Atmospheric observations in Pfynwald

Projektleitung

Stefan Hunziker

Stellvertretung

Jonas Gisler

Projektmitarbeitende

Marcus Schaub

The current and long-term conditions of the atmosphere impact the physiological functioning of trees. Therefore, many atmospheric variables are measured in Pfynwald (see Pfynwald research platform) to better understand processes and interactions with the forest. The measurements are also required for the operation of the Vapor Pressure Deficit (VPD) manipulation system of the VPDrought project.

Continuous and automatic measurements of atmospheric variables are taken with a temporal resolution of one minute. These measurements include air temperature, relative humidity, precipitation, global radiation, photosynthetically active radiation (PAR), wind speed, wind direction, and leaf wetness. All these measurements are taken above the canopy, and many of them are also taken along the canopy gradient. Some current measurements can be seen here. Additional to the automatic precipitation measurements (which also distinguish between rain, snow, and hail), there are manual rain gauges installed above and below the canopy to estimate the interception in different parts of the Pfynwald research site.

The VPD is calculated from the air temperature and relative humidity measurements. This parameter is then used in combination with the wind speed and direction measurements to control the operation of the VPD manipulation system. For the trees exposed to a reduced VPD, there are always five measurement points: two at the outer points of the tree crowns close to the nozzle fields, one in the center, and two at the outer positions with the greatest distance to the nozzle field.  

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