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

Abstract

The newly developed land surface scheme SURFEX (Surface Externalisée) is implemented into a limited area 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 gives improvements or neutral impact on the 2 m temperature, 2 m relative humidity, and 10 m wind. However, it seems that SURFEX has a tendency to produce higher maximum temperatures at high elevation stations during winter daytime which degrades the 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 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 decreases obviously 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 upper air scores, the introduction of SURFEX either gives improvement or neutral impact in the free atmosphere

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

“…We evaluated this contribution with respect to the regional climate simulated by the original setup of ALARO-0 with ISBA. The present study corroborates the finding of Hamdi et al (2014), that the use of the SURFEX scheme improves the performance of the ALARO-0 configuration of the ALADIN system.…”

“…This reduction is strongest during summer. This is in line with earlier conclusions by Hamdi et al (2014) showing that SURFEX reduces the total accumulated precipitation during summer compared to ISBA. The use of FS has a neutral impact on the winter precipitation with respect to CON, except for the Mediterranean, where the SSTs could be the factor explaining the difference.…”

“…The output from the EURO-CORDEX simulations was subset to the time period of interest and regridded to the study domain and to a 20 km horizontal resolution (called hereafter CRDX, Table 1), to compare it with the results of both downscaling strategies. This comparison allowed to examine the effect of SURFEX on the climate mode, as was previously done for NWP (Hamdi et al, 2014).…”

Assimilation of zenith total delays in the AROME France convective scale model: a recent assessment

“…AROME also includes a dedicated surface assimilation scheme based on local optimum interpolation for the prognostic variables of the land surface schemes (Giard and Bazile, 2000;Mahfouf et al, 2009). This soil analysis scheme has been recently extended from the ISBA scheme to the other surface schemes available within the externalised modelling platform SURFEX (Masson et al, 2013;Hamdi et al, 2014). As input, this assimilation scheme uses increments of an analysis of screen-level temperature and relative humidity based on a bi-dimensional optimum interpolation called CANARI, considering SYNOP observations from the surface weather network.…”

Similarity-Based Semilocal Estimation of Post-Processing Models

“…It operates on a large domain covering Europe, north Africa and the northern Atlantic and the currently running GLAMEPS version 2 is a combination of the subensembles from two versions of the Aire Limite Application de la Recherche l’Operationnel (ALARO) model int ractions soil biosphere atmosph re and surface externalis e schemes; see, for example, Noilhan and Planton () and Hamdi et al . ()) and two versions of the HIRLAM model (Kain–Fritsch and soft transition condensation schemes; see, for example, Kain and Fritsch () and Sass ()). Each subensemble consists of 12 perturbed members and a control forecast, and half of the perturbed members are lagged by 6 h (Deckmyn, ).…”