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Input function and simulated distributions of tritium in the North Pacific

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Science China Earth Sciences 2010年第3期53卷 441-453页

作者： BA Qi1,2 & XU YongFu1 1 State Key Laboratory of atmospheric Boundary Layer physics and atmospheric chemistry, Institute of atmospheric physics, Chinese Academy of Sciences, Beijing 100029, China 2 Graduate University of Chinese Academy of Sciences, Beijing 100049, China State Key Laboratory of atmospheric Boundary Layer physics and atmospheric chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Graduate University of Chinese Academy of Sciences Beijing China

An ocean general circulation model (OGCM) of the North Pacific with a southern open boundary condition is used to simulate the distribution and transport of tritium in the North Pacific. First, the observed tritium in precipitation dataset of GNIP/ISOHIS is chosen, and used to develop an input function of tritium for the model domain from 1951 to 1997 in terms of the triangulation for interpolation. Then, the input function is used as an upper flux for the tritium model. The OGCM with tritium is integrated for 47 years with the initial condition of zero tritium concentrations. Compared with the observations from GEOSECS and WOCE, the model generates a meridional gradient of surface tritium concentrations and the high tritium concentrations in the subsurface layer, which is consistent with that indicated in the observations. The simulated time series of total tritium fluxes from the atmosphere to the ocean shows a spike in 1963. The total inventory of tritium in the ocean changes slowly with time after 1975. Tritium enters the higher-latitude region, and then is mainly transported by the subsurface process towards the equatorial region, which is well simulated in the model. However, the difference mainly occurs at 30°N–40°N, which can be seen also in the simulation of CFCs. This difference may partly originate from the insufficient description of physical processes in the OGCM. Nevertheless, some uncertainties exist in the development of the tritium input function, which can also influence the simulated results.

关键词： North Pacific basin-wide ocean general circulation model tritium input function tritium distributions

On the parameterization scheme of gravity wave drag effect on the mean zonal flow of mesosphere

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Chinese Science Bulletin 2003年第10期48卷 1020-1023页

作者： GAO Shouting & RAN Lingkun State Key Laboratory of Atmosphere physics and chemistry (LAPC), Institute of atmospheric physics, Chinese Academy of Sciences, Beijing 100029, China State Key Laboratory of Atmosphere physics and chemistry (LAPC) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Based on McFarlane抯 parameterization scheme of gravity wave drag, a refined gravity-wave-drag scheme is presented. Both the drag effect of the momentum flux and the dissipation effect of gravity wave breaking on the mean zonal flow are included in the refined parameterization scheme. The dissipation effect can be formulated with the gravity wave numbers and the mean quantities. The refined parameterization scheme may represent a complete drag effect of stationary gravity wave breaking on the mean zonal flow.

关键词：参数化法重力波阻纬向气流中间层大气动力学

The mechanism of the effects of the upwelling mean on the ENSO event mature phase locking

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Science China Earth Sciences 2007年第8期50卷 1266-1272页

作者： YAN BangLiang CMSR, Institute of atmospheric physics, Chinese Academy of Sciences, Beijing 100029, China CMSR Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

The mechanism of the effects of the upwelling mean on the ENSO event mature phase locking is ex-amined by using a mixed-mode model. The results show that the positive feedback process of the ef-fects of the seasonal variation of the upwelling mean on the Kelvin wave is the mechanism of the locking of the event mature phase to the end of the calendar year. The memory of the Rossby waves for the sign-shifting of the sea surface temperature anomaly from positive to negative 6 months before the cold peak time is the other mechanism of the locking of the La Nia event mature phase to the end of the calendar year. The results here are different from previous ones which suggest that the balance between cold and warm trends of sea surface temperature anomaly is the mechanism involved. The cold trend is caused by the upwelling Kelvin wave from upwelling Rossby wave reflected at the western boundary, excited by the westerly anomaly stress over the central Pacific and amplified by the seasonal variation of the coupled strength in its way propagating westward. The warm trend is caused by the Kelvin wave forced by the western wind stress over the middle and eastern equatorial Pacific. The cause of the differences is due to the opposite phase of the seasonal variation of the upwelling mean to that in the observation and an improper parameterization scheme for the effects of the seasonal varia-tion of the upwelling mean on the ENSO cycle in previous studies.

关键词： Kelvin wave Rossby wave interaction between atmosphere and sea positive feedback

Simulation of Soil Organic Carbon Dynamics in Chinese Rice Paddies from 1980 to 2000

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Pedosphere 2007年第1期17卷 1-10页

作者： ZHANG Wen YU Yong-Qiang SUN Wen-Juan HUANG Yao State Key Laboratory of atmospheric Boundary Layer physics and atmospheric chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100059 China

Changes in soil organic carbon (SOC) of rice paddies in China were simulated from 1980 to 2000 by linking a coupled bio-physical model to GIS database. The coupled model consists of two sub-models including Crop-C for simulating net primary productivity and hence residue retention and Soil-C for computing the turnover rates of SOC. The GIS database included parameters of climate, soils and agricultural activities with the resolution of 10 km×10 km. Model simulation indicated that Chinese rice paddies covering 22.6 Mha sequestrated a considerable amount of C, about 0.15±0.07 Pg C from 1980 to 2000. Annual sequestration rate increased sharply from -180±45 kg C ha-1 year-1 in 1980 to 440±170 kg C ha-1 year-1 in 1989. Thereafter, a steady sequestration rate of 460±170 kg C ha-1 year-1 occurred till 1994 and declined since then. Approximately 84% of the Chinese rice paddies sequestrated carbon, while 15% lost carbon and 1% kept balance over the 20 years. Great SOC sequestration occurred in eastern, southern and central China, while a slight decline of SOC existed in some regions of northeastern and southwestern China.

关键词：土壤稻谷 1980年有机碳

Study of ozone “weekend effect” in Shanghai

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Science China Earth Sciences 2008年第9期51卷 1354-1360页

作者： TANG WenYuan1↑, ZHAO ChunSheng1, GENG FuHai1,2, PENG Li2, ZHOU GuangQiang2, GAO Wei2, XU JianMing2 & TIE XueXi2,3 1 Department of atmospheric Science, School of physics, Peking University, Beijing 100871, China 2 atmospheric chemistry Laboratory of Shanghai Meteorological Bureau, Shanghai 200030, China 3 atmospheric chemistry Division, NCAR, Boulder CO 80301, USA Department of atmospheric Science School of Physics Peking University Beijing China atmospheric chemistry Laboratory of Shanghai Meteorological Bureau Shanghai China atmospheric chemistry Division NCAR Boulder USA

Analysis of observed ozone data in 2006 from five monitoring sites (Xujiahui, Chongming, Baoshan, Pudong, Jinshan) in Shanghai reveals that ozone (O_3) concentrations in Xujiahui are higher at week-ends than those on weekdays, despite the fact that emissions of ozone precursor substances, such as oxides of nitrogen (NOx), carbon monoxide (CO) and volatile organic compounds (VOCs) are lower at weekends than those on weekdays. The possible chemical cause of ozone "weekend effect" is that NO_2/NO ratio increases at weekends by 25.61% compared with those on weekdays. In addition, because of an average 12.13% reduction in NOx (NO + NO_2) in the early morning (05:00-09:00) at weekends compared with that on weekdays, the ozone inhibition period ends 0.5 h earlier at weekends resulting in the longer duration of ozone accumulation and the higher ozone production rate. The rate of ozone production is a function of VOCs and NOx in the atmosphere. VOCs/NOx ratio in Xujiahui is 4.55 at weekends, and 4.37 on weekdays, belonging to the "NOx-limited". The increasing VOCs/NOx ratio at weekends leads to ozone enhancement from 73 ppbv to 80 ppbv, which are consistent with ozone "weekend effect" in Xujiahui. Furthermore, combining with MICAPS cloud amount data, the fact that ozone "weekend effect" in Xujiahui weakens gradually along with the increasing of cloud amount indicates that ozone photochemical production leads to ozone "weekend effect" in Xujiahui of Shanghai.

关键词： Shanghai ozone photochemical pollution "weekend effect"

Abrupt climate change and collapse of ancient civilizations at 2200BC-2000BC

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Progress in Natural Science:Materials International 2005年第10期15卷 46-52页

作者： WANG Shaowu (Department of atmospheric Science, School of physics, Peking University, Beijing 100871, China) Department of atmospheric Science School of Physics Peking University Beijing 100871 China

Plentiful evidence of historical, archaeological and palaeoclimatic studies proved that an abrupt change from wetter to drier climate occurred over the Nile Valley,the Mesopotamia, the Indus Valley and Huanghe River Valley at 2200BC-2000BC. The abrupt change was developed based on the general lowering of temperature in the middle latitudes, and was a strong cold event since the beginning of the Megathermal (8.5-3.0 kaBP). Collapse of Nile civilization appeared at the First Intermediate Period (2181BC-2040BC). Civilization of Mesopotamia began collapse following the disintegration of Akkadian Empire. This process lasted to the foundation of Babylon Kingdom from 2200BC to 1900BC. Indus civilization abruptly fell off at 1800BC. A widespread alternation of archaeological cultures happened in China at ca. 2000BC except only in its central part. Longsheng culture was replaced by the Erlitou culture, which is now acknowledged in China as Xia Culture. Foundation of Xia Dynasty at 2070BC opened a new chapter in the development of Chinese civilization. Studies indicated that abrupt climate change may be caused by the weakening of the Thermohaline Circulation (THC).

关键词： 2200BC-2000BC abrupt climate change collapse of ancient civilization.

An improved δ-Eddington approximation

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Chinese Science Bulletin 1999年第4期44卷 304-309页

作者： QIU JinhuanInstitute of atmospheric physics , Chinese Academy of Sciences , Beijing 100029, China Institute of atmospheric physics Chinese Academy of Sciences Beijing China

Based on an accuracy analysis of two-stream approximations, an improved δ-Eddington ap-proximation is developed. The approximation has much better accuracy than all exiting two-stream ap-proximations as the optical depth is less than unity. As the surface reflectance is zero and the opticaldepth is less than unity, errors in both transmission and reflection calculated by the present approxima-tion are more one time less than those by other two-stream approximations. In the case of aerosol opti-cal depth of<1, surface reflectance of < 0.6, solar zenith angle of < 78°and aerosol imaginary indexof < 0.05, transmission and reflection errors calculated by the improved δ-Eddington approximationare generally less than 3.5% and 2.6%, respectively. The errors are over 41% and one times lessthan those by Eddington or δ-Eddington.

关键词： radiation flux fractional factor of δ-function Eddington approximation.

Sensitivity of sea ice and ocean simulations to sea ice salinity in a coupled global climate model

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Science China Earth Sciences 2010年第6期53卷 911-918页

作者： LIU JiPing State Key Laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics, Institute of atmospheric physics, Chinese Academy of Sciences, Beijing, 100029, China State Key Laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

The impacts of the spatiotemporal variations of sea ice salinity on sea ice and ocean characteristics have not been studied in detail, as the existing climate models neglect or misrepresent this process. To address this issue, this paper formulated a parameterization with more realistic sea ice salinity budget, and examined the sensitivity of sea ice and ocean simulations to the ice salinity variations and associated salt flux into the ocean using a coupled global climate model. Results show that the inclusion of such a parameterization leads to an increase and thickening of sea ice in the Eurasian Arctic and within the ice pack in the Antarctic circumpolar region, and a weakening of the North Atlantic Deep Water and a strengthening of the Antarctic Bottom Water. The atmospheric responses associated with the ice changes were also discussed.

关键词： sea ice salinity coupled global climate model Arctic and Antarctic

North Pacific sea ice cover, a predictor for the Western North Pacific typhoon frequency?

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Science China Earth Sciences 2007年第8期50卷 1251-1257页

作者： FAN Ke Institute of atmospheric physics, Chinese Academy of Sciences, Beijing 100029, China Department of atmospheric Science, Yun-nan University, Kunming 650091, China Institute of atmospheric physics Chinese Academy of Sciences Beijing China Department of atmospheric Science Yunnan University Kunming China

The relationship between the sea ice cover in the North Pacific and the typhoon frequency has been studied in this paper. It follows that the index for the sea ice cover in the North Pacific (ISA) both in December-January-February (DJF) and in March-April-May (MAM) is negatively correlated with annual typhoon number over the western North Pacific (TNWNP) during 1965―2004, with correlation coeffi-cients of -0.42 and -0.49 respectively (above 99% significant level). Large sea ice cover in the North Pacific tends to decrease TNWNP. Positive ISA (MAM) is associated with the tropical circulation and SST anomalies in the North Pacific, which may lead to unfavorable dynamic and thermal conditions for typhoon genesis over WNP from June to October (JJASO). The variability of the atmospheric circula-tion over the North Pacific, associated with the ISA anomaly in MAM is connected to the tropical at-mospheric circulation variability in MAM via the teleconnection wave train. Besides, as the tropical circulation has strong seasonal persistency from the MAM to JJASO, thus, the ISA in MAM-related variability of the tropical atmospheric circulation as well as the SST can affect the typhoon activity over the western North Pacific.

关键词： typhoon sea ice cover North Pacific teleconnection