Central Arctic Ocean

Data from the NP program (1951-91), the IABP (1979-present), and the SHEBA project provide a reasonably comprehensive picture of the climate of the central Arctic Ocean. Figure 2.20 provides information on mean surface air temperatures for the central Arctic Ocean from IABP records. For 1981 onwards, surface temperatures are

Figure 8.7 Mean annual cycles of surface air temperature, precipitation, cloud cover and downwelling shortwave radiation for Barrow, Alaska, based on a number of different data sources (courtesy of M. Lavrakas, NSIDC, Boulder, CO).

also provided from AVHRR satellite retrievals (Comiso, 2003). Aspects of the surface energy budget 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 8.8 gives mean annual cycles of climate elements for the central Arctic Ocean by aggregating all of the available NP observations. The NP data were collected 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

8.4 Central Arctic Ocean

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Figure 8.8 Mean annual cycles of surface air temperature, precipitation, cloud cover and downwelling shortwave radiation for the central Arctic Ocean, based on data from the Russian North Pole program (courtesy of M. Lavrakas, NSIDC, Boulder, CO).

JFMAMJJASOND Month and early autumn, corresponding broadly to the seasonal maximum 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 summer 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.

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