Land Cover Control on the Drivers of Evaporation and Sensible Heat Fluxes: An Observation‐Based Synthesis for the Netherlands

• Published in: Water resources research Vol. 59; no. 11
• Main Authors: Jansen, Femke A., Jongen, Harro J., Jacobs, Cor M. J., Bosveld, Fred C., Buzacott, Alexander J. V., Heusinkveld, Bert G., Kruijt, Bart, Molen, Michiel, Moors, Eddy, Steeneveld, Gert‐Jan, Tol, Christiaan, Velde, Ype, Voortman, Bernard, Uijlenhoet, Remko, Teuling, Adriaan J.
• Format: Journal Article
• Language: English
• Published: 01.11.2023
• Subjects: data‐driven analysis; eddy covariance; evaporation; land cover; sensible heat flux; The Netherlands
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/2022WR034361

Land cover controls the land‐atmosphere exchange of water and energy through the partitioning of solar energy into latent and sensible heat. Observations over all land cover types at the regional scale are required to study these turbulent flux dynamics over a landscape. Here, we aim to study how the control of daily and midday latent and sensible heat fluxes over different land cover types is distributed along three axes: energy availability, water availability and exchange efficiency. To this end, observations from 19 eddy covariance flux tower sites in the Netherlands, covering six different land cover types located within the same climatic zone, were used in a regression analysis to explain the observed dynamics and find the principle drivers. The resulting relative position of these sites along the three axes suggests that land cover partly explains the variance of daily and midday turbulent fluxes. We found that evaporation dynamics from grassland, peatland swamp and cropland sites could mostly be explained by energy availability. Forest evaporation can mainly be explained by water availability, urban evaporation by water availability and exchange efficiency, and open water evaporation can almost entirely be explained by exchange efficiency. We found that the sensible heat flux is less sensitive to land cover type. This demonstrates that the land‐atmosphere interface plays an active role in the shedding of sensible heat. Our results contribute to a better understanding of the dynamics of evaporation over different land cover types and may help to optimize, and potentially simplify, models to predict evaporation. Plain Language Summary At the land surface solar energy is divided into evaporation and warming of the air (sensible heat). Land cover controls the land‐atmosphere exchange of water and energy through this division. Over the past years, there is a growing interest in how land use management can be used to optimize local water and climate services by influencing this division. However, this requires a good understanding of the drivers of evaporation and sensible heat. In this study, we aim to study the role of land cover type on the drivers of daily and midday evaporation and sensible heat during warm seasons. Therefore, we used fields observations, the eddy covariance technique, from 19 sites in the Netherlands covering six different land cover types in a regression analysis. The drivers are expressed along three axes: energy availability, water availability and exchange efficiency. We found that evaporation dynamics from grassland, peatland swamp and cropland sites could mostly be explained by energy availability. Forest evaporation can mainly be explained by water availability, urban evaporation by water availability and exchange efficiency, and open water evaporation can almost entirely be explained by exchange efficiency. We also found that sensible heat fluxes are less sensitive to land cover type. Key Points The drivers of latent and sensible heat fluxes in the Netherlands were studied over various land cover types based on regression analyses Drivers of evaporation associated with energy availability, water availability, exchange efficiency vary substantially per land cover type In natural landscape mosaics limitation of evaporation by water availability, energy availability and exchange efficiency coexist