Solar Radiation Observations 1982

METEOROLOGICAL SERVICE SOLAR RADIATION OBSERVATIONS 1982 U.D.C. \.. SS1. 506.3 5S!. 521. 12(419.6) DUBLIN 1983 Price;! 1·75 CONTENTS Solar Radiation Observations at Valentia Observatory Page 1. Introduction 1 2. Site of Observatory 1 3. Measurement of Global Solar Radiation 1 4. Measurement of Diffuse Solar Rodiation 2 5. Measurement of Di rect Sun Radiation 3 6. ~~asurement of Long-wove (Infra-Red) Radiation 3 7. Direct Sun Observations 3 8. Radiation Balance 5 Figure 1 Mop showing site of Valentia Observatory and its environs 6 Figure 2 General layout of Observatory 7 Figure 3 Exposure diagram showing Azimuth and Elevation of 8 all objects which obscure the pyronometers together with Azimuth and Elevation of the sun at different times of the year Solar Radiation Observations at Kilkenny Meteorological Station 1. Introduction 9 2. Site of Observations 9 3. Measurement of Globol Solar Radiation 9 4. Measurement-of Diffuse Solar Radiation 9 Figure 4 Mop· showing··si te - 10 Figure 5 Layout of buildings and instruments 11 Figure 6 Exposure diagram showing Azimuth and Elevotion of 12 all objects which obscure the pyranometers together with AZimuth and Elevation of the sun at different times of the year Solar Radiation Observations at Birr Meteorological Station 1. Introduction 13 2. Site of Observations 13 3. Measurement of Global Solar Radiation 13 4. Measurement of Diffuse Solar Radiation 13 Figure 7 Mop showing site 14 Figure 8 Layout of buildings and instruments 15 Figure 9 Exposure diagram showing Azimuth and Elevation of 16 all objects which obscure the pyranometers together with Azimuth and Elevation of the sun at different times of the year Solar Radiation Observotions at Dublin Airport 1. Introduction 17 2. Site of Observations 17 3. I.~asurement of Global Solar Radiation 17 4. Measurement of Diffuse Solar Radiation 17 Figure 10 Map shOWing si te 18 Figure 11 Layout of specific instruments on Terminal 19 Building Figure 12 Exposure diagram showing Azimuth and Elevation of 20 all objects which obscure the pyronometers together with Azimuth and Elevation of the sun at different times of the year CON TEN T S (Contd). Solar Radiation Observations at ~~lin Head Page 1. Introduction 21 2. Site af Observations 21 3. Measurement of Global Solar Radiation 21 4. Measurement of Diffuse Solar r-adiation 21 Figure 13 ~~p showing si te 22 Figure 14 Layout of buildings and instruments 23 Figure 15 Exposure diogram showing Azimuth and Elevation of 24 all objects which obscure the pyronometers together with Azimuth and Elevation of the sun at different times of the year Solar Radiation Observations at Clones 1. Introduction 25 2. Site of Observations 25 3. ~~asurement of Global Solar Radiation 25 4. Measurement of Diffuse Solar Radiation 25 Figure 16 Mop showing site 26 Figure 17 Layout of buildings and instruments 27 Figure 18 Exposure diagram showing Azimuth and Elevation of 28 all objects which obscure the pyranameters together with Azimuth and Elevation of the sun at different times of the year Solar Radiation Observations at Belmullet 1. Introduction 29 2. Site of Observations 29 3. Measurement of Global Solar Radiation 29 Figure 19 ~bp showing site 30 Figure 20 Layout of buildings and instruments 31 Figure 21 Exposure diagram showing Azimuth and Elevation of 32 all objects which obscure the pyranometers together with Azimuth and Elevation of the sun at different times of the year APPENDIX. Instruments used in 1982 33 Table 1 Doily Totals of Global Solar Radiation at Valentia 34 Table 2 Doily Totals of Diffuse Solar Radiation at Valentia 35 Table 3 Doily Totals of Radiation Balance at Valentia 36 Table 4 Instantaneous Values of Direct Solar Radiation at 37 Normal Incidences at Valentia Table 5 Doily Totals of Direct Solar Radiation at Normal 41 Incidence at Valentia Table 6 Doily Totals of Long-wove (Infra-Red) Radiation at Valentia 42 Table 7 Doily Totals of Global Solar Radiation at Kilkenny 43 Table 8 Doily Totals of Diffuse Solar Radiation at Kilkenny 44 Table 9 Doily Totals of Global Solar Radiation at Birr 45 Table 10 Doily Totals of Diffuse Solar Radiation at Birr 46 Table 11 Doily Totals of Global Solar Radiation at Dublin Airport 47 Table 12 Doily Totals of Diffuse Solor Radiation at Dublin Airport 48 Table 13 Doily Totals of Global Solar Radiation at ~blin Head 49 Table 14 Doily Totals of Diffuse Solar Radiation at Molin Head 50 Table 15 Doily Totals of Global Solar Radiation at Clones 51 Table 16 Doily Totals of Diffuse Solar Radiation at Clones 52 Table 17 Doily Totals of Global Solar Radiation at Belmullet 53 SUMMARY This volume contoins a brief description af the site, equipment and observing procedures in use at the seven stations in the Irish network of Solar Rodiation measuring stations Le. Valentia Observatory, Kilkenny, Birr. Dublin Airport, Malin Heod, Clones and Belmullet. The network diagram is on the following page. In previous yeors hourly volues were published but as ond from Jonuory 1976, only doily totals are published oport from the spot volues of Direct Sun ot Normol Incidence (TobIe 4). The hourly values moy be hod on request from: The Director. Meteorological Service, Glasnevin Hill. Dublin 9. In compliance wi th a World Meteorologicol Orgonisation (WMO) recommendation 0 new radiotion scole has been odopted from 1st Jonuory 1981. This is the World Rodiometric Reference 1981 (WRR 1981) and reploces the Internotional Pyrheliometer Scole, 1956 (IPS 1956) which hos been in use for all rodiotion dota published to dote by the Irish ~~teorological Service. The WRR (1981) scole is 2.2 percent greoter thon the IPS (1956) scole. Archived rodiotion data up to 31st December 1980 will not be increased by the 2.2 percent. However. all radiation volues in the following Tables are in the World Radiometric Reference Scale. 1981. '. Belmullet r--~ __' G 1981 G 1977 Clones e D 1981 . G 1976 Dubll n. D 1976 Birr. g1§~~ Kilkenny ..,~ GD 1969 1979 Scale 0r---- __50 _ _100 Kilometres .' IRISH METEOROLOGICAL SERVICE SOLAR RADIATION STATION NETWORK - 1 - SOLAR RADIATION OBSERVATIONS AT VALENTIA OBSERVATORY 1982 1. Introduction Solar radiation observations were begun at Valentia Observatory in September, 1954. At that time a Mall thermopile pyranometer and a recording millivoltmeter were installed, and hove, since then, prOVided a continuous record of Global Solar Radiation. A Linke-Feussner thermoelectric iron clad Actinometer (Kipp and Zonen) was also brought into use at the some time and a schedule of routine observations on direct sunlight hos been maintained when weather conditions permitted. In 1962, a second Moll thermopile pyranometer, fitted with shading ring, was installed to provide a record of Diffuse Solar Radiation. Measurement of the Radiatian Balance with a Funk type Net Pyrradiameter was introduced on a routine basis as from 1st January, 1971. Measurements of the Direct Sun radiation, using on Eppley Normal Incidence Pyrheliometer, and of Infra-Red radiation, using an Eppley Precision Radiometer (Pyrgeometer), were introduced on a routine basis as and from 1st January 1979. Data derived from these instruments and the results obtained from the direct sunlight observations for the period 1954 - 1959 have been published in [1]. The data for 1960 and subsequent years have been published in annual volumes. This volume contains the data for 1982. 2. Site of the Observatory The Observator which is in the extreme south-west of Ireland, (Lot. 51 0 56' N; Long. 10 6 15'W), is situated on the south-east side of the narrow estuary of Valentia River, which runs from approximately north east to south-west (Fig. 1). It is about 1.2 Km to the south-west of the town of Cohirciveen. To the north, across the river estuary, is a range of hills 120 to 360 m high. To the north-east, beyond the town of Cahirciveen, the estuary opens out considerably and the terrain is generally on open boggy basin with only a gentle gradient. To the south-east, however, the ground rises rapidly again to a range of hills 270 to 360 m high, the highest peak (Bentee 375 m) being only 1.5 Km from the Observatory, To the south, the country opens out ta a distance af nearly 8 Km from the Observatory, where the Kilkeaveragh range of hills runs east west, varying in height from 120 to 390 m. There is on opening to the sea to the south-west between the mainland and Valentia Island. The hills on the Island rise ta a height of 270 m. North of the island there is another opening to the sea, and the circle af hills is completed by a range to the north-west, 120 to 270 m high, separated by a narrow gulley from the '. range to the northward. 3 .. Measurement of Global Solar Radiation 3.1 Exposure of the Pyranometer The layout of the Observatory is shown in Fig. 2. The sensor is exposed on the roof of the Radiation House and the recording instruments are installed inside the hause. The pyranometer is at a height of 4 metres above ground level and 20 metres above ~~an Sea Level. The nature of the exposure can be seen in Fig. 3, in which the outline of all obscuring objects is plotted on on Elevation-Azimuth diagram. Agart from one sector, the obscuring objects have on elevation of less than 5 so that their effect - 2 - on the diffuse rodiotion is negligible. In the sector 0800 to 150 0 E from north, the elevation of the obscuring objects lies between 80 ond 10.50 approximately. The loss of diffuse radiation according to Blackwell's formula [2] works out at approximately 1%.

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