteorological Instrumentation in India*

J" S. )L\TIlUH

Lid ia .1Leteurul/J/j icul [A'jHITI/lle/lI, S c,c lJelhi

(R<'cd ml 2V J Ulluar!J 100:)

t. IntroductionJ . l. Perhaps there can be no better prouf

uf the proyerb : '.Necc:-iSity is the )I other ofInvent ion ' than t he dl~\'('lopment of meteorulogi ­cal instrumentation in the India )!etcorolngicalDepa rt ment . \r ith the growing need for meteoro­logical data for various scientific disciplines andother applied fields, it became necessary to extendourmeteorologicalobserving net-workon a. country­wide ha..'-s iNand ahlU equip our obscrvntorics withmore and more tmphiliticutCtl instruments. In thocontext uf limited flnauciul resourccs, particnla.rlyi ll terms of foreign exchange, there was 110 otheraltcrnntivo but to take up the mrul1lfact uw of in­st ruments in Hie dcpurt meut its elf. A stnrt. wnsmade first in th o early thirt ies of this century bysetting up two smnll repairand maintellance unit sat Agra and PtJ011l~ in regard to upper air andsurface meteorological instruments respective ly.In course of time these t wo small units hccarne th ecent res of design, development and prOlluction ofroutin e meteorological instruments.

1·2. By 1938, tho workshop organisation at.Agra became a fairly well est ablished manufac­turingunit. aud started product ion of self-recordingmeteorcgrsphs and ot her simple meteorologicalinstrument s, far the exp loration of the upperatmosphere from a few selected stat ions in India.Similarly, the meteorological workshop at Poonastarted manufacturing tho routine surface meteo­rological instruments, such as, raingsuges andnnemometers. In t he yea r 1911, the workshop atAgTl\ \\0\5 moved to t ho now site of t he UpperAir Office at New Delhi. Progress was madehere on th o development of a suirable radi osondefor Indian conditions, which could be easilyfabricat ed from compo nents and materials locallyavailable and employing a simple techniqueso that t ho the n nvuiluble scient ific staff couldhandle t he instruments without much d ifficulty .I II order to expedite the development of SIlC] , aninstrument, tho t. wo unit s at NeW' Delhi and Poenawere encouraged to evolve a. suitable radiosc ude011 a compctitiv~ hl\.'iilol. This proved to he :\ vcry

-Presented at tho UNESCO Seminar on " Iasrrumcnentlou"(CSIO) and held at Chandlgarh from 12 to 16 November 1961

crhcaciou s method for the quick dcvvlojnueut ofthc ins trumen t. By 19-1':.! , both the centres evolvedtwo different t )1 )(':8 of radiosondes one using aclock-work called the e-Type Radiosonde and thoother using a fan called the F-Typo Radoisoudc.

1-3 During World War ll , need arose for gettingupper air temperature and humidity (bta from anumber of sturious in India ami these two cent reshelped in setting Ill' 13 to 1-1 radiosonde stationswithin a. few ycal'ij . The two types of rudioaoudoinstruments UfC still in use at six teen stat ions inIndia. These are, however, 011 the verge of ro­placcmmcnt by nudio-frequeucy modulated radio­sondea in which the meteorological parnm cterschan ge the electrical proI,erty of the sensor whichis made to frequency-modulate an nudio signal.Tho extent of audio-modulation det erm ines dievalue of meteorological parameter in quest ion.This development also came 1\S a matter cf nc­cessity, Tho previous sondes were of the mechnni­cal ~nHl nnd t herefure. subject tu errors due to zero­shift, and hysteresis. These Ronde' placed seriouslimitat ions 011 the accuracy of measurement andthe maximum height of observation. TIll' adventof jet. aircraft.in tho post-war period aml suporsonioaircraft of the future have made the need fa r morepressing for probing the atmosphere to \'cry llighlevels. A progri.unme of rcorg.lnising and expand­ing our workshops has been made to meet thoneeds of the time.

1,·1. Besides t he producti on of the convcu tion almeteorological instruments both for surface a llliupper air observations, tho department a lso pro­duces a very large number of specialised instru­ment s in t he field of geoph)'sic.., agr icul turalmeteorology and other a llied branches. In thesubsequent paragraphs a brief accuunt it! givenof some of th ese instruments.

2. Departmental Workshops

Each oue of t he workshops at Now Doll'; a llllPOOll:~ hi\~ three main divi sions, dz., (1) Machiuo­shop, (II) Assembly-shop and (iii) Design andDevelopment -shop_

organised by Central Scien ti flc Instrumcete Organisation