Characteristics and Life Cycles of Anticyclonic Tropopause Polar Vortices

Abstract Tropopause polar vortices (TPVs) are subsynoptic, long-lived, closed circulation features located in the upper troposphere and lower stratosphere. Most previous studies focused only on cyclonic TPVs (CTPVs), especially due to their direct influence on Arctic cyclones, cold-air outbreaks, and severe convection in midlatitudes. CTPV longevity is unique to polar regions due to the relatively limited role of latent heating and the more dominant role of longwave radiative cooling. CTPVs are also important to global circulations, as recent studies have shown that CTPVs can exit the Arctic, causing the initiation of Rossby wave packets on the polar jet. Rossby wave initiation and subsequent Rossby wave breaks (RWBs) and blocking patterns cause high-impact weather, from droughts and floods to heat waves and cold-air outbreaks. However, current models have low skill when forecasting the impacts of blocking patterns in the subseasonal to seasonal time frame. This study aims to determine if anticyclonic TPVs (ATPVs) have the same unique longevity as CTPVs. ATPVs’ life cycles are also examined to determine their possible connection to RWBs and the maintenance of blocking patterns. It is hypothesized that ATPVs form from poleward RWBs and are important potential vorticity anomalies aiding in the maintenance of blocks. ERA5 data are used to create ATPV and block tracks. Results show that the most common ATPV genesis regions also have high RWB and blocking frequencies. Blocks with multiple ATPVs in close spatial proximity have longer lifetimes than those without. Significance Statement Atmospheric blocks have the potential to cause extreme weather such as heat, drought, cold, and flooding over large areas for an extended time. However, predicting the mechanisms contributing to atmospheric block persistence is difficult. This study defines features in the Arctic known as anticyclonic tropopause polar vortices (ATPVs) and investigates whether they contribute to atmospheric block longevity. It is found that ATPVs’ lifetimes are connected to their initial intensity, which could aid in forecasting. Although further work is needed, initial findings show that atmospheric blocks connected to ATPVs have longer lifetimes than blocks not connected to ATPVs, so ATPVs could provide a tool for predicting atmospheric block longevity.