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Bold/italic numbers denote the most humid/warm 5-year period from 1951 to 2000;" - Data from 1958;" - data for 1951-1999;c - data from 1957;d - data without 1997-1998;" - data for 1951-1998; * data for 1958-60

Similar to annual totals, positive anomalies of P in the 1990s also dominated in all examined seasons, mostly in spring and least in summer (Figure 9.9). Their relations with T are much more complicated than in the case of annual totals. In winter, the highest anomalies of P (> 20 mm) occurred in the southwestern part of the Canadian Arctic, in the southern part of PACR, in the Barents Sea, and in two small parts on the coast of Greenland, (Figure 9.9). Slight negative anomalies of P were observed in the southeastern part of the Canadian Arctic, particularly in the area of IARCSRp and in the central part of SIBR. In the Canadian and Norwegian Arctic, there is a greater consistency among the areas of increase / decrease in T and increase / decrease in P (compare Figures 9.3 and 9.9).

As has been mentioned earlier, positive spring anomalies of P are most common in the Arctic. However, the area with the greatest anomalies (> 20 mm)

Figure 9,8. The spatial distribution of the trends in annual P (in mm/10 years, lower map) over the period 1951-2000 and the anomalies of mean annual 10-year (1991-2000) P, with the 1951-1990 mean (in mm, upper map) in the Arctic.

Key: negative trends (anomalies) are hatched; dashed contours over the Arctic Ocean indicate that the data are extrapolated from the coastal stations.

Figure 9,8. The spatial distribution of the trends in annual P (in mm/10 years, lower map) over the period 1951-2000 and the anomalies of mean annual 10-year (1991-2000) P, with the 1951-1990 mean (in mm, upper map) in the Arctic.

Key: negative trends (anomalies) are hatched; dashed contours over the Arctic Ocean indicate that the data are extrapolated from the coastal stations.

is the smallest one in this season. The anomalies occur only in small parts of the southwestern Canadian Arctic, in the Barents Sea between the islands of Hopen and Bjornoya, and in the western part of the Russian Arctic. Negative anomalies occurred in central parts of the eastern Canadian Arctic, in BAFR, between Iceland and the southern part of the eastern coast of Greenland, between Zemlya Frantza Josifa and Spitsbergen, in the northern part of PACR and the adjacent IARCSRp. Relations between T and P, described in the context of winter, are most pronounced in the Canadian Arctic and in BAFR.

Figure 9.9. The spatial distribution of the anomalies of mean seasonal 10-year (1991-2000) P (in mm) with the 1951-1990 mean in the Arctic. Key as in Figure 9.8.

Even though warming occurred in around 85-90% of the examined area of the Arctic (Figure 9.3), positive P in summer was observed in around 60% of the region (Figure 9.9). Positive anomalies occurred mainly in the continental parts of the Arctic, in the Arctic Ocean, and in the northern part of the Canadian Arctic. The highest anomalies (> 20 mm) were observed in the west-era part of the Russian Arctic where the summer tended to cool or to reveal a slight warming. The decrease in P in this decade was most common in ATLR and in BAFR. Moreover, it stretched from the central part of the Canadian

Arctic to central SIBR. The anomalies ofP dropped below -20 mm only along the coast of southern Greenland.

In the decade 1991-2000, the distribution of the anomalies of P in the Arctic in autumn was very similar to that in spring (Figure 9.9). However, negative anomalies covered a greater area of ATLR in autumn. The greatest positive anomalies in the southwestern part of the Canadian Arctic and in the western part of the Russian Arctic covered an area that was two or three times greater than in spring. Similar large anomalies were also observed in a small part of southeastern Canadian Arctic. A comparison of this distribution of these anomalies with an analogous distribution of the anomalies of T (Figure 9.3), demonstrates that, similar to summer, high positive anomalies of P in the western part of the Russian Arctic were accompanied by negative or slightly positive anomalies of T. The most consistent relations between T and P again occurred in the Canadian Arctic; however, even there the highest anomalies of P did not occur in the area with the greatest warming of that time.

Thus, it must be concluded that even though the tendencies of the changes in P and the global warming that prevailed in the decade 1991-2000 were consistent with prognoses, these relations looked different in many areas of the Arctic, as has been demonstrated above.

Research has revealed that the 1990s was the warmest period between 1951 and 2000. Values of trends of T, calculated earlier for the period 19511990 (Figure 5.20), were modified significantly when the data from this decade were considered (Figure 9.2 (upper map)). In contrast to the said period, positive trends clearly predominated from 1951 to 2000; however, they were statistically significant for only a few stations. When contrasted with the previous forty years, the above analysis demonstrates that, similar to T, P increased significantly in the decade 1991-2000. Thus, it should be concluded that, in comparison to the distribution for the period 1951-1990, the spatial distribution of the trends of P in the period 1951-2000 also underwent great changes. A comparison of the trends presented in Figures 9.8 (lower map) and 6.11 confirms this conclusion. Even though the general distribution of the regions where positive and negative trends of the annual totals of P remained unchanged, the area with negative trends in the period 1951-1990 was significantly limited after the data from the 1990s had been considered. Negative trends occurred mainly in the Russian Arctic and in small areas of Baffin Island, in BAFR, and around Jan Mayen Island. At the same time, the value of negative trends decreased significantly, particularly in the Russian Arctic where these trends had been statistically significant in the previous period (see Table 6.6). On the other hand, there was an increase in the size of the area in the southwestern part of the Canadian Arctic, where high positive trends of the annual P (> 20 mm/10 years) were noted. Their value in this region also increased (Figure 9.8 (lower map)). A statistically significant in crease in P occurred both in the area under discussion and in the northern part of the Canadian Arctic (Table 9.5). The remaining area of the Arctic was dominated by statistically insignificant changes in P. As has already been concluded from the analysis of their anomalies in the decade 1991-2000, the greatest consistency in the observed annual trends of T and P in the period 1951-2000 (cf. Figures 9.8 (lower map) and 9.2 (upper map)) occurred in the Canadian Arctic and, to a lesser degree, in BAFR and in PACR (except its northern part).

Table 9.5. Seasonal (DJF, MAM, JJA and SON) and annual (ANNUAL) atmospheric precipi tation trends (in mm/10 years) in the Arctic

Station

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