The article deals with the comparison of humidity measuring instrument calibration evaluation carried out in two climatic chambers under predetermined conditions. The approach of measuring instrument calibration evaluation, including measurement uncertainties, with consideration of confidence, is shown on specific example of measurement in climatic chamber. The article is focused on the compare of two calibrations evaluation. and Príspevok sa zaoberá porovnaním vyhodnotenia kalibrácie meradla vlhkosti vykonaných v dvoch klimatických komorách za vopred stanovených podmienok. Na konkrétnom príklade merania v klimatickej komore je ukázaný prístup vyhodnotenia kalibrácie meradla vrátane neistôt merania s uvažovaním spoľahlivosti. Príspevok porovnáva vyhodnotenie dvoch kalibrácií.
We conducted an experiment to assess the predictive capability of a leaf optical meter for determining leaf pigment status of Acer mono Maxim., A. ginnala Maxim., Quercus mongolica Fisch., and Cornus alba displaying a range of visually different leaf colors during senescence. Concentrations of chlorophyll (Chl) a, Chl b, and total Chl [i.e., Chl (a+b)] decreased while the concentration of carotenoids (Car) remained relatively static for all species as leaf development continued from maturity to senescence. C. alba exhibited the lowest average concentration of Chl (a+b), Chl a, and Car, but the highest relative anthocyanin concentration, while Q. mongolica exhibited the highest Chl (a+b), Chl b, and the lowest relative anthocyanin concentration. A. mono exhibited the highest Chl a and Car concentrations. The relationships between leaf pigments and the values measured by the optical meter generally followed an exponential function. The strongest relationships between leaf pigments and optical measurements were for A. mono, A. ginnala, and Q. mongolica (R2 ranged from 0.64 to 0.95), and the weakest relationships were for C. alba (R2 ranged from 0.13 to 0.67). Moreover, optical measurements were more strongly related to Chl a than to Chl b or Chl (a+b). Optical measurements were not related to Car or relative anthocyanin concentrations. We predicted that weak relationships between leaf pigments and optical measurements would occur under very low Chl concentrations or under very high anthocyanin concentrations; however, these factors could not explain the weak relationship between Chl and optical measurements observed in C. alba. Overall, our results indicated that an optical meter can accurately estimate leaf pigment concentrations during leaf senescence - a time when pigment concentrations are dynamically changing - but that the accuracy of the estimate varies across species., Future research should investigate how species-specific leaf traits may influence the accuracy of pigment estimates derived from optical meters., G. Y. Li, D. P. Aubrey, H. Z. Sun., and Obsahuje bibliografii
The aim of this work was testing and subsequent calibration of RGB colorimeters. RGB colorimeters are cost-effective tools allowing to perform a number of colorimetric measurements. The aim of this work was to verify their accuracy and to develop methods for their calibration. We show how the calibration method proposed in this paper allows to work even with probes that provide inaccurate measurements due to faulty hardware. and Cílem této práce bylo testování a následná kalibrace RGB kolorimetrů. RGB kolorimetry představují cenově dostupné nástroje umožňující provádět celou řadu kolorimetrických měření. Cílem naší práce bylo ověření jejich přesnosti a vypracování metody jejich kalibrace. Ukazujeme, jak námi navržená metoda kalibrace umožňuje pracovat i se sondami, které již samy o sobě vlivem hardwarových chyb poskytují nepřesná data.
Longwave radiation, as part of the radiation balance, is one of the factors needed to estimate potential evapotranspiration (PET). Since the longwave radiation balance is rarely measured, many computational methods have been designed. In this study, we report on the difference between the observed longwave radiation balance and modelling results obtained using the two main procedures outlined in FAO24 (relying on the measured sunshine duration) and FAO56 (based on the measured solar radiation) manuals. The performance of these equations was evaluated in the April–October period over eight years at the Liz experimental catchment and grass surface in the Bohemian Forest (Czech Republic). The coefficients of both methods, which describe the influence of cloudiness factor and atmospheric emissivity of the air, were calibrated. The Penman-Monteith method was used to calculate the PET. The use of default coefficient values gave errors of 40–100 mm (FAO56) and 0–20 mm (FAO24) for the seasonal PET estimates (the PET was usually overestimated). Parameter calibration decreased the FAO56 error to less than 20 mm per season (FAO24 remained unaffected by the calibration). The FAO56 approach with calibrated coefficients proved to be more suitable for estimation of the longwave radiation balance.