CNRM-ALADIN64 regional climate evaluation simulation: output to study the summer 2019 heatwave over the Iberian Peninsula

The CNRM-ALADIN64 model (Nabat et al., ACP, 2020) has been used to carry out regional climate simulations over the Med-CORDEX domain, driven by the ERA5 reanalysis (evaluation simulation). The whole period covers the 1979-2022 period, but the present output focus on the period of the summer 2019 heatwave over the Iberian Peninsula (20 June - 05 July 2019). The objective of these simulations was to study the effect of dust aerosols on this heatwave.

Therefore, three pairs of simulations have been carried out with and without taking into account dust aerosols and their radiative effects in the model, depending on the use of spectral nudging in the domain to constrain the model. Spectral nudging is used to constrain the large-scale meteorological evolution within the simulation. The function used imposes a constant rate above 700 hPa and a relaxation zone between 700 and 850 hPa, while the levels below 850 hPa are free. The spatial wavelengths are similarly nudged beyond 400 km, with a relaxation zone between 200 and 400 km. Thus this method gives the model enough freedom to generate the aerosols at the surface while keeping the large scale conditions that are essential to simulate the real chronology. The following configurations have been used:

 - SN-All: temperature, humidity, surface pressure and wind are nudged.

 - SN-Wind: only wind is nudged.

 - SN-No : no variable is nudged.

For each of these three simulations, two simulations (with and without dust aerosols) have been carried out.

The following variables are available here :

cloud fraction (total, low and high-level clouds)

aerosol optical properties at 550 nm : total aerosol optical depth, dust aerosol optical depth, extinction coefficient, asymmetry parameter and single scattering albedo

shortwave and longwave radiation at the surface and at the top of the atmosphere

dust aerosol radiative forcing for shortwave and longwave at the surface and at the top of the atmosphere

near-surface temperature and wind

sea-level pressure

liquid water path

vertical profiles of specific humidity and temperature