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Surface and upper-level features associated with wintertime cold surge outbreaks in South Korea 总被引：1，自引：0，他引：1
The surface and upper-level features associated with a sharp drop of wintertime daily temperature over South Korea is investigated in this study. This sharp drop in daily temperature is called a cold surge and is one of the most hazardous weather phenomena in East Asian winters. An upper-level baroclinic wave of 60°wavelength propagating eastward at a phase speed of 12°longitude per day across the continent of northern China from the west of Lake Baikal toward the eastern coast of China causes the outbreak of cold air over South Korea. The cooling associated with the upper-level baroclinic wave is found at all altitudes under the geopotential height-fall center near the tropopause. The development in the ridge seems to derive the early evolution of the eastward-propagating sinusoidal wave, whereas the trough is connected directly with the tropospheric temperature-drop. An enhancement of the wintertime East Asian jet stream after the outbreak of a cold surge is a response to the steep temperature gradient associated with the developing baroclinic wave. 相似文献
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Effects of atmospheric river landfalls on the cold season precipitation in California 总被引：2，自引：0，他引：2
Jinwon Kim Duane E. Waliser Paul J. Neiman Bin Guan Ju-Mee Ryoo Gary A. Wick 《Climate Dynamics》2013,40(1-2):465-474
Effects of atmospheric river (AR) landfalls in the California coast on the cold-season precipitation in California are examined for the cold seasons of 10 water years (WYs) 2001–2010 using observed data and regional modeling in conjunction with AR-landfall inventory based on visual inspections of precipitable water vapor (PWV) from remote sensing and reanalysis. The PWV in the SSM/I and SSMIS retrievals and the ERA-Interim reanalysis shows 95 AR-landfall days in the California coast that are almost evenly split between the northern and southern coasts across 37.5N. The CPC/NCEP gridded daily precipitation analysis shows that 10–30% of the cold-season precipitation totals in California have occurred during these AR landfalls. The analysis also reveals that the percentage of precipitation and the precipitation intensity during AR landfalls in California are characterized by strong north-to-south gradient. This north–south contrast in the AR precipitation is reversed for the non-AR precipitation in the coastal range. The frequency of AR landfalls and the cold-season precipitation totals in the Sierra Nevada region are only marginally correlated. Instead, AR landfalls are closely related with the occurrence of heavy precipitation events. The freezing-level altitudes are systematically higher for AR wet days than non-AR wet days indicating warmer low-troposphere during AR storms. Cold season simulations for the 10 WYs 2001–2010 show that the Weather Research and Forecast (WRF) model can reasonably simulate important features in both the seasonal and AR precipitation totals. The daily pattern correlation coefficients between the simulated and ERA-Interim upper-air fields exceed 0.9 for most of the period. This suggests that the simulated temporal variations in the atmospheric circulation agree reasonably with the reanalysis over seasonal time scales, characteristics critical for reliable simulations of regional scale hydrologic cycle. The simulated seasonal and AR precipitation totals also agree reasonably with the CPC/NCEP precipitation analysis. The most notable model errors include the overestimation (underestimation) of the season-total and AR precipitation in the northern (southern) California region. The differences in the freezing-level altitudes during the AR- and non-AR wet days in the simulation agree with those from the ERA-Interim reanalysis. The freezing level altitudes are systematically overestimated in the simulations, suggesting warm biases in the low troposphere. Overall, WRF appears to perform reasonably in simulating the key features in the cold season precipitation related with AR landfalls, an important capability for assessing the impact of global climate variations and change on future hydrology in California. 相似文献
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Pil-Hun Chang Chun-Ho Cho Sang-Boom Ryoo 《Asia-Pacific Journal of Atmospheric Sciences》2011,47(5):497-501
Recent changes of Mixed Layer Depth (MLD) in the East/Japan Sea (EJS) is investigated by using ocean reanalysis data. There is a significant shoaling of MLD in the southern EJS for 1994-2007, showing the change rate of - 1.24 m yr?1. The present study demonstrates that the wind stress curl mostly attributes to the MLD changes. The long-term variation of wind stress curl with a positive trend in the southern EJS is generally well consistent with the MLD variation. In addition, upward displacement estimated from the wind stress curl reaches 14.6 m during 14 years, which is comparable to the shoaling of MLD (i.e., 17.4 m). Thus, the wind stress curl with positive trend would induce the increase of upward Ekman pumping which in turn lead to the shoaling of MLD. The change of temperature structure in the subsurface layer, that is shrinking and upward displacement of thermal layer from the reanalysis and observational data, also supports this conclusion. 相似文献
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Y.-H. Kim S.-B. Ryoo J.-J. Baik I.-S. Park H.-J. Koo J.-C. Nam 《Theoretical and Applied Climatology》2008,92(3-4):239-248
Summary Changes in local thermal environment associated with the restoration of an inner-city stream in Seoul, Korea, are investigated
using observational data. The stream, called the Cheonggye stream, which had been hidden and covered with cement/asphalt for
46 years, runs 5.8 km eastward through a central region of Seoul. Intensive observations were made in the stream area for
a number of summertime periods before, during, and after the stream restoration to detect the effects of the stream on local
environment and to quantify them. It is estimated that after the stream restoration the near-surface temperature averaged
over the stream area dropped by 0.4 °C, with the largest local temperature drop being 0.9 °C. However, it cannot be stated
that this 0.4 °C temperature drop is due entirely to the stream effect only, because synoptic-scale and local-scale weather
conditions during the two periods were inevitably not identical. The stream effect on air temperature is also evident in the
temperature distribution along a street traversing the stream. In the daytime after the stream restoration, the sensible heat
flux was greatly reduced and the ratio of sensible heat flux to net radiative flux dramatically decreased. These first-time
results of the restored-stream effects on urban thermal environment could contribute to the scientific basis of urban planning
which aims to make a large city comfortable to live in and nature- and environment-friendly.
Authors’ addresses: Yeon-Hee Kim, Il-Soo Park, Hae-Jung Koo, and Jae-Cheol Nam, Meteorological Research Institute, Korea Meteorological
Administration, Seoul 156-720, Korea; Sang-Boom Ryoo, Suwon Meteorological Office, Korea Meteorological Administration, Suwon
441-856, Korea; Jong-Jin Baik, School of Earth and Environmental Sciences, Seoul National University, Seoul 151-742, Korea 相似文献
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Yong-Kwon Koh Byoung-Young Choi Seong-Taek Yun Hyeon-Su Choi Bernhard Mayer Si-Won Ryoo 《Journal of Volcanology and Geothermal Research》2008
In the Jungwon area, South Korea, two contrasting types of deep thermal groundwater (around 20–33 °C) occur together in granite. Compared to shallow groundwater and surface water, thermal groundwaters have significantly lower δ18O and δD values (> 1‰ lower in δ18O) and negligible tritium content (mostly < 2 TU), suggesting a relatively high age of these waters (at least pre-thermonuclear period) and relatively long subsurface circulation. However, the hydrochemical evolution yielded two distinct water types. CO2-rich water (PCO2 = 0.1 to 2 atm) is characterized by lower pH (5.7–6.4) and higher TDS content (up to 3300 mg/L), whereas alkaline water (PCO2 = 10− 4.1–10− 4.6 atm) has higher pH (9.1–9.5) and lower TDS (< 254 mg/L). Carbon isotope data indicate that the CO2-rich water is influenced by a local supply of deep CO2 (potentially, magmatic), which enhanced dissolution of silicate minerals in surrounding rocks and resulted in elevated concentrations of Ca2+, Na+, Mg2+, K+, HCO3− and silica under lower pH conditions. In contrast, the evolution of the alkaline water was characterized by a lesser degree of water–rock (granite) interaction under the negligible inflow of CO2. The application of chemical thermometers indicates that the alkaline water represents partially equilibrated waters coming from a geothermal reservoir with a temperature of about 40 °C, while the immature characteristics of the CO2-rich water resulted from the input of CO2 in Na–HCO3 waters and subsequent rock leaching. 相似文献
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Mineralization Characteristics and Structural Controls of Hydrothermal Deposits in the Gyeongsang Basin, South Korea 总被引：1，自引：0，他引：1
Abstract. Hydrothermal deposits in the Gyeongsang Basin show the genetic relationship with igneous activity from Late Cretaceous to Early Tertiary in the spatial and temporal viewpoints. Many hydrothermal Au-Ag-Cu-Pb-Zn and clay deposits are dominantly distributed within the Gyeongsang Basin. The Gyeongsang Basin is divided into seven metallogenic provinces by spatial distribution. The age ranges of igneous activity and mineralization are 140∼40 Ma and 100∼40 Ma, respectively, and the most dominant age ranges of the both activities are from 90 Ma (Coniacian) to 50 Ma (Eocene). The age consistency between igneous activity and mineralization suggests that this age range is the climactic period of the hydrothermal activity of the Gyeongsang Basin. The metallogenic epochs in the Gyeongsang Basin are divided into three epochs of 100∼80 Ma (western part of the Gyeongsang Basin), 80∼60 Ma (central part of the Gyeongsang Basin), and 60∼40 Ma (eastern part of the Gyeongsang Basin). The mineralization and igneous activity tend to become young eastward in the Gyeongsang Basin.
NNW-SSE mineralized veins from 100 to 80 Ma in the western part of the Gyeongsang Basin are interpreted as the control of the parallel tensional fissures caused by NNW-SSE compressional stress. NW-SE mineralized veins from 80 to 60 Ma in the central part of the Gyeongsang Basin seem to have been formed under the same stress as that of the Gaeum and Yangsan Fault Systems. Namely, NW-SE tensional stress is associated with a conjugate set of fracturing of the WNW-ESE Gaeum Fault System and NNE-SSW Yangsan Fault System. Also NE-SW mineralized veins from 60 to 40 Ma in the eastern part of the Gyeongsang Basin seem to be controlled by the NE-SW fractures. The fractures are related with NE-SW compressional stress and are developed as secondary fractures within the dextral strike slip Yangsan Fault System. 相似文献
NNW-SSE mineralized veins from 100 to 80 Ma in the western part of the Gyeongsang Basin are interpreted as the control of the parallel tensional fissures caused by NNW-SSE compressional stress. NW-SE mineralized veins from 80 to 60 Ma in the central part of the Gyeongsang Basin seem to have been formed under the same stress as that of the Gaeum and Yangsan Fault Systems. Namely, NW-SE tensional stress is associated with a conjugate set of fracturing of the WNW-ESE Gaeum Fault System and NNE-SSW Yangsan Fault System. Also NE-SW mineralized veins from 60 to 40 Ma in the eastern part of the Gyeongsang Basin seem to be controlled by the NE-SW fractures. The fractures are related with NE-SW compressional stress and are developed as secondary fractures within the dextral strike slip Yangsan Fault System. 相似文献
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