scholarly journals Cloud Response to the Meandering Kuroshio Extension Front

2013 ◽  
Vol 26 (23) ◽  
pp. 9393-9398 ◽  
Author(s):  
Hiroyuki Tomita ◽  
Shang-Ping Xie ◽  
Hiroki Tokinaga ◽  
Yoshimi Kawai
Keyword(s):  
Kuroshio Extension ◽  
Lower Atmosphere ◽  
Warm Water ◽  
Cloud Base ◽  
Cumulus Clouds ◽  
The North ◽  
Strong Inversion ◽  
Stratocumulus Clouds ◽  
The Kuroshio ◽  
Kuroshio Extension Front

A unique set of observations on board research vessel (R/V) Mirai in April 2010 captured a striking cloud hole over a cold meander of the Kuroshio Extension (KE) east of Japan as corroborated by atmospheric soundings, ceilometer, shipboard radiation data, and satellite cloud images. Distinct differences were also observed between the warm meander farther to the north and warm water south of the KE. The atmosphere is highly unstable over the warm meander, promoting a well-mixed marine atmospheric boundary layer (MABL) and a layer of solid stratocumulus clouds capped by a strong inversion. Over the warm water south of the KE, MABL deepens and is decoupled from the ocean surface. Scattered cumulus clouds develop as captured by rapid variations in ceilometer-derived cloud base. The results show that the meandering KE front affects the entire MABL and the clouds. Such atmospheric response can potentially intensify the baroclinicity in the lower atmosphere.

scholarly journals On the Relationship between Synoptic Wintertime Atmospheric Variability and Path Shifts in the Gulf Stream and the Kuroshio Extension

2009 ◽  
Vol 22 (12) ◽  
pp. 3177-3192 ◽  
Author(s):  
Terrence M. Joyce ◽  
Young-Oh Kwon ◽  
Lisan Yu
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Gulf Stream ◽  
Kuroshio Extension ◽  
Storm Track ◽  
Western Boundary ◽  
Atmospheric Variability ◽  
The North ◽  
The Kuroshio ◽  
The North Pacific

Abstract Coherent, large-scale shifts in the paths of the Gulf Stream (GS) and the Kuroshio Extension (KE) occur on interannual to decadal time scales. Attention has usually been drawn to causes for these shifts in the overlying atmosphere, with some built-in delay of up to a few years resulting from propagation of wind-forced variability within the ocean. However, these shifts in the latitudes of separated western boundary currents can cause substantial changes in SST, which may influence the synoptic atmospheric variability with little or no time delay. Various measures of wintertime atmospheric variability in the synoptic band (2–8 days) are examined using a relatively new dataset for air–sea exchange [Objectively Analyzed Air–Sea Fluxes (OAFlux)] and subsurface temperature indices of the Gulf Stream and Kuroshio path that are insulated from direct air–sea exchange, and therefore are preferable to SST. Significant changes are found in the atmospheric variability following changes in the paths of these currents, sometimes in a local fashion such as meridional shifts in measures of local storm tracks, and sometimes in nonlocal, broad regions coincident with and downstream of the oceanic forcing. Differences between the North Pacific (KE) and North Atlantic (GS) may be partly related to the more zonal orientation of the KE and the stronger SST signals of the GS, but could also be due to differences in mean storm-track characteristics over the North Pacific and North Atlantic.

“Eddy Resolving” Observation of the North Pacific Subtropical Mode Water

2011 ◽  
Vol 41 (4) ◽  
pp. 666-681 ◽  
Author(s):  
Eitarou Oka ◽  
Toshio Suga ◽  
Chiho Sukigara ◽  
Katsuya Toyama ◽  
Keishi Shimada ◽  
...  
Keyword(s):  
High Resolution ◽  
North Pacific ◽  
Kuroshio Extension ◽  
Uniform Structure ◽  
Mode Water ◽  
Subtropical Mode Water ◽  
The North ◽  
Late Fall ◽  
The Kuroshio ◽  
The North Pacific

Abstract Hydrographic data obtained by high-resolution shipboard observations and Argo profiling floats have been analyzed to study the mesoscale structure and circulation of the North Pacific Subtropical Mode Water (STMW). The float data show that in the late winter of 2008, STMW having a temperature of approximately 18.8°, 17.7°, and 16.6°C formed west of 140°E, at 140°–150°E, and east of 150°E, respectively, in the recirculation gyre south of the Kuroshio Extension. After spring, the newly formed STMW gradually shift southward, decreasing in thickness. Simultaneously, the STMWs of 16.6° and 17.7°C are gradually stirred and then mixed in terms of properties. In late fall, they seem to be integrated to form a single group of STMWs having a temperature centered at 17.2°C. Such STMW circulation in 2008 is much more turbulent than that in 2006, which was investigated in a previous study. The difference between the two years is attributed to the more variable state of the Kuroshio Extension in 2008, associated with stronger eddy activities in the STMW formation region, which enhance the eddy transport of STMW. High-resolution shipboard observations were carried out southeast of Japan at 141°–147°E in the early fall of 2008. To the south of the Kuroshio Extension, STMW exists as a sequence of patches with a horizontal scale of 100–200 km, whose thick portions correspond well to the mesoscale deepening of the permanent pycnocline. The western (eastern) hydrographic sections are occupied mostly by the 17.7°C (16.6°C) STMW, within which the 16.6°C (17.7°C) STMW exists locally, mostly at locations where both the permanent pycnocline depth and the STMW thickness are maximum. This structure implies that the STMW patches are transported away from their respective formation sites, corresponding to a shift in the mesoscale anticyclonic circulations south of the Kuroshio Extension. Furthermore, 20%–30% of the observed STMW pycnostads have two or three potential vorticity minima, mostly near temperatures of 16.6° and 17.7°C. The authors presume that such a structure formed as a result of the interleaving of the 16.6° and 17.7°C STMWs after they are stirred by mesoscale circulations, following which they are vertically mixed to form the 17.2°C STMW observed in late fall. These results indicate the importance of horizontal processes in destroying the vertically uniform structure of STMW after spring, particularly when the Kuroshio Extension is in a variable state.

scholarly journals Southward spreading of the Fukushima-derived radiocesium across the Kuroshio Extension in the North Pacific

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Yuichiro Kumamoto ◽  
Michio Aoyama ◽  
Yasunori Hamajima ◽  
Tatsuo Aono ◽  
Shinya Kouketsu ◽  
...  
Keyword(s):  
North Pacific ◽  
Kuroshio Extension ◽  
The North ◽  
The Kuroshio ◽  
The North Pacific

scholarly journals Evolution and Structure of the Kuroshio Extension Front in Spring 2019

2020 ◽  
Vol 8 (7) ◽  
pp. 502
Author(s):  
Jiahao Wang ◽  
Kefeng Mao ◽  
Xi Chen ◽  
Kelan Zhu
Keyword(s):  
Saline Water ◽  
Kuroshio Extension ◽  
Intermediate Water ◽  
North Pacific Intermediate Water ◽  
Water Region ◽  
Diffusive Convection ◽  
Thermohaline Intrusions ◽  
Salt Fingering ◽  
The Kuroshio ◽  
Kuroshio Extension Front

Satellite data products and high-resolution in situ observations were combined to investigate the evolution and structure of the Kuroshio Extension Front in Spring 2019. The former reveals the variation of the front is influenced by the northward movement of the Kuroshio Extension through transporting warm and saline water to a cold and brackish water region. The latter indicates steep upward slopes of the isopycnals, tilting northward in the frontal zone, as well as several ~300 m thick blobs of North Pacific Intermediate Water between 26.25 and 26.75 kg/m3, where conspicuous thermohaline intrusions occur. Further analysis indicates these thermohaline intrusions prefer to alternate salt fingering and diffusive convection interfaces, and are affected by strong shears.

scholarly journals Aerosols, clouds, and precipitation in the North Atlantic trades observed during the Barbados aerosol cloud experiment – Part 1: Distributions and variability

2016 ◽  
Vol 16 (13) ◽  
pp. 8643-8666 ◽  
Author(s):  
Eunsil Jung ◽  
Bruce A. Albrecht ◽  
Graham Feingold ◽  
Haflidi H. Jonsson ◽  
Patrick Chuang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Cloud Base ◽  
Cumulus Clouds ◽  
Air Masses ◽  
Shallow Marine ◽  
Cloud Radar ◽  
Aerosol Cloud ◽  
The North ◽  
The North Atlantic

Abstract. Shallow marine cumulus clouds are by far the most frequently observed cloud type over the Earth's oceans; but they are poorly understood and have not been investigated as extensively as stratocumulus clouds. This study describes and discusses the properties and variations of aerosol, cloud, and precipitation associated with shallow marine cumulus clouds observed in the North Atlantic trades during a field campaign (Barbados Aerosol Cloud Experiment- BACEX, March–April 2010), which took place off Barbados where African dust periodically affects the region. The principal observing platform was the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter (TO) research aircraft, which was equipped with standard meteorological instruments, a zenith pointing cloud radar and probes that measured aerosol, cloud, and precipitation characteristics.The temporal variation and vertical distribution of aerosols observed from the 15 flights, which included the most intense African dust event during all of 2010 in Barbados, showed a wide range of aerosol conditions. During dusty periods, aerosol concentrations increased substantially in the size range between 0.5 and 10 µm (diameter), particles that are large enough to be effective giant cloud condensation nuclei (CCN). The 10-day back trajectories showed three distinct air masses with distinct vertical structures associated with air masses originating in the Atlantic (typical maritime air mass with relatively low aerosol concentrations in the marine boundary layer), Africa (Saharan air layer), and mid-latitudes (continental pollution plumes). Despite the large differences in the total mass loading and the origin of the aerosols, the overall shapes of the aerosol particle size distributions were consistent, with the exception of the transition period.The TO was able to sample many clouds at various phases of growth. Maximum cloud depth observed was less than ∼ 3 km, while most clouds were less than 1 km deep. Clouds tend to precipitate when the cloud is thicker than 500–600 m. Distributions of cloud field characteristics (depth, radar reflectivity, Doppler velocity, precipitation) were well identified in the reflectivity–velocity diagram from the cloud radar observations. Two types of precipitation features were observed for shallow marine cumulus clouds that may impact boundary layer differently: first, a classic cloud-base precipitation where precipitation shafts were observed to emanate from the cloud base; second, cloud-top precipitation where precipitation shafts emanated mainly near the cloud tops, sometimes accompanied by precipitation near the cloud base. The second type of precipitation was more frequently observed during the experiment. Only 42–44 % of the clouds sampled were non-precipitating throughout the entire cloud layer and the rest of the clouds showed precipitation somewhere in the cloud, predominantly closer to the cloud top.

scholarly journals Spreading of warm water from the Kuroshio Extension into the Perturbed Area

1998 ◽  
Vol 54 (3) ◽  
pp. 257-271 ◽  
Author(s):  
Susana Sainz-Trápaga ◽  
Takashige Sugimoto
Keyword(s):  
Kuroshio Extension ◽  
Warm Water ◽  
The Kuroshio

scholarly journals Rapid Eddy-Induced Modification of Subtropical Mode Water during the Kuroshio Extension System Study

2014 ◽  
Vol 44 (7) ◽  
pp. 1941-1953 ◽  
Author(s):  
Stuart P. Bishop ◽  
D. Randolph Watts
Keyword(s):  
Kuroshio Extension ◽  
Unstable State ◽  
System Study ◽  
Mode Water ◽  
Unstable Regime ◽  
Subtropical Mode Water ◽  
Eddy Diffusivities ◽  
The North ◽  
Extension System ◽  
The Kuroshio

Abstract From 2004 to 2006 an observational array of current- and pressure-recording inverted echo sounders (CPIES) were deployed as part of the Kuroshio Extension (KEx) System Study (KESS). KESS observed a transition from a weakly meandering (“stable”) to strongly meandering (“unstable”) state (Qiu and Chen). As the KEx made this transition, potential vorticity (PV) observed within the southern recirculation gyre (SRG) rapidly increased from January to July 2005. In this study, the authors diagnose eddy PV fluxes (EPVFs) in isentropic coordinates within the subtropical mode water (STMW) layer from the CPIES data to determine the role of mesoscale eddies in this rapid increase of PV. The rapid increase in PV within the SRG coincided with enhanced cross-front EPVFs and eddy PV flux convergence upstream of a mean trough in the KEx path and adjacent to the SRG. The enhanced cross-front EPVFs were the result of the formation of a cold-core ring (CCR) and the interaction of the jet with a preexisting CCR. Eddy diffusivities are diagnosed for the unstable regime with values that range from 100 to 2000 m2 s−1. The high eddy diffusivities during the unstable regime reflect the nature of mesoscale CCR formation and CCR–jet interaction as efficient mechanisms for stirring and mixing high PV waters from the north side of the KEx into the low PV waters of the SRG where STMW resides. This mechanism for cross-frontal exchange can explain observed increases in the STMW PV in the SRG over the 16 months of KESS observations.

scholarly journals Small meanders of the Kuroshio Extension and associated northward spreading of warm water: Three‐vessel simultaneous observations and an eddy‐resolving ocean model simulation

2016 ◽  
Vol 121 (7) ◽  
pp. 5315-5337 ◽  
Author(s):  
Fumiaki Kobashi ◽  
Yukino Onikata ◽  
Naoto Iwasaka ◽  
Yoshimi Kawai ◽  
Eitarou Oka ◽  
...  
Keyword(s):  
Model Simulation ◽  
Kuroshio Extension ◽  
Ocean Model ◽  
Warm Water ◽  
The Kuroshio

scholarly journals Winter Extreme Flux Events in the Kuroshio and Gulf Stream Extension Regions and Relationship with Modes of North Pacific and Atlantic Variability

2015 ◽  
Vol 28 (12) ◽  
pp. 4950-4970 ◽  
Author(s):  
Xiaohui Ma ◽  
Ping Chang ◽  
R. Saravanan ◽  
Dexing Wu ◽  
Xiaopei Lin ◽  
...  
Keyword(s):  
North Pacific ◽  
Gulf Stream ◽  
Kuroshio Extension ◽  
Storm Track ◽  
Propagation Path ◽  
Northwestern Pacific ◽  
Boreal Winter ◽  
The North ◽  
The Kuroshio ◽  
The North Pacific

Abstract Boreal winter (November–March) extreme flux events in the Kuroshio Extension region (KER) of the northwestern Pacific and the Gulf Stream region (GSR) of the northwestern Atlantic are analyzed and compared, based on NCEP Climate Forecast System Reanalysis (CFSR), NCEP–NCAR reanalysis, and NOAA Twentieth Century Reanalysis data, as well as the observationally derived OAFlux dataset. These extreme flux events, most of which last less than 3 days, are characterized by cold air outbreaks (CAOs) with an anomalous northerly wind that brings cold and dry air from the Eurasian and North American continents to the KER and GSR, respectively. A close relationship between the extreme flux events over KER (GSR) and the Aleutian low pattern (ALP) [east Atlantic pattern (EAP)] is found with more frequent occurrence of the extreme flux events during a positive ALP (EAP) phase and vice versa. A further lag-composite analysis suggests that the ALP (EAP) is associated with accumulated effects of the synoptic winter storms accompanied by the extreme flux events and shows that the event-day storms tend to have a preferred southeastward propagation path over the North Pacific (Atlantic), potentially contributing to the southward shift of the storm track over the eastern North Pacific (Atlantic) basin during the ALP (EAP) positive phase. Finally, lag-regression analyses indicate a potential positive influence of sea surface temperature (SST) anomalies along the KER (GSR) on the development of the extreme flux events in the North Pacific (Atlantic).

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