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1.
Recovery of thermohaline circulation under CO2 stabilization and overshoot scenarios 总被引：1，自引：0，他引：1
Norikazu. Nakashiki Dong-Hoon Kim Frank O. Bryan Yoshikatsu Yoshida Daisuke Tsumune Koki Maruyama Hideyuki Kitabata 《Ocean Modelling》2006,15(3-4):200
In this study we examine the behavior of the thermohaline circulation, as simulated by the Community Climate System Model version 3 (CCSM3), for several centuries following CO2 stabilization for the SRES B1 and A1B scenarios and for an “overshoot” scenario in which CO2 levels temporarily reach the same level as in the A1B scenario before declining to an ultimate stabilization level that is identical to the B1 case. While we find no evidence for irreversible changes of the thermohaline circulation in the overshoot experiment, the interplay of the different timescales of the temperature response of the surface and interior ocean does lead to a number of differences in the long-term response of the ocean between it and the B1 stabilization scenario where the same GHG levels are approached by different paths. The stronger initial warming and its slow penetration into the deeper ocean, followed by a transient surface cooling in the overshoot scenario leads to lower static stability, deeper mixing, and a more rapid recovery of the thermohaline circulation than in the B1 stabilization scenario. While the overshoot scenario recovers surface conditions (e.g. SST, sea ice extent) very similar to the B1 scenario shortly after reaching the same GHG levels, the additional accumulation of heat in the interior ocean during the period of higher forcing causes the global mean ocean temperature and steric sea level to remain higher than in the B1 stabilization scenario for at least another several centuries. 相似文献
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Brian Sheen 《Astronomy& Geophysics》2000,41(1):1.4-1.4
Pedro Augusto and Nectaria Gizani report on an unusual way to watch a meteor storm.
Click HERE to view the article. 相似文献
Click HERE to view the article. 相似文献
4.
Chlorophyll a of total and particles retained on 30 μm mesh plankton net were both determined in surface waters along two cruise tracks
ranging from the Subtropical water to the marginal ice zone in the Pacific sector of the Southern Ocean in austral summer.
Total surface chlorophyll a in the study area was mostly less than 1 μg chl a 1−1, and showed distributions with no obvious trend associated with different waters masses of the Antarctic and the Subantarctic,
although total chlorophyll a concentrations changed greatly within each water mass. Particularly low concentrations of chlorophyll a were detected in the marginal ice zone. Chlorophyll a contained in 30 μm netplankton made up 5∼60% of total chlorophyll a: large near the marginal ice zone and becoming small with travel towards the north. High percentage shares of netplankton
chlorophyll a were confirmed even in low total chlorophyll a concentrations in summer in the Southern Ocean. A positive relation was observed between the percentage of 30 μm netplankton
and the “average total chlorophyll a”, although there was great scatter.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
Yoo-Geun Ham Jong-Seong Kug Daehyun Kim Young-Ho Kim Dong-Hoon Kim 《Climate Dynamics》2013,40(5-6):1551-1568
In this study, the phase-locking of El Nino Southern Oscillation (ENSO) in a coupled model with different physical parameter values is investigated. It is found that there is a dramatic change in ENSO phase-locking in response to a slight change in the Tokioka parameter, which is a minimum entrainment rate threshold in the cumulus parameterization. With a smaller Tokioka parameter, the model simulates ENSO peak in the boreal summer season rather than in the winter season as observed. It is revealed that the differences in climatological zonal sea surface temperature (SST) gradient and its associated mean state changes are crucial to determine the phase-locking of ENSO. In the simulations with smaller Tokioka parameter values, climatological zonal SST gradient during the boreal summer is excessively large, because the zonally-asymmetric SST change (i.e., SST increase is relatively smaller over the eastern Pacific) is maximum during the boreal summer when the eastern Pacific SST is the coolest of the year. The enhanced climatological zonal SST gradient in boreal summer reduces the convection over the eastern Pacific, which leads to a weakening of air–sea coupling strength. The minimum coupling strength during summer prevents SST anomalies from further development in the following season, which favors SST maximum during summer. In addition, enhanced zonal SST gradient and resultant thermocline shoaling over the eastern Pacific lead to excessive zonal advective feedback and thermocline feedback. Atmospheric damping is also weakened during boreal summer season. These changes due to feedback processes allow an excessive development of SST anomalies during the summer time, and lead to a summer peak of ENSO. The importance of basic state change for the ENSO phase-locking is also validated in a multi-model framework using the Coupled Model Intercomparison Project phase-3 archive. It is found that several of the climate models have the same problem in producing a summer peak of ENSO. Consistent with the simulations with different physical parameter values, these models have minimum air–sea coupling strength during the boreal summer season. Also, they have stronger climatological zonal SST gradient and shallower climatological thermocline depth over the eastern Pacific during the boreal summer season. 相似文献
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An analysis is presented of data on chlorophyll a concentrations of the total and the netplankton (>10 μm), determined either in April to June or in August to September from
48°N to 15°S along 175°E in the Pacific Ocean during 6 years by the NOPACCS (Northwest Pacific Carbon Cycle Study). Particular
attention was given to the variability of absolute concentrations of the netplankton chlorophyll a and their percentage shares of the total chlorophyll a concentration. Below 0.2 μg l−1 of surface total chlorophyll a, the netplankton chlorophyll a showed low percentage shares (such as 12.7% on average) with a large variation, but above 0.2 μg l−1 it was 35.9% on average with less variation, showing an accelerated increase at high total chlorophyll a concentrations. High netplankton chlorophyll a concentrations in surface waters were observed at high latitudes, in waters having high chlorophyll a concentrations at sub-surface depth, and in equatorial upwelling. The percentage shares of netplankton in the total chlorophyll
a in the euphotic zone were 8.5% and 25.9% above and below 0.2 μg l−1, respectively, although the data points scattered over a wide range (from 7.2% to 53.8%) depending on differences in water
masses, depths and seasons. High chlorophyll a concentrations and high percentage shares of netplankton corresponded to high ambient nitrate plus nitrite concentrations.
Integrated netplankton chlorophyll a concentrations in the euphotic zone varied from 0.7 to 19.5 mg m−2 in waters below 0.2 μg l−1 of surface total chlorophyll a, and from 2.0 to 29.5 mg m−2 above 0.2 μg l−1, and the percentage shares of netplankton for the former were 7.4% on average and 23.7% for the latter.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Shaw‐Wen Sheen 《The Professional geographer》2000,52(3):397-406
In this paper, I develop global karst chemical denudation models using chemical equilibrium equations. Theoretical karst chemical denudation rates are calculated as soil carbon dioxide concentration varies from 10?3.5 atm to 10?1.0 atm, temperature varies from 0°C to 30°C, and annual runoff varies from 500 mm to 3,000 mm. Both open and closed karst solution systems are examined. The Drake (1980) and the Brook‐Folkoff‐Box (1983) soil pCO2 equations are used to develop chemical denudation models for different carbonate rocks (limestone and dolomite), climate (tropical, temperate, and arctic/alpine terrains), and karst solution type (open and closed systems). The major conclusion is that the karst solution type, least known in the past karst studies, is an important factor in controlling chemical denudation rates. 相似文献
8.
Ocean Science Journal - Estuaries are one of the most productive regions in ecosystems and serve as important nursery and recruitment habitats for various living resources. However, information on... 相似文献
9.
Yeon-Soo Jang Daehyun Kim Young-Ho Kim Dong-Hoon Kim Masahiro Watanabe Fei-Fei Jin Jong-Seong Kug 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(2):193-199
Many recent studies have reported the presence of two types of El Niño events in observation: Cold Tongue (CT) El Niño and Warm Pool (WP) El Niño. We investigate the sensitivity of a model simulating two types of El Niño by changing a convective triggering parameter (Tokioka parameter). When deep convections are highly suppressed with a large Tokioka parameter, the model is capable of simulating distinct two-types of El Niño. However, the model has a problem in simulating two-types of El Niño distinctively when the Tokioka parameter is small, because the location of the maximum precipitation anomaly related to the CT El Niño is significantly shifted westward, leading to an atmospheric response pattern similar to that of the WP El Niño. Our results suggest that the mean precipitation over the eastern equatorial Pacific and the resultant zonal distribution in atmospheric feedback associated with ENSO can be one of the crucial factors for simulating two-types of El Niño. 相似文献
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Junichi Tsutsui Yoshikatsu Yoshida Dong-Hoon Kim Hideyuki Kitabata Keiichi Nishizawa Norikazu Nakashiki Koki Maruyama 《Climate Dynamics》2007,28(2-3):199-214
From multi-ensembles of climate simulations using the Community Climate System Model version 3, global climate changes have been investigated focusing on long-term responses to stabilized anthropogenic forcings. In addition to the standard forcing scenarios for the current international assessment, an overshoot scenario, where radiative forcings are decreased from one stabilized level to another, is also considered. The globally-averaged annual surface air temperature increases during the twenty-first century by 2.58 and 1.56°C for increased forcings under two future scenarios denoted by A1B and B1, respectively. These changes continue but at much slower rates in later centuries under forcings stabilized at year 2100. The overshoot scenario provides a different pathway to the lower B1 level by way of the greater A1B level. This scenario results in a surface climate similar to that in the B1 scenario within 100 years after the forcing reaches the B1 level. Contrasting to the surface changes, responses in the ocean are significantly delayed. It is estimated from the linear response theory that temperature changes under stabilized forcings to a final equilibrium state in the A1B (B1) scenario are factors of 0.3–0.4, 0.9, and 17 (0.3, 0.6, and 11) to changes during the twenty-first century, respectively, for three ocean layers of the surface to 100, 100–500, and 500 m to the bottom. Although responses in the lower ocean layers imply a nonlinear behavior, the ocean temperatures in the overshoot and B1 scenarios are likely to converge in their final equilibrium states. 相似文献