tag:blogger.com,1999:blog-5337555368793819627.post1410749484843622231..comments2021-02-03T01:55:52.783-05:00Comments on More Grumbine Science: Technical followup on the simplest climate modelRobert Grumbinehttp://www.blogger.com/profile/10783453972811796911noreply@blogger.comBlogger10125tag:blogger.com,1999:blog-5337555368793819627.post-1767909199959424832012-05-12T21:48:45.471-04:002012-05-12T21:48:45.471-04:00Just for reference, here is a really basic excel E...Just for reference, here is a really basic excel EBM.<br />http://cires.colorado.edu/steffen/classes/geog5211/1-D_EBM.htmlRon Broberghttp://rhinohide.wordpress.comnoreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-11022880530271822082012-04-01T18:24:47.575-04:002012-04-01T18:24:47.575-04:00Did my other comment on this post get lost in the ...Did my other comment on this post get lost in the spam filter? It was some thoughts on a slightly more physical model (in which the Earth has a heat capacity, and the radiative imbalance causes the temperature change).Nick Barneshttps://www.blogger.com/profile/00057838251997644583noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-31147659320442498992012-03-29T13:54:15.854-04:002012-03-29T13:54:15.854-04:00Regarding your comments on computer arithmetic: it...Regarding your comments on computer arithmetic: it is certainly the case that anyone using a computer to do sums should educate themselves about the numerical systems used by their computer. They aren't very complicated, and their behaviours are generally very well-specified. But even among scientists one can encounter a kind of cargo-cult approach to floating-point sums.Nick Barneshttps://www.blogger.com/profile/00057838251997644583noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-27474232033234723062012-03-29T13:50:48.476-04:002012-03-29T13:50:48.476-04:00More better Python code, and more illustrations, h...More better Python code, and more illustrations, <a href="http://code.google.com/p/climatecode/source/browse/trunk/doc/2012-03-20/grumbine/" rel="nofollow">here</a>. Probably not a great introduction to Python, but anyone who really wants to give it a go should first install the Enthought Python Distribution and learn how to use the iPython notebook (started with the command "ipython notebook --pylab inline").<br /><br />The real problem with this model is that the root-finding algorithm is slow (may take a very large number of iterations to find a root, specifically the cold root, because the derivative of the expected albedo is close to zero there) and unstable (may not find local roots, specifically the warm root(s), because the rate step can leap over them). There are better root-finding algorithms, but the underlying problem is ill-conditioned: the warm roots (with the default Gaussian albedo) are so touch-and-go that if the parameters are even slightly different (e.g. min_albedo=0.302, or T_central=256) then those roots disappear altogether, and only the cold root exists.Nick Barneshttps://www.blogger.com/profile/00057838251997644583noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-68826620029194941222012-03-26T17:23:37.717-04:002012-03-26T17:23:37.717-04:00I have discovered that when you open the files the...I have discovered that when you open the files they are in read only mode. The .ods version has to be saved on your computer before any changes can be made.<br /><br />Cheers, Alastair.Alastairhttps://www.blogger.com/profile/15152292130415788120noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-38945171440890406092012-03-26T12:12:38.450-04:002012-03-26T12:12:38.450-04:00Thanks Alastair for the link and Bob for the Excel...Thanks Alastair for the link and Bob for the Excel. Bob, your latest Excel spreadsheet is different from what I got when I imported the ods file. (I did try the import a couple times and I did examine both sheets within the file too.) So, I have the working file now and experiment with it later today.jghttps://www.blogger.com/profile/00588440067862480858noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-69440093910463516862012-03-26T10:55:10.139-04:002012-03-26T10:55:10.139-04:00I'm puzzled by the difficulty people have had ...I'm puzzled by the difficulty people have had with the spreadsheet. One issue, perhaps, is that the original seems to open automatically to sheet 2, rather than 1. On 2, I was looking at some other things. But on going to 1, all equations were present as I expected them to be. Also the open document vs. excel issue. Don't know how/why that surfaced.<br /><br />I've resaved the sheet so that it only has the first page and verified that it opens automatically to that from a download. Try http://www.radix.net/~bobg/blogsupport/simplest2.ods<br /><br />I've also saved it as Excel format (XP version, as written by openoffice), http://www.radix.net/~bobg/blogsupport/simplest2.xls<br /><br />Please let me know if these work for you (all)!Robert Grumbinehttps://www.blogger.com/profile/10783453972811796911noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-43074634277678837422012-03-26T10:46:52.942-04:002012-03-26T10:46:52.942-04:00Hi,
You can download Openoffice for free from her...Hi,<br /><br />You can download Openoffice for free from here:<br /><a href="http://openoffice.filewin.net/?p=UK&gclid=CKnu16PmhK8CFZARfAodMynq1A" rel="nofollow">http://openoffice.filewin.net/?p=UK&gclid=CKnu16PmhK8CFZARfAodMynq1A</a><br /><br />Cheers, Alastair.Alastairhttps://www.blogger.com/profile/15152292130415788120noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-49059948999614601642012-03-25T18:36:57.381-04:002012-03-25T18:36:57.381-04:00Hi Bob,
I have the same question as above. Do I ne...Hi Bob,<br />I have the same question as above. Do I need Open Office to get a working spreadsheet. Perhaps there's a way to import into Excel without losing the formulae? I will be sticking around, as other lessons you've provided have been worth the wait.<br />jgjghttps://www.blogger.com/profile/00588440067862480858noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-16170758467894686782012-03-25T01:46:25.759-04:002012-03-25T01:46:25.759-04:00I've never used Python before (as I stated in ...I've never used Python before (as I stated in the previous thread, I believe).<br /><br />So based on this thread I've installed 2.7.2 from the Python site.<br /><br />Also downloaded the PDF documentation for 2.7.2<br /><br />When I download simplest.ods it wants to save it as simplest.zip, which appears to be the bits and pieces (mostly appears to be XML code) code) to make the simplest2.ods spreadsheet file.<br /><br />But if I save it as simplest2.ods, than the spreadsheet itself emerges, but all numbers are "static".<br /><br />I've also downloaded Nick Barnes albedo.py file. Double clicking on that file briely opens/closes a CLI window<br /><br />Like I stated at the beginning, I have no Python experience at all. Don't know where to install the albedo.py, simplest2.zip and/or simplest.ods files. And don't know how to execute and/or change the code to generate a new simplest.ods file.<br /><br />Now what was the point of all this again?<br /><br />I mean, I guess I assumed that the simplest climate model would be rather simple to use.<br /><br />Like a simple Excel spreadsheet with "dynamic" cell references (changable cells from the preameter list section).<br /><br />I'a actually quite good at Excal, but don't know diddly about Python.<br /><br />Sorry, but without further help, I'll just have to leave the Python basrs simplest climate model to Python programmers. Which meand that, in fact, the simplest climate model, may be just that, given that one is an experienced Python programmer. To all other peopls the label simplest climate model is a bit of an oxymoron IMHO.<br /><br />If you really want it to be the simplest climate model, it does not get much simpler than an Excel spreadsheet with "dynamic" cells.<br /><br />Perhaps if I installed Open Office the simplest2.ods spreadsheet would look different (e. g. with dynamic cells)?<br /><br />In closing, to date, two articles, but virtually no understanding of how to use the simplest climate model, at my end, from what has been stated to date.<br /><br />Sorry, but I'm moving on.<br /><br />Object lesson? KISS.EFS_Juniornoreply@blogger.com