18. Derived Atmospheric Parameters

So far we have focused on plotting variables that exist in a given data file (e.g., temperature, mean sea-level pressure, geopotential heights). However, there may be times when you will want to plot an atmospheric variable (e.g., thickness, temperature advection, relative vorticity, divergence) that is not in the model output file. For that we will have to learn (or remember) a little math and how we can calculate new variables in using MetPy calculations.

In this chapter you will learn about a few of the common derived variables (e.g., atmospheric thickness, vorticity, absolute vorticity, and advection) we can use to describe different aspects of the atmosphere. The following chapter will demonstrate how variables can be easily calculated through either simple mathematical operations or from functions built into the MetPy module. Certain functions will only be able to be used on model output or other gridded data, and not actual surface or upper-air observations. Others will work for point observations only. However, we will start this chapter by describing the importance of some of these important and interesting meteorological parameters.