A Climatology of Integrated Water Vapor Transport in the Northeast and its Relationship to Atmospheric Rivers

Atmospheric rivers (ARs) have been frequently studied along the west coast of the United States. Rutz et al. (2014) defines an AR as having values of integrated water vapor transport (IVT) of at least 250 kg/m/s (IVT250), over a length of at least 2,000 km. Often, Ars in this region are less than 1000-km wide. However, ARs can also be found in the northeastern U.S. where they have received considerably less study. The purpose of this study is to analyze the frequency of IVT250 in the northeast and determine how frequently IVT250 is associated with ARs by creating a five year climatology spanning 2013–2017.

This work demonstrates that IVT250 is most frequent over the ocean adjacent to the northeast in every month and season. The most frequent months for IVT250 are the summer months (June, July, August) and the least frequent are the winter months (December, January, February). An examination of the frequency of IVT250 associated with ARs shows the opposite pattern. The percentage of IVT250 associated with ARs has the highest values in the winter, and the lowest values in the summer. Thus, even though there are ARs in the summer, there are also many more days with IVT250 and no ARs. This climatology is an important first step in linking ARs to high moisture values, and their relationship to flooding events in this domain.