How to obtain/plot/analyze data

Submitted by Cathy.Smith@noaa.gov on Thu, 10/07/2010 - 14:23

Data extraction

  1. The Global Observing Systems Information Center contains extensive links to many observational datasets http://www.gosic.org/
  2. GOAT: A MATLAB based tool for the retrieval, analysis and visualization of geophysical data.

Data visualization

  1. Radiosonde based observations and their difference with reanalyses. Description page

 

Anonymous (not verified)

Fri, 05/20/2016 - 10:52

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I want to pose a series of questions regarding wave spectrum analysis with limited data and without the use of wave modeling software. Let's assume that the data sources is ICOADS, and that for a particular point in space and time, we have these two known variables: wave height (WH): 1 meter; swell height (SH): 2 meters Note: The wave and swell heights are reported in ICOADS as half-meters, but assume that I have already converted them to the values shown above in whole meters. Next, let's assume that the data were observed at sea in deep water, say, 250 m. If I want to determine the significant wave height (Hs or H 1/3), I can use this formula: Hs = ((WH^2) + (SH^2))^0.5 ≈ 2.236 m Then... Hmax = 2.0 (Hs) ≈ 4.472 m Question: From these known variables, how is maximum crest height (Hc) determined? During my review of DNV published literature, it was suggested that, "the maximum crest to wave height ratio for a Stokes wave is 0.635." Following that, is it correct to say that the maximum crest height, based on Hmax is: Hc = 0.635 (Hmax) ≈ 2.840 m Or, is there a more appropriate formula (and/or conversion ratio) to use? Again, please assume that there are no additional data available and that no wave spectrum modeling is available. I want to pose more questions along the same line, but I will stop with this one for now until it is resolved. Thank you.

Dear Anonymous, Particularly because you are mentioning that you will have additional questions, may I suggest obtaining an account here at reanalyses.org and posting your question as a new page under the Ocean or under the Observations area? Then, responses can be added to your page (either by you or the responder). Instructions for how to make a page appear under a Help menu item visible after you log in. Please let me know if I can provide more information. best wishes,

Giuseppe Provenzano (not verified)

Tue, 05/26/2015 - 10:12

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Dear Sir, is it possible to obtain long series of daily short/long wave radiations measurements for mediterranean bacin and particularly for Egypt? Thank you for your kind reply Giuseppe Provenzano University of Palermo, Italy

Dear Giuseppe, For what time period are you interested in data? For data from reanalyses, please see the output lists at each of the reanalysis data providers http://reanalyses.org/atmosphere/overview-current-reanalyses Almost all (if not all) of the reanalysis datasets provide both of these variables. You will need to subset them yourself, however. For reanalysis datasets that are opendap enabled, you can use something like "ncks" (http://nco.sourceforge.net/) to select only particular gridpoints. However, these are not "measurements". For this, you will need to consult with experts on these variables. The Baseline Surface Radiation Network (http://bsrn.awi.de/stations/maps.html) might be a good place to start to get some possible data sources (http://bsrn.awi.de/services/contact.html). Please respond back with additional questions if we can be of more help. best wishes

Steven Worley (not verified)

Tue, 06/24/2014 - 14:33

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For the marine surface go to http://rda.ucar.edu/datasets/ds540.0/ - sign in go do data access and create a subset - try it as often as you like. For 20C reanalysis, http://rda.ucar.edu/datasets/ds131.1, do as above For the ISPD, noted above, go to http://rda.ucar.edu/datasets/ds132.0, do as above For global surface observations, 1999 - ongoing, go to http://rda.ucar.edu/datasets/ds461.0, do as above There are many other option in the Research Data Archive - look around.

gilbert.p.comp…

Mon, 06/23/2014 - 23:55

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From the reanalysis datasets, see https://reanalyses.org/atmosphere/how-obtainplotanalyze-data for many options. Please post there with more questions about obtaining variables from reanalysis, and include more details: what time resolution, what period, what region?

For directly measured observations, see some links at http://reanalyses.org/observations/surface if you are interested in surface measurements. For pressure, in particular, the International Surface Pressure Databank http://reanalyses.org/observations/international-surface-pressure-databank may be helpful.