SEARCH AGRICULTURE. Solar Radiation at Geneva, New YorkVariations in Intensity and. Duration INSTRUMENTATION VOLUME 5, NUMBER 9

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1 VOLUME 5, NUMBER SEARCH AGRICULTURE SEED AND VEGETABLE SCIENCES (Geneva) 3 NEW YORK STATE AGRICULT URAL EXPERIMENT STATION, GENEVA, A DIVISION OF THE NEW YORK STATE COLLEGE OF AGRICULTURE AND LIFE SCIENCES, A STATUTORY COLLEGE OF THE STATE UNIVERSITY, CORNELL UNIVERSITY, ITHACA Solar Radiation at Geneva, New YorkVariations in Intensity and Dration N. H. Peck, G. H. Gibbs, and J. Barnard The intensity and dration of energy received from the sn, as incident direct solar radiation and as diffse sky radiation, has a large inflence, either directly or indirectly, on growth, development, initiation of reprodction, matration, and yield of pla:nts. Plant responses (13), evapotransp.iration (8), evaporation of water (5), air temperatre (9), and soil temperatre (7) are inflenced by solar and sky radiation. Physical characteristics of energy from the sn and its effects on earth are described by Robinson (11), Gates (6), and Baker (2). Variations in incident solar and sky radiation occr in both short time intervals of mintes or hors as well as in long time intervals of days and seqences of days. Solar radiation data have been statistically analyzed to measre variability (12, 3). The intensity and dration of solar radiation intercepted on a horizontal plane was measred, over a 1O-year period, at the climatological reference weather station at the Vegetable Research Farm of the New York State Agricltral Experiment Station, Geneva, New York. The station is nmber in the U. S. Department of Commerce, National Oceanic and Atmospheric Administration network. The location is latitde 42 53'N, longitde 77 2'W, and the elevation is 718 feet above sea level. Th.e solar radiation data presented here may be related to past physical and biological processes and may be sed to estimate solar radiation and the reslting physical and biological responses in the ftre. INSTRUMENTATION A pyranometer intercepts direct solar radiation as well as diffse sky radiation. A pyrheliometer intercepts direct solar radiation only. Solar and sky radiation are generally referred to herein as solar radiation. The interceptors of solar and sky radiation sed at Geneva from 1961 to 1971 have been described previosly (1). In September 1971, a new Eppley Model 2 pyranometer was installed. According to the manfactrer 1, this pyranometer has a receiver coated with Parsons' black lacqer (nonwavelength-selective absorption). The inner and oter concentric hemispheres over the sensing elements are clear glass transparent from a wavelength of abot 285 to 2,8 millimicrons. The 1971 pyranometer was tested by the U. S. Department of Commerce, Environmental Science Services Administration, Weather Brea, Silver Spring, Maryland on March 1 and 4, They reported: "This pyranometer has been compared with the Weather Brea reference standard. The derived vale of the constant for this instrment is 4.89 millivolts per langley per minte at 85 F on the 1956 International Pyrheliometric Scale " (1 langley / minte=1 g cal/cm 2/minte). Another Eppley pyranometer Model 2, with a calibration of 4.82 millivolts per langley per minte at 86 F, is sed as an alternate at the climatological reference station. Solar and sky radiation intercepted by the pyranometer sensing element generates an electromotive force (emf) proportional to the intensity of the radiation. The emf is recorded on a strip chart recorder with a chart speed of 2 inches/hor. Intensity and dration of solar and sky radiation is compted as g cal / cm 2. For every 2-minte time interval on the strip chart records, a reference line is drawn parallel to the direction of movement of the chart and perpendiclar to the time lines on the chart in sch a manner that the reference lines intersect the radiation crve at a point where two eqal areas (above and below the reference line) are delineated by the reference line, the radiation crve, and the two time lines that identify the 2minte time perioel. Smmations of radiation in g cal/cm2 per 2 mintes give g cal/cm2 per hor and per day. Solar radiation was recorded on tre solar time. The daily solar radiation data were pnched on cards, were analyzed 1 Eppley Laboratory, Inc., Newport, Rhode Island

2 by an IBM 18 compter, and were graphed by a Honeywell 53 X-Y plotter. Crves representing solar radiation were smoothed by a 15-day moving average techniqe (4). DAILY SOLAR RADIATION The average daily solar radiation overthe 1O-year period varied from approximately 1 g cal I cm2 per day in December to 5 in Jne-Jly (Fig. 1). On any given calendar day, there were large variations in the amont of, solar radiation. Line 1H represents the highest daily vale, and line 1L represents the lowest daily vale observed on each calendar day dring the 1 years. For example, for each calendar day in Jne, radiation exceeded 7 g cal l cm 2 I day at least 1 year in 1 and was less than 2 g cal l cm 2 I day at least 1 year in 1, based on the smoothed crves. Lines 2H, 3H, 4H, and lines 2L, 3L, 4L represent the second, third, and forth highest (H) and lowest (L) daily vales, respectively, for each calendar date. SEQUENCE OF DAYS: AVERAGE DAILY VALUE The average daily intensity of solar radiation for drations of 3 (Fig. 2) and 5 (Fig. 3) consective days rang ed from abot 1 g cal/cm 2 per day in NovemberDecember to 5 in Jne-Jly. These crves may be sed to estimate solar rad iation over a seqence of days when the total radiation over the seqence inflences physical processes sch as heating soil and bildings or drying crops. Also, they may be sed to estimate biological processes reslting from the cmlative effect of heat sch as growth, development, flower initiation, and matrity of plants. SEQUENCE OF DAYS: MINIMUM DAILY VALUE Data were analyzed to determ ine minimm daily vale of solar radiation within a seqence of days. This was done for both 3-day (Fig. 4) and 5-day (Fig. 5) seqences. These crves demonstrate the occrrence of drations of days with a minimm daily vale. They may be related to physical characteristics sch as the qantity and dration of storage of energy from the sn sed for heating. Also, they may be related to certain biological processes sch as the metabolization of nitrate to nitrogen componds in plants dring a seqence of days containing 1 day with low solar radiation > C\I 5 E 4... ) OL- JAN FEB MAR - L L - APR MAY JUN _ JUt AUG Figre 1. -A verage daily solar radiation. 2 SEP OCT NOV DEC

3 BOO 7 6 >.. ""... C'f 5 E... 4 Ol 3 2 O JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figre 2. -A veragf daily solar radiation for seqences of 3 days. BOO 7 6 >.. 5."... C'f 4 E 3 Q) 2 1 o -L L- JAN FEB MAR APR MA Y JUN JUt AUG SEP OCT NOV DEC Figre 3. -A verage daily solar radiation for seqences of 5 days. 3

4 BOO 7 6 > ('.I' E 4, Cl OL- -L JAN FEB MAR APR MA Y JUN JUL AUG SEP OCT NOV DEC Figre 4.-Average minimm daily solar radiation for seqences of 3 days., > N E 4 ::::: Cl 3 2 JAN FEB MAR APR MAY JUN JUt AUG SEP OCT NOV DEC Figre 5.-Average minimm daily solar radiation for seqences of 5 days. 4

5 LITERATURE CITED 1. Anonymos Manal of radiation observations. Weather Brea, U.S. Dep. of Commerce. 2. Baker, D. G Climate of Minnesota Part VI. Solar radiation at St. Pal Agr. Exp. Sta., Univ. of Minn. Tech. Bll Branton, C. I., R. H. Shaw, and L. D. Allen Solar and net radiation at Palmer, Alaska, I nst. of Agr. Sci., Univ. of Alaska. Tech. Bll Crabb, G. A., Jr Solar radiation investigations in Michigan. Michigan Agr. Exp. Sta. Tech. Bll Crabb, G. A., Jr Insolation: a primary factor in evaporation from a free water srface in Mich igan. Mich. Agr. Exp. Sta. Qart. Bll. 35: Gates, D.M. Energy exchange in the biosphere. Harper and Row Biological Monographs. Harper and Row, Pbl., New York. 7. McWhorter, J. C. and B. P. Brooks, Jr Climatological and solar radiation relationships. Miss. Agr. Exp. Sta. Bll Mielke, L. N. and N. H. Peck Evapotranspiration by snap beans grown in sand ntrient cltre. Agron. J. 59: Peck, N. H., M. T. Vittm, and G. H. Gibbs Growing season weather at Geneva, New York, NY. State Agr. Exp. Sta., Geneva. Bll Peck, N. H. and G. H. Gibbs, 197. Solar radiation at Geneva, New Yark, NY. State Agr. Exp. Sta., Geneva. Res. Cire Robinson, N Solar Radiation. pp Elsevier Pbl. Co., Amsterdam/London/ New York. 12. Sakamoto, C. M. and D. V. Dnlap Solar radiation at New Brnswick, New Jersey. New Jersey Agr. Exp. Sta. Bll Slatyer, R. O. Ed Plant Response to Climatic FactOJs. UNESCO. pp Place de Fonteroy, Paris. 5

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8 Accepted for pblication Jne 1975