Climate Regimes of the Arctic - The Arctic Climate System - page 268

greater than at Isfjord Radio (22°C). Like Resolute, conditions are quite dry, with
less than 5 mm of precipitation (discounting gauge biases) from December through
May, and an August maximum of about 23 mm. Compared to Resolute, there is
slightly more winter cloud cover.

8.4

Central Arctic Ocean

Data from the NP program, the IABP, and the SHEBA project provide a reason-
ably comprehensive picture of the climate of the central Arctic Ocean. Figure 2.21
provides information on mean surface air temperatures for the central Arctic Ocean
from IABP records. Aspects of surface energy exchanges based on SHEBA data are
summarized in Chapter 5 . Characteristics of snow cover over the Arctic Ocean from
the NP records are discussed in Chapter 2 .
Figure 8.11 gives mean annual cycles of climate elements for the central Arctic
Ocean by aggregating all of the available NP observations. The NP data were col-
lected over thick ice floes. Mean temperature ranges from about −33°C in January
(similar to Resolute) to 0°C in July. The proximity of the July mean temperature
to the freezing point reflects the effects of the melting ice surface. Precipitation
peaks in late summer and early autumn, corresponding broadly to the seasonal max-
imum in cyclone activity in this region. This represents a combination of systems
migrating into the Arctic Ocean from the weakened (but still present) North Atlantic
cyclone track and those generated over Eurasia, many in association with the sum-
mer Arctic frontal zone ( Chapter 4 ). As evaporation rates are low, precipitation and
P-ET are quite similar, with the precipitation hence primarily driven by the large-
scale vapor flux convergence. As seen in Figure 6.7 , even in July, roughly half of the
precipitation that falls is in solid form.

Figure 8.11. Mean annual cycles of surface air temperature, precipitation, cloud cover,
and downward shortwave radiation for the central Arctic Ocean, based on data from the
Russian North Pole program (courtesy of M. Lavrakas, NSIDC, Boulder, CO).