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<br />PRECIPITATION GAUGE SITES
<br />
<br />689
<br />
<br />altitude, from approximately 100 mm to 800 mm; this corresponds to 5-30 per cent of the measured values.
<br />Correction values are subject to the influence not only of altitude but also to regional differences, as a result
<br />of differentiated wind speeds and precipitation intensities. For stations in central Switzerland and in the
<br />valleys ofTicino and Valais, only small corrections needed to be made, larger ones were required for stations
<br />in northern and western Switzerland, the Jura, and the lower alpine regions, and major corrections were
<br />necessary for the stations in high alpine regions. Based on this analysis a new precipitation map for
<br />Switzerland, for the period 1951-1980, was drawn up (Kirchhofer and Sevruk, 1992). It is the first map with
<br />corrected annual precipitation amounts.
<br />
<br />CONCLUSIONS
<br />
<br />The suggested classification system of precipitation gauge site exposure provides a basis for quality control
<br />and error assessment of past and present precipitation data. The four classes of exposure can satisfy the
<br />practical requirements of most precipitation data users. Three additional interim classes are needed for
<br />studies of climate change and detailed investigations of systematic error of precipitation measurement,
<br />particularly the wind-induced losses in windy areas with much snow. It is recommended to all national
<br />meteorological services to adopt a classification programme for their gauge sites as soon as possible, because
<br />in many parts of the world historical station records have already been lost or destroyed and the possibility
<br />exists that this could happen to other stations.
<br />
<br />REFERENCES
<br />
<br />Brown, N. J. and Peck. E. L. 1962. 'Reliability of precipitation measurements as related to exposure'. J. Appl Mereoro/.. I (2).
<br />203-207.
<br />Fedorova, E. G. 1966, 'Calculation of wind speed at the level of the precipitation gauge considering the degree of stations protection'.
<br />Trans, Voyeykor Main Geophys, Observ., Leningrad, 195,63-68 (in Russian).
<br />Kirchhofer, W. and Sevruk, B, 1992, 'Mean annual corrected precipitation amounts 1951-1980'. in Spreafico. M. and Weingartner.
<br />R. (eds), Hydrological Atlas of S..'ir=erland. Part 2,2. Landestopographie, Bern,
<br />Korhonen, V. V. 1944. 'New approach to correct snow measurement' Ann, Acad. Scie, Fennicae, Ser, A, /..24.3-15 (in German).
<br />Moss, J. M. 1960, 'Exposure factors affecting the accuracy of precipitation measurement'. Seminar on Rain, Sydney. Vol. 4, Paper 2.
<br />p.20.
<br />Sevruk. B. 1973. 'The effect of growing woods on the precipitation measurement in the Baye de Montreux basin'. Weller und Leben.
<br />Vienna, 25 (1-2). 1-6 (in German with English abstract).
<br />Sevruk. B. 1981. 'Methodical investigation of systematic error of Hellmann rain gauges in the summer season in Switzerland '. Trans,
<br />VersuchsanstaJt fur Wasserbau. Hydrologie und Gla=iologie. ETH Zurich, Mitt. No. 52, p, 297, (in German).
<br />Sevruk, B. (ed,) 1986a. 'Correction of precipitation measurements', Proceedings, Workshop on the Correcrion of Precipitarion
<br />Measuremellls. Zurcher Geographische Schriften. ETH Zurich. No. 23, p. 289.
<br />Sevruk. B. 1986b. 'Correction of precipitation m~asuremen[s: Swiss experience'. in Sevruk, B. (ed,). Proceedings. Workshop on rhe
<br />Correcrion of Precipiration Measurements. Zurch~r Geographische Schriften, ETH Zurich, No. 23. pp, 187-196.
<br />Sevruk, B, 1988, 'Wind speed estimation at the pr~cipitation gauge orifice level', in WMO Technical Conference on Instruments and
<br />Merhods of Observation (TECO-/988). /nstrumellls and Observing Methods, World Meteorological Organization, Geneva. Report
<br />No. 33, pp, 317-320.
<br />Sevruk, B. 1989. (ed,). 'Precipitation measurement'. Proceedings. Internarional Workshop on Precipitation Measuremelll, St Moritz. 3-7
<br />December 1989, Institute of Geography, Swiss Federal Institute of Technology, ETH Zurich. p. 589.
<br />Sevruk, B. 1992. 'Checking precipitation gauge performance', in S. Couling (ed.) Measurements of airborne pollutallls. pp. 88-107.
<br />Butterworth Heinemann. Oxford. 1993.
<br />Sevruk, B. and Kirchhofer. W. 1992. 'Mean annual corrections of measured precipitation amounts 1951-1980', in Spreafico, M. and
<br />Weingartner, R, (eds), Hydrological Atlas of S,,'ir=erland, Part 2.3, Landestopographie, Bern.
<br />Sevruk, B. and Klemm, S. 1989, 'Types of standard precipitation gauges', in Sevruk, B. (ed.), Precipitarion Measuremelll, Proceedings.
<br />Illlernariona/ Workshop on Precipitation Measurt'menr, St Moritz, 3-7 December 1989, Institute of Geography, Swiss Federal Institute
<br />of Technology, ETH Zurich. pp. 227-232.
<br />Sevruk, B. and Zahlavova, L. 1992, 'Statistics for precipitation gauge site exposure changes', in Zwiers, F, (ed.). Proceedings. 5th
<br />International Meering all S[{/risrim/ C1imat%gL Canadian Climate Centre, Toronto. pp, 383-386,
<br />Shyer, C. A. 1965. Investigation of Observation (l( Rain Gauge and Precipilalion Gauge. Hydrometeorological Publishers, Leningrad.
<br />p. 169 (in Russian),
<br />Symons, G. J. 1868, Report. British Rainfall. &-1 L
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