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Home > 9. Operational/Synoptic > 9.19 NOGAPS Meteo

9.19 Visualizing Winds & Precipitation from the NOGAPS Model in IDV: USGODAE

  • Exercise Title:  Visualizing Winds and Precipitation from NOGAPS Model in IDV: USGODAE

  • Abstract:  In this exercise you'll investigate the very useful USGODAE website where many climatological and some operational datasets are organized into a catalog.  Select in item in the catalog to see various options for obtaining the data.  We'll focus on the NOGAPS (see below) modeled datasets, included in the catalog.  They are accessible through an OPeNDAP-ordered Live Access Server.  We'll briefly look at one LAS product, but the main purpose there will be to learn how to obtain special OPeNDAP URLs for online data collections to be used in IDV.  Using 3 NOGAPS products we'll see how to combine a scalar quantity (precipitation intensity) with vector arrows (winds).  THIS LESSON IS PROVIDED FOR EDUCATIONAL PURPOSES ONLY.  NO ONE SHOULD ATTEMPT TO RELY ON THESE ANALYSIS PRODUCTS FOR NAVIGATION OR FOR ANY OPERATIONAL PURPOSES AT SEA.

  • Preliminary Reading (in OceanTeacher, unless otherwise indicated):

  • Required Software:

  • Other Resources: 

  • Author:  Murray Brown

  • Version:  1-29-2015

1.  Open the main USGODAE website and read a bit about its purpose and scope. 
2.  Along the upper margin, find and click on DATA SETS.  You'll see this master list.  Later, on your own time, come back to explore some of the interesting options.

USGODAE Data Catalog - Summary View

COAMPS - Coupled Ocean Atmosphere Mesoscale Prediction System
FAROP - Forecast of Aerosol Radiative Optical Properties
NAVGEM -Navy Global Environmental Model
NOGAPS -Navy Operational Global Atmospheric Prediction System
NOGAPS ANGM - Navy Operational Global Atmospheric Prediction System Angular Momentum
NOGAPS Computational Grids
FNMOC High Resolution SST/Sea Ice Analysis for GHRSST
FNMOC High Resolution Ocean Analysis for GODAE
GOES - FNMOC GOES 10 Satellite Retrievals
MCSST - AVHRR SST retrievals from FNMOC Ocean QC Process
Meteorological Data
PROFILE - Fixed/drifting buoy, bathy, and PALACE float data
SFCOBS - Surface Observations: Ship, fixed/drifting buoy, and CMAN in-situ surface temperatures
SWH - FNMOC Sea Wave Height from Satellite Altimeters
TRACK - FNMOC Ship Track SST measurements
WW3 - FNMOC Wave Watch III
WW3 Central America - FNMOC Wave Watch III
WW3 Mediterranean - FNMOC Wave Watch III
TROPICAL CYCLONE - JTWC/NHC Tropical Cyclone Warnings
World Ocean Atlas 2001
World Ocean Atlas 1998
Navy GDEM Climatology
NAVO MCSST - NAVOCEANO daily sea surface temperature (SST) retrievals
US Navy 5 Minute Bathymetry DBDBV
Smith and Sandwell Satellite Bathymetry
7 Seas - Aerosol-meteorological products in support of the Seven Southeast Asian Studies Mission, from Java through the Malay Peninsula and Southeast Asia to Taiwan
COAMPS Central California Atmospheric Model Gridded Fields (CeNCOOS)
ICAP MME - The International Cooperative for Aerosol Prediction (ICAP) Multi-Model Ensemble (MME)
MODIS L3 - Level 3 filtered, corrected, and aggregated MODIS AOD
NAAPS 550nm Aerosol Optical thickness reanalysis
AMSR-E (Advanced Microwave Scanning Radiometer)
3.  Select the first NOGAPS item in the list, and click GO.  This will take you to a page listing all sorts of ways to access the NOGAPS data.
4.  Click on the Live Access Server option to open the actual client application.  LAS is becoming extremely popular and widely used.

Different versions are sometimes presented, so don't be surprised if you see a slightly different page.

5.  In the upper left corner, click CHOOSE DATASET to open this list.  You'll see that the USGODAE LAS contains much more than NOGAPS.

There are 3 NOGAPS items in the list:

  • Tau = 0000 (surface, nowcast)
  • Tau = 003 (surface, forecast for 3 hours hence)
  • NOGAP Rectangular = many of the same variables, but at atmospheric heights of interest.
6.  Take some time to browse through the various menu items to see what's available.  Click on the PLUS SIGNS by an item to the data subsets offered.
7.  Open the subsets available from NOGAPS Tau = 0000.


8.  Immediately the data menu disappears, and this control panel for the data maps appears.  It controls all aspects data selection and display.
9.   Select the PAN MAP tool from the icons along the top of the map.  Then use your cursor to drag the map right or left to center it near your area of interest (Liberia).
10. Select the ZOOM tool.
11.  Use your cursor to draw a box that is OVER your area and BIGGER THAN your area.
12.  Then change the map coordinates, slowly and carefully.  Make the changes in this order:
  • TOP
  • LEFT

The map interface is not perfect, so you might have to do this more than once to get it right.  Just go back to Panel 9 and start over.

13.  Set the date for today, or another desired date. 

Make note of this date/time so you can synchronize your work with possible other products.

14.  Check the box by UPDATE PLOT to request the data map.
15.  And here's the data plot for the time we ordered.
16.  Actually, we came to this LAS for 2 reason:
  • Making maps of the grids, as you see above,
  • Get the actual links to the data locations

To find the desired data locations, click on EXPORT TO DESKTOP APPLICATION.

17.  Click OK.
18.  This very important Access Scripts page opens.  Notice that the 6th line is important URL you'll need for IDV work.  This URL is a permanent link between IDV and all NOGAPS precipitation products.
19.  NOTE ABOUT UNITS:  If you have any questions about the units of the data, then click the INFO link in the above panel.

Here's the information about precipitation rate (kg/m**2).  The units for wind speed (below) are always m/sec, so you don't need to check there.

20.  You now have this URL:

We need 2 more links to NOGAPS products, which we'll capture in the next panels.

21.  It is very quick and easy to "harvest" the other NOGAP links.  Just use the drop-down menu, and select the product(s) you want.

For example, select Surface Wind Speed (East).  Then you can use Export to Desktop Application to get the URL. 

No need to make maps, just harvest the link.

22.  In exactly the same way, you can harvest the URL for the Surface Wind Speed (North).
23.  Now you have these links to NOGAPS data products:

The only differences in these URLs are slight spelling differences near the end.  Look to find them..

24.  You can use any LAS you find to harvest the URLs of the datasets they serve.  Both here with NOGAPS and with any other LAS mentioned in MDL exercises, simply capture the URL and save it for future use.

You can close this LAS for now, and the associated USGODAE webpages, if you wish.

25.  Now run IDV.
26.  You should have the dashboard open also.  If not, then find the dashboard icon in the upper-left end of the top row and click it once or twice.
27.  Select the Data Choosers tab.
  • Select General = URLs
  • For Data Source Type, select Grid Files (NetCDF, GRIB, OPeNDAP, GEMPAK)
  • For URL, insert the URL for the Total Precipitation Rate (see above)

Then click Add Source

28.  After a short wait, the FIELDS and DISPLAYS columns appear with content as you see here.

Notice the huge number of available times and the many types of analyses that can be made.

29.  We want to limit the TIMES and AREAS.  So right-click on the data object under DATA SOURCES, and select PROPERTIES.


30.  This window with 5 tabs opens.  We will use TIMES and SPATIAL SUBSET most often.

Notice that you can set the PROPERTIES tab to check and reload any dataset at desired intervals, for really careful operational work.

31.  Select the TIMES tab, and uncheck the USE DEFAULT box.  Now you can scroll down and select the very last item. Note that the actual time selected is 2012-06-27 12:00:00Z.  [This is later than in Panel 13, because the author took a long nap...really.]
32.  Select the SPATIAL SUBSET tab.  Then use your cursor to draw any kind of box anywhere.  This "activates" the set of 4 boxes on the left, where exact values can be entered.
33.  Enter the exact values for your area of interest (here for Liberia).

Then click OK.

35.  This very simple figure appears.  Too much blue, and not enough detail.
36.  Go to the DISPLAYS tab.
37.  Click on COLOR TABLE > DEFAULT > RADAR >DbZ to get a rainbow palette.
38.  Check VISIBLE RANGE and click on CHANGE.  You'll see that it's set from 0 to a particular low value, and can assume that all those 0 value are responsible for the blue field.
39.  Change the FROM value to the smallest value that matches the digits in the TO field.  Then click OK.
40.  The settings should look like this.
41.  And the data product should look like this.

NOTE:  If the author knew more about precipitation, then the TO value in Panel 39 above should probably have been set to some sensible known maximum value of merit. 

42.  Now we're going to add wind vectors to this figure.  We'll do it as easily as possible, by referring to the actions above.
43.  Use the URLs you saved above to add the east and north winds to the Data Sources.
44.  Click on FORMULAS just above them to open this new menu of possible analyses.
45.  Navigate through the FIELDS > GRIDS formulas to find MAKE FLOW VECTORS FROM U AND V DATA.



46.  The last thing IDV needs to know is which one is U and which one is V.  Make the proper selections, and click OK.
47.  You get a huge flock of tiny arrows, like bees on the map.  We need to make them bigger and easier to see.
48.  On the DISPLAYS tab:
  • Use the slider control by SIZE to increase the size to 21
  • Use the slider control by SKIP to 2, so only every second arrow will be shown (avoids crowding)
  • Set COLOR to WHITE.
  • Set the RANGE to smaller values, such as -2 to 2.  Experiment if this doesn't work well.
49.  Here's the results of your adjustments.  The vectors look pretty good.
50.  NOTE:  There is a useful method to color-code the vector arrows, in Visualizing Ocean Model Simulations (Vectors) in IDV: HYCOM (Direct Connect), if you want to discriminate better between the values.
51.  You can navigate to LIBERIA > PRODUCTS > IDV and save the above synthesis product as precip_winds_20120627_liberia_nogaps_usgodae.xidv
52.  NOTE:  If you return to this synthesis by opening the XIDV file, then you can use the TIMES tabs to change the time of the analysis to later or earlier dates, or to time periods (to make animations).  The ANIMATIONS CONTROL is along the top-right side of the main map.