Northeast United States growing season moisture conditions: Associations with a North American mid‐tropospheric wave train. (23rd August 2018)

• Record Type: Journal Article
• Authors: Suriano, Zachary J.; Benjamin, Andrew E.; Leathers, Daniel J.; Schroeter, Derek; Corradina, Victoria
• Is Part Of: International journal of climatology. Volume 38:Number 15(2018)
• Page Start: 5542
• Page End: 5550
• Publication Date: 2018-08-23
• Subjects: Arctic oscillation -- atmospheric wave train -- drought -- North Atlantic oscillation -- PDSI; Climatology -- Periodicals; Climat -- Périodiques; Climatologie -- Périodiques; 551.605
• DOI: 10.1002/joc.5746
• Languages: English
• ISSNs: 0899-8418

Abstract

Abstract : The Palmer Drought Severity Index is examined in the Northeast United States during the May–September growing seasons of 1950–2016, seeking to better understand the role of atmospheric circulation in moisture variability. Moist conditions for the Northeast are associated with the development of a mid‐tropospheric wave train over the United States, with enhanced ridging over the west, a trough over the Ohio Valley, and ridging over the Atlantic Ocean east of Newfoundland that favours enhanced uplift, precipitation, and southeasterly flow at the surface in the Northeast. A scalar representation of the wave train, a Summer Atmospheric Drought Index (SADI), is developed and robustly validated as a strong indicator of the Northeast moisture conditions. The SADI mid‐tropospheric wave train is the second largest mode of 500 hPa height variability over the North American sector from 1950–2016, and has an increasing trend such that the ridge‐trough‐ridge pattern is more prevalent and/or has become more enhanced with time. The wave train pattern has a significant and positive relationship to the phases of the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO). This indicates that when the AO and NAO indices are positive, the wave train pattern favours the ridge‐trough‐ridge configuration over North America, and can lead to moist conditions in the Northeast. The opposite pathway is also valid and can lead to dry conditions in the Northeast. This pathway provides a physical link between Northeast moisture conditions and global‐scale variability, improving the understanding of atmospheric influences on regional drought and excessive moisture conditions. Abstract : The variability of drought and moisture conditions in the Northeast United States is found to be partially controlled by the presence and persistence of a mid‐tropospheric wave train over North America during the growing season. The ridge‐trough‐ridge wave train (pictured here) results in enhanced precipitation and uplift in the Northeast leading to more moist conditions.