reply to post by ElectricUniverse
WOW Electric Universe...
I just keep coming up with this amazing information (The stuff that you said I couldn't substantiate) the effects of Global Warming. By the way, in
the last article, it specifically talks about Carbon Monoxide etc...
Now, I know that this isn't a pop-up book, but, I'd like to go ahead and share...you know, since I was arguing out of my ass and all.
Here's some more...
The Arctic and Antarctic Oscillations and their Projected Changes Under Global Warming
J.C. Fyfe, G.J. Boer and G.M. Flato
Canadian Centre for Climate Modelling and Analysis, Atmospheric Environment Service, University of Victoria, Victoria, BC, Canada
Abstract. The Arctic Oscillation (AO) and the Antarctic Oscillation (AAO) are the leading modes of high-latitude variability in each hemisphere as
characterized by the first EOF of mean sea-level pressure. Observations suggest a recent positive trend in the AO and it is speculated that this may
be related to global warming. The CCCma cou- pled general circulation model control simulation exhibits a robust and realistic AO and AAO. Climate
change simula- tions for the period 1900-2100, with forcing due to green- house gases and aerosols, exhibit positive trends in both the AO and the
AAO. The model simulates essentially un- changed AO/AAO variations superimposed on a forced cli- mate change pattern. The results do not suggest that
a sim- ulated trend in the AO/AAO necessarily depends on strato- spheric involvement nor that forced climate change will be expressed as a change in
the occurence of one phase of the AO/AAO over another. This pattern of climate change projects exclusively on the AAO pattern in the southern
hemisphere but not in the northern hemisphere where other EOFs are involved. The extent to which this forced climate change pattern and the unforced
modes of variation are de- termined by the same mechanisms and feedbacks remains an open question.
The leading modes of variability in the northern and southern hemispheres have been shown to have similar, roughly zonally symmetric, structures
[Thompson and Wal- lace, 1998; Thompson and Wallace, Annular Modes in the Extratropical Circulation Part I: Month-to-month Variabil- ity (and
references contained therein), submitted to the Journal of Climate, 1999; hereafter referred to as TWa and TWb respectively]. These modes, termed the
Arctic Os- cillation (AO) and Antarctic Oscillation (AAO), emerge as the leading empirical orthogonal function (EOF) of north- ern and southern
hemisphere mean sea-level pressure with associated regression patterns of temperature, zonal wind, and geopotential height from the surface to the
stratosphere. Observations suggest that the AO, and the more spatially confined North Atlantic Oscillation (NAO), have exhibited a positive trend
since the early 1980s (TWa; Hurrell, 1995), which Shindell et al.  attribute to greenhouse gas in- duced climate warming based on model
Results from the Canadian Centre for Climate Modelling and Analysis (CCCma) coupled climate model are examined to demonstrate its ability to simulate
the AO and AAO and
Copyright 1999 by the American Geophysical Union.
Paper number 1999GL900317. 0094-8276/99/1999GL900317$05.00
to investigate their evolution in forced climate change sim- ulations. The coupled model is described in Flato et al. [The Canadian Centre for Climate
Modeling and Analysis Global Coupled Model and its Climate, submitted to Cli- mate Dynamics, 1998] and the forced climate change simu- lations in Boer
et al. [A transient climate change simulation with greenhouse gas and aerosol forcing: projected climate change in the 21st century, submitted to
Climate Dynamics, 1998] hereafter referred to as BFR.
The atmospheric component of the coupled model is a global primitive equation spectral model with T32 triangu- lar truncation and 10 unequally-spaced
vertical levels with the top level at 12 hPa (McFarlane et al., 1992). The ocean component is a global primitive equation grid-point model at with
1.875◦resolution and 29 vertical levels, based on the GFDL MOM1.1 code (Pacanowski et al., 1993). A 200-year control simulation and an ensemble of
three independent cli- mate change simulations forced with changing greenhouse gas (GHG) concentrations and aerosol loadings (following the forcing
specification of Mitchell et al., 1995), are avail- able for the period 1900 to 2100.
The analysis of the model results parallels the observa- tional analyses of TWa and TWb to facilitate comparison. Plate 1 displays the first three
simulated EOF patterns for the northern hemisphere (north of 20◦N), wintertime (us- ing November-April monthly means), mean sea-level pres- sure
(SLP) calculated from the 200-year control simulation. These first three EOFs account for 24, 11, and 9 percent of the variance respectively. The
first EOF is identified as the AO, the second apparently includes variability that is partly identified with the more localized NAO, and the third is
dominated by the variability of the Aleutian low. Plate 1 also displays the first three EOF patterns calculated from observations for the period
1900-1992 (updated from Trenberth and Paolino, 1980), with EOF2 and EOF3 in- terchanged to make the correspondence with the simulated patterns
clearer. These first three observed EOFs account for 18, 12, and 11 percent of the variance. The observed and simulated patterns are remarkably
similar and account for similar percentages of the variance, although the midlat- itude centers of action in the simulated AO are somewhat weaker than
observed. All the EOFs displayed in Plate 1 are separated according to the criterion of North et al. . In the southern hemisphere the first EOF
dominates the variability in the simulations (observations are not readily available) and accounts for 28 percent of the variance.
Plate 2 displays both the AO and AAO and the associ- ated regression maps of surface air temperature (SAT) and mean zonal wind ([U]) for the control
simulation. The simu-
1602 FYFE ET AL.: SIMULATED TRENDS IN THE ARCTIC AND ANTARCTIC OSCILLATIONS EOF1 EOF2 EOF3 SLP SAT [U]
EOF1 EOF3 EOF2
Plate 1. Leading EOF patterns of the November-April monthly mean SLP anomaly fields as calculated from the 200-year control simulation and 1900-1992
observations (scaled by the standard deviation of their associated prin- cipal component (PC) time series). Contour intervals are 1 hPa
(...-1.5,-0.5,0.5...) with blue and red (or pink) contours indicating negative and positive values, respectively. Ob- servational grids points with
less that 25 percent temporal coverage are excluded from the calculation.
lation results are remarkably similar to those based on obser- vations in TWb (their Plates 4 and 9) including, perhaps for- tuitously, the asymmetry
in the temperature pattern across Antarctica. The coupled model produces a robust and real- istic AO and AAO.
Plate 3 displays the same results as Plate 2 for one of the GHG+aerosol forced simulations (all of which give similar results). Plate 4 gives the
principal component (PC) time series (i.e. the amplitude) of the AO and AAO from the observations, the control simulation, and each of the three
SLP SAT [U]
Plate 2. The AO and AAO and associated regression patterns of November-April SAT and zonal-mean zonal wind. Contours for SLP, SAT and [U] are 1 hPa
(...-1.5,- 0.5,0.5...), 0.5◦K (...-0.75,-0.25,0.25...) and 0.5 m/s (...- 0.75,-0.25,0.25...), respectively
Plate 3. As in Plate 2, but for a climate change simulation from 1900-2100 with greenhouse gas and aerosol forcing.
forced GHG+aerosol warming simulations. The forced cli- mate change simulations all show a trend to increasingly positive values (the positive phase
of the AO/AAO has lower pressures over the polar regions) which is absent in the unforced control simulation. Whereas lower tropospheric anomalies
appear coupled to month-to-month fluctuations of the winter stratospheric polar vortex (Baldwin et al., 1994; Perlwitz and Graf, 1995; Cheng and
Dunkerton, 1995; Kitoh et al., 1996; Kodera et al., 1996; TWa, b) the connection of the AO and AAO to the stratosphere does not appear to play a
controlling role in the forced change we see here since the model does not resolve the stratosphere in any detail. This is in constrast to Shindell et
al. , who conclude that a detailed stratosphere is required to capture an AO trend in their mo del.
The AO and AAO represent dynamical and linked ther- modynamical behaviour of the system and account for an important part of the variance. A change in
the behaviour of the AO and AAO under forced climate change could take a number of forms. The AO/AAO could exhibit no change, although this is not the
case for the CCCma coupled model (while it is the case for some models according to Shindell et al., 1999). The AO/AAO could express the forced cli-
mate change as a change in the frequency of the modes as suggested by Palmer . This would seem to imply that the PC time series of Plate 4 would
preferentially exhibit positive values but also that the (less frequent) negative val- ues would still span the same range of values. This is not the
case in Plate 4 where both positive excursions increase and negative excursions decrease in tandem. The AO/AAO could exhibit important changes in
structure and there is some suggestion for this in Plate 3.