DISCUSSION OF CERTAIN CONCLUSIONS DRAWN FROM THE STUDY OF THE 



SYNCHRONOUS CHARTS OF SEA-LEVEL PRESSURE FOR NOON G.M.T. 



WITH WIND AND AIR TEMPERATURE. 



THE PATHS OF THE CYCLONIC DEPRESSIONS OF THE SOUTHERN OCBAN. 



Hitherto adequate information has been wanting for the purpose of defining the average paths of 

 cyclonic depressions which visit the Southern Ocean and Southern Continents during the several seasons 

 of the year, and this information these circumpolar charts to some extent supply. 



An attempt was made by the present writer in the year 1890 to determine, by the aid of observation* 

 extracted from a large number of logs relating to voyages between the Cape of Good Hope ami Australasia 

 during the three years 1887-9, the mean paths of the centres of cyclonic systems moving eastward South 

 of the 38th parallel of latitude,* and subsequently to trace the centres of high- and low-pressure systems 

 in transit eastward over Australasia,! by reference principally to synoptic charts prepared at the Sydney 

 Observatory under the direction of the late Mr. H. C. RUSSELL, then Government Astronomer for New 

 South Wales. 



From the information obtained by means of the data contained in the logs referred to it was inf' 

 that East of the 30th meridian of East longitude the centres of atmospheric disturbances appi-.-in-d t 

 travel to the eastward usually on paths lying South of the 43rd parallel of latitude during winter months 

 and South of the 46th parallel during summer months. The evidence afforded by the daily synoptic 

 charts of Australasia also appeared to favour this assumption, which is now confirmed by the testimony of 

 the daily charts under notice. 



In a memoir by the writer upon the Climatology of South Victoria Land and the Neighbouring Seas,t 

 which is included in the published results of meteorological observations of the "Discovery" Expedition, 

 during the years 1901 to 1904, attention is directed to the exceptionally favourable position, regarded a< 

 a meteorological station in the Southern Ocean, in which the Winter Quarters of the Exploring Ship 

 " Gauss," of the German Antarctic Expedition, was situated. The value of the data obtained at this 

 station, on the fringe of Antarctica, is, moreover, considerably enhanced by observations recorded at the 

 German station on Kerguelen Island, because together they throw light upon points in connexion with 

 the surface distribution of pressure and wind in cyclonic systems of the Southern Ocean, in regard to 

 which little has hitherto been known. 



The following remarks in this connexion, which appear in the memoir referred to, are ba-a-d upon tin- 

 data incorporated in the daily charts; it is, therefore, considered admissible to repeat them in 

 pages. 



Lying to the South of the westerly winds of the Southern Ocean, and at the limits of the southern 

 segment of those low-pressure areas which move from West to East with the westerly air current of the 

 Southern Hemisphere, the Winter Quarters of the German Antarctic Expedition were exceptionally well 

 situated as an observing station from a meteorological point of view. 



It has been thought by meteorologists, who have attacked the problem, that, associated with the 

 depressions which traverse the Southern Oceans, depressions which are usually elliptical in shape and have 

 their major axes extended in a northerly and southerly direction, the easterly winds in the southern 

 segment of the system are almost always light or moderate in force. Ships running down the easting in 



* "Wind Systems and Trade Routes between the Cape of Good Hope and Australia," 'Quarterly Journal, Royal 

 Meteorological Society,' Vol. XVII. (1891), pp. 21-27. 



( " The Tracts of Ocean Wind Systems in Transit across Australasia," ' Quarterly Journal, Km al M.-tour.>U>gi,-al S,,, iety,' 

 Vol. XIX. (1893), pp. 34r-38. 



{ " Climatology of Victoria Land and the Neighbouring Seas," ' National Antarctic Expedition, Meteorology,' Prt I. 



C 



