Fig. 1: Indian Ocean warming – induced North American wintertime (December–January–February, DJF) climate anomalies retrieved from ERA5 reanalysis dataset and simulated in CAM5 model experiment. | Nature Communications

Fig. 1: Indian Ocean warming – induced North American wintertime (December–January–February, DJF) climate anomalies retrieved from ERA5 reanalysis dataset and simulated in CAM5 model experiment.

From: Unveiling the Indian Ocean forcing on winter eastern warming – western cooling pattern over North America

Fig. 1

a–c Partial regressions of DJF North American surface air temperature (SAT, a), snowfall (b), and snow cover (c) against the normalized Indian Ocean Basin Mode (IOBM) index during the 1979-2020 period, with the Niño 3.4 index removed. d–f The simulated responses of DJF SAT (d), snowfall (e), and snow cover (f) in the CAM5 ensemble model experiment, only driven by the observed tropical Indian Ocean sea surface temperature variability. The magenta plus signs represent the areas with statistically significant regression coefficients at a level of <10% based on Student’s t test. The black circles in a and c signify locally significant grid points at the same significance level through controlling false discovery rate (see Methods). Three regions with pronounced SAT variations are selected in a over the west coast (blue box, 119°W-104°W, 28°N-43°N), the east coast (red box, 79°W-65°W, 42°N-53°N), and over Alaska (cyan box, 168°W-145°W, 59°N-72°N) to quantify. The blue box (126°W-110°W, 38°N-46°N) and the red box (90°W-74°W, 38°N-46°N) in c indicate the areas with significantly increased and decreased snow cover, respectively.

Back to article page