Performance of the synthetic storm technique in a low elevation 5° slant path at 44.5 GHz in the French Pyrénées

We show that the Synthetic Storm Technique can be applied to slant paths of very low elevation angle, but with caution and some limitations. To this end, we have processed the rain attenuation measurements collected in the years 1999 and 2000, in a 5° slant path radio link at 44.5 GHz between the top of Pic du Midi (altitude 2865 m) and Lannemezan (altitude 600 m), a 28-km path length, in the French Pyrénées (experiment known as CELESTE), to obtain the exceedance probability distributions of rain attenuation and fade duration. Then we have compared the experimental distributions to those predicted by the Synthetic Storm Technique with strictly concurrent measurements of rain rate time series. We have found that if the rainy path length assumed in the Synthetic Storm Technique modeling is limited to 13~15 km, instead of 28 km, then, for a large attenuation range: (a) the probability distribution of rain attenuation is well reproduced; (b) the experimental probability distribution of fade duration is well reproduced for fade durations longer than about 10 minutes.