Regional Weather Patterns during Anomalous Air–Sea Fluxes at the Kuroshio Extension Observatory (KEO)*

2008 ◽  
Vol 21 (8) ◽  
pp. 1680-1697 ◽  
Author(s):  
Nicholas A. Bond ◽  
Meghan F. Cronin
Keyword(s):  
Atmospheric Circulation ◽  
High Frequency ◽  
Kuroshio Extension ◽  
Warm Season ◽  
Cold Season ◽  
Surface Fluxes ◽  
Interannual Variations ◽  
Data Set ◽  
Weather Patterns ◽  
The Kuroshio

Abstract The weather patterns during periods of anomalous surface fluxes in the Kuroshio recirculation gyre of the western North Pacific are documented. Separate analyses are carried out for the cold season (October– March) when the net surface heat flux is controlled by the combination of the turbulent sensible and latent heat fluxes (Qturb), and for the warm season (May–August) when the net heating is dominated by the net radiative fluxes (Qrad). For analysis of high-frequency (daily to weekly) variations in the fluxes, direct measurements from the Kuroshio Extension Observatory (KEO) for the period June 2004–November 2005 are used to specify flux events. For analysis of interannual variations, these events are selected using NCEP–NCAR reanalysis estimates for Qturb in the cold season, and International Comprehensive Ocean–Atmosphere Data Set (ICOADS) data for cloud fraction, as a proxy for Qrad, in the warm season. During the cold season, episodic high-frequency flux events are associated with significant anomalies in the east–west sea level pressure gradients, and hence meridional winds and lower-tropospheric air temperature, reflecting the dominance of the atmospheric forcing of the flux variability. On the other hand, interannual variations in Qturb are associated with relatively weak atmospheric circulation anomalies, implying a relatively important role for the ocean. During the warm season, high-frequency fluctuations in the net surface fluxes occur due to a mix of anomalies in Qturb and Qrad. Enhanced cloudiness in the vicinity of KEO, and hence reduced Qrad, tends to occur in association with weak cyclonic disturbances of extratropical origin. A regional atmospheric circulation favoring these types of events also was found for warm seasons that were cloudier on the whole. Results suggest that the ocean’s influence on air–sea fluxes at KEO is manifested mostly on interannual time scales during the cold season.

scholarly journals Influence of the Meridional Shifts of the Kuroshio and the Oyashio Extensions on the Atmospheric Circulation

2011 ◽  
Vol 24 (3) ◽  
pp. 762-777 ◽  
Author(s):  
Claude Frankignoul ◽  
Nathalie Sennéchael ◽  
Young-Oh Kwon ◽  
Michael A. Alexander
Keyword(s):  
Atmospheric Circulation ◽  
North Pacific ◽  
Large Scale ◽  
Kuroshio Extension ◽  
Statistical Significance ◽  
The North ◽  
Enso Teleconnections ◽  
Historical Temperature ◽  
The Kuroshio ◽  
Sst Anomalies

Abstract The meridional shifts of the Oyashio Extension (OE) and of the Kuroshio Extension (KE), as derived from high-resolution monthly sea surface temperature (SST) anomalies in 1982–2008 and historical temperature profiles in 1979–2007, respectively, are shown based on lagged regression analysis to significantly influence the large-scale atmospheric circulation. The signals are independent from the ENSO teleconnections, which were removed by seasonally varying, asymmetric regression onto the first three principal components of the tropical Pacific SST anomalies. The response to the meridional shifts of the OE front is equivalent barotropic and broadly resembles the North Pacific Oscillation/western Pacific pattern in a positive phase for a northward frontal displacement. The response may reach 35 m at 250 hPa for a typical OE shift, a strong sensitivity since the associated SST anomaly is 0.5 K. However, the amplitude, but not the pattern or statistical significance, strongly depends on the lag and an assumed 2-month atmospheric response time. The response is stronger during fall and winter and when the front is displaced southward. The response to the northward KE shifts primarily consists of a high centered in the northwestern North Pacific and hemispheric teleconnections. The response is also equivalent barotropic, except near Kamchatka, where it tilts slightly westward with height. The typical amplitude is half as large as that associated with OE shifts.

scholarly journals A Frequency-Dependent Description of Propagating Sea Level Signals in the Kuroshio Extension Region

2014 ◽  
Vol 44 (6) ◽  
pp. 1614-1635 ◽  
Author(s):  
Hongyang Lin ◽  
Keith R. Thompson ◽  
Jianyu Hu
Keyword(s):  
Sea Level ◽  
High Frequency ◽  
Rossby Waves ◽  
Kuroshio Extension ◽  
Frequency Mode ◽  
Global Ocean ◽  
Western Boundary ◽  
Frequency Dependent ◽  
The Kuroshio ◽  
Kuroshio Extension Region

Abstract Hilbert empirical orthogonal function analysis is used to provide a frequency-dependent description of observed sea level variability in the Kuroshio Extension region, 1993–2012 inclusive. The dominant high-frequency mode (periods between 140 and 350 days) describes signals that propagate westward with the largest amplitudes in the vicinity of the Shatsky Rise and Emperor Seamounts. Based on the close correspondence between the variance of the high-frequency variability and the underlying bathymetry, it is speculated that this mode is driven by jet–bathymetry interactions. The dominant low-frequency mode (periods longer than 350 days) is explained in terms of wind-forced, jet-trapped Rossby waves that propagate along the mean Kuroshio Extension jet. One of the most surprising findings of this study is that sea level changes north of the jet in the meander region anticipate changes south of the jet by about 3 yr. Based on correlations of observed sea level with the Pacific decadal oscillation, and western boundary transport variability estimated from the Global Ocean Reanalysis and Simulations (GLORYS), it is speculated that this anticipation is due to the differences in time taken for (i) Rossby waves to travel from the eastern North Pacific to the meander region and (ii) the much faster barotropic response of western boundary transport, and sea level north of the jet, to large-scale forcing by the wind stress curl.

Mesoscale energy balance and air-sea interaction in the Kuroshio Extension: low-frequency versus high-frequency variability

2020 ◽  
Author(s):  
Haiyuan Yang ◽  
Lixin Wu ◽  
Ping Chang ◽  
Bo Qiu ◽  
Zhao Jing ◽  
...  
Keyword(s):  
High Frequency ◽  
Kuroshio Extension ◽  
Baroclinic Instability ◽  
Low Frequency ◽  
Heat Fluxes ◽  
Budget Analysis ◽  
High Frequency Variability ◽  
Community Earth System Model ◽  
Frequency Window ◽  
The Kuroshio

AbstractUsing eddy-resolving Community Earth System Model (CESM) simulations, this study investigates mesoscale energetics and air-sea interaction at two different time-scale windows in the Kuroshio Extension (KE) region. Based on an energy budget analysis, it is found that both baroclinic and barotropic pathways contribute to eddy energy generation within the low-frequency window (longer than 3 weeks) in this region, while both air-sea heat fluxes and wind stresses act as prominent eddy killers that remove energy from ocean. In contrast, within the high-frequency window oceanic variability is mainly fed by baroclinic instability and regulated by turbulent thermal wind (TTW) processes, while the positive wind work is derived primarily from ageostrophic flow, i.e., Ekman drift, and along with air-sea heat fluxes has little influence on geostrophic mesoscale eddies.

scholarly journals PM measurement campaign HOVERT in the Greater Berlin area: model evaluation with chemically specified particulate matter observations for a one year period

2007 ◽  
Vol 7 (1) ◽  
pp. 55-68 ◽  
Author(s):  
M. Beekmann ◽  
A. Kerschbaumer ◽  
E. Reimer ◽  
R. Stern ◽  
D. Möller
Keyword(s):  
Particulate Matter ◽  
Warm Season ◽  
Correlation Coefficients ◽  
Inorganic Ions ◽  
Cold Season ◽  
Air Quality Model ◽  
Quality Model ◽  
Data Set ◽  
University Of Berlin ◽  
Rural Sites

Abstract. The HOVERT (HOrizontal and VERtical Transport of ozone and particulate matter) campaign held in the Berlin Brandenburg area in Eastern Germany from September 2001 to September 2002 allowed to collect a unique data set of the aerosol chemical speciation (daily averages) at traffic, urban and rural sites. These observations are used for a thorough evaluation of the aerosol part in the REM-CALGRID model (RCG) developed at the Free University of Berlin (FUB). For inorganic ions (sulphate, nitrate and ammonium), simulated annual averages agree to observations within ±30% at more than half of the sites and always within a factor of two. Correlation coefficients are larger than in previous studies for SO42− and NH4+ (>0.7). For nitrate, less elevated correlations, 0.4–0.7 in the cold season, 0.2–0.4 in the warm season, are encountered. To our knowledge, this is one of the first comparisons of air quality model simulated elemental and organic carbon (EC and OC) with daily observations for a whole year. It suggests an overestimation of EC and OC emissions in the Berlin area (through a scaling techniques between EC, OC and NOx and when assuming correct NOx emissions), and an underestimation of EC and OC at rural sites. Secondary organic aerosol (SOA) formation, recently introduced into the model (SORGAM module, Schell et al., 2001), is simulated as a very variable process, SOA levels varying from close to zero for most days to more than 5 μg/m3. Correlation between simulated SOA to observed OC is about 0.6, indicating that simulated variability partly corresponds to reality.

Regional Features of Interannual Variations in Water Temperature in the Subarctic Pacific

2021 ◽  
pp. 67-79
Author(s):  
I. D. Rostov ◽  
◽  
E. V. Dmitrieva ◽  
Keyword(s):  
Water Temperature ◽  
Global Climate ◽  
Heat Content ◽  
Warm Season ◽  
Cold Season ◽  
Climate Indices ◽  
Interannual Variations ◽  
Study Region ◽  
Subarctic Pacific ◽  
Regional Features

Based on the NOAA climate datasets, trends, regional features, and possible causal relationships of interannual variations in water temperature on the surface (SST) and in the upper 750-meter layer of the subarctic Pacific with variations in the fields of air temperature, air pressure, wind, and climate indices over the past four decades are identified. The results revealed a degree of heterogeneity of the study region response to the ongoing global climate change, identified isolated areas, and quantified the warming rate in these areas. It is shown that in the west of the region, the SST trends are much higher than in the east, and in the warm season, they are about twice higher than in the cold season. Changes in water temperature and heat content anomalies in the water column of different regions are extremely uneven. The phases of alternating warm and cold periods are consistent with trends in the characteristics of the atmospheric centers of action, climate indices, and different climatic parameters.

scholarly journals PM measurement campaign HOVERT in the Greater Berlin area: model evaluation with chemically specified particulate matter observations for a one year period

2006 ◽  
Vol 6 (4) ◽  
pp. 7285-7321
Author(s):  
M. Beekmann ◽  
A. Kerschbaumer ◽  
E. Reimer ◽  
R. Stern ◽  
D. Möller
Keyword(s):  
Particulate Matter ◽  
Warm Season ◽  
Correlation Coefficients ◽  
Inorganic Ions ◽  
Cold Season ◽  
Air Quality Model ◽  
Quality Model ◽  
Data Set ◽  
University Of Berlin ◽  
Rural Sites

Abstract. The HOVERT (Horizontal and VERtical Transport of Ozone and particulate matter) campaign held in the Berlin Brandenburg area in Eastern Germany from September 2001 to September 2002 allowed to collect a unique data set of the aerosol chemical speciation (daily averages) at traffic, urban and rural sites. These observations are used for a thorough evaluation of the aerosol part in the REM-CALGRID model (RCG) developed at the Free University of Berlin (FUB). For inorganic ions (sulphate, nitrate and ammonium), simulated annual averages agree to observations within ±30% at more than half of the sites and always within a factor of two. Correlation coefficients are larger than in previous studies for SO42- and NH4+ (>0.7). For nitrate, less elevated correlations, 0.4–0.7 in the cold season, 0.2–0.4 in the warm season, are encountered. To our knowledge, this is one of the first comparisons of air quality model simulated elemental carbon (EC and OC) with daily observations for a whole year. It suggests an overestimation of EC and OC emissions in the Berlin area (through a scaling techniques between EC, OC and NOx and when assuming correct NOx emissions), and an underestimation of EC and OC at rural sites. Secondary organic aerosol (SOA) formation, recently introduced into the model (SORGAM module, Schell et al., 2001), is simulated as a very variable process, SOA levels varying from close to zero for most days to more than 5 µg/m3. Correlation between simulated SOA to observed OC is about 0.6, indicating that simulated variability partly corresponds to reality.

Cold air outbreak over the Kuroshio extension region

OCEANS 2009 ◽  
2009 ◽  
Author(s):  
T. G. Jensen ◽  
T. Campbell ◽  
T. A. Smith ◽  
R. J. Small ◽  
R. Allard
Keyword(s):  
Kuroshio Extension ◽  
Cold Air ◽  
Cold Air Outbreak ◽  
The Kuroshio ◽  
Kuroshio Extension Region

scholarly journals Variability of the nutrient stream near Kuroshio's origin

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chen-Tung Arthur Chen ◽  
Ting-Hsuan Huang ◽  
Chi-Hsuan Wu ◽  
Haiyan Yang ◽  
Xinyu Guo
Keyword(s):  
Pacific Ocean ◽  
Continental Shelf ◽  
East China Sea ◽  
Kuroshio Extension ◽  
Subsurface Water ◽  
East China ◽  
The East China Sea ◽  
High Productivity ◽  
China Sea ◽  
The Kuroshio

AbstractThe Kuroshio—literally “the Black Stream”—is the most substantial current in the Pacific Ocean. It was called the Black Stream because this oligotrophic current is so nutrient-poor in its euphotic zone that the water appears black without the influence of phytoplankton and the associated, often colored dissolved organic matter. Yet, below the euphotic layer, nutrient concentrations increase with depth while current speed declines. Consequently, a core of maximum nutrient flux, the so-called nutrient stream, develops at a depth of roughly between 200 and 800 m. This poorly studied nutrient stream transports nutrients to and supports high productivity and fisheries on the East China Sea continental shelf; it also transports nutrients to and promotes increased productivity and fisheries in the Kuroshio Extension and the subarctic Pacific Ocean. Three modes of the Kuroshio nutrient stream are detected off SE Taiwan for the first time: one has a single-core; one has two cores that are apparently separated by the ridge at 120.6–122° E, and one has two cores that are separated by a southward flow above the ridge. More importantly, northward nutrient transports seem to have been increasing since 2015 as a result of a 30% increase in subsurface water transport, which began in 2013. Such a nutrient stream supports the Kuroshio's high productivity, such as on the East China Sea continental shelf and in the Kuroshio Extension SE of Japan.

Sign in / Sign up

Export Citation Format

Share Document