{"id":410,"date":"2018-05-15T20:13:50","date_gmt":"2018-05-15T20:13:50","guid":{"rendered":"http:\/\/www.kochanski.org\/kelly\/?p=410"},"modified":"2020-07-14T20:46:49","modified_gmt":"2020-07-14T20:46:49","slug":"classification-of-self-organized-snow-surfaces","status":"publish","type":"post","link":"https:\/\/www.kochanski.org\/kelly\/classification-of-self-organized-snow-surfaces\/","title":{"rendered":"Classification of self-organized snow surfaces"},"content":{"rendered":"

Update: <\/em>This work was published in GRL!<\/a> (Got a paywall? Here’s the preprint<\/a>.)<\/p>\n

Snow bedforms – such as dunes, ripples, and anvil-shaped sastrugi – cover as much as 11% of the surface of the Earth. They decrease the reflectivity of the surface, increase its aerodynamic drag, and change the way that wind-blown particles, like dust and sulfates, deposit on the snow.<\/p>\n

These effects have the potential to change Earth’s climate. In order to include these effects in weather and climate models, however, we need to know where bedforms are.<\/p>\n

Field data<\/strong><\/p>\n

For the past three winters, I’ve documented the evolution of snow bedforms in the Colorado Front Range using time-lapse videos. You can see some of the observations below:<\/p>\n

\"Photo<\/a>
Photos from the field<\/figcaption><\/figure>\n
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Videos<\/figcaption><\/figure>\n
\"\"<\/a>
Link to complete article<\/figcaption><\/figure>\n

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Building classifiers<\/strong><\/h3>\n

We used our observations, along with weather data from the Niwot Ridge LTER<\/a>, to generate the first predictions of bedform presence as a function of time.<\/p>\n

These predictions take the form of softmax classifiers<\/a>. Each classifier explains the probability of a snow surface falling in a particuar category (e.g. “flat” vs “not flat”) as a result of one or more weather variables.<\/p>\n

To make good predictions, we had to identify the most important weather variables. We therefore built ~450 classifiers using different combinations of weather variables, and selected the best for our results.<\/p>\n

We validated the classifiers using bootstrapping<\/a>.<\/p>\n

Results<\/strong><\/p>\n

We found that (1) snow is never flat when winds are faster than 7 m\/s or when the snow is older than 0.5 days, (2) the largest bedforms, sastrugi, are formed by wind speeds higher than 15-30 m\/s, and (3) bedforms that reach melting temperatures cease evolving.<\/p>\n

Read the whole study in ‘Statistical classification of self-organized snow surfaces’.<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Update: This work was published in GRL! (Got a paywall?…<\/p>\n","protected":false},"author":1,"featured_media":381,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[68,83,6,4],"tags":[62,65,49,64,26,63],"class_list":["post-410","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research-updates","category-polar-climate","category-publications","category-research","tag-classification","tag-research","tag-sastrugi","tag-science","tag-snow","tag-wind"],"_links":{"self":[{"href":"https:\/\/www.kochanski.org\/kelly\/wp-json\/wp\/v2\/posts\/410","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.kochanski.org\/kelly\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.kochanski.org\/kelly\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.kochanski.org\/kelly\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.kochanski.org\/kelly\/wp-json\/wp\/v2\/comments?post=410"}],"version-history":[{"count":1,"href":"https:\/\/www.kochanski.org\/kelly\/wp-json\/wp\/v2\/posts\/410\/revisions"}],"predecessor-version":[{"id":411,"href":"https:\/\/www.kochanski.org\/kelly\/wp-json\/wp\/v2\/posts\/410\/revisions\/411"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.kochanski.org\/kelly\/wp-json\/wp\/v2\/media\/381"}],"wp:attachment":[{"href":"https:\/\/www.kochanski.org\/kelly\/wp-json\/wp\/v2\/media?parent=410"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.kochanski.org\/kelly\/wp-json\/wp\/v2\/categories?post=410"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.kochanski.org\/kelly\/wp-json\/wp\/v2\/tags?post=410"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}