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.
Select NOAA NCDC DAILY GLOBALSOD*.
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.
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
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.
Select Ethiopia EMI monthly climatologies*.
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 us 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.)
Example: Select data at the grid point nearest to 40°E, 8°N.
Method 1: Data Selection tab
Select the "Data Selection" tab in the function tabs.
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 us use the rfe merged data as an example.
Select the "rfe merged" link.
CHECK
Enter "40E" and "8N" 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 middle of Ethiopia 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 climatologies dataset main page using the source bar.
CHECK
Select the "Expert Mode" tab in the function tabs.
CHECK
Enter the following sets of lines in the text box below the text already there. (Again,
we must select a variable and use rfe merged as an example.)
.rfe_merged
Y (8N) VALUES
X (40E) 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.
Example: Select the data in the region defined by 34.5°-39°E, 4.5°-9°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 rfe merged
data as an example.
Go back to the climatologies dataset main page using the source bar. CHECK
Select the "rfe merged" link under the Datasets and variables heading.
Select one of the [X,Y] views links (e.g., colored or contoured) in the Views tab.
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 Views tab.
Enter "9N", "4.5N", "34.5E", and "39E" into their appropriate lat/lon text boxes and
click "Redraw".
You have now selected gridded rfe merged data for a South West part of Ethiopia. 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 right bubbles of the source bar indicate
your data selections.
Method 2: Data Selection tab
Go back to the climatologies dataset main page via the source bar.
Select the "Data Selection" tab in the function tabs.
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 us use the rfe merged data again.
Select the "rfe merged" 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 "34.5E to 39E" and "4.5N to 9N" 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 a South West part of Ethiopia and this region
of data is again indicated in the source bar.
Method 3: Expert Mode
Go back to the rfe merged dataset main page.
Select the "Expert Mode" tab in the function tabs.
As noted above, there is more than one acceptable lat/lon convention. They can be
string of characteres in parentheses, in which case the letter of the cardinal direction
can be indicated (N, S, E, W); or they can be numerical (no parentheses) and then
can take negative values.
Enter one of the following sets of lines in the text box below the text already there.
Y (4.5N) (9N) RANGE X (34.5E) (39E) RANGEOR
Y 4.5 9 RANGE X 34.5 39 RANGEClick "OK". CHECK
Note that 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.