What Has Been Inspired by Onions and Diamonds in Soundings? - A review

In situ observation of tropical convective systems has been a cornerstone in modern tropical meteorology. Dr. Edward J. Zipser's original landmark studies on mesoscale convective systems (MCSs) using data from field campaigns, especially unsaturated downdrafts that was shown as onion/diamond-shaped atmospheric soundings described in Zipser (1969, 1977), have inspired many later studies. This talk will first provide a review of observational and modeling studies on the topic. We will then focus on most recent results on TC genesis using aircraft dropsonde observations from the Impact of Typhoons on the Ocean in the Pacific (ITOP) field campaign in 2010. It was found that onion soundings with various shapes/strengths are ubiquitous throughout the ITOP aircraft missions from the precursor disturbance to the tropical storm stages, which is considered to be the underappreciated ingredient in TC genesis (Kerns and Chen 2015). The warming partially erodes the lower-troposphere (850–600 hPa) cool anomalies. This warming results in increased surface pressure falls when superposed with the upper-troposphere warm anomalies associated with the long-lasting MCSs/cloud clusters. Given the enormous number of MCSs in the tropics, we suspect that the dynamic and thermodynamic effects of these unsaturated mesoscale downdrafts may have important implication for the global weather and climate system. Dr. Zipser's legacy will continue inspire new science in tropical meteorology and beyond in the years to come.