Selecting Stations and Regions

This section is divided into two parts representing station and gridded data. If you are only interested in using gridded data, then you may want to use the tab to skip ahead to that section. Otherwise, it is suggested that you work through both sections to become acquainted with the operations for both types of data.

Station Data

Select NOAA NCDC DAILY GLOBALSOD*.

Selecting stations
Selecting a region

Selecting stations

Example: Select the stations in Buenos Aires, Argentina.

Method 1: Searches

Select the "Searches" link to the right of the dataset map. CHECK
This page has many options with which you can search for stations. We should use the WMO Station Name option for this example.

Enter "Buenos Aires" into the "WMO Station Name" text box in the search table and select the "Search NOAA NCDC DAILY GLOBALSOD" button. CHECK
You can see that there are three stations in Buenos Aires in this dataset and the information offered about each station in the search results includes its lat/lon coordinates, station call letters, and elevation. There are two ways to obtain data for some or all of these stations. If we want to obtain data for all three of those stations, then it is most efficient to:

Select the "Dataset (and map) with all data found in search" link below the search table. CHECK
Go back to search page by selecting the "Searches" link again.

If we want to select only the Ezeiza and Moron stations, then we should:

Select the WMO ID boxes for the Ezeiza and Moron stations and select the "Get Marked Stations" button. CHECK
Note the source bar. The lowest level indicates your station selection. They may be difficult to make out, but the stations you selected are indicated by black dots on the dataset map as well.

Method 2: Expert Mode
This method can be used if you know the WMO IDs of the stations for which you want data. Note, however, that the WMO station identifiers in the datasets drop the last two digits which are typically zeros. The ID numbers for the three Buenos Aires stations are 875740, 875760, and 875850.
Go back to GLOBALSOD dataset main page via the source bar. CHECK
Select the "Expert Mode" link in the function bar.
Enter the following line in the text box below the text already there.

IWMO 875740 875760 875850 VALUES

Click "OK". CHECK
Again, note that the lowest level of the source bar indicates your station selection.

Selecting a region

Example: Select all of the stations in the region defined by 70°-20°W, 10°S-10°N.
Method 1: Data Viewer
Go back to the GLOBALSOD dataset main page via the source bar.
The utilities of this map are described in the previous section. If you are unfamiliar with how to use this map or need to review these options, then please refer to this previous discussion. While it is possible to select a single station using the data viewer, this tool is most appropriately used when selecting numerous stations from a specific geographic location.

Enter "10N", "10S", "70W", and "20W" into their appropriate lat/lon text boxes in the data viewer and click "Redraw". CHECK
This new map allows you to see all of the stations (black dots) in this lat/lon defined region. You have the option to click on one of those dots to select a single station. but right now we will continue with the steps that allow you to select all of the stations in the region.

Select the "List of stations in current view" link below the map. CHECK
You now have search results in the same format as when you searched for the stations in Buenos Aires. As in that example, you may select any number of those stations by clicking on their WMO ID box and then the "Get Marked Stations" button. We will continue through the steps that allow you to select all of the stations in this region.

Select the "Dataset (and map) with all data found in search" link below the gray table. CHECK
You have now selected stations from a region in northeastern South America. Note that the page now looks very much like the dataset main page on which we started, with the exception of the source bar. Your station selection resides in the lowest level of the source bar. You should also note that only stations within your selected region appear on the dataset map.

Method 2: Searches
Go back to the GLOBALSOD dataset main page using the source bar.
Select the "Searches" link to the right of the dataset map. CHECK
We should use the lat/lon limits search option for this example.

Enter "-70" (top left box), "-20" (bottom left box), "-10" (upper right box), and "10" (bottom right box) into the appropriate lat/lon text boxes and select the "Search NOAA NCDC DAILY GLOBALSOD" button. (Note the different lat/lon format from that in the data viewer example above.) CHECK
You now have search results that are identical to those found by Method 1. Below the the search results table you can see that there are 177 stations within these lat/lon limits. The steps to select only specific stations or all of the stations is identical as in Method 1 of of the previous example.

Method 3: Expert Mode
Go back to the NOAA NCDC DAILY GLOBALSOD dataset main page using the blue navigation bar.
Select the "Expert Mode" link in the function bar .
Enter the following lines in the text box below the text already there.
lon
290 340 masknotrange
SELECT
lat
-10 10 masknotrange
SELECT
Click "OK". CHECK

Note the convention for indicating the latitude and longitude. The latitude is given in order from south to north with latitudes in the southern hemisphere assigned negative values. The longitude is given in order from west to east and as °E. There is another way to indicate longitude as well. This additional sign convention still gives the limits in order from west to east, but assigns negative values to longitudes in the western hemisphere. Try this other sign convention.

Replace 290 340 masknotrange with the following line.
-70 -20 masknotrange
Click "OK". CHECK
You have the same data selection as in the previous methods and should see your selection in the source bar, dataset map, and the grid information.

We will return to a discussion of selecting a data variable for station data in the next section after the following discussion of selecting grid points/regions in a gridded dataset. If you are not interested in gridded datasets, you may want to skip directly to this next section.

Gridded Data

Select NOAA NCEP EMC CMB GLOBAL Reyn_SmithOIv1*.

You should note that all of the options used in the previous example to search for stations were dependent on characteristics of the individual stations. Because we are now dealing with a gridded dataset, these characteristics and their associated searching mechanisms are not applicable, except for the lat/lon coordinates. Selecting lat/lon limits is the only way to select a specific region for a gridded dataset. Let's take a look at the different methods that can be used to select lat/lon limits for gridded datasets. (Note: Some of these methods are similar to those used with station datasets.)

Selecting a single grid point
Selecting a region

Selecting a single grid point

Example: Select data at the grid point nearest to 120°E, 25°N.
Method 1: Data Selection Link
Select the "Data Selection" link in the function bar.
We will discuss this link again in the next section "Selecting a Data Variable". In this operation, we must select a data variable before selecting our geographic region of interest. Let's use the climatological SST data as an example.

Select the "climatology Sea Surface Temperature" link. CHECK
Enter "120E" and "25N" in the appropriate text boxes in the Setting Ranges table.
Note the default ranges in the gray Data Selection box at the top of the page.
Select the "Restrict Ranges" button. CHECK
The ranges in the Data Selection box are now indicative of the coordinates you entered.

Select the "Stop Selecting" button in the Data Selection box. CHECK
You have selected data at a single grid point in the Formosa Strait and, as always, this is indicated in the source bar and in the grid information. Note that the point we entered does not exactly coincide with the location of a grid point. The grid point nearest to our selected point is automatically chosen. Remember that you can find information on the grid resolution of the dataset on the dataset main page under the Grids heading.

Method 2: Expert Mode
Go back to the Reyn_Smith dataset main page using the source bar. CHECK
Select the "Expert Mode" link in the function bar . CHECK
Enter the following sets of lines in the text box below the text already there. (Again, we must select a variable and use climatological sst as an example.)
.climatology .sst
Y (25N) VALUES
X (120E) VALUES
Click "OK". CHECK
You have selected the same grid point as in Method 1 and should see your selection in the source bar and in the grid information.

Selecting a region

Example: Select the data in the region defined by 70°-20°W, 10°S-10°N.
Method 1: Data Viewer
When dealing with a gridded dataset we must select a data variable before being able to use the Data Viewer. We will talk more about the information available when selecting a data variable in the next section, but for right now we will use the climatological sea surface temperature data as an example.

Go back to the Reyn_Smith dataset main page using the source bar. CHECK
Select the "climatology" link under the Datasets and variables heading.
Select one of the [X,Y] views links (e.g., colored or contoured) in the function bar (lower left corner of the bar). CHECK
You have now entered the data viewer. Keep in mind that you can always reach the data viewer by selecting one of the views links in the function bar.

Enter "10N", "10S", "70W", and "20W" into their appropriate lat/lon text boxes and click "Redraw". CHECK
You have now selected gridded climatological sea surface temperature data for the Atlantic Ocean off of northeastern South America. To exit the data viewer and save this geographic selection...

Select the "data in view" button in the table at the bottom of the page. CHECK
Note that the lowest levels of the source bar indicate your data selections.

Method 2: Data Selection Link
Go back to the Reyn_Smith dataset main page via the navigation banner or the source bar.
Select the "Data Selection" link in the function bar.
We will discuss this step again in the next section "Selecting a Data Variable". As in Method 1, we must select a data variable before selecting our geographic region of interest. Let's use the climatological data again.

Select the "climatology Sea Surface Temperature" link. CHECK
Take a moment to look at the hints offered below the Setting Ranges table as they include valuable information. According to the hints we should enter our lat/lon limits in the following way:

Enter "70W to 20W" and "10S to 10N" in the appropriate text boxes in the Setting Ranges table.
Note the default ranges in the gray Data Selection box at the top of the page.
Select the "Restrict Ranges" button. CHECK
The ranges in the Data Selection box should now be indicative of the limits you entered.

Select the "Stop Selecting" button in the Data Selection box. CHECK
You have again selected gridded data for the Atlantic Ocean off of northeastern South America and this region of data is again indicated in the source bar.

Method 3: Expert Mode
Go back to the Reyn_Smith dataset main page.
Select the "Expert Mode" link in the function bar .
As noted above, there is more than one acceptable lat/lon convention.
Enter one of the following sets of lines in the text box below the text already there.

Y (10S) (10N) RANGE
X (70W) (20W) RANGE

Y (-10) (10) RANGE
X (-70) (-20) RANGE

Click "OK". CHECK

Note that the lowest levels of the source bar will match which convention you chose to follow. Again, you have selected data for a region identical to those in Methods 1 and 2.