EMS Annual Meeting Abstracts
Vol. 20, EMS2023-88, 2023, updated on 06 Jul 2023
EMS Annual Meeting 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Towards uniformity in the near-surface temperature profile

Judith Boekee1, Iris Verouden2, Paul Nollen2, Yi Dai2, Marie-Claire ten Veldhuis1, Steven van der Linden2, and Bas van de Wiel2
Judith Boekee et al.
  • 1Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands
  • 2Department of Geoscience and Remote Sensing, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands

Accurate estimations of the surface temperature are crucial to determine the exchange of energy and moisture between the surface and atmosphere. Temperature profiles in the atmospheric surface layer (ASL) are generally represented by the Monin-Obukov Similarity Theory (MOST). The logarithmic behavior in the lowest part of the ASL requires the introduction of the thermal roughness length. However, existing models for the thermal roughness length, such as the ratio to the roughness length for momentum, are not well-defined and may be based on incorrect physical assumptions. Therefore, it remains a challenge to predict the surface temperature from standardized temperature measurements at higher levels.

A reason for this uncertainty is the high vertical measurement resolution that would be required to validate the models near the surface. In this study, we designed a Distributed Temperature Sensing (DTS) structure that measures the air temperature vertically up to 1 m above the surface with a resolution of 2 cm and from 1-8 m with a 30 cm resolution. We placed this structure at a grassland site in the Netherlands in May 2022. We saw how the conventional MOST model accurately describes the logarithmic layer. However, we noticed a strong misalignment with the observed temperatures in the lowest 1 to 2 m.

We have introduced an alternative length scale into the existing model concept, omitting the need for the thermal roughness length. We show how one month of temperature profile observations under stable conditions takes one universal form by normalizing the temperature observations with θ∗ and normalizing height by the new length scale. We can describe this form, from directly above the vegetation up to and including the logarithmic layer, using a fully physically based model. Comparisons are also made against alternative models, including a tall canopy model and an adapted MOST model.

How to cite: Boekee, J., Verouden, I., Nollen, P., Dai, Y., ten Veldhuis, M.-C., van der Linden, S., and van de Wiel, B.: Towards uniformity in the near-surface temperature profile, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-88, https://doi.org/10.5194/ems2023-88, 2023.