Proceedings with Extended Abstracts (single PDF file) - Radio ...

Fig. 5 Passage of typhoon Hayan on 14 – 18 October 2001. The upper panel shows meanvertical velocity, the centre panel reflectivity and the lower panel direction and distance to thetyphoon eye. We clearly see that the radar reflectivity is stratified when the typhoon is far away.From the radar. A strong reflectivity band then moves upward to eight kilometres when thetyphoon approaches and falls down again when the typhoon departs.Short conclusions:(1) Spiral bands in the typhoon circulation pattern are not immediately resulting in strong rainfall,whereas this occurs during time of closest approach of the typhoon. These spiral bands have substructureswith periods (in the Eulerian frame over the fixed radar location).(2) Mean potential refractivity gradient does not reflect the region of strong reflectivity asexpected from theory. Comparison with radiosonde data indicates that humidity may play a moreprominent role in the radar reflectivity than replicated in the standard formalism.(3) The observed three typhoon show quite some different features in reflectivity, which needsmore observations and comparisons with other meteorological observations.References:Röttger, J., C.J. Pan, C.H. Liu, and S.Y. Su, Wind field and reflectivity variations investigatedwith the Chung-Li VHF Radar during typhoon passage, Proc. Int'l. Conf. Mesoscale Meteor., Met.Soc. ROC and AMS, Taipei, 3-6 Dec. 1991, 737-379, 1991.Shibagaki, Y., M. Yamanaka, M. Kita-Fukase, H. Hashiguchi, Y. Maekawa and S. Fukao, Mesoalpha-scalewind field and precipitating clouds in typhoon 9426 (Orchid) observed by the MUradar, J. Met. Soc. Japan, 81.2, 211-228, 2003.277