The Outflow Interactions Between Binary Tropical Cyclones

The three-dimensional representation of an outflow jet can be used to assess whether interactions may have occurred between the outflows of binary, or spatially proximate, tropical cyclones, as outflow jets represent a dominant portion of the upper-tropospheric outflow for TCs. A novel algorithm, POJ3, for identifying and creating a three-dimensional representation of the principal outflow jet(s) of tropical cyclones is proposed. Validation of the algorithm is accomplished by comparing the output to previous findings that (1) the outflow jets of tropical cyclones preferentially form in regions of low potential vorticity and (2) outflow jets have a secondary circulation, which can be seen through signatures in relative humidity. We use POJ3 to investigate whether outflow interactions occurred between two pairs of binary tropical cyclones, Hurricanes Marco and Laura (2020) and Hurricanes Irma and Jose (2017). An examination of the three-dimensional jet locations together with the synoptic history, steering flow, and centroid-relative motion (or lack thereof) for the pairs of TCs indicates that Marco and Laura did not have significant outflow interactions whereas outflow interactions between Irma and Jose may be responsible for a significant diversion in Jose's track.