I want to do a series of arithmetic operations on my data. Can you help me?

Q: I want to do a series of arithmetic operations on my data. Specfically, I want to sum the squares of individual wind components and then find the square-root of that result.

A: Let's use zonal and meridional wind data from the NCEP-NCAR Reanalysis.

This example begins in expert mode with the dataset and u- and v-wind components selected at the the 1000 hPa pressure level. You can find more information about these steps in the Data Library Tutorial. Part I will show you how to locate datasets and Part II will show you how to select data and variables.

Click here to start the step-by-step example.

Step 1: Square each of the wind components by putting the following text below the "P (1000) VALUE" lines in the text box.
dup mul Check Step

Step 2: Add the two resulting squares by putting the following text below the text already in the text box.
add

Step 3: Calculate the sqaure-root of the resulting sum by putting the following text below the text already in the text box.
sqrt

Step 4: Click "OK". Check Step
You should see the calculations represented in the source bar.

Information about other simple arithmetic operations can be found in Part III of the Data Library Tutorial.

--Michael Bell / Emily Grover