Description: Es werden die Daten des Polarfront-Programms während des Internationalen Geophysikalischen Jahres 1957/58 verwendet, um die Frage des Eindringens jahresperiodischer Oberflächenstörungen zu untersuchen. Nach der Diskussion der Oberflächenstörungen und der bei der Ermittlung der Eindringtiefe auftretenden Fehler werden durch den Vergleich von TS-Kurven die gesuchten Tiefenwerte gefunden. Für das Seegebiet südöstlich Grönlands wird eine spezielle Untersuchung durchgeführt. Unter stark vereinfachten Verhältnissen werden vertikale Austauschkoeffizienten ermittelt. Zum Abschluß wird die Frage untersucht, wieweit die für das Jahr 1958 gefundenen Verhältnisse repräsentativ für das Untersuchungsgebiet sind. Data of the "Polar Front Survey", one of the most extensive oceanographic programs during the International Geophysical Year 1957/58, were used to determine the maximum depth of penetration of seasonal surface disturbances. The area of investigation covers the North Atlantic between 40°N-65°N and 10°W-45°W. It is established, that next to the annual water budget and the annual cycle of windspeed, the heat budget is the most important factor causing variations of yearly periods in deeper layers. The maximum depth of penetration is determined by comparing temperature - salinity curves both from spring and from autumn, which are obtained by means of a suitable averaging process (see plate 8, 9). The resulting depths reach from less than 200 m in the southern part of the area to more than 600 m west of Scotland and south of Iceland (see plate 10, fig. 20). The mean error of these depths was found to be about 15%, The weak haline stratification in the area southeast of Greenland gives rise to the sinking of cooled surface water in winter. Therefore extreme depths of more than 2000 m may be reached by annual surface disturbances (see plate 11). This area is well known as one of the sources of North Atlantic deep water. By means of strong simplifications vertical exchange coefficients were estimated (see table 2 and 3).