Portal de Periódicos da CAPES

Characteristics of Photosynthetic Active Radiation (PAR) Through Statistical Analysis at Larnaca, Cyprus

2017; Volume: 2; Issue: 2 Linguagem: Inglês

10.36876/smjbb.1009

2573-5470

Stelios Pashiardis, Kalogirou SA, A Pelengaris,

Atmospheric chemistry and aerosols

Measurements of Photosynthetically Active Radiation (PAR) and global solar radiation at Larnaca (a coastal site in Cyprus) during the period 3013-2015 were used to investigate the seasonal characteristics of PAR and PAR/G ratio (PAR fraction or fFEC).PAR showed seasonal features with higher values in summer and lower values in winter.The annual mean values of PPFD and fFEC being 40.3 mol m -2 d -1 and 2.03 mol M J -1 , respectively.Monthly average daily PAR increased from 19.1 mol m -2 d -1 (in December) to 59.6 mol m -2 d -1 (in June).The monthly daily average of fFEC remained almost constant throughout the year at Larnaca.The spatial variability of PAR was also investigated using measurements from other four sites with different climate characteristics.The annual mean daily PAR value ranged between 31.7 to 40.0mol m -2 d -1 .The highest values are recorded in the coastal stations (Larnaca and Paralimni).The annual average value of fFEC at the five observation sites ranged from 1.82 mol MJ -1 to 2.03 mol MJ -1 , in accordance to what is observed in most parts of the world.The highest appeared in the coastal sites of Larnaca and Paralimni due to the presence of high water vapour atmospheric concentrations.Elevation plays a significant role on the values of the above variables.As a general trend, fFEC followed the order Clear<Partly cloudy<Cloudy.In all cases fFEC was decreased with elevation but with a different rate.Three linear or multilinear and three power law models were tested and validated under all sky conditions.All the models showed high coefficients of determination (R 2 ) (close to 1), which indicates that the proposed models are suitable for predicting hourly PAR values.The linear and multilinear models (models 1 to 3) have the same coefficient of determination (0.996).The relative error values for the first five models ranged between 3.3% and 4.5%, while the sixth model showed higher relative error (8.4%).