Latent Heat

Latent heat fluxes in the Arctic are significantly weaker in January than sensible heat fluxes. In this month (Figure 3.13), evaporation is very slight in the Arctic because of low temperature and a surface covered by sea ice and snow. As a result, the latent heat fluxes do not exceed -1 kJ/cm: in the central Arctic. Near the sea-ice edge the loss of energy gets higher (-4 kJ/cm!) and in the open water areas it reaches its maximum (-39 kJ/cm2). Polynya areas show a loss of energy up to -4 kJ/cm2.

In April (Figure 3.13), the situation is very similar to that of January. The loss of energy in most of the Arctic is only a little stronger.

in July (Figure 3.14), the Arctic losses significantly more energy via evaporation than in winter. The highest negative fluxes occur in the continental parts of the Arctic and also in the coastal areas of the Arctic islands (-14 kJ/cm2 to -19 kJ/cm2). Also negative fluxes (but about 6-7 times smaller) occur in the Arctic Ocean (-2 kJ/cm2 to -3 kJ/cm2), Between these two areas, i.e. in the Arctic seas (excluding the Norwegian Sea and the western part of the Barents Sea and the southern part of the Kara and Chukchi seas), positive latent heat fluxes occur (up to 4-8 kJ/cm2). Polynya areas lose up to -4 kJ/cm2,

In Octobcr (Figure 3.14), the latent heat fluxes in the entire Arctic become negative again. In the Arctic Ocean and seas covered by sea ice, the negative values oscillate from -0.8 kJ/cm2 (the North Pole) to about -4 kJ/cm2 and -6 kJ/cnv near the sea-ice edge. On the open water areas the loss of energy is significantly greater and in the Norwegian and Greenland seas it reaches a maximum equal to -28 kJ/cm2 and -24 kJ/cm2, respectively.

Annual values of latent heat fluxes in the Arctic (Figure 3.12b) are negative in all areas. In the Arctic Ocean these values oscillate between -16 kJ/cm2 and -19 kJ/cm2 and their absolute values are only slightly lower than the sensible heat fluxes. Thus, for the Arctic Ocean these two fluxes almost cancel themselves out (compare Figure 3.12a and Figure 3,12b). However, for the Arctic seas they already have mostly the same signs (excluding the Beaufort, Chukchi, and East Siberian seas, as well as the western part of the Greenland Sea). The negative latent heat fluxes are stronger here than the sensible heat fluxes, apart from a small pail of the Greenland Sea near the coast of Spitsbergen, where they are very similar. The losses of energy from the continental part of the Arctic are more than twice as large as the sensible heat fluxes and reach almost -50 kJ/cm2.

Figure 3.13. Average monthly (January and April) totals (in kj/cm2) of the latent heat in the Arctic (after Khrol 1992).

July October

Figure 3.14. Average monthly (July and October) totals (in kJ/crrr) of the latent heat in the Arctic (after Khrol 1992).
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