This
page compares weather observations made on the Fury and Hecla with recent
expected values (1961-90 normals). Observations were made of
sea-temperature (SST), air-temperature (AT), and Pressure (SLP). It is
also possible to infer the sea-ice cover the ships experienced and
compare that to recent expected values. Both observed and comparative
recent values depend both on the date (position in the seasonal cycle)
and the position of the ship - here we show time-series comparisons
comparing the actual observations with those which would be expected by
a hypothetical ship following the same course, at the same time of
year, in recent decades. In all the figures below, observations from the two sources are distinguished by colour: those from the published account are in red, and those from lieutenant Austin's log in blue.
Sea temperatureObserved (coloured dots) and modern equivalent (black line) sea-surface temperatures. The lower graph shows the range in expected sea-ice coverage - max and min values from HadISST for 1961-90.
Air TemperatureObserved (coloured dots) and modern equivalent (black line) air temperatures. The lower graph shows the range in expected sea-ice coverage - max and min values from HadISST for 1961-90.
PressureThe
seasonal cycle in pressure is much smaller than the short-term
variability, so it's not very useful to compare modern averages with
point observations. But, just to be consistent, here's the same plot
for pressure: Observed (coloured dots) and modern average (black line) air pressures.Sea-IceThe
meteorological logs contain no explicit information on the sea-ice
cover, but it is possible to make inferences about the state of the
sea-ice from the information available. Sea-ice slows the ship down, it
is associated with low sea and air temperatures, and complete sea-ice
cover increases the air temperature variability (see AT graph above) -
effectively switching from a marine to a continental climate. From each
of these sources we can make an estimate of the sea ice cover: as proxy
observations they are likely to be imprecise, but collectively they
give a reasonable indication of the likely state of the ice coverage. Estimates of local sea-ice coverage from four different proxies (coloured points) and the range in expected recent sea-ice coverage - max and min values from HadISST for 1961-90.
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