scholarly journals Air temperature profile and air/sea temperature difference measurements by infrared and microwave scanning radiometers

Radio Science ◽  
2003 ◽  
Vol 38 (3) ◽  
pp. n/a-n/a ◽  
Author(s):  
D. Cimini ◽  
J. A. Shaw ◽  
E. R. Westwater ◽  
Y. Han ◽  
V. Irisov ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Air Temperature ◽  
Temperature Difference ◽  
Sea Temperature

scholarly journals A Study of Developing a Prediction Equation of Electricity Energy Output via Photovoltaic Modules

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1503
Author(s):  
Minsu Kim ◽  
Hongmyeong Kim ◽  
Jae Hak Jung
Keyword(s):  
Experimental Data ◽  
Real Time ◽  
Air Temperature ◽  
Temperature Difference ◽  
Prediction Accuracy ◽  
Prediction Equation ◽  
Energy Output ◽  
Photovoltaic Modules ◽  
Mean Error ◽  
Pv Module

Various equations are being developed and applied to predict photovoltaic (PV) module generation. Currently, quite diverse methods for predicting module generation are available, with most equations showing accuracy with ≤5% error. However, the accuracy can be determined only when the module temperature and the value of irradiation that reaches the module surface are precisely known. The prediction accuracy of outdoor generation is actually extremely low, as the method for predicting outdoor module temperature has extremely low accuracy. The change in module temperature cannot be predicted accurately because of the real-time change of irradiation and air temperature outdoors. Calculations using conventional equations from other studies show a mean error of temperature difference of 4.23 °C. In this study, an equation was developed and verified that can predict the precise module temperature up to 1.64 °C, based on the experimental data obtained after installing an actual outdoor module.

scholarly journals Difference in Canopy and Air Temperature as an Indicator of Grassland Water Stress

2013 ◽  
Vol 1 (No. 4) ◽  
pp. 127-138 ◽  
Author(s):  
Duffková Renata
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Moisture Content ◽  
Air Temperature ◽  
Temperature Difference ◽  
Soil Moisture Content ◽  
Growing Season ◽  
Plant Residues ◽  
Dead Plant ◽  
Linear Correlations

In 2003–2005 in conditions of the moderately warm region of the Třeboň Basin (Czech Republic) the difference between canopy temperature (Tc) and air temperature at 2 m (Ta) was tested as an indicator of grass­land water stress. To evaluate water stress ten-minute averages of temperature difference Tc–Ta were chosen recorded on days without rainfall with intensive solar radiation from 11.00 to 14.00 CET. Water stress in the zone of the major portion of root biomass (0–0.2 m) in the peak growing season (minimum presence of dead plant residues) documented by a sudden increase in temperature difference, its value 5–12°C and unfavourable canopy temperatures due to overheating (> 30°C) was indicated after high values of suction pressure approach­ing the wilting point (1300 kPa) were reached. High variability of temperature difference in the conditions of sufficient supply of water to plants was explained by the amount of dead plant residues in canopy, value of va­pour pressure deficit (VPD), actual evapotranspiration rate (ETA) and soil moisture content. At the beginning of the growing season (presence of dead plant residues and voids) we proved moderately strong negative linear correlations of Tc–Ta with VPD and Tc–Ta with ETA rate and moderately strong positive linear correlations of ETA rate with VPD. In the period of intensive growth (the coverage of dead plant residues and voids lower than 10%) moderately strong linear correlations of Tc–Ta with VPD and multiple linear correlations of Tc–Ta with VPD and soil moisture content at a depth of 0.10–0.40 m were demonstrated.

scholarly journals Non-stationary temporal characterization of the temperature profile of a soil exposed to frost in south-eastern Canada

2008 ◽  
Vol 15 (3) ◽  
pp. 409-416 ◽  
Author(s):  
F. Anctil ◽  
A. Pratte ◽  
L. E. Parent ◽  
M. A. Bolinder
Keyword(s):  
Time Series ◽  
Soil Temperature ◽  
Temperature Profile ◽  
Air Temperature ◽  
Soil Depth ◽  
Time Lag ◽  
Power Spectra ◽  
Temperature Time Series ◽  
Soil Temperatures ◽  
Temperature Time

Abstract. The objective of this work was to compare time and frequency fluctuations of air and soil temperatures (2-, 5-, 10-, 20- and 50-cm below the soil surface) using the continuous wavelet transform, with a particular emphasis on the daily cycle. The analysis of wavelet power spectra and cross power spectra provided detailed non-stationary accounts with respect to frequencies (or periods) and to time of the structure of the data and also of the relationships that exist between time series. For this particular application to the temperature profile of a soil exposed to frost, both the air temperature and the 2-cm depth soil temperature time series exhibited a dominant power peak at 1-d periodicity, prominent from spring to autumn. This feature was gradually damped as it propagated deeper into the soil and was weak for the 20-cm depth. Influence of the incoming solar radiation was also revealed in the wavelet power spectra analysis by a weaker intensity of the 1-d peak. The principal divergence between air and soil temperatures, besides damping, occurred in winter from the latent heat release associated to the freezing of the soil water and the insulation effect of snowpack that cease the dependence of the soil temperature to the air temperature. Attenuation and phase-shifting of the 1-d periodicity could be quantified through scale-averaged power spectra and time-lag estimations. Air temperature variance was only partly transferred to the 2-cm soil temperature time series and much less so to the 20-cm soil depth.

scholarly journals On the seasonal variation of atmospheric temperature in the British Isles and its relation to wind-direction, with a note on the effect of sea temperature on the seasonal variation of air temperature

1902 ◽  
Vol 69 (451-458) ◽  
pp. 61-85 ◽  
Keyword(s):  
Seasonal Variation ◽  
Air Temperature ◽  
Wind Direction ◽  
Atmospheric Temperature ◽  
British Isles ◽  
Sea Temperature ◽  
The Subject

The following paper is mainly concerned with the analysis of the seasonal variation of temperature of the British Islands into a series of simple harmonic curves. The variation of temperature is so irregular that the use of this method of analysis for the investigation of the subject may seem to he arbitrary and inappropriate, and a few words of introduction are accordingly necessary to indicate the circumstances under which this mode of dealing with the subject showed itself to be specially adapted for the purpose.

scholarly journals Modelling of room air temperature profile with displacement ventilation

2019 ◽  
Vol 19 (2) ◽  
pp. 112-126 ◽  
Author(s):  
Natalia Lastovets ◽  
Risto Kosonen ◽  
Panu Mustakallio ◽  
Juha Jokisalo ◽  
Angui Li
Keyword(s):  
Temperature Profile ◽  
Air Temperature ◽  
Displacement Ventilation

scholarly journals Use of Reflectance Indices to Assess Vine Water Status under Mild to Moderate Water Deficits

Agronomy ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 346 ◽  
Author(s):  
Cristina González-Flor ◽  
Lydia Serrano ◽  
Gil Gorchs
Keyword(s):  
Air Temperature ◽  
Temperature Difference ◽  
Water Status ◽  
Canopy Structure ◽  
Similar Response ◽  
Water Deficits ◽  
Potted Plants ◽  
Significant Relationships ◽  
Leaf Level ◽  
Reflectance Indices

The monitoring of vine water status is of interest for irrigation management in order to improve water use while optimizing both berry yield and quality. Remote-sensing techniques might provide accurate, rapid, and non-destructive estimates of vine water status. The objective of this study was to test the capability of the reflectance-based water index (WI) and the photochemical reflectance index (PRI) to characterize Vitis vinifera L. cv. Xarel·lo water status under mild to moderate water deficits. The study was conducted at the leaf level in irrigated potted plants and at the plant level on five commercial rain-fed vineyards in 2009 and 2010. In potted plants, the reflectance indices PRI and WI closely tracked variation in the leaf-to-air temperature difference (ΔT) with r2 = 0.81 and r2 = 0.83, for WI and PRI, respectively (p < 0.01). In addition, in potted plants, both PRI and WI showed significant relationships with light-use efficiency (LUE)—calculated as the ratio between net CO2 assimilation rate (An) and incident photosynthetic active radiation (PAR) at the leaf surface—with r2 = 0.92 and r2 = 0.74 for PRI and WI, respectively. At the canopy level, vine predawn water potential (Ψpd) was related to the canopy-to-air temperature difference (ΔTm) across years (r2 = 0.37, p < 0.05). In the years of study, the relationships between PRI and WI showed variable degrees of correlation against Ψpd and ΔTm. Across years, PRI and WI showed significant relationships with Ψpd, with r2 = 0.41 and r2 = 0.37 (p < 0.01), for WI and PRI, respectively. Indices formulated to account for variation in canopy structure (i.e., PRInorm and WInorm) showed similar degrees of correlation against Ψpd to their original formulations. In addition, PRI and WI were capable of differentiating (p < 0.01) between mild (Ψpd > −0.4 MPa) and moderate (Ψpd < −0.4 MPa) water deficits, and a similar response was observed when PRInorm and WInorm—formulated to account for variation in canopy structure—were considered. Thus, at the leaf level, our result suggest that WI and PRI can be used to adequately predict the diurnal dynamics of stomatal aperture and transpiration. In addition, at the canopy level, PRI and WI effectively differentiated vines under mild water deficits from those experiencing moderate water deficits. Thus, our results show the capability of WI and PRI in characterizing vine water status under mild to moderate water deficits.

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