(Note: For strict validity the anomaly baseline period of
the GISTEMP map series was first adjusted to match the CRU data.)
January 21, 2014:
The GISTEMP maps webpage now defaults to using the Robinson map projection.
Not exact matches
[Response: http://data.giss.nasa.gov/
gistemp/FAQ.html «Q.Why is the number in the right hand corner of the global
maps sometimes different from the corresponding value from the
GISTEMP data files (tables and graphs)?
However, the impact of coverage bias is pretty clear; it can be seen by simply looking at a coverage and anomaly
map as we did here, or by assessment of coverage bias using
GISTEMP, or by the less valid but independent assessment using UAH.
Coverage bias estimates are shown for both HadCRUT versions using the
GISTEMP land - ocean series and the UAH series to provide the temperature
maps.
(As with
GISTEMP the anomaly periods must match, so both CRU and UAH
map anomalies were baselines with respect to 1981 - 1990.)
The
GISTEMP analysis was not affected by this error, i.e. none of the results, tables,
maps, graphs about global or regional means changed.
Unfortunately the
GISTEMP site's
mapping capability is down at the moment, otherwise I would show you.
CCF MapView is a
map - based visualization of the
GISTEMP climate analysis via ccc - g
GISTEMP climate analysis via ccc -
gistempgistemp.
The basic unit in the
GISTEMP analysis is a grid of 8000 sub-boxes designed to contain equal area across the globe (although they appear uneven on a
map).
The gridded temperature values computed by ccc -
gistemp can be overlaid on the
map by selecting a source — ocean, land, or mixed.
I've run a benchmark with the actual
GIStemp code on real data and the anomaly
map changes.
So
GIStemp carries temperature data to the end, then makes an anomaly
map out of it after most of the damage was already done to the temperature data.
There are regions of cooling in the 100 year
gistemp trend
map for March in northern Canada and in central Australia but is seems doubtful that these local cooling trends make a warming attributable heat wave less likely in those areas.
There is an option to create
maps of the differences between two datasets using the KNMI Climate Explorer, but, first, there isn't an option for selecting the base years as I had for these
maps, and, second, I haven't been able to make the option work comparing surface temp (
GISTEMP or NCDC) and UAH TLT.