Optical and radio probing of lightning-associated phenomena in the atmosphere and ionosphere

The monitoring and/or sounding of lightning discharges and their associated phenomena (mesospheric optical emissions etc.) has been performed by radio and optical measurements. We pay attention to the winter lightning in the Hokuriku area (Japan Sea side) of Japan, because it is extremely important to investigate whether lighting discharges in the Hokuriku area (whole spatial scale is relatively small in comparison with the conventional summer lightning in the US) could trigger the mesospheric optical emissions. The optical observation of those mesospheric emissions and the corresponding radio sounding by ELF and VHF radio waves of their parent lightning, have been reported. The observing systems are firstly presented, and our latest observational facts on the mesospheric emissions in the Hokuriku area, their parent lightning and some computer simulations on the sprite initiation, are presented.