Observations and modelling of water balance components with the Noah-MP land surface model in a Mediterranean pine forest

The Noah-MP land surface model is a multi-parameterization model that simulates the components of the energy and water balances at the land surface and the interaction of these components with the atmosphere. Modifying and parameterizing the model equations with the use of field observations can improve model applications for the local area but also for areas with similar environmental conditions. Our objective is to improve the simulation of ET (evaporation, transpiration, interception) in Noah-MP, using soil moisture, sapflow and throughfall observations from a monitoring site in a pine forest near the 78-km² Peristerona watershed in Cyprus. The model simulations and evaluation period cover the years 2014 - 2018. The Jarvis stomatal conductance model in Noah-MP was modified to account for nocturnal transpiration.  The use of the Jarvis model with the nocturnal transpiration resulted in a substantial increase in transpiration. The modified Noah-MP simulated ET to amount to 79% of the total precipitation, close to the observed fraction of 76%, compared to a fraction of 45% obtained with the baseline set-up of Noah-MP with the Ball-Berry stomatal conductance model. The improved Noah-MP can be combined with the WRF-Hydro model and other hydrological models to simulate the entire terrestrial hydrological cycle.

This research has received financial support from the PRIMA (2018 Call) SWATCH Project, funded by the Republic of Cyprus through the Cyprus Research and Innovation Foundation. The PRIMA programme is supported by Horizon 2020, the European Union's Framework Program for Research and Innovation.