Boike, Julia; Grau, Thomas; Heim, Birgit; Günther, Frank; Langer, Moritz; Muster, Sina; Gouttevin, Isabelle; Lange, Stephan (2015): Snow cover trend analysis 2000-2011, Central Yakutia, Siberia [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.855122,

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In supplement to: Boike, J et al. (2016): Satellite-derived changes in the permafrost landscape of central Yakutia, 2000–2011: Wetting, drying, and fires. Global and Planetary Change, 139, 116-127, https://doi.org/10.1016/j.gloplacha.2016.01.001

Snow cover was analyzed using the MOD10CM product (Hall et al., 2006), which is also configured on a 0.05° latitude/longitude MODIS Climate Model Grid (CMG), yielding figures for monthly average snow cover (as percentages). (See also "Source data set" link). It was downloaded from ftp://n5eil01u.ecs.nsidc.org/pub/MOST/MOD10CM.005 for the Years 2000 to 2011.

Linear trend calculations for the 11 year interval were performed separately for each bi-monthly mean value in each grid cell, using the least squares method. We decided to use two-monthly intervals since the timing of thawing and freezing vary from year to year and do not necessarily occur over just one month in the year, or in the same month each year. We used a student t-test to calculate the significance of each trend, based on the assumption that there was no relationship between the date and the trend (null hypothesis).

The file snow_bimonthly_trends_2000-2011.zip contains six single maps (ascii-files) who show the trend for two month intervals over the 11 year interval ('grad_snow_janfeb', 'grad_snow_marapr','grad_snow_mayjun', 'grad_snow_julaug', 'grad_snow_sepoct', 'grad_snow_novdec').

The file snow_monthly_trends_2000-2011.zip contains twelve single maps who show the trend in snow for single months over the 11 year interval ('grad_snow_mar', 'grad_snow_apr', 'grad_snow_may', 'grad_snow_jun', 'grad_snow_jul', 'grad_snow_aug', 'grad_snow_sep', 'grad_snow_oct', 'grad_snow_nov', 'grad_snow_dec', 'grad_snow_jan', 'grad_snow_feb').

The files snow_t_p_bimonthly.zip and snow_t_p_monthly.zip contain the corresponding p-values of the statistical t-tests for the bimonthly and monthly trends , respectively.

The snow_TtestIsolines.zip files contains the isolines (as ESRI shapefiles) from the t-test for 75%, 90%, 95% and 97.5% confidence intervals for the bimonthly intervals of April/May and September/October.

All files have an extent of WGS84, upper left corner: lat 65, long 117.55, lower right corner: lat 61.05, long 131.05.