Interannual Variability of Northern Hemisphere Storm Tracks in Coarse-Gridded Datasets

Figure 3

NH winter (JFM) PNA positive-PNA negative cyclone track frequency composite for (a) NCEP1_5801, (b) like (a) but for ERA40_5801. Units: no. of cyclones per 5° Lat × 5° Lon box. Hatched areas are significant at 90% for 2-tailed 𝑡-test. (c) NH winter (JFM) NAO positive-NAO negative cyclone track intensity composite for NCEP1_5801. (d) like (c) but for ERA40_5801. Units: hPa. Hatched areas are significant at 90% for 2-tailed 𝑡-test.

(a)

(b)

(c)

(d)