Fig. 5
The snow cover extent in the extratropical Andes is connected with the SAM index. Times series of snow cover extent (black dotted line) and precipitations (red line), in the following regions: (a) 27–31°S, (b) 31–34°S, and (c) 34–36°S. The times series of the Southern Annular Mode (SAM) index (red dotted line), and sea surface temperature (SST) anomalies in the Niño 3.4 region (black line) are also shown for comparisons. The correlation coefficients between the snow cover extent and the precipitations, the SAM index, and the SST anomalies in the Niño 3.4 region are indicated in the plots. Additional basin-level statistics are presented in Table 2. As shown in Table 2, the correlations between the snow cover extent and the SST in the Niño 1 + 2 region are not significant. Snow cover data (averaged from September to December) are based on satellite-derived estimates from MODIS/Terra Snow Cover Daily L3 Global 500 m SIN Grid, version 6.1, available at https://nsidc.org/data/mod10a1/versions/61. Precipitation data (averaged from June to September) come from the ERA5 reanalysis48 available at https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era5. Weekly SST anomalies in the Nino 3.4 region (averaged from August to September) come from the Climate Prediction Center (CPC), part of the National Oceanic and Atmospheric Administration (NOAA) available at https://www.cpc.ncep.noaa.gov/data/indices/wksst8110.for. Estimates of the SAM index (averaged from March to June) were obtained from Climate Prediction Center (National Weather Service, National Oceanic and Atmospheric Administration – NOAA). Daily estimates of the SAM index are available at: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/aao/aao.shtml#publication. Plots were generated using Python’s Matplotlib library49, version 3.4.3, https://matplotlib.org/3.4.3/contents.html.
