tag:blogger.com,1999:blog-4572286363399496963.post3143866923157391539..comments2023-10-03T09:00:57.410-08:00Comments on Deep Cold: Alaska Weather & Climate: AMO Climate InfluenceRickhttp://www.blogger.com/profile/03946704894714514716noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-4572286363399496963.post-80862396144641917932015-01-03T06:06:30.885-09:002015-01-03T06:06:30.885-09:00I like #3 too; correlation doesn't require cau...I like #3 too; correlation doesn't require causation. And the Atlantic and Pacific temperature variations are certainly not independent.<br />Richard Jameshttps://www.blogger.com/profile/08313902028896263276noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-91782060690898083592015-01-03T06:04:02.743-09:002015-01-03T06:04:02.743-09:00Eric, there would be many ways of testing signific...Eric, there would be many ways of testing significance - some I'm surely not aware of. If we consider a binomial distribution, the chance of having 5 or less out of 21 years on the same side of normal (as in July and August) is 1.3%. With 12 months of the year, the chance of one month meeting this criterion just by random chance is 14%, but the probability of two or more months like this is only 1%. So I think we can say the July-August result for negative AMO is certainly significant.<br /><br />Another approach would be to re-sample repeatedly from the historical temperature distribution and find out how often an anomaly this large is observed in a sample of 21 years.<br /><br />Some problems with multivariate regression are the rather small sample size for multiple predictors (85 years) and the non-linearity of the response to each predictor, i.e. the positive phase sometimes doesn't have the opposite influence of the negative phase. There's also the problem of non-linear interference, e.g. negative AMO might affect Alaska quite differently in positive or negative PDO; the combined effect is not a simple linear addition. Having said that, I think there is potential for useful investigation in the area of combined index influences... it's really a data mining problem.<br />Richard Jameshttps://www.blogger.com/profile/08313902028896263276noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-55255543272578385392015-01-02T18:34:58.620-09:002015-01-02T18:34:58.620-09:00Now we're getting into a global coupled genera...Now we're getting into a global coupled general circulation model and CM2.X analyses. Thermohaline circulation stuff and enhanced El Nino teleconnections.<br /><br />I like Eric's #3 for the above reasons, but without a definitive substantiation. <br /><br />GaryNL7Yhttps://www.blogger.com/profile/15874712728971005352noreply@blogger.comtag:blogger.com,1999:blog-4572286363399496963.post-46370254570287194562015-01-02T18:09:40.427-09:002015-01-02T18:09:40.427-09:00How do we know that July is significant? How can ...How do we know that July is significant? How can we quantify this?<br /><br />This is really making me wonder what a multivariate fitting would show for AMO, PDO, ENSO and all of the other alphabet indices.<br /><br />I can think of three things that connect an Alaskan July and the AMO: 1. Back-propagation from a blocking pattern. 2. Forward propagation of AMO enhancements to Alaska which would be amazing. 3. Not AMO at all. Just that AMO and July have a common source perhaps in the Pacific.Eric Lundellhttps://www.blogger.com/profile/17914784378747801359noreply@blogger.com