Storm Tracks:

There are various measures of storm activity within GCMs.  Large-scale
dynamical mid-latitude storms are a function of the frequency and intensity
of cyclonic activity, which must be computed from daily or more frequent
measurments.  One simple measurement is the variance of the sea level
pressure or 1000 mb geopotential height.  The CGCM1 data are
presented as simple variances of the 1000 mb geopotential height, whereas
the HADCM2 data are calculated as standard deviations of the sea level
pressure, filtered with a Murakami filter, which isolates the
synoptic variability between 2.5 and 8 days.  Both modeling groups have also
provided data from a more complex (and robust) cyclone tracking method.  
This method provides a more accurate measurement of storm activity than the
other measures of variance.  However, since variance measurements have been
widely used in the literature, they have been included here.  
Please
see Carnell et al., 1996; Carnell and Senior, 1998; and Lambert, 1995
for more details.


CGCM1:

I have prepared these files in (FORTNER Transform) format:

cvabl.tra (1990-2020): variance of 1000 mb geopotential height
cva20.tra (2006-2036): variance of 1000 mb geopotential height
cva85.tra (2070-2100): variance of 1000 mb geopotential height
(all data are DJF) 

The top four lines are headers, with the third line listing the latitudes
and the fourth line listing the longitudes.  Then there are 18 lines (one
line for each latitude) of 31 longitudes, formated (31e12.5). The longitudes
are all West, though the negative sign is not indicated.  The region covered
is North America only and corresponds to the images on this page.

cstbl.tra (1901-1910): cyclone tracking
cst20.tra (2017-2028): cyclone tracking
cst90.tra (2091-2100): cyclone tracking
(all data are DJF)

Units are total number of storms counted 2x daily over the respective time 
periods per 200000 km2.  Storm counts were computed north of 30N.

The top four lines are headers, with the third line listing the latitudes
and the fourth line listing the longitudes.  Then there are 31 lines (one
line for each latitude) of 144 longitudes, formated (144f11.2), corresponding
to a grid spacing of 2.5x2.5 degrees.  The region covered
is the northern hemisphere poleward of 15 degrees N.  The data were interpolated
from a polar sterographic projection, so the -999999 values are lat-lon  
intersections which could not be interpolated from the 47x51 since they
are outside the grid (D. Joseph, personal communication). 

I'd like to thank Steven Lambert for providing these data.


HADCM2:

I have prepared these files in (FORTNER Transform) format:

hvabl.tra (1990-2020): filtered standard deviation of sea level pressure 
  from the unforced control
hva20.tra (2006-2036): filtered standard deviation of sea level pressure 
  from the tranient run
hva85.tra (2070-2100): filtered standard deviation of sea level pressure
  from the transient run
(all data are DJF)

The top four lines are headers, with the third line listing the latitudes
and the fourth line listing the longitudes.  Then there are 73 lines (one
line for each latitude) of 96 longitudes, formated (96(f13.3,x)). The region
covered is the entire globe.


hstbl.tra (1990-2110): cyclone tracking from the unforced control
hst20.tra (2006-2036): cyclone tracking from the transient run
hst85.tra (2070-2100): cyclone tracking from the transient run
(all data are DJF)

Units are seasonal mean storms per 1,000,000 km2.  Storm counts were 
computed north of 30N.

The top four lines are headers, with the third line listing the latitudes
and the fourth line listing the longitudes.  Then there are 36 lines (one
line for each latitude) of 96 longitudes, formated (96(f13.7,x)). The region
covered is the entire northern hemisphere.

I'd like to thank Ruth McDonald (Carnell) for providing these data.

Note:  In the images, grey denotes deltas < 0 or ratios < 1 (i.e. decreases
from the baseline).

References:

Carnell, R. E., Senior, C. A., and Mitchell, J. F. B. (1996). An assessment of
measures of storminess: simulated changes in northern hemisphere winter due to
increasing CO2. Climate Dynamics. 12:467-476.

Carnell, R. E. and Senior, C. A. (1998). Changes in mid-latitude variability
due to increasing greenhouse gases and sulphate aerosols. Climate Dynamics.
14:369-383.

Lambert, S. J. (1995). The effect of enhanced greenhouse warming on winter
cyclone frequencies and strengths. Journal of Climate. 8(5):1447-1452.


Benjamin Felzer