TCBL Response to Prescribed Background Steering and Shear

Several CM1 simulations were conducted using background-profile nudging, with simulations varying in their use of background steering and shear. Mean-layer steering (0 to 14-km height) and deep-layer shear (2- to 14-km height) in the background profile are used to represent prescribed measures of steering and shear, respectively.

Simulations are codenamed following the pattern MX-SY-ZZZ, where:

• X is the prescribed steering magnitude (m/s)
• Y is the prescribed shear magnitude (m/s)
• ZZZ is the prescribed angle between background steering and shear (deg), increasing with counterclockwise rotation of the shear vector relative to steering.

For example, a control simulation was run with no background wind profile, so there was neither steering nor shear prescribed. Therefore, X=0, Y=0, ZZZ=000, and the simulation is codenamed M0-S0-000.

Experimental simulations fall into univariate and multivariate groups. Simulations in the univariate group prescribe either non-zero X or non-zero Y, but not both. Simulations in the multivariate group prescribe both non-zero X and Y. To limit the scope of this work, multivariate simulations have equal X and Y.