Here are the current Papers & Articles under the research topic Planetary Waves (Rossby Waves). Click on the title of a paper you are interested in to go straight to the full paper.
A global climatological perspective on the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events
2021 paper. Abstract:
Extreme precipitation events (EPEs) frequently cause flooding with dramatic socioeconomic impacts in many parts of the world. Previous studies considered two synoptic-scale processes, Rossby wave breaking and intense moisture transport, typically in isolation, and their linkage to such EPEs in several regions. This study presents for the first time a global and systematic climatological analysis of these two synoptic-scale processes, in tandem and in isolation, for the occurrence of EPEs. To this end, we use 40-year ERA-Interim reanalysis data (1979–2018) and apply object-based identification methods for (i) daily EPEs, (ii) stratospheric potential vorticity (PV) streamers as indicators of Rossby wave breaking, and (iii) structures of high vertically integrated horizontal water vapour transport (IVT). First, the importance of these two synoptic-scale processes is demonstrated by case studies of previously documented flood events that inflicted catastrophic impacts in different parts of the world. Next, a climatological quantification shows that Rossby wave breaking is associated with >90 % of EPEs over central North America and the Mediterranean, whereas intense moisture transport is linked to >95 % of EPEs over many coastal zones, consistent with findings of atmospheric river-related studies. Combined Rossby wave breaking and intense moisture transport contributes up to 70 % of EPEs in several subtropical and extratropical regions, including (semi)arid desert regions where tropical–extratropical interactions are of key importance for (heavy) rainfall. Odds ratios of EPEs linked to the two synoptic-scale processes suggest that intense moisture transport has a stronger association with the occurrence of EPEs than Rossby wave breaking. Furthermore, the relationship between the PV and IVT characteristics and the precipitation volumes shows that the depth of the wave breaking and moisture transport intensity are intimately connected with the extreme precipitation severity. Finally, composites reveal that subtropical and extratropical EPEs, linked to Rossby wave breaking, go along with the formation of upper-level troughs and cyclogenetic processes near the surface downstream, reduced static stability beneath the upper-level forcing (only over water), and dynamical lifting ahead (over water and land). This study concludes with a concept that reconciles well-established meteorological principles with the importance of Rossby wave breaking and intense moisture transport for the formation of EPEs. Another conclusion with major implications is that different combinations of Rossby wave breaking and intense moisture transport can reflect a large range of EPE-related weather systems across climate zones and can thus form the basis for a new classification of EPE regimes. The findings of this study may contribute to an improved understanding of the atmospheric processes that lead to EPEs and may find application in climatic studies on extreme precipitation changes in a warming climate.
Amplified Rossby waves enhance risk of concurrent heatwaves in major breadbasket regions
2019 paper. Abstract:
In an interconnected world, simultaneous extreme weather events in distant regions could potentially impose high-end risks for societies1,2. In the mid-latitudes, circum-global Rossby waves are associated with a strongly meandering jet stream and might cause simultaneous heatwaves and floods across the northern hemisphere3–6. For example, in the summer of 2018, several heat and rainfall extremes occurred near-simultaneously7. Here we show that Rossby waves with wave numbers 5 and 7 have a preferred phase position and constitute recurrent atmospheric circulation patterns in summer. Those patterns can induce simultaneous heat extremes in specific regions: Central North America, Eastern Europe and Eastern Asia for wave 5, and Western Central North America, Western Europe and Western Asia for wave 7. The probability of simultaneous heat extremes in these regions increases by a factor of up to 20 for the most severe heat events when either of these two waves dominate the circulation. Two or more weeks per summer spent in the wave-5 or wave-7 regime are associated with 4% reductions in crop production when averaged across the affected regions, with regional decreases of up to 11%. As these regions are important for global food production, the identified teleconnections have the potential to fuel multiple harvest failures, posing risks to global food security.
Extreme weather events in early summer 2018 connected by a recurrent hemispheric wave-7pattern
2019 paper. Abstract:
The summer of 2018 witnessed a number of extreme weather events such as heatwaves in NorthAmerica, Western Europe and the Caspian Sea region, and rainfall extremes in South-East Europe andJapan that occurred near-simultaneously. Here we show that some of these extremes were connectedby an amplified hemisphere-wide wavenumber 7 circulation pattern. We show that this patternconstitutes an important teleconnection in Northern Hemisphere summer associated with prolongedand above-normal temperatures in North America, Western Europe and the Caspian Sea region. Thispattern was also observed during the European heatwaves of 2003, 2006 and 2015 among others. Weshow that the occurrence of this wave 7 pattern has increased over recent decades.