A Tropospheric Assessment of the ERA-40, NCEP, and JRA-25 Global Reanalyses in the Polar Regions

The reliability of the global reanalyses in the polar regions is investigated. The overview stems from an April 2006 Scientific Committee on Antarctic Research (SCAR) workshop on the performance of global reanalyses in high latitudes held at the British Antarctic Survey. Overall, the skill is much higher in the Arctic than the Antarctic, where the reanalyses are only reliable in the summer months prior to the modern satellite era. In the Antarctic, large circulation differences between the reanalyses are found primarily before 1979, when vast quantities of satellite sounding data started to be assimilated. Specifically for ERA-40, this data discontinuity creates a marked jump in Antarctic snow accumulation, especially at high elevations. In the Arctic, the largest differences are related to the reanalyses depiction of clouds and their associated radiation impacts; ERA-40 captures the cloud variability much better than NCEP1 and JRA-25, but the ERA-40 and JRA-25 clouds are too optically thin for shortwave radiation. To further contrast the reanalyses skill, cyclone tracking results are presented. In the Southern Hemisphere, cyclonic activity is markedly different between the reanalyses, where there are few matched cyclones prior to 1979. In comparison, only some of the weaker cyclones are not matched in the Northern Hemisphere from 1958-2001, again indicating the superior skill in this hemisphere. Although this manuscript focuses on deficiencies in the reanalyses, it is important to note that they are a powerful tool for climate studies in both polar regions when used with a recognition of their limitations

13 ways of looking at a blackbird

Short fiction printed letterpress from Bembo types on Curtis Rag paper. Calligraphy for folios, cover and title page, as well as several small drawings printed relief. Foil stamping and embossing on paper wrap. Smythe sewn and pasted in paper wrapperUNL SPEC copy--Limited ed. of 250 copies numbered and signed by the author; this is no. 225; calligraphy: Terry McGrath; monotype composition: Mackenzie-Harris, Inc.,; binding: Cardoza-Jame

13 ways of looking at a blackbird

Short fiction printed letterpress from Bembo types on Curtis Rag paper. Calligraphy for folios, cover and title page, as well as several small drawings printed relief. Foil stamping and embossing on paper wrap. Smythe sewn and pasted in paper wrapperUNL SPEC copy--Limited ed. of 250 copies numbered and signed by the author; this is no. 225; ; calligraphy: Terry McGrath; monotype composition: Mackenzie-Harris, Inc.,; binding: Cardoza-Jame

13 ways of looking at a blackbird

Short fiction printed letterpress from Bembo types on Curtis Rag paper. Calligraphy for folios, cover and title page, as well as several small drawings printed relief. Foil stamping and embossing on paper wrap. Smythe sewn and pasted in paper wrapperUNL SPEC copy--Limited ed. of 250 copies numbered and signed by the author; this is no. 225; calligraphy: Terry McGrath; monotype composition: Mackenzie-Harris, Inc.; binding: Cardoza-Jame