Intensive “porpoising” with a research aircraft to determine atmospheric structure during the SALLJEX and NAME programs

Two recent field programs have focused on describing aspects of low-level jets in the Americas. Both programs have used one of the NOAA WP-3D research aircraft to make mesoscale measurements about the jets, with the object of describing the 3-dimensional structure of the flow over relatively large areas. The strategy used during both field programs relied heavily on using the P-3 as a probe, moving the aircraft vertically while carrying out flight patterns that were mostly predetermined. The object was to describe both the horizontal structure of the jet while also describing the vertical variation of the flow. This invariably involved trade-offs in the design of the flights. The SALLJEX flights sampled a deeper jet flow, necessitating greater vertical coverage and lesser horizontal resolution. The NAME flights were intended to sample a shallow jet that was confined by topography. This presentation summarizes the advantages and disadvantages of using the aircraft in a porpoising mode, with examples shown from both experiments. The objective is to explain the benefits (and limitations) of the procedure and discuss how it may be employed most effectively.