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Weihong Qian, Jun Du, and Yang Ai

signal is much smaller than the background climate, the important detailed information of a weather disturbance is often hidden (too weak to show) and overlooked in a conventional weather chart. In contrast, an anomaly field (i.e., a departure from climate) is found to be more directly associated with a local weather event than a full field ( Qian et al. 2016b ). This situation is illustrated by Fig. 1 , where the two “positive” events and one “negative” event are hardly visible in the full field

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John M. Lyman and Gregory C. Johnson

1. Introduction Most of the earth’s warming signal arising from anthropogenic climate change is thought to reside in the upper ocean ( Hansen et al. 2005 ; Levitus et al. 2005 ). To understand past and present global warming trends, and so to provide data for improvement of predictions of future changes, it is necessary to refine estimates of global upper ocean heat content anomalies (OHCA) and their uncertainties. Here the effect of the irregular sampling of the world’s ocean over the last

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Chi-Cherng Hong and Tim Li

transient time scale, and the temperature drop caused by a cold surge rarely persists for more than two weeks ( Zhang et al. 1997 ; Compo et al. 1999 ; Chan and Li 2004 ). In February 2008, an extreme persistent cold anomaly (ECA) accompanied by a long-persisting northerly anomaly and a sequence of cold advection occurred over Southeast Asia. The ECA persisted for nearly one month, which not only broke the lowest temperature record for the past 50 yr but also resulted in numerous agriculture and

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Sang-Ki Lee, Chunzai Wang, and Brian E. Mapes

Rossby wave that forms to the northwest and southwest of the heat source. These damped baroclinic Kelvin and Rossby waves depicted by the Matsuno–Gill model are the cornerstones for our understanding of heat-induced atmospheric circulations in the tropics. However, the Matuno–Gill model completely fails outside of the tropics. As demonstrated by Hoskins and Karoly (1981) and by Horel and Wallace (1981) , a diabatic heating anomaly associated with El Niño can also excite a stationary barotropic

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John W. Nielsen-Gammon and David A. Gold

( Shapiro and Keyser 1990 ). The presence of these strong horizontal PV gradients will be shown to lead to substantial changes in the structure and intensity of the balanced atmospheric response to a PV anomaly. Here and elsewhere, “balanced” refers to that portion of the time-dependent flow recoverable from PV inversion, following Davis et al. (1996) . Thorpe (1986) produced well-known diagrams of the balanced atmospheric structure associated with a circular vortex on the tropopause. Juckes (1999

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Claude Frankignoul and Nathalie Sennéchael

1. Introduction In the 1960s and early 1970s, it was often speculated on the basis of contemporary correlations that North Pacific sea surface temperature (SST) anomalies have an influence on the large-scale atmospheric circulation on the seasonal time scale (e.g., Namias 1963 ). However, Davis (1976) showed that the cross correlation between SST and sea level pressure (SLP) anomalies reflected the atmosphere driving the ocean. This was consistent with the stochastic climate model of

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Motoki Nagura and Masanori Konda

1. Introduction Sea surface temperature (SST) anomalies in the Indian Ocean are characterized by a zonal dipole pattern called the Indian Ocean dipole mode ( Reverdin et al. 1986 ; Hastenrath et al. 1993 ; Harrison and Larkin 1998 ; Saji et al. 1999 ; Webster et al. 1999 ). Past studies have suggested that a possible forcing to induce the Indian Ocean dipole mode event is El Niño–Southern Oscillation (ENSO) events in the Pacific Ocean. For example, results from numerical experiments ( Lau

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Norman W. Junker, Richard H. Grumm, Robert Hart, Lance F. Bosart, Katherine M. Bell, and Frank J. Pereira

type of event. More recently, Reynolds (1996) pointed out the similarities in the synoptic patterns for three major rainstorms during 1995. Each was associated with a strong synoptic-scale system that helped produce strong onshore flow. Pandey et al. (1999) noticed that a strong negative height anomaly to the northwest of California was associated with the 20 heaviest precipitation cases found over the Sierra Nevada during the period 1948–88. Grumm and Hart (2001a) found that significant

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Randall A. Graham and Richard H. Grumm

the greatest media attention. When viewed objectively, through the use of anomalies, some well-known storms may prove to be not nearly as meteorologically rare as lesser-known storms that impacted areas of lower population. The methodology presented in HG01 attempts to utilize the normalized anomalies for a variety of elements and a series of levels to objectively rank synoptic events. However, the original work presented in HG01 only examined historical normalized anomalies for the eastern

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Martha Shulski, John Walsh, Eric Stevens, and Richard Thoman

aggregate mean of 5.1°C for Alaska’s interior ( Shulski and Wender 2007 ). Temperature anomalies normally last on the time scale of several days to a week, or the length of time for a synoptic pattern to move through the state. Along with atmospheric circulation, another important factor for wintertime climatology at this latitude is the presence of a semipermanent temperature inversion at or near the surface ( Wexler 1936 ; Wendler and Nicpon 1975 ; Kahl 1989 ; Overland and Guest 1991 ). Under a

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