scholarly journals Assimilating the Southern Annular Mode over the Common Era using Drought Atlases and a Global Proxy Network

2021 ◽  
Author(s):  
Jonathan King ◽  
Kevin Anchukaitis ◽  
Kathryn Allen ◽  
Tessa Vance ◽  
Amy Hessl
2020 ◽  
Vol 25 (2) ◽  
pp. 338-357
Author(s):  
Cornelius Berthold

AbstractKoran manuscripts that fit comfortably within the palm of one’s hand are known as early as the 10th century CE.For the sake of convenience, all dates will be given in the common era (CE) without further mention, and not in the Islamic or Hijra calendar. Their minute and sometimes barely legible script is clearly not intended for comfortable reading. Instead, recent scholarship suggests that the manuscripts were designed to be worn on the body like pendants or fastened to military flag poles. This is corroborated by some preserved cases for these books which feature lugs to attach a cord or chain, but also their rare occurrence in contemporary textual sources. While pendant Korans in rectangular codex form exist, the majority were produced as codices in the shape of an octagonal prism, and others as scrolls that could be rolled up into a cylindrical form. Both resemble the shapes of similarly dated and pre-Islamic amulets or amulet cases. Building on recent scholarship, I will argue in this article that miniature or pendant Koran manuscripts were produced in similar forms and sizes because of comparable modes of usage, but not necessarily by a deliberate imitation of their amuletic ‘predecessors’. The manuscripts’ main functions did not require them to be read or even opened; some of their cases were in fact riveted shut. Accordingly, the haptic feedback they gave to their owners when they carried or touched them was not one of regular books but one of solid objects (like amulets) or even jewellery, which then reinforced this practice.


2010 ◽  
Vol 67 (9) ◽  
pp. 2854-2870 ◽  
Author(s):  
Tingting Gong ◽  
Steven B. Feldstein ◽  
Dehai Luo

Abstract This study examines the relationship between intraseasonal southern annular mode (SAM) events and the El Niño–Southern Oscillation (ENSO) using daily 40-yr ECMWF Re-Analysis (ERA-40) data. The data coverage spans the years 1979–2002, for the austral spring and summer seasons. The focus of this study is on the question of why positive SAM events dominate during La Niña and negative SAM events during El Niño. A composite analysis is performed on the zonal-mean zonal wind, Eliassen–Palm fluxes, and two diagnostic variables: the meridional potential vorticity gradient, a zonal-mean quantity that is used to estimate the likelihood of wave breaking, and the wave breaking index (WBI), which is used to evaluate the strength of the wave breaking. The results of this investigation suggest that the background zonal-mean flow associated with La Niña (El Niño) is preconditioned for strong (weak) anticyclonic wave breaking on the equatorward side of the eddy-driven jet, the type of wave breaking that is found to drive positive (negative) SAM events. A probability density function analysis of the WBI, for both La Niña and El Niño, indicates that strong anticyclonic wave breaking takes place much more frequently during La Niña and weak anticyclonic wave breaking during El Niño. It is suggested that these wave breaking characteristics, and their dependency on the background flow, can explain the strong preference for SAM events of one phase during ENSO. The analysis also shows that austral spring SAM events that coincide with ENSO are preceded by strong stratospheric SAM anomalies and then are followed by a prolonged period of wave breaking that lasts for approximately 30 days. These findings suggest that the ENSO background flow also plays a role in the excitation of stratospheric SAM anomalies and that the presence of these stratospheric SAM anomalies in turn excites and then maintains the tropospheric SAM anomalies via a positive eddy feedback.


2013 ◽  
Vol 27 (3) ◽  
pp. 950-961 ◽  
Author(s):  
Carolina O. Dufour ◽  
Julien Le Sommer ◽  
Marion Gehlen ◽  
James C. Orr ◽  
Jean‐Marc Molines ◽  
...  

2013 ◽  
Vol 26 (14) ◽  
pp. 5220-5241 ◽  
Author(s):  
Isla R. Simpson ◽  
Theodore G. Shepherd ◽  
Peter Hitchcock ◽  
John F. Scinocca

Abstract Many global climate models (GCMs) have trouble simulating southern annular mode (SAM) variability correctly, particularly in the Southern Hemisphere summer season where it tends to be too persistent. In this two-part study, a suite of experiments with the Canadian Middle Atmosphere Model (CMAM) is analyzed to improve the understanding of the dynamics of SAM variability and its deficiencies in GCMs. Here, an examination of the eddy–mean flow feedbacks is presented by quantification of the feedback strength as a function of zonal scale and season using a new methodology that accounts for intraseasonal forcing of the SAM. In the observed atmosphere, in the summer season, a strong negative feedback by planetary-scale waves, in particular zonal wavenumber 3, is found in a localized region in the southwest Pacific. It cancels a large proportion of the positive feedback by synoptic- and smaller-scale eddies in the zonal mean, resulting in a very weak overall eddy feedback on the SAM. CMAM is deficient in this negative feedback by planetary-scale waves, making a substantial contribution to its bias in summertime SAM persistence. Furthermore, this bias is not alleviated by artificially improving the climatological circulation, suggesting that climatological circulation biases are not the cause of the planetary wave feedback deficiency in the model. Analysis of the summertime eddy feedbacks in the models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) confirms that this is indeed a common problem among GCMs, suggesting that understanding this planetary wave feedback and the reason for its deficiency in GCMs is key to improving the fidelity of simulated SAM variability in the summer season.


2000 ◽  
Vol 69 (3) ◽  
pp. 519-557 ◽  
Author(s):  
Robert C. Gregg

In the aftermath of the 1967 “Six Days' War,” 254 ancient inscribed stones were found in forty-four towns and villages of the Golan Heights—241 in Greek, 12 in Hebrew or Aramaic, and 1 in Latin. These stones, along with numerous architectural fragments, served as the basis of the 1996 book by myself and Dan Urman, Jews, Pagans, and Christians in the Golan Heights—a study of settlement patterns of people of the three religions in this region in the early centuries of the common era.1 The area of the Golan heights, roughly the size of Rhode Island, was in antiquity a place of agriculture and, for the most part, small communities. Though historians of religions in the late Roman period have long been aware of the “quartering” of cities, and of the locations of particular religious groups in this or that section of urban areas, we have had little information concerning the ways in which Hellenes, Jews, and Christians took up residence in relation to each other in those rural settings featuring numerous towns and hamlets— most presumably too small to have “zones” for ethnic and religious groups. The surviving artifacts of a number of the Golan sites gave the opportunity for a case study. Part 1 of this article centers on evidence for the locations and possible interactions of members of these religious groups in the Golan from the third to the seventh centuries and entails a summary of findings in the earlier work, while part 2 takes up several lingering questions about religious identity and ways of “marking” it within Golan countryside communities. Both sections can be placed under a rubric of “boundary drawing and religion.”


2021 ◽  
pp. 1
Author(s):  
Jacob Coburn ◽  
S.C. Pryor

AbstractThis work quantitatively evaluates the fidelity with which the Northern Annular Mode (NAM), Southern Annular Mode (SAM), Pacific-North American pattern (PNA), El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) and the first-order mode interactions are represented in Earth System Model (ESM) output from the CMIP6 archive. Several skill metrics are used as part of a differential credibility assessment (DCA) of both spatial and temporal characteristics of the modes across ESMs, ESM families and specific ESM realizations relative to ERA5. The spatial patterns and probability distributions are generally well represented but skill scores that measure the degree to which the frequencies of maximum variance are captured are consistently lower for most ESMs and climate modes. Substantial variability in skill scores manifests across realizations from individual ESMs for the PNA and oceanic modes. Further, the ESMs consistently overestimate the strength of the NAM-PNA first-order interaction and underestimate the NAM-AMO connection. These results suggest that the choice of ESM and ESM realizations will continue to play a critical role in determining climate projections at the global and regional scale at least in the near-term.


2006 ◽  
Vol 33 (23) ◽  
Author(s):  
N. P. Gillett ◽  
T. D. Kell ◽  
P. D. Jones

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