SIMULTANEOUS OBSERVATIONS OF THE 2-DAY WAVE AT LONDON (43-DEGREES-N, 81-DEGREES-W) AND SASKATOON (52-DEGREES-N, 107-DEGREES-W) NEAR 91 KM ALTITUDE DURING THE 2 YEARS OF 1993 AND 1994

Simultaneous observations are valuable in providing further insights i nto the character of the quasi 2-day wave. In this study we investigat e the period and amplitude for the quasi 2-day wave near 91 km using M F radars at London and Saskatoon, Canada, and in addition look at poss ible values of the zonal wave number. The results of the present study bring out certain new aspects of the quasi 2-day wave at midlatitudes in the Northern Hemisphere. In particular we show that the period of the quasi 2-day wave determined from our study (specially at large amp litudes) is smaller (46-47 h) than the 51-52 h period often suggested by other Northern Hemisphere results, and that the periods also showed variability as a function of time. We also draw attention to the annu al variability, and especially highlight the occurrence of the wave in non-summer months. Our observations show significant wave correlation between the London and Saskatoon sites during time intervals of stron g 2-day wave activity. These results suggest that the 2-day waves of 1 993/4 are westward propagating waves of zonal wave number 3, although sometimes the zonal wave number 5 is also indicated (specially at larg e amplitudes). Our study also contributes additional mid-latitude geog raphical data which should aid in developing a better picture of the q uasi 2-day wave.