Initiation of the Northern Hemisphere continental ice

• Main Authors: David H. Bromwicha, E. Richard Toracintaa, Sheng-hung Wanga
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.670.5100; http://polarmet.osu.edu/PMG_publications/bromwich_toracinta_qi_2002.pdf

The 50+ years National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis data set is used to locate distinct atmospheric circulation patterns favoring glacial initiation over northeastern North America (50–801N, 60–901W). These patterns yield abundant winter snowfall and anomalously cool summer temperatures. We assume that atmosphere/ ocean boundary conditions during the last interglacial and today are similar. Atmospheric circulation patterns inferred from composite mean sea level pressure (MSLP) anomaly fields for the extreme cold summers and wet winters are consistent with the respective composite summer 2-m temperature and winter precipitation anomaly patterns. Summer 2-m temperatures (winter precipitation rate) are strongly (weakly) correlated with North Atlantic sea surface temperatures (SST). Extreme season MSLP anomalies and associated wind stress may augment the SST anomalies via Ekman transport. The contemporary climate record over the study region shows substantial interannual variability, consistent with the lack of glaciation. The extreme cold summer/wet winter criteria for glaciation occur in the contemporary record, but are rare. Mass balance calculations using NNR demonstrate that a perennial snowfield is possible in the study region, but glacial onset requires a change in the frequency distribution of climatic events to yield a sustained (decadal) period of cold summers that preserve the winter