Royal - HKU Libraries - The University of Hong Kong

More documents

Recommendations

Info

A weather radar is mainly used to monitor the location,movement and-development of rain areas, and is particularlyuseful in locating the centres of tropical cyclones withinthe radar's range.The Royal Observatory began using radar for weatherobservation and forecasting in 1959. The first installationwas a Decca storm warning radar with a maximum range of250 nautical miles based on top of Tate's Cairn. Thisequipment was used for nearly 20 years, until June 1979.However, in December 1966, a second radar, with amaximum range of 240 nautical miles, had been installed atTate's Cairn.In early 1983 a new computer-based radar was installed atTate's Cairn. This equipment has three elements: the Tate'sCairn installation; a data processing station at the RoyalObservatory; and a remote display station at the airportmeteorological office.Computerised equipment at each station can produce aconstant altitude plane position indicator — basically adisplay of a horizontal cross-section of the atmosphere at aspecified altitude. Other special displays can also beproduced on a coloured screen. Different rainfall intensitiesare indicated by different colours.The radar antenna at Tate's Cairn is a 3.6 metre diameterdish. The sensitive receiver can detect rainfall rates aslow as 0.6 mm an hour at the radar's maximum range of450 kilometres.In normal operation the antenna scans helically upwardsat six revolutions a minute. At the maximum elevation of 37degrees, the antenna is lowered and the helical scan repeated.Microprocessors generate cross-sectional displays up to 20kilometres in height at one kilometre intervals. A microwavelink carries the data to the Observatory.At the Observatory, a minicomputer can generate one ormore of these special displays at the operator's command:• An echo top map showing the heights of the tops ofrain areas;123
* Vertical section through the atmosphere across anytwo selected points;* A rainfall accumulation map displaying accumulatedrainfall over a specified time;* A forecast of horizontal cross-sections for two hoursahead, based on past movement and development of rainareas;* A forecast of rainfall rate for a specified period for 16selected points, and* Map overlays.These displays can be sent to the airport meteorologicaloffice. A time lapse system allows up to 100 displays of anytype to be stored and replayed at high speed to help aforecaster follow the movement and development of rainareas.If necessary, the scan data can be stored on magnetic tapefor future research.The system thus allows forecasters to monitor the threedimensionalmovement and development of rain areaswithin a volume 450 kilometres in radius and 20 kilometreshigh centred on Tate's Cairn.It also provides the information required for short range(two hours ahead) forecasts of rainfall intensities, which areuseful for heavy rain warnings. The storage ability givesresearchers much valuable information about the movementand development of weather systems in the Hong Kongarea.Royal Observatory computer use:In 1968 the Royal Observatory began to use computersat the Government Data Processing Division for annualclimatological summaries. By the early 1970s, the amount ofdata available through the World Meteorological Organisationhad increased greatly, and in 1973 the Observatoryobtained its own computer system to receive and transmitmeteorological messages. This initial installation wasreplaced in July 1978, and the new system was enlarged in1982 to provide more facilities.124
Page 2:
UNIVERSITY OFHQ,NG KONG>**"/////»I
Page 5:
The Royal Observatory, Hong KongJIM
Page 8 and 9:
The effect of climate on human cond
Page 11 and 12:
IntroductionIifc on earth is possib
Page 13 and 14:
Theories had been developed: as ear
Page 15 and 16:
Then came another important scienti
Page 17 and 18:
thirty feet high, huge grotesque lo
Page 20 and 21:
Ancient Chinese astronomical instru
Page 22 and 23:
Chapter 1KSJSJOJ/ do think that, of
Page 24 and 25:
work of the observatory made no pro
Page 26 and 27:
its physical observations of the ph
Page 28 and 29:
period. The main building was recta
Page 30 and 31:
on metal pipe frames, were too ligh
Page 32 and 33:
Blackhead's Hill (Signal Hill) and
Page 34 and 35:
many previous storms when the wind
Page 36 and 37:
coast ports and the police in fact
Page 39 and 40:
European assistants, at least one o
Page 41 and 42:
... Mr. da Silva has resigned. . .
Page 43 and 44:
few minutes' warning of one of the
Page 45:
water height by up to several metre
Page 50 and 51:
I he early European traders, mercha
Page 52 and 53:
the sun's rays in tropical climates
Page 54 and 55:
coast; trees are broken or rooted u
Page 56 and 57:
Professor S. Wells Williams, anothe
Page 58 and 59:
We had a striking example in Hong K
Page 60 and 61:
Hong Kong lies just within the trop
Page 62 and 63:
Chapter 3OFCOTWETSEverybody talks a
Page 64 and 65:
The sun's disc had a diameter on th
Page 66 and 67:
Such detailed rules failed to impre
Page 68 and 69:
the periods before winter droughts
Page 70 and 71:
crossed into Hong Kong, followed by
Page 72 and 73:
inlet of Tola Harbour in the New Te
Page 74 and 75:
The war in Europe had spurred the d
Page 76:
Inset: The backs of these cigarette
Page 79 and 80:
It 8 am on 8 December 1941, 12 Japa
Page 81 and 82:
The records are all in pencil, neat
Page 83 and 84:
The civil staff was soon put to the
Page 85 and 86:
The department is in fact primarily
Page 87 and 88:
temperature down to 3J°C at the Ob
Page 89 and 90: moving directly towards Hong Kong,
Page 91 and 92: If the weather in 1965 was comparat
Page 93 and 94: since Typhoon Shirley in 1968. It h
Page 95 and 96: Radar observations early on 26 July
Page 97 and 98: almost as accurately as from a reco
Page 99 and 100: Waves smash over the praya at Kenne
Page 101 and 102: Chapter 5CLICKINGCCFTHEAt the prese
Page 103 and 104: November and December are normally
Page 105 and 106: move them a substantial distance in
Page 107 and 108: .. . wind blowing through the long
Page 109 and 110: for a series of fine weather and ca
Page 111 and 112: The typhoon of Saturday September 2
Page 113 and 114: Above: How the 1874 typhoon destroy
Page 115 and 116: Above: Aftermath of the 1923 blow w
Page 117 and 118: its of storm water which could be s
Page 119 and 120: he splitting of time into microscop
Page 121 and 122: The Third Congress of the World Met
Page 123 and 124: small craft. It includes 24-hour ar
Page 125 and 126: much of the Observatory's work invo
Page 127 and 128: The marine meteorology section of t
Page 129 and 130: The water shortage having become ve
Page 131 and 132: The signal was received by a helica
Page 133 and 134: The shock occurring yesterday after
Page 135 and 136: The Royal Observatory is part of tw
Page 137 and 138: acquired its own radar, which was u
Page 139: grass. Soil temperatures are read f
Page 143: of Mineral Resources recommended a
Page 148: Much of Hong Kong's population live
Page 153 and 154: BibliographyABEL, Clarke, Narrative
Page 155 and 156: IndexAbel, Clarkevisit to Hong Kong
Page 157 and 158: Macdonnell, Governor Sir Richard, 2
show all

Royal - HKU Libraries - The University of Hong Kong

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?