CLWRF is a set of modifications to the WRF v3.1.1 code by the Santander Meteorology Group (SMG) to perform more flexible regional climate simulations with WRF-ARW. Currently, CLWRF adds two main capabilities to the model: (1) flexible GHG scenario usage and (2) output of mean and extreme statistics of surface variables. CLWRF extensions are activated at compile time.
The CAM3 radiation scheme in WRF 3.1.1 has a hard-coded SRES A2 scenario for CO2, while the rest of the trace gases are kept constant along the simulation. CLWRF modifications provide a more flexible approach by reading the CO2, N2O, CH4, CFC11 and CFC12 concentrations from an ASCII file. The user can apply the GHG concentrations used in the boundary global model without modifying or recompiling the WRF code. Climate simulations are also concerned with averaged, maximum or minimum variables and not just the instantaneous values. Averages are available for some variables offered as accumulations, however, the computation of maximum or minimum values is lacking. For instance, the computation of maximum temperature out of the model instantaneous values would require a high output frequency of surface temperature and would be dependent on this output frequency. CLWRF adds WRF output variables recording statistical values (minimum, maximum, mean, standard deviation and time of min/max) from the internal time-step values for different surface variables: T2, Q2, U10, V10, RAINCV and RAINNCV.
A sensitivity study to the variation of trace gas mixing ratios is presented in order to show the new trace gas reading. At the same time, some statistical values for surface variables are also presented. Both results are based on simulations for the entire African continent encompassed within the CORDEX initiative. CLWRF is an ongoing initiative and we are currently working in the addition of other variables such as: sunshine duration, daily maximum 1h rainfall rate and gust wind.
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