Pagecontent:
Project OC1 – Winter and summer blocking variability in the North Atlantic region - evidence from long-term observational and proxy data from southwestern Greenland
N. Rimbu, G. Lohmann
The interannual and decadal variability of the North Atlantic atmospheric blocking frequency and distribution in connection with long-term observational and proxy records from southwestern Greenland is investigated. It is shown that warm (cold) conditions in southwestern Greenland during winter are related with high (low) blocking activity in the Greenland-Scandinavian region. The pattern of winter temperature-blocking variability is more complex than the blocking pattern associated to the North Atlantic Oscillation (NAO). We find, furthermore, that a North Atlantic blocking index is significantly correlated with seasonally resolved stable isotope records from Greenland ice cores. Both suggest a possible reconstruction of blocking variability in this region. During summer, high (low) blocking activity in the Euro-Atlantic region is associated with cold (warm) conditions in southwestern Greenland. We conclude that historical temperature records, as well as proxy data from Greenland, can be used to obtain information related to interannual and multidecadal variation of winter and summer blocking during past periods.
Figure 1: Composite maps of winter blocking (1908-1970) corresponding to (a) high and (c) low values of a Greenland temperature reconstruction based on stable isotope records from Greenland ice-cores (Vinther et al., 2003) represented in (b). Units are percentage of blocked days to total number of days per winter.
Rimbu, N, Lohmann, G (2011) Winter and summer blocking variability in the North Atlantic region - evidence from long-term observational and proxy data from southwestern Greenland, Climate of the Past, 7, 543–555 Reprint