BVOC emissions from mechanical wounding of leaves and branches of <Emphasis Type="Italic">Eucalyptus sideroxylon</Emphasis> (red ironbark)     

Leesun Kim  Ian E. Galbally  Nichola Porter  Ian A Weeks  Sarah J Lawson 《Journal of Atmospheric Chemistry》2011,68(3):265-279

Emissions of biogenic volatile organic compounds (BVOCs) from mechanical wounding of leaves and branches of plants can contribute to the atmospheric burden of volatile organic compounds (VOCs) in both (a) urban airsheds (from urban garden maintenance) and (b) the global atmosphere (from large scale forest harvesting). These emissions of BVOCs are poorly understood and quantified, and their role in urban and global emissions inventories neglected. This paper presents measurements of the magnitude, duration and composition of emissions of BVOCs, carbon dioxide (CO₂) and methane (CH₄) from freshly cut leaf mulch and wood chips derived from a common eucalypt tree, Eucalyptus sideroxylon (red ironbark), found in southeastern Australian forests and gardens. The emissions of BVOCs from freshly cut and shredded leaves and wood of E. sideroxylon were found to be 2.3 ± 0.6 and 0.05 ± 0.04 mg g^-1 DM (Dry Mass) from leaf mulch and wood chips respectively and to last typically for 1 day following cutting. Three sampling techniques were used for VOC speciation and the 12 most abundant BVOCs released from the mulch materials were identified. The specific BVOCs emitted in order of decreasing abundance from leaf mulch are: (a) stored plant oils, 1,8-cineole, α–pinene and o-cymene which make up the major part of the emissions, (b) a minor contribution from chemicals associated with environmental stress and wound defence, (Z)–3–hexenyl acetate, (E)-2-hexenal and (Z)-3-hexen-1-ol, and (c) a second minor contribution from metabolic products, acetaldehyde and acetone. The observed integrated emissions of BVOCs from leaves following mulching are equivalent to more than half and perhaps all of the likely stored plant oils in the leaves. For the two comparable studies available, one of a plant with stored oils (this study) and one of a plant without stored plant oils, the emissions of leaf wound defence BVOCs are in the same range for both plants. In the plant with stored plant oils, the plant oil emissions are about a factor of 11 larger in emission rate than the plant wound defence BVOCs. A compilation of available leaf wounding BVOC emission studies indicates that for plants with stored plant oils, plant oil emissions dominate, whereas with other plants, leaf wound defence BVOCs dominate the emissions.  相似文献   

Characteristics of adjoint sensitivity to potential vorticity     

Hyun Mee Kim  Robert J. Beare 《Meteorology and Atmospheric Physics》2011,111(3-4):91-102

Structures of adjoint sensitivities to potential vorticity for specific initial and final norm are investigated for a short-range cyclone forecast in a three-dimensional quasigeostrophic (QG) model. Moreover, adjoint sensitivities to potential vorticity are compared with nonlinear sensitivities calculated for the same cyclogenesis case in the QG model. The adjoint sensitivities using different initial and final norms (e.g., total QG disturbance energy and potential enstrophy) show approximately similar characteristics for the horizontal and vertical structures and evolutions. Consistent with previous studies, the horizontal structure of the adjoint sensitivity is smaller for the energy norm than for the potential enstrophy norm. The dynamical mechanism of cyclone development by adjoint sensitivity coincides with that of nonlinear sensitivity, with slight differences in the region of sensitivity maxima over the upstream (nascent) low for the adjoint (nonlinear) sensitivity. The adjoint sensitivities show different vertical distributions from the nonlinear sensitivities. Consistent with the sensitive regions denoted by singular vectors and error evolution in the QG model, maxima of the adjoint sensitivities are located at both the upper and lower boundaries, with prominent secondary peaks in the lower to mid-troposphere of the domain. The level of the secondary maxima changes depending on the initial and final norm used. The secondary peak is located in the lower to mid- (mid-) troposphere for the total QG disturbance energy (potential enstrophy) as the initial and final norm. Based on the correspondence in the level of the sensitivity maxima in the interior of the domain between the adjoint and nonlinear sensitivities, adjoint sensitivities may serve as an alternative to nonlinear sensitivities given the enormous computing expenses in nonlinear sensitivity calculation.  相似文献   

Possible linkage between East Asian summer drought and North Pacific Oscillation   总被引：1，自引：0，他引：1  

Ki-Seon Choi  Su-Bin Oh  Hi-Ryong Byun  R. H. Kripalani  Do-Woo Kim 《Theoretical and Applied Climatology》2011,103(1-2):81-93

The May North Pacific Oscillation Index and the summer (May and June?CJuly?CAugust??JJA) Effective Drought Index have a strong negative correlation in the East Asian region, particularly in northern China, Korea, and the southwestern regions of Japan (here termed ??Northeast Asia??); this signifies an intensification of the summer drought during positive North Pacific Index (NPI) phase in this region, and the presence of such a phenomenon has been observed in this study. The low-south/high-north anomalous pressure pattern forming in all layers of the troposphere in Northeast Asian region has been a cause of drought. This unusual pressure pattern gives rise to a cold northeasterly and intensifies downward flow and reduces relative humidity. In addition, this cold northeasterly hinders the northward movement of the western North Pacific high and reduces the frequency of tropical cyclones passing through this region, thereby further intensifying drought.  相似文献   

Impact of vegetation feedback on the temperature and its diurnal range over the Northern Hemisphere during summer in a 2 × CO2 climate     

Su-Jong Jeong  Chang-Hoi Ho  Tae-Won Park  Jinwon Kim  Samuel Levis 《Climate Dynamics》2011,37(3-4):821-833

This study examines the potential impact of vegetation feedback on the changes in the diurnal temperature range (DTR) due to the doubling of atmospheric CO₂ concentrations during summer over the Northern Hemisphere using a global climate model equipped with a dynamic vegetation model. Results show that CO₂ doubling induces significant increases in the daily mean temperature and decreases in DTR regardless of the presence of the vegetation feedback effect. In the presence of vegetation feedback, increase in vegetation productivity related to warm and humid climate lead to (1) an increase in vegetation greenness in the mid-latitude and (2) a greening and the expansion of grasslands and boreal forests into the tundra region in the high latitudes. The greening via vegetation feedback induces contrasting effects on the temperature fields between the mid- and high-latitude regions. In the mid-latitudes, the greening further limits the increase in T _max more than T _min, resulting in further decreases in DTR because the greening amplifies evapotranspiration and thus cools daytime temperature. The greening in high-latitudes, however, it reinforces the warming by increasing T _max more than T _min to result in a further increase in DTR from the values obtained without vegetation feedback. This effect on T _max and DTR in the high latitude is mainly attributed to the reduction in surface albedo and the subsequent increase in the absorbed insolation. Present study indicates that vegetation feedback can alter the response of the temperature field to increases in CO₂ mainly by affecting the T _max and that its effect varies with the regional climate characteristics as a function of latitudes.  相似文献   

Spring Arctic Oscillation-East Asian summer monsoon connection through circulation changes over the western North Pacific   总被引：5，自引：0，他引：5  

Dao-Yi Gong  Jing Yang  Seong-Joong Kim  Yongqi Gao  Dong Guo  Tianjun Zhou  Miao Hu 《Climate Dynamics》2011,37(11-12):2199-2216

In the present study the links between spring Arctic Oscillation (AO) and East Asian summer monsoon (EASM) was investigated with focus on the importance of the North Pacific atmospheric circulation and sea surface temperature (SST). To reduce the statistical uncertainty, we analyzed high-pass filtered data with the inter-annual time scales, and excluded the El Ni?o/Southern Oscillation signals in the climate fields using a linear fitting method. The significant relationship between spring AO and EASM are supported by the changes of multi-monsoon components, including monsoon indices, precipitation, and three-dimensional atmospheric circulations. Following a stronger positive spring AO, an anomalous cyclonic circulation at 850?hPa appears in southeastern Asia and the western North Pacific in summer, with the easterly anomalies spanning from the Pacific to Asian continent along 25°N?C30°N and the westerly anomalies south of 15°N. At the same time, the summer western North Pacific subtropical high becomes weaker. Consistently, the positive precipitation anomalies are developed over a broad region south of 30°N stretching from southern China to the western Pacific and the negative precipitation anomalies appear in the lower valley of the Yangtze River and southern Japan. The anomalous cyclone in the western North Pacific persisting from spring to summer plays a key role in modulating EASM and monsoon precipitation by a positive air-sea feedback mechanism. During spring the AO-associated atmospheric circulation change produces warmer SSTs between 150°E?C180° near the equator. The anomalous sensible and latent heating, in turn, intensifies the cyclone through a Gill-type response of the atmosphere. Through this positive feedback, the tropical atmosphere and SST patterns sustain their strength from spring to summer, that consequently modifies the monsoon trough and the western North Pacific subtropical high and eventually the EASM precipitation. Moreover, the SST response to AO-circulation is supported by the numerical simulations of an ocean model, and the anomalous atmospheric circulation over the western North Pacific is also reproduced by the dedicated numerical simulations using the coupled atmosphere?Cocean model. The observation evidence and numerical simulations suggest the spring AO can impact the EASM via triggering tropical air-sea feedback over the western North Pacific.  相似文献   

Diagnostic metrics for evaluation of annual and diurnal cycles   总被引：1，自引：0，他引：1  

Bin Wang  Hyung-Jin Kim  Kazuyoshi Kikuchi  Akio Kitoh 《Climate Dynamics》2011,37(5-6):941-955

Two sets of diagnostic metrics are proposed for evaluation of global models?? simulation of annual and diurnal cycles of precipitation. The metrics for the annual variation include the annual mean, the solstice and equinoctial asymmetric modes of the annual cycle (AC), and the global monsoon precipitation domain and intensity. The metrics for the diurnal variation include the diurnal range, the land?Csea contrast and transition modes of the diurnal cycle (DC), and the diurnal peak propagation in coastal regions. The proposed modes for the AC and DC represent faithfully the first two leading empirical orthogonal functions and explain, respectively, 82% of the total annual variance and 87% of the total diurnal variance over the globe between 45°S and 45°N. The simulated AC and DC by the 20-km-mesh MRI/JMA atmospheric general circulation model (AGCM) are in a wide-ranging agreement with observations; the model considerably outperforms any individual AMIP II GCMs and has comparable performance to 12-AMIP II model ensemble simulation measured by Pearson??s pattern correlation coefficient. Comparison of four versions of the MRI/JMA AGCM with increasing resolution (180, 120, 60, and 20?km) reveals that the 20-km version reproduces the most realistic annual and diurnal cycles. However, the improved performance is not a linear function of the resolution. Marked improvement of the simulated DC (AC) occurs at the resolution of 60?km (20?km). The results suggest that better represented parameterizations that are adequately tuned to increased resolutions may improve models?? simulation on the forced responses. The common deficiency in representing the monsoon domains suggests the models having difficulty in replicating annual march of the Subtropical Highs that is largely driven by prominent east-west land?Cocean thermal contrast. Note that the 20-km model reproduces realistic diurnal cycle, but fails to capture realistic Madden-Julian Oscillation.  相似文献   

Representation of tropical storms in the northwestern pacific by the Modern-Era Retrospective analysis for research and applications     

Myong-In Lee  Siegfried D. Schubert  Dongmin Kim 《Asia-Pacific Journal of Atmospheric Sciences》2011,47(3):245-253

This study examines the tropical storms simulated in the Modern-Era Retrospective analysis for Research and Applications (MERRA) global atmospheric reanalysis for the recent 12 years (1998–2009), focusing on the tropical storm activity over the Northwestern Pacific. For validation, the International Best Track Archive for Climate Stewardship (IBTrACS) dataset is used as an observational counterpart. Climatological-mean features of the tropical storm genesis, tracks and their maximum intensity are the primary interests in this study. Regarding the genesis location of tropical storms, MERRA is reasonable in resolving major development regions over the South China Sea and the Northwestern Pacific close to the Philippines. The seasonal variation of the number of storms is also reproduced in a realistic way in MERRA, with peak values occurring from July to September. In addition, MERRA tends to reproduce the observed interannual variation of the number of tropical storms during the 12-years, though with a limited accuracy. The simulated paths toward higher latitudes are also reasonable in MERRA, where the reanalysis corresponds well with the observations in resolving frequent paths of westward moving storms and recurving storms toward the northeast. Regarding the intensity, MERRA captures the linear relationship between the minimum center pressure and the maximum wind speed near the surface at the maximum development. Some discrepancies from the observed features are found in the reanalysis, such as less frequent development of storms over the South China Sea and less frequent paths over this region. The reanalysis also does not attain the observed maximum intensity for the resolved tropical storms, particularly underestimating the center pressure. These deficiencies are likely related to limitations in the horizontal resolution and the parameterized physics of the data assimilation system.  相似文献   

Long-term simulations of the sulfur concentrations over the China, Japan and Korea: A model comparison study     

Cheol-Hee Kim  Lim-Seok Chang  Jeong-Soo Kim  Fan Meng  Mizuo Kajino  Hiromasa Ueda  Yuanhang Zhang  Hye-Young Son  Youjiang He  Jun Xu  Keiichi Sato  Chang-Keun Song  Soo-Jin Ban  Tatsuya Sakurai  Zhiwei Han  Lei Duan  Suk-Jo Lee  Shang-Gyoo Shim  Young Sunwoo  Tae-Young Lee 《Asia-Pacific Journal of Atmospheric Sciences》2011,47(4):399-411

Three comprehensive acid deposition models were used to simulate the sulfur concentrations over northeast Asia over the period covering entire year of 2002, and discussed the aggregated uncertainties and discrepancies of the three models. The participating models are from the countries participating in the project of Longrange Transboundary Air Pollutants in Northeast Asia (LTP): China, Japan and Korea. The Eulerian Model-3/CMAQ (by China), Regional Air Quality Model (RAQM, by Japan), and Comprehensive Acid Deposition Model (CADM, by Korea) were employed by each country with common emissions data established by the administrative agencies of China, Japan and Korea. The episodic simulation results between 1 to 15, March 2002 are also presented, during which aircraft measurements were carried out over the Yellow sea. The episodic results show both a wide short-term variability in simulations against measurements, and maximum concentration differences of 3～5 times among the three models, requiring that further attention before confidence among the three models can be claimed for short-term simulations. However, the year-long cumulative simulations showed almost the same general features, with lower aggregated uncertainties between the three models, produced by the long term integration over northeast Asia.  相似文献   

An algorithm for fast 3D inversion of surface electrical resistivity tomography data: application on imaging buried antiquities     

N.G. Papadopoulos  P. Tsourlos  C. Papazachos  G.N. Tsokas  A. Sarris  J.H. Kim 《Geophysical Prospecting》2011,59(3):557-575

In this work a new algorithm for the fast and efficient 3D inversion of conventional 2D surface electrical resistivity tomography lines is presented. The proposed approach lies on the assumption that for every surface measurement there is a large number of 3D parameters with very small absolute Jacobian matrix values, which can be excluded in advance from the Jacobian matrix calculation, as they do not contribute significant information in the inversion procedure. A sensitivity analysis for both homogeneous and inhomogeneous earth models showed that each measurement has a specific region of influence, which can be limited to parameters in a critical rectangular prism volume. Application of the proposed algorithm accelerated almost three times the Jacobian (sensitivity) matrix calculation for the data sets tested in this work. Moreover, application of the least squares regression iterative inversion technique, resulted in a new 3D resistivity inversion algorithm more than 2.7 times faster and with computer memory requirements less than half compared to the original algorithm. The efficiency and accuracy of the algorithm was verified using synthetic models representing typical archaeological structures, as well as field data collected from two archaeological sites in Greece, employing different electrode configurations. The applicability of the presented approach is demonstrated for archaeological investigations and the basic idea of the proposed algorithm can be easily extended for the inversion of other geophysical data.  相似文献   

Comment on ‘Causes,consequences and chronology of large‐magnitude palaeoflows in Middle and Late Pleistocene river systems of northwest Europe’ by Westaway and Bridgland (2010)     

Freek S. Busschers  Kim M. Cohen  Jef Vandenberghe  Ronald T. Van Balen  Cornelis Kasse  Jakob Wallinga  Henk J. T. Weerts 《地球表面变化过程与地形》2011,36(13):1836-1840

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