Data Services:Example2

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Advanced Example to get JRO data from the CEDAR Database

What kind of data are available?

There are 2 distinct Jicamarca (JRO) data types:

  1. Faraday data (Ne, Te, Ti)
  2. Drift data (Vi)

It is impossible to get both data types during 1 campaign since the data are taken at different times employing different techniques.

Read information on both types on the Jicamarca page.

(Can also get the data for each period plotted there also, but will get ALL the data, not just what you may want, although it is often good to get everything!) This page is also the most concise place to see when the 2 different data types have data.

From the Jicamarca page you can see that the Faraday data (Ne,Te,Ti) are in 1966-1969, Jun 1984, and intermittantly from Oct 1996 to Aug 2004. Note beginning in Nov 2000, that the only summary plots are uncorrected Ne, Te and Ti, whereas from Oct 1999 and earlier, there was alo a plot of 'corrected Ne'. Please note that the 'corrected Ne' given and plotted, is CONSIDERABLY WORSE than the uncorrected Ne. In other words, the 'corrected Ne' is found from a different, and inferior technique, and you should just use the 'uncorrected Ne', and correct for the Te, Ti and radar wavelength as listed on this page.

Ne (corrected) = Ne (uncorrected) * 0.5*(1+alpha*alpha+Te/Ti)*(1+alpha*alpha)

where alpha*alpha=7.654e+5 Te/(Ne(corrected)*lambda*lambda), Ne in m-3, Te,Ti in K and lambda in m (=6.0 m for JRO) [PLEASE READ JRO AND headers!]

The drift data is for 1984-1995 (except for June 1984 which is Faraday data), with new data from David Hysell from Sep 1994 to Nov 2004. As explained in JRO (and in the headers), the drift data contain both coherent and incoherent echoes. The incoherent echoes only for the new drifts are in the F-region average drifts (kindats ending in '1', and URL names ending in 'b' instead of 'a', or possibly 'c' instead of 'b'). These are probably the only drifts that should be used for ExB. These kindats give 6 averages of 4 range gates over the 24 range gates from 218 and 577 km plus an overall average from the 24 range gates for the eastward drifts (Vpe) and the vertical (Vpn) drifts. Drifts parallel to the horizontal magnetic field in the north-south direction, are not found from the East-West drift experiment.

Getting the data and header info from the summary plot page and also from altering the URL

On the Jicamarca page go to end and click on Nov 2004 drift plots to see them. See only Vpn (vertical) drifts (no Vpe this time and never Vpar). Now click on 'data' for this period. This gives a choice (after signing in with your webname and password) of 2 URLs labelled jro041109a or jro041109b. Most drift data comes 1 campaign at a time and so there are hundreds of URLs of drift data labelled with the station (JRO) the year (04), month (11) and day of month (09) of the first data of the campaign. The 'a' is for all the range gate data from coherent and incoherent echoes, while the 'b' is for all the ExB incoherent F region only averages (kindats ending in '1'). Since we are often interested only in ExB averages, click on the 'jro041109b' line which is second. The small data amount comes up quickly.

Now click in the URL area and change 'tab' to 'info' and return. This returns the header for these kindat 1911 data. Save this and print it out. Change 'info' back to 'tab' and return to get the original screenful of data. Note there is a 'constraint' with the date for these data (although you actually get all the data) between %22 values. You can change these dates to whatever you wish, but will get nothing but the Nov 2004 campaign, since that is the URL which is attached. To get many years of data means many URLs and that is easiest in another method (C). But we can also add other kinds of constraints as well in the URL.

Getting the data and header info from the regular interface and adding constraints to the URL

  1. On web go to: http://cedarweb.hao.ucar.edu/wiki/
  2. Click on Data Services on the left
  3. Click on Get/Plot Data (this will take you to the VSTO data portal)
  4. Click on the 'Data' tab at the top of the page
  5. Click on 'Start by Instrument'
  6. Check 'Show Instrument Code' and click 'Reload'
  7. Select '10 Jicamarca Peru I.S. Radar', the first one
  8. Click 'Next'
  9. Select 2004 from the Start Year selection
    • For 2004, Feb, early Mar, mid-Apr, mid-May and Aug data are Faraday, while mid and late Mar, early Apr, early May, June and Nov data are drifts.
  10. Select 02 (February) from the Month list
    • For Feb 2004, 17-19 are Faraday data.
  11. Select 17 from the Day list
  12. Put 31 for the # Days. Notice that currently the maximum number of days that you can select is 31.
  13. Click 'Next' button
  14. A page comes up with TAB FLAT INFO ... and with a list of the available parameters below.

From here you can select all of the data in one of the different formats (TAB, FLAT, DAS, etc...) or you can continue to constrain your search by selecting the parameters that you would like to see.

  1. Check 'Show Parameter Codes' and click the 'Reload' button
  2. Almost the only parameters not needed here may be '402 - pulse length' (ordinarily this is an indispensible ISR parameter since short pulse lengths should be used in the E region and long pulse lengths in the F region, and both are taken in both regions) and '432 - Cod baud n: No. bauds in code'. You must choose parameters at this time. To choose nothing means you have to use your back button and choose some. Hold the 'Control' key down while choosing parameters. NEVER SKIP ERROR BARS!
    • Check all the parameters except 'pulse length' and 'No. bauds in code'.
  3. Click 'Next'
  4. You will now get a page with all the possible data products listed (TAB, FLAT, INFO, ...)
  5. Select INFO first
  6. If you have not yet logged in you will get a page asking you to do so. Once you've logged in you should see your data
  7. You should now see the Info page for your selections in a new browser window or browser tab.
  8. Close this window/tab in your browser. You should now see the page with the data products listed again (TAB, FLAG, INFO, ...)
  9. This time, click on TAB or FLAT. The data will appear in the window.

From here you can save the page as text and read it using the Software to read TAB or FLAT files

If you are so bold, you can now edit the URL. The URLs are much different from what they used to be. Cedar data access is now accomplished using the OPeNDAP Back-End Server (BES).

For each data file (container) in the URL you will see a constraint. For example, you will see:

jro001109b.constraint=%22date(2004,217,0,0,2004,319,2359,5999);parameters(1282,3113,115,1040,-500,-660,660,120,60,1252,406...)%22

Knowing the Cedar data system, let's add a constraint for the record_type. For each of the constraints, before 'parameters(' add the following:

record_type(10/1911);

After changing the URL hit enter, you should now see the data with the new constraint for the record_type.

Now let's add a constraint for a parameter. Code 1252 is Vpn (vertical), and -1252 is the error bar for Vpn. You can see that many values of Vpn are missing (=-32767), so if we only want values that are non-missing, we can add another constraint in the URL. In the parameter list, find 1252 and add >0 after it, like so:

parameters(...,120,60,1252>0,406...)%22

After changing the URL hit enter, and again you should see the data with your new parameter constraint.