Influential Role of Moisture Supply from the Kuroshio/Kuroshio Extension in the Rapid Development of an Extratropical Cyclone

Abstract

This study focused on an explosive cyclone migrating along the southern periphery of the Kuroshio/ Kuroshio Extension in the middle of January 2013 and examined how those warm currents played an active role in the rapid development of the cyclone using a high-resolution coupled atmosphere-ocean regional model. The evolutions of surface fronts of the simulated cyclone resemble the Shapiro-Keyser model. At the time of the maximum deepening rate, strong mesoscale diabatic heating areas appear over the bent-back front and the warm front east of the cyclone center. Diabatic heating over the bent-back front and the eastern warm front is mainly induced by the condensation of moisture imported by the cold conveyor belt (CCB) and the warm conveyor belt (WCB), respectively. The dry air parcels transported by the CCB can receive large amounts of moisture from the warm currents, whereas the very humid air parcels transported by the WCB can hardly be modified by those currents. The well-organized nature of the CCB plays a key role not only in enhancing surface evaporation from the warm currents but also in importing the evaporated vapor into the bent-back front. The imported vapor converges at the bent-back front, leading to latent heat release. The latent heating facilitates the cyclone's development through the production of positive potential vorticity in the lower troposphere. Its deepening can, in turn, reinforce the CCB. In the presence of a favorable synoptic-scale environment, such a positive feedback process can lead to the rapid intensification of a cyclone over warm currents.

Numerical Investigation of Development Processes of Baiu Frontal Depressions Part I: Case Studies

“…5) could be associated with linearly aligned convections in the frontal region (not shown). These features were also found in other studies of extratropical cyclones (e.g., Hirata et al 2015). Moreover, a region of negative PV production also exists around the cyclone center in the later stage (Fig.…”

Storm-Track Response to SST Fronts in the Northwestern Pacific Region in an AGCM

“…These results suggest that the SST front over the NWP enhances precipitation near the cyclone center through the large surface LHF from the Kuroshio and its extension. The precipitation enhancement causes the explosive deepening over the NWP in CNTL, consistent with regional model experiments for explosive cyclones due to SST fronts (Booth et al 2012;Iizuka et al 2013;Hirata et al 2015). The precipitation difference between CNTL and SMTHK associated with the explosive deepening also affects the upper troposphere.…”

“…The present results suggest that the coupling between explosive cyclones and SST fronts is important for the climate state and variability as well as numerical weather prediction, as demonstrated by Hirata et al (2015). Although some recent studies have shown that model biases and uncertainties related to explosive cyclones and the storm track in CMIP models are passively affected by the large-scale environment (Nishii et al 2015;Harvey et al 2015;Seiler and Zwiers 2016), the present study suggests that the explosive cyclone biases can be a result of the interaction between explosive cyclones and the large-scale environment.…”

“…Because the magnitude of the negative contribution of the low SSTs is comparable to the positive contribution due to the strong vertical wind shear associated with the sharp SST front in CNTL, the EGR difference between CNTL and SMTHK over the NWP SST front becomes small. The different characteristics of the sensible and latent heat fluxes can explain the small change in the EGR contradicting the substantial increase in explosive contributes to the explosive deepening through precipitation (Yoshida and Asuma 2004;Kuwano-Yoshida and Asuma 2008;Hirata et al 2015). However, the negative anomaly in the sensible heat flux north of the SST front weakens the EGR at approximately 438N, suppressing cyclone development north of the SST front.…”

Synoptic Conditions Causing an Extreme Snowfall Event in the Kanto-Koshin District of Japan on 14-15 February 2014

“…A strong blocking anticyclone maintained over the northwestern Pacific for about two weeks would contribute such synoptic conditions (e.g., Yamazaki et al 2015). Approaches from both global and local viewpoints are necessary for understanding of record heavy snowfall events (e.g., Tachibana et al 2007), also considering the Kuroshio path which would decide cyclone paths or intensification (Nakamura et al 2012;Hirata et al 2015).…”