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." '\ aJJ75~ ~ ,-, f~+_) -9- METECROLOOlCAL STUDIES 2. Possible Solar Bffects on Atmospheric Wind Systems The very high atmosphere is primarilY' under control of the sun. The variable solar emissions cause high atmospheric changes which affect'-radio communications and even distortions in the earth's magnetic field. At lower levels, the v.l.nd sY'stems are essentia.ll:r oontrolled by meteorologica.l phenomena such as the interplaY' between oceans and continents or polar .regions and the tropics. But what about the transition regions between these levela - to what extent does an interrelationship exist? These are questions which we believe D1USt be answered before accurate long-range weather pre- dictions can be :made. During the past two years, part of the work at the High Altitude Observatory has been directed toward investigat:Lng possible changes in the earth's atmospheric circroJ.ation in response to changes in solar activity. A suggestive new result has been the detection of apparent change in circulation at the "jet stream." level of the. atmosphere (about 30,000 ft.), following abrupt increases in solar corpuscular emission. These changes have occurred during the past two ld.nters (l956-57 and 1957-58). The changes begin about three days after the magnetic disturbance, vhich signals the arrival of a corpuscular oloud from the sun, and reach a mA..-I11l1lD1 about five or six days later. The resultant wind field pattern produces a strong meridional (north-south) transport of air at relatively frequent intervals in comparison to other .years, and, in part at least, :may be associated with the breaking of the extended droughts in the southwestern United S'tates. . At the S!Ulle time, research at other institutes throughout the world indicates there :maY' also be an influence on the earth's atmosphere introduced b1 changes in the sun's ultraviolet radiation. Thus the evidence is moun~ing that solar changes produce pronounced effects on the earth's wind systems. In turn, it seems plausible that basic changes in atmospheric circulation :maY' be .the cause _of extended periods of. drought or rainfall over large areas. But D1Uch remains to be. done - not just in efforts to understand solar influences, b1t in understanding the effects of disturbed wind systems sm such weather elements as rainfall and temperatures. The High Altitude Observatory believes that a well organ- ized attack should be :made on this problem for at least two years. This will l:"equire the close coordination of solar and upper-atmos- pheric physicists with meteorolgists.