Significant direct interactions with tropospheric weather patterns would require power levels of 100 MW or more. However, even at 3.6 MW significant experiments could be performed. Balsley et al have studied the modulation of the auroral electrojet and found correlation with modulation of the zonal winds at 88 KM altitude. I recently have revisited the potential for electromagnetic beam modification of weather in a series of papers written with the support of the European Space Agency. They asked me to investigate potential applications in which a Solar Power Satellite was the source of energy.
Safety is emphasized in both papers.