Anomalous winds
; Atmospheric conditions
; Atmospheric process
; Climate signals
; Eastern tropical pacific
; ENSO
; High Latitudes
; Model experiments
; Sea surface temperatures
; Teleconnection patterns
; Teleconnections
; Tornado outbreak
; Vertical wind shear
; Atmospheric pressure
; Atmospheric temperature
; Climate models
; Experiments
; Nickel compounds
; Tropics
; Tornadoes
; climate signal
; El Nino-Southern Oscillation
; sea surface temperature
; teleconnection
; tornado
; troposphere
; westerly
; wind shear
; Pacific Ocean
; Pacific Ocean (Tropical)
; United States
英文摘要:
The record-breaking U.S. tornado outbreaks in the spring of 2011 prompt the need to identify long-term climate signals that could potentially provide seasonal predictability for U.S. tornado outbreaks. This study uses both observations and model experiments to show that a positive phase TransNiñ o may be one such climate signal. Among the top 10 extreme outbreak years during 1950-2010, seven years including the top three are identified with a strongly positive phase TransNiñ o. The number of intense tornadoes in AprilMay is nearly doubled during the top 10 positive TransNiñ o years from that during 10 neutral years. TransNiñ o represents the evolution of tropical Pacific sea surface temperatures (SSTs) during the onset or decay phase of the El Niñ o-Southern Oscillation. A positive phase TransNiñ o is characterized by colder than normal SSTs in the central tropical Pacific and warmer than normal SSTs in the eastern tropical Pacific. Modeling experiments suggest that warmer than normal SSTs in the eastern tropical Pacific work constructively with colder than normal SSTs in the central tropical Pacific to force a strong and persistent teleconnection pattern that increases both the upper-level westerly and lower-level southwesterly over the central and eastern United States. These anomalous winds advect more cold and dry upper-level air from the high latitudes and more warm andmoist lower-level air fromtheGulf ofMexico converging into the east of the Rockies, and also increase both the lower-tropospheric (0-6 km) and lower-level (0-1 km) vertical wind shear values therein, thus providing large-scale atmospheric conditions conducive to intense tornado outbreaks over the United States.
Cooperative Institute for Marine and Atmospheric Studies, University of Miami, and Atlantic Oceanographic and Meteorological Laboratory, NOAA, Miami, United States; Atlantic Oceanographic and Meteorological Laboratory, NOAA, Miami, FL, United States
Recommended Citation:
Lee S.-K.,Atlas R.,Enfield D.,et al. Is there an optimal ENSO pattern that enhances large-scale atmospheric processes conducive to tornado outbreaks in the United States?[J]. Journal of Climate,2013-01-01,26(5)