scholarly journals Future changes in the Great Plains Low‐Level Jet governed by seasonally dependent pattern changes in the North Atlantic Subtropical High

2020 ◽  
Author(s):  
Wenyu Zhou ◽  
L. Ruby Leung ◽  
Fengfei Song ◽  
Jian Lu
Keyword(s):  
Great Plains ◽  
North Atlantic ◽  
Subtropical High ◽  
Low Level ◽  
North Atlantic Subtropical High ◽  
The North ◽  
Low Level Jet ◽  
The North Atlantic

scholarly journals Modelling Hydrometeorological Extremes Associated to the Moisture Transport Driven by the Great Plains Low-Level Jet

2021 ◽  
Author(s):  
Luis Gimeno-Sotelo ◽  
Patricia de Zea Bermudez ◽  
Iago Algarra ◽  
Luis Gimeno
Keyword(s):  
Great Plains ◽  
North Atlantic ◽  
Source Region ◽  
Lower Troposphere ◽  
Dynamical Instability ◽  
Low Level ◽  
Extremal Dependence ◽  
The North ◽  
Low Level Jet ◽  
The North Atlantic

Abstract The Great Plains Low-Level Jet system consists of very strong winds in the lower troposphere that transport a huge amount of moisture from the Gulf of Mexico to the American Great Plains. This paper aims to study the extremes of the Transported Moisture (TM) from the GPLLJ source region to the jet domain; and, for low and high TM, to analyze the extremal dependence between the upper tail of the precipitation in the GPLLJ sink region and the lower tail of the tropospheric stability in that region (omega). The declustered extremes of TM were analyzed using Peaks Over Threshold (POT). A non-stationary Exponential model was fitted to the cluster maxima. Estimated return levels show that the extremes of TM are expected to decrease in the future. This is meteorologically congruent with the known displacement of the western edge of the North Atlantic Subtropical High, which controls atmospheric circulation in the North Atlantic, and to a higher scale with the change of phase from negative to positive of the Atlantic Multidecadal Oscillation. Bilogistic and Logistic models were fitted to the extremes of (-omega, precipitation) for low and high TM, respectively. The extremal dependence between "-omega" and precipitation proves to be stronger in the case of high TM. This confirms that dynamical instability represented by “-omega” is the most important parameter for achieving high values of precipitation once there is a mechanism that allows the continuous supply of large amounts of moisture, such as the derived from a low-level jet system.

scholarly journals East Asian Monsoon Forcing And North Atlantic Subtropical High Modulation of Summer Great Plains Low-Level jet

2022 ◽  
Author(s):  
Kelsey Malloy ◽  
Ben P. Kirtman
Keyword(s):  
Great Plains ◽  
North Atlantic ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
East Asian ◽  
Subtropical High ◽  
Low Level ◽  
North Atlantic Subtropical High ◽  
Low Level Jet ◽  
Upper Level

Abstract Dynamic influences on summertime seasonal United States rainfall variability are not well understood. A major cause of moisture transport is the Great Plains low-level jet (LLJ). Using observations and a dry atmospheric general circulation model, this study explored the distinct and combined impacts of two prominent atmospheric teleconnections – the East Asian monsoon (EAM) and North Atlantic subtropical high (NASH) – on the Great Plains LLJ in the summer. Separately, a strong EAM and strong western NASH are linked to a strengthened LLJ and positive rainfall anomalies in the Plains/Midwest. Overall, NASH variability is more important for considering the LLJ impacts, but strong EAM events amplify western NASH-related Great Plains LLJ strengthening and associated rainfall signals. This occurs when the EAM-forced Rossby wave pattern over North America constructively interferes with low-level wind field, providing upper-level support for the LLJ and increasing mid- to upper-level divergence.

scholarly journals Influence of the North Atlantic Subtropical High on wet and dry sea-breeze events in North Carolina, United States

2017 ◽  
pp. 9 ◽  
Author(s):  
Nicholas T. Luchetti ◽  
Rosana Nieto Ferreira ◽  
Thomas M. Rickenbach ◽  
Mark R. Nissenbaum ◽  
Joel D. McAuliffe
Keyword(s):  
United States ◽  
North Carolina ◽  
North Atlantic ◽  
Convective Available Potential Energy ◽  
Sea Breeze ◽  
The United States ◽  
Subtropical High ◽  
North Atlantic Subtropical High ◽  
The North ◽  
The North Atlantic

The sea-breeze (SB) is an important source of summertime precipitation in North Carolina (NC, southeast United States). However, not all SB events produce precipitation. A climatology of wet and dry SB events in NC is used to investigate the conditions that are conducive to precipitation associated with the sea breeze. Radar imagery was used to detect 88 SB events that occurred along the NC coast between May-September of 2009-2012. The majority (85%) of SB events occurred during offshore flow (53%) or during flow that was parallel to the coast (22%). SB events were separated into dry (53%) and wet (47%) events and differences in the dynamic and thermodynamic parameters of the environment in which they formed were analyzed. Significant differences in dynamic and thermodynamic conditions were found. SB dry events occurred under stronger winds (6.00 ± 2.36 ms-1) than SB wet events (4.02 ± 2.16 ms-1). Moreover, during SB wet events larger values of convective available potential energy and lower values of convective inhibition were present, conditions that favor precipitation. Overall, the SB wet events accounted for 20-30% of the May-September precipitation along the NC coastal region. The position of the North Atlantic Subtropical High (NASH) controls both moisture availability and winds along the NC coast, thus providing a synoptic-scale control mechanism for SB precipitation. In particular, it was shown that when the NASH western ridge is located along the southeast coast of the United States, it causes a moist southwesterly flow along the NC coast that may favor the occurrence of SB wet events.

Reply to “Comments on ‘Changes to the North Atlantic Subtropical High and Its Role in the Intensification of Summer Rainfall Variability in the Southeastern United States’”

2013 ◽  
Vol 26 (2) ◽  
pp. 683-688 ◽  
Author(s):  
Wenhong Li ◽  
Laifang Li ◽  
Rong Fu ◽  
Yi Deng ◽  
Hui Wang
Keyword(s):  
North Atlantic ◽  
Rainfall Variability ◽  
Southeastern United States ◽  
Summer Rainfall ◽  
Subtropical High ◽  
North Atlantic Subtropical High ◽  
The North ◽  
Westward Movement ◽  
The North Atlantic ◽  
Potential Impact

Abstract Recently Diem questioned the western ridge movement of the North Atlantic subtropical high (NASH) reported in a 2011 paper of Li et al. This reply shows more analysis that further strengthens the conclusions originally put forth by Li et al. Diem’’s analysis of the trend in the western ridge of the NASH was based on the data over a 30-yr period (1978–2007), whereas the main conclusions in Li et al. were drawn according to the data over a 60-yr period (1948–2007). Over the last 60 years, the NASH has shown a significant trend of westward movement, the meridional movement of the western ridge of the NASH has enhanced in the recent three decades, and the potential impact of global warming cannot be ruled out in an attempt to explain these changes of the NASH.

Impacts of the North Atlantic Subtropical High on Daily Summer Precipitation over the Conterminous United States

2021 ◽  
Author(s):  
Enrico Zorzetto ◽  
Laifang Li
Keyword(s):  
United States ◽  
North Atlantic ◽  
Daily Rainfall ◽  
Summer Precipitation ◽  
Subtropical High ◽  
Rainfall Events ◽  
North Atlantic Subtropical High ◽  
The North ◽  
The North Atlantic ◽  
The Impact

AbstractBy modulating the moisture flux from ocean to adjacent land, the North Atlantic Subtropical High (NASH) western ridge significantly influences summer-season total precipitation over the Conterminous United States (CONUS). However, its influence on the frequency and intensity of daily rainfall events over the CONUS remains unclear. Here we introduce a Bayesian statistical model to investigate the impacts of the NASH western ridge position on key statistics of daily-scale summer precipitation, including the intensity of rainfall events, the probability of precipitation occurrence, and the probability of extreme values. These statistical quantities play a key role in characterizing both the impact of wet extremes (e.g., the probability of floods) and dry extremes. By applying this model to historical rain gauge records (1948-2019) covering the entire CONUS, we find that the western ridge of the NASH influences the frequency of rainfall as well as the distribution of rainfall intensities over extended areas of the CONUS. In particular, we find that the NASH ridge also modulates the frequency of extreme rainfall, especially that over part of the Southeast and upper Midwest. Our analysis underlines the importance of including the NASH western ridge position as a predictor for key statistical rainfall properties to be used for hydrological applications. This result is especially relevant for projecting future changes in daily rainfall regimes over the CONUS based on the predicted strengthening of the NASH in a warming climate.

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