scholarly journals Atmospheric Responses to Kuroshio SST Front in the East China Sea under Different Prevailing Winds in Winter and Spring

2015 ◽  
Vol 28 (8) ◽  
pp. 3191-3211 ◽  
Author(s):  
Mimi Xu ◽  
Haiming Xu
Keyword(s):  
East China Sea ◽  
Surface Wind ◽  
Vertical Mixing ◽  
East China ◽  
Atmospheric Response ◽  
The East China Sea ◽  
Sst Front ◽  
Front Condition ◽  
Temperature And Pressure ◽  
Sst Gradient

Abstract Atmospheric responses to the Kuroshio SST front in the East China Sea under different prevailing winds are examined using high-resolution observations and numerical modeling. Satellite data reveal a significant in-phase relationship between SST and surface wind speed, indicative of ocean-to-atmosphere influence. The atmospheric response varies according to the relative surface wind direction with respect to the SST front orientation. Under the alongfront condition, low (high) SLP anomalies are found on the warmer (colder) flank of the front, accompanied by surface wind convergence (divergence). Enhanced precipitation and frequent cumulus convection appear over the warm Kuroshio, suggesting an atmospheric response extending into the free troposphere. Under the cross-front condition, when the air blows from cold to warm (warm to cold) SST, divergence (convergence) is located directly over the SST front, and its magnitude is proportional to the downwind SST gradient. Under such prevailing winds, the SST front has little effect on the SLP and precipitation. The Weather Research and Forecasting (WRF) Model is used to investigate the mechanism responsible for the atmospheric adjustment. The results show that under the alongfront condition, large temperature and pressure perturbations in the boundary layer are caused by SST gradients, while stability and turbulent mixing are less affected. By contrast, under the cross-front condition, the perturbations of temperature and pressure are small and shifted downstream, while the SST gradient exerts stronger impact on vertical mixing. The modeling results confirm that the pressure adjustment mechanism contributes more to the atmospheric response under alongfront prevailing winds, while the vertical mixing mechanism dominates the atmospheric adjustment under cross-front winds.

scholarly journals Deep Atmospheric Response to the Spring Kuroshio over the East China Sea*

2011 ◽  
Vol 24 (18) ◽  
pp. 4959-4972 ◽  
Author(s):  
Haiming Xu ◽  
Mimi Xu ◽  
Shang-Ping Xie ◽  
Yuqing Wang
Keyword(s):  
Wind Speed ◽  
East China Sea ◽  
Surface Wind ◽  
Convective Precipitation ◽  
East China ◽  
Atmospheric Response ◽  
The East China Sea ◽  
Sst Front ◽  
China Sea ◽  
The Kuroshio

Abstract The atmospheric response to the spring Kuroshio Front over the East China Sea is investigated using a suite of high-resolution satellite data and a regional atmospheric model. The atmospheric response appears to extend beyond the marine atmospheric boundary layer, with frequent occurrence of cumulus convection. In spring, Quick Scatterometer (QuikSCAT) wind speed shows a clear effect of sea surface temperature (SST), with high (low) wind speed observed over the warm (cold) tongue. This in-phase relationship between SST and surface wind speed is indicative of SST influence on the atmosphere. Wind convergence is found on the warmer flank of the Kuroshio Front, accompanied by a narrow rainband. The analysis of satellite-borne radar measurements indicates that deep convection appears over the Kuroshio warm tongue in the spring season, with enhanced convective precipitation, frequent occurrence of cumulus convection, and increased precipitation (cloud) tops in altitude. These deep convective activities along the Kuroshio warm tongue are further supported by enhanced lightning flash rate observed by satellite and atmospheric heating estimated by a Japanese reanalysis. The Weather Research and Forecasting (WRF) model is used to investigate the precipitation response to the spring Kuroshio SST front over the East China Sea. Forced by observed SST [control (CTL)], the model well simulates a narrow band of precipitation, high wind speed, and surface wind convergence that closely follows the Kuroshio warm current, consistent with satellite observations. This narrow rainband completely disappears in the model when the SST front is removed by horizontally smoothed SST (SmSST). The results show that it is convective precipitation that is sensitive to the Kuroshio SST front. A case study for an eastward-moving extratropical cyclone indicates that convective precipitation increases its intensity and duration in the CTL run compared to the SmSST run. Local enhancement of upward sensible and latent heat fluxes and convective instability in the lower atmosphere are the key to anchoring the narrow band of convective precipitation that closely follows the Kuroshio.

Transition of low clouds in the East China Sea and Kuroshio region in winter: A regional atmospheric model study

2020 ◽  
Author(s):  
Jingchao Long ◽  
Yuqing Wang ◽  
Suping Zhang ◽  
Jingwu Liu
Keyword(s):  
East China Sea ◽  
Vertical Mixing ◽  
Atmospheric Model ◽  
Cloud Layer ◽  
Latent Heating ◽  
The East China Sea ◽  
Sst Front ◽  
Regional Atmospheric Model ◽  
The Kuroshio ◽  
Kuroshio Region

<p>Bias in simulating the stratocumulus-to-cumulus transition remains a main source of uncertainties in regional climate projection and can significantly affect the energy budget in climate models. To gain insights into the transition, this study investigates the cloud transition forced by the sea surface temperature (SST) front and synoptic disturbances in the East China Sea and Kuroshio region in winter based on both observations and regional atmospheric model simulations. The Kuroshio SST front greatly accelerates cloud transition by enhancing surface turbulent heat flux, marine atmospheric boundary layer (MABL) dynamical adjustment and cloud-top entrainment. With the sharp SST increase from the cold flank to the Kuroshio SST warm tongue (KWT), surface wind convergence (SWC) over the KWT induced by the SST front and synoptic disturbances[Office1]  enhances the coupling between the cloud layer and subcloud layer. An underlying positive feedback between the SWC and latent heating in the cloud layer can enhance abrupt change in cloud properties and maintain cloud band over the KWT against the decoupling through the so-called “Deepening-Warming” mechanism induced by latent heating. From the KWT downwind southward, the surface layer turbulent mixing weakens, while latent heating in the cloud layer and cloud-top longwave radiative cooling enhance buoyancy and vertical mixing in the cloud layer. This difference in vertical mixing between the cloud layer and subcloud layer facilitates the MABL decoupling and impedes upward moisture transport. Meanwhile, decreasing lower tropospheric stability is conducive to the entrainment of drier and warmer air from above into the cloud layer, strengthening cloud evaporation.</p>

A role of vertical mixing on nutrient supply into the subsurface chlorophyll maximum in the shelf region of the East China Sea

2017 ◽  
Vol 143 ◽  
pp. 139-150 ◽  
Author(s):  
Keunjong Lee ◽  
Takeshi Matsuno ◽  
Takahiro Endoh ◽  
Joji Ishizaka ◽  
Yuanli Zhu ◽  
...  
Keyword(s):  
East China Sea ◽  
Vertical Mixing ◽  
Nutrient Supply ◽  
East China ◽  
The East China Sea ◽  
China Sea ◽  
Chlorophyll Maximum ◽  
Subsurface Chlorophyll Maximum ◽  
Shelf Region

scholarly journals Two Types of Surface Wind Response to the East China Sea Kuroshio Front*

2013 ◽  
Vol 26 (21) ◽  
pp. 8616-8627 ◽  
Author(s):  
Jing-Wu Liu ◽  
Su-Ping Zhang ◽  
Shang-Ping Xie
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
East China Sea ◽  
Time Scales ◽  
Vertical Mixing ◽  
Sea Surface ◽  
The East China Sea ◽  
Sst Front ◽  
Vector Wind ◽  
Different Time Scales

Abstract Effects of the sea surface temperature (SST) front along the East China Sea Kuroshio on sea surface winds at different time scales are investigated. In winter and spring, the climatological vector wind is strongest on the SST front while the scalar wind speed reaches a maximum on the warm flank of the front and is collocated with the maximum difference between sea surface temperature and surface air temperature (SST − SAT). The distinction is due to the change in relative importance of two physical processes of SST–wind interaction at different time scales. The SST front–induced sea surface level pressure (SLP) adjustment (SF–SLP) contributes to a strong vector wind above the front on long time scales, consistent with the collocation of baroclinicity in the marine boundary layer and corroborated by the similarity between the thermal wind and observed wind shear between 1000 and 850 hPa. In contrast, the SST modulation of synoptic winds is more evident on the warm flank of the SST front. Large thermal instability of the near-surface layer strengthens temporal synoptic wind perturbations by intensifying vertical mixing, resulting in a scalar wind maximum. The vertical mixing and SF–SLP mechanisms are both at work but manifest more clearly at the synoptic time scale and in the long-term mean, respectively. The cross-frontal variations are 1.5 m s−1 in both the scalar and vector wind speeds, representing the vertical mixing and SF–SLP effects, respectively. The results illustrate the utility of high-frequency sampling by satellite scatterometers.

scholarly journals Deep Atmospheric Response to the Spring Kuroshio Current over the East China Sea

2011 ◽  
pp. 110415071529000
Author(s):  
Haiming Xu ◽  
Mimi Xu ◽  
Shang-Ping Xie ◽  
Yuqing Wang
Keyword(s):  
East China Sea ◽  
Kuroshio Current ◽  
East China ◽  
Atmospheric Response ◽  
The East China Sea ◽  
China Sea

scholarly journals Behavior and fluxes of particulate organic carbon in the East China Sea

2013 ◽  
Vol 10 (3) ◽  
pp. 4271-4302 ◽  
Author(s):  
C.-C. Hung ◽  
C.-W. Tseng ◽  
G.-C. Gong ◽  
K.-S. Chen ◽  
M.-H. Chen ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
East China Sea ◽  
Sediment Resuspension ◽  
Vertical Mixing ◽  
Mixing Model ◽  
Outer Shelf ◽  
East China ◽  
The East China Sea ◽  
Inner Shelf

Abstract. To better understand carbon cycling in marginal seas, particulate organic carbon (POC) concentrations, POC fluxes and primary production (PP) were measured in the East China Sea (ECS) in summer 2007. Higher concentrations of POC were observed in the inner shelf and lower POC values were found in the outer shelf. Similar to POC concentrations, elevated uncorrected POC fluxes (720–7300 mg C m−2 d−1) were found in the inner shelf and lower POC fluxes (80–150 mg C m−2 d−1) were in the outer shelf, respectively. PP values (~340–3380 mg C m−2 d−1) had analogous distribution patterns to POC fluxes, while some of PP values were significantly lower than POC fluxes, suggesting that contributions of resuspended particles to POC fluxes need to be appropriately corrected. A vertical mixing model was used to correct effects of bottom sediment resuspension and the corrected POC fluxes ranging from 41 ± 20 to 956 ± 443 mg C m−2 d−1, which were indeed lower than PP values. The results suggest that 49–93% of the POC flux in the ECS might be from the contribution of resuspension of bottom sediments rather than from the actual biogenic carbon sinking flux. While the vertical mixing model is not a perfect model to solve sediment resuspension because it ignores biological degradation of sinking particles, Changjinag plume (or terrestrial) inputs and lateral transport, it makes significant progress in both correcting resuspension problem and in assessing a reasonable quantitative estimate in a marginal sea.

Vertical mixing in the bottom mixed layer near the continental shelf break in the East China Sea

1994 ◽  
Vol 50 (4) ◽  
pp. 437-448 ◽  
Author(s):  
Takeshi Matsuno ◽  
Seiichi Kanari ◽  
Chikashi Kobayashi ◽  
Toshiyuki Hibiya
Keyword(s):  
Continental Shelf ◽  
East China Sea ◽  
Mixed Layer ◽  
Vertical Mixing ◽  
Shelf Break ◽  
East China ◽  
The East China Sea ◽  
China Sea ◽  
Continental Shelf Break

scholarly journals Offshore Detachment Process of the Low-Salinity Water around Changjiang Bank in the East China Sea

2010 ◽  
Vol 40 (5) ◽  
pp. 1035-1053 ◽  
Author(s):  
Jae-Hong Moon ◽  
Naoki Hirose ◽  
Jong-Hwan Yoon ◽  
Ig-Chan Pang
Keyword(s):  
East China Sea ◽  
Tidal Current ◽  
Spring Tide ◽  
Vertical Mixing ◽  
East China ◽  
The East China Sea ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Salinity Water ◽  
Tide Period

Abstract A patchlike structure of low-salinity water detached from the Chanjiang “Diluted Water” (CDW) is frequently observed in the East China Sea (ECS). In this study, the offshore detachment process of CDW into the ECS is examined using a three-dimensional numerical model. The model results show that low-salinity water is detached from the CDW plume by the intense tide-induced vertical mixing during the spring tide period when the tidal current becomes stronger. During the spring tide, thickness of the bottom mixed layer in the sloping bottom around Changjiang Bank reaches the mean water depth, implying that the stratification is completely destroyed in the entire water column. As a result, the offshore detachment of CDW occurs in the sloping side of the bank where the tidal energy dissipation is strong enough to overcome the buoyancy effect during this period. On the other hand, the surface stratification is retrieved during the neap tide period, because the tidal current becomes substantially weaker than that in the spring tide. Wind forcing over the ECS as well as tidal mixing is a critical factor for the detachment process because the surface wind primarily induces a northeastward CDW transport across the shelf region where tide-induced vertical mixing is strong. Moreover, the wind-enhanced cross-isobath transport of CDW causes a larger offshore low-salinity patch, indicating that the freshwater volume of the low-salinity patch closely depends on the wind magnitude.

scholarly journals Modeled MABL Responses to the Winter Kuroshio SST Front in the East China Sea and Yellow Sea

2019 ◽  
Vol 124 (12) ◽  
pp. 6069-6092 ◽  
Author(s):  
HaoKun Bai ◽  
HaiBo Hu ◽  
Xiu‐Qun Yang ◽  
XueJuan Ren ◽  
HaiMing Xu ◽  
...  
Keyword(s):  
East China Sea ◽  
Yellow Sea ◽  
East China ◽  
The East China Sea ◽  
Sst Front ◽  
China Sea
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