Early history of NAO research …
Saabye 1770-8
Teisserence de Bort 1883
Hann 1890
Hildebrandsson 1897
Meinardus 1898
Pettersson 1905
Exner 19??
Walker 1908, 1924, 1932
Defant 1924
Loewe 1937
Van Loon and Rogers 1978
+ many others …