Comparison of air temperature measured in a vineyard canopy and at a standard weather station

Abstract

The complex environment within a crop canopy leads to a high variability of the air temperature within the canopy, and, therefore, air temperature measured at a weather station (WS) does not represent the internal energy within a crop. The objectives of this study were to quantify the difference between the air temperature measured at a standard WS and the air temperature within a six-year-old vineyard (cv. Chardonnay) and to determine the degree of uncertainty associated with the assumption that there is no difference between the two temperatures when air temperature is used as input in grapevine models. Thermistors and thermocouples were installed within the vine canopy at heights of 0.5 m and 1.2 m above the soil surface and immediately adjacent to the berry clusters. In the middle of the clusters sensors were installed to determine the temperature of the air surrounding the clusters facing east and west. The data were recorded within the canopy from December 2015 to June 2017 as well as at the standard WS that was installed close to the vineyard (410 m). Significant differences were found between the air temperatures measured at the WS and those within the vineyard during the summer when the average daily minimum air temperature within the canopy was 1.2˚C less than at the WS and the average daily maximum air temperature in the canopy was 2.0˚C higher than at the WS. The mean maximum air temperature measured in the clusters facing east was 1.5˚C higher and west 4.0˚C higher than the temperature measured at the WS. Therefore, models that assume that air temperature measured at a weather station is similar to air temperature measured in the vineyard canopy could have greater uncertainty than models that consider the temperature within the canopy.

New Aspects of In Situ Measurements for Downy Mildew Forecasting

“…Distinct differences were found between the measurements of the canopy average when compared to the weather station. Peña Quiñones, et al (2020) [13] showed that day air temperature measured within the berry clusters was higher than that measured by weather stations, which is in accordance with the present study. Blaeser (1978) described the dependency of temperature compared with relative humidity in relation to the lifetime of sporangium [2]; fungus inoculum lost vitality when the temperature was above 30 °C for at least six hours.…”

“…This discrepancy can lead to variable forecasting accuracies. Peña et al [ 13 ] showed that temperatures inside canopies (at heights of 2 m) and berry clusters showed differences when compared to values respective of weather stations. This study provides evidence for the adjustment of the accuracy of the prediction model parameters to improve fungal disease management at vineyards.…”

Hysteresis Between Canopy Temperature and Atmospheric Temperature and Their Drivers on Winter Wheat

“…2). Similar diel hysteresis patterns have been observed on other plants (Mahan et al, 2016;Peña Quiñones et al, 2020). For example, studied time-lag effect between sap flow and vapor pressure deficit of larix principis-rupprechtii mayr.…”

High-resolution weather network reveals a high spatial variability in air temperature in the Central valley of California with implications for crop and pest management

“…It is noteworthy that the stations we used were inside the orchards above the canopy. However, temperatures inside the canopy can be on average 1.2°C lower for the minimum and 2°C higher for the daily maximum temperature [ 32 ]. There is also the distance factor, as this study did not count with a side by side comparison of a CIMIS station with an in-orchard station on the same site.…”