Evaluating the performance of SURFEXv5 as a new land surface scheme for the ALADINcy36 and ALARO-0 models

Abstract

Abstract. The newly developed land surface scheme SUR-FEX (SURFace EXternalisée) is implemented into a limitedarea numerical weather prediction model running operationally in a number of countries of the ALADIN and HIRLAM consortia. The primary question addressed is the ability of SURFEX to be used as a new land surface scheme and thus assessing its potential use in an operational configuration instead of the original ISBA (Interactions between Soil, Biosphere, and Atmosphere) scheme. The results show that the introduction of SURFEX either shows improvement for or has a neutral impact on the 2 m temperature, 2 m relative humidity and 10 m wind. However, it seems that SUR-FEX has a tendency to produce higher maximum temperatures at high-elevation stations during winter daytime, which degrades the 2 m temperature scores. In addition, surface radiative and energy fluxes improve compared to observations from the Cabauw tower. The results also show that promising improvements with a demonstrated positive impact on the forecast performance are achieved by introducing the town energy balance (TEB) scheme. It was found that the use of SURFEX has a neutral impact on the precipitation scores. However, the implementation of TEB within SURFEX for a high-resolution run tends to cause rainfall to be locally concentrated, and the total accumulated precipitation obviously decreases during the summer. One of the novel features developed in SURFEX is the availability of a more advanced surface data assimilation using the extended Kalman filter. The results over Belgium show that the forecast scores are similar between the extended Kalman filter and the classical optimal interpolation scheme. Finally, concerning the vertical scores, the introduction of SURFEX either shows improvement for or has a neutral impact in the free atmosphere.

Reinitialised versus continuous regional climate simulations using ALARO-0 coupled to the land surface model SURFEXv5

“…The simulations were applied for a 10-year period from 1991 to 2000, for a western European domain. The performance of ALARO-0 with SURFEX has already been validated for NWP applications (Hamdi et al, 2014), and here we present an evaluation for long-term climate simulations.…”

“…A NWP application with SURFEXv5 within ALARO-0 has shown neutral effects on the winter 2 m temperature and on the vertical profile of the wind speed. However, it has shown positive effects on the summer 2 m temperature, 2 m relative humidity, and resulted in improved precipitation scores compared to the previously used ISBA model (Hamdi et al, 2014). Whereas the validation of the implementation of SURFEXv5 within ALARO-0 has been done in a NWP context, this validation is also required in the context of long-term climate simulations.…”

“…In addition, this set-up has been validated for continuous climate simulations and is now contributing to the EURO-CORDEX project (Giot et al, 2016;Jacob et al, 2014). Meanwhile the more recent land surface model SURFEX, with additional parameterisations for urban surface types, has been implemented in the ALARO-0 model (Hamdi et al, 2014). A NWP application with SURFEXv5 within ALARO-0 has shown neutral effects on the winter 2 m temperature and on the vertical profile of the wind speed.…”

Investigation of the impact of anthropogenic heat flux within an urban land surface model and PILPS-urban

“…Numerical weather prediction (NWP) models have included surface processes for many years (e.g., Manabe 1969), but it is only within the last decade that representations of urban areas have been included (e.g., Best 2005, Lemonsu et al 2009, Hamdi et al 2014, even though urban energy balance models themselves have been developed over a much longer period (e.g., models evaluated by Ross and Oke 1988, Masson 2000, Martilli et al 2002. The increasing resolution for NWP models has now reached the stage where urban areas can make up a large proportion of a grid-box, or in some instances actually be resolved.…”

The ALADIN System and its canonical model configurations AROME CY41T1 and ALARO CY40T1

“…For instance, the ALARO CMC calls the ISBA surface scheme directly, but it is possible to call the SURFEX scheme from the ALARO configurations. The performance of such an inclusion has been tested by Hamdi et al (2014) in cycle CY36 of the ALADIN System. Additionally the interfaces to the radiation scheme have been cleaned and the ACRANEB2 radiation scheme (Mašek et al, 2016;Geleyn et al, 2017) of the ALARO configurations can be called from the AROME physics package, relying on the common physics-dynamics interface INTFLEX.…”