Diurnal variation of CO₂ concentration, Δ¹⁴C and δ¹³C in an urban forest: estimate of the anthropogenic and biogenic CO₂ contributions     

Hiroshi A. Takahashi  Eiichi Konohira  Tetsuya Hiyama  Masayo Minami  Toshio Nakamura  Naohiro Yoshida 《Tellus. Series B, Chemical and physical meteorology》2002,54(2):97-109

Diurnal variation in the atmospheric CO₂ concentration and the carbon isotopic composition (Δ¹⁴C and δ¹³C) was measured in a forest in an urban area on 9 February 1999. The carbon isotope approach used in the present study differentiated between the quantitative contributions from anthropogenic and biogenic CO₂ sources in the urban atmosphere. The anthropogenic (fossil fuel) and biogenic (soil respiration) contributions was estimated, and they ranged from 1 to 16% and from 2 to 8% of the total atmospheric CO₂. The diurnal variation of the anthropogenic CO₂ was the major cause of the total atmospheric CO₂ variation, while the biogenic CO₂ remained relatively constant throughout the day. Estimating the contribution of soil respired CO₂ provided the mean residence time of soil respired CO₂ within the forest atmosphere.  相似文献   

Vertical profiles and storage fluxes of CO₂, heat and water in a tropical rainforest at Pasoh, Peninsular Malaysia     

SHINJIRO OHKUBO  YOSHIKO KOSUGI  SATORU TAKANASHI  NAOKO MATSUO  MAKOTO TANI  ABDUL RAHIM NIK 《Tellus. Series B, Chemical and physical meteorology》2008,60(4):569-582

Ambient CO₂ concentration, air temperature and relative humidity were measured intermittently for a 3-year period from the floor to the canopy top of a tropical rainforest in Pasoh, Peninsular Malaysia. Mean diurnal CO₂ storage flux ( S _c; μmol m⁻² s⁻¹) and sensible and latent heat storage fluxes ( Q _a and Q _w; W m⁻²) ranged from −12.7 to 3.2 μmol m⁻² s⁻¹, −15 to 27 W m⁻² and −10 to 20 W m⁻², respectively. Small differences in diurnal changes were observed in S _c and Q _a between the driest and wettest periods. Compared with the ranges of mean diurnal CO₂ eddy flux (−14.7 to 4.9 μmol m⁻² s⁻¹), sensible eddy flux (−12 to 169 W m⁻²) and latent eddy flux (0 to 250 W m⁻²), the contribution of CO₂ storage flux was especially large. Comparison with summertime data from a temperate Japanese cypress forest suggested a higher contribution of S _c in the tropical rainforest, probably mainly due to the difference in nighttime friction velocity at the sites. On the other hand, differences in Q _a and Q _w were smaller than the difference in S _c, probably because of the smaller nighttime sinks/sources of heat and water vapour.  相似文献   

A recent build-up of atmospheric CO₂ over Europe. Part 1: observed signals and possible explanations     

By MICHEL RAMONET  PHILIPPE CIAIS  TUULA AALTO  CÉLINE AULAGNIER  FRÉDÉRIC CHEVALLIER  DOMENICO CIPRIANO  THOMAS J. CONWAY  LASZLO HASZPRA  VICTOR KAZAN  FRANK MEINHARDT  JEAN-DANIEL PARIS  MARTINA SCHMIDT  PETER SIMMONDS  IRÈNE XUEREF-RÉMY  JAROSLAW N. NECKI 《Tellus. Series B, Chemical and physical meteorology》2010,62(1):1-13

We analysed interannual and decadal changes in the atmospheric CO₂ concentration gradient (ΔCO₂) between Europe and the Atlantic Ocean over the period 1995–2007. Fourteen measurement stations are used, with Mace-Head being used to define background conditions. The variability of ΔCO₂ reflects fossil fuel emissions and natural sinks activity over Europe, as well as atmospheric transport variability. The mean ΔCO₂ increased by 1–2 ppm at Eastern European stations (∼30% growth), between 1990–1995 and 2000–2005. This built up of CO₂ over the continent is predominantly a winter signal. If the observed increase of ΔCO₂ is explained by changes in ecosystem fluxes, a loss of about 0.46 Pg C per year would be required during 2000–2005. Even if severe droughts have impacted Western Europe in 2003 and 2005, a sustained CO₂ loss of that magnitude is unlikely to be true. We sought alternative explanations for the observed CO₂ build-up into transport changes and into regional redistribution of fossil fuel CO₂ emissions. Boundary layer heights becoming shallower can only explain 32% of the variance of the signal. Regional changes of emissions may explain up to 27% of the build-up. More insights are given in the Aulagnier et al. companion paper.  相似文献   

Anthropogenic and biogenic winter sources of Arctic CO₂—a model study     

JENNY BRANDEFELT  KIM HOLMÉN 《Tellus. Series B, Chemical and physical meteorology》2001,53(1):10-21

Long‐range transport of anthropogenic and biogenic CO₂ to a remote site in the Arctic is studied. A limited area, off‐line, Eulerian atmospheric transport model is used, and the results are compared to the observed CO₂ concentration at the "Ny‐Alesund International Arctic Research and Monitoring Facility". Inventories of anthropogenic CO₂ emissions and estimates of biogenic CO₂ emissions are used to investigate the respective impact of these emissions on Arctic CO₂ variations during 4 winter months. A direct comparison of the modelled and observed concentrations reveals remarkably good timing in the modelled variations as compared to the observed variations for most of the time. The correlation of observed versus modelled CO₂ concentration is significant at the 95% confidence level. The biogenic and the anthropogenic CO₂ emissions are shown to have approximately equal influence on Arctic CO₂ variations during winter. Europe is found to be the dominant source of anthropogenic CO₂ at the monitoring station, while Siberia and Northern America have little influence on Arctic CO₂, during the months studied. These results contradict Engardt and Holmén whose results indicate that the lower‐Ob region in western Siberia has a large impact on Arctic CO₂.  相似文献   

Spring initiation and autumn cessation of boreal coniferous forest CO₂ exchange assessed by meteorological and biological variables     

By T. THUM  T. AALTO  T. LAURILA  M. AURELA  J. HATAKKA  A. LINDROTH  T. VESALA 《Tellus. Series B, Chemical and physical meteorology》2009,61(5):701-717

We studied the commencement and finishing of the growing season using different air temperature indices, the surface albedo, the chlorophyll fluorescence (Fv/Fm) and the carbon dioxide (CO₂) tropospheric concentration, together with eddy covariance measurements of CO₂ flux. We used CO₂ flux data from four boreal coniferous forest sites covering a wide latitudinal range, and CO₂ concentration measurements from Sammaltunturi in Pallas. The CO₂ gas exchange was taken as the primary determinant for the growing season to which other methods were compared.
Indices based on the cumulative temperature sum and the variation in daily mean temperature were successfully used for approximating the start and cessation of the growing season. The beginning of snow melt was a successful predictor of the onset of the growing season. The chlorophyll fluorescence parameter Fv/Fm and the CO₂ concentration were good indicators of both the commencement and cessation of the growing season. By a derivative estimation method for the CO₂ concentration, we were also able to capture the larger-scale spring recovery. The trends of the CO₂ concentration and temperature indices at Pallas/Sammaltunturi were studied over an 11-yr time period, and a significant tendency towards an earlier spring was observed. This tendency was not observed at the other sites.  相似文献   

Simulating effects of land use changes on carbon fluxes: past contributions to atmospheric CO₂ increases and future commitments due to losses of terrestrial sink capacity     

K. M. STRASSMANN  F. JOOS  G. FISCHER 《Tellus. Series B, Chemical and physical meteorology》2008,60(4):583-603

The impact of land use on the global carbon cycle and climate is assessed. The Bern carbon cycle-climate model was used with land use maps from HYDE3.0 for 1700 to 2000 A.D. and from post-SRES scenarios for this century. Cropland and pasture expansion each cause about half of the simulated net carbon emissions of 188 Gt C over the industrial period and 1.1 Gt C yr⁻¹ in the 1990s, implying a residual terrestrial sink of 113 Gt C and of 1.8 Gt C yr⁻¹, respectively. Direct CO₂ emissions due to land conversion as simulated in book-keeping models dominate carbon fluxes due to land use in the past. They are, however, mitigated by 25% through the feedback of increased atmospheric CO₂ stimulating uptake. CO₂ stimulated sinks are largely lost when natural lands are converted. Past land use change has eliminated potential future carbon sinks equivalent to emissions of 80–150 Gt C over this century. They represent a commitment of past land use change, which accounts for 70% of the future land use flux in the scenarios considered. Pre-industrial land use emissions are estimated to 45 Gt C at most, implying a maximum change in Holocene atmospheric CO₂ of 3 ppm. This is not compatible with the hypothesis that early anthropogenic CO₂ emissions prevented a new glacial period.  相似文献   

Feedback mechanisms and sensitivities of ocean carbon uptake under global warming   总被引：5，自引：1，他引：5  

G.&#;K. PLATTNER  F. JOOS  T. F. STOCKER  O. MARCHAL 《Tellus. Series B, Chemical and physical meteorology》2001,53(5):564-592

Global warming simulations are performed with a coupled climate model of reduced complexity to investigate global warming–marine carbon cycle feedbacks. The model is forced by emissions of CO₂ and other greenhouse agents from scenarios recently developed by the Intergovernmental Panel on Climate Change and by CO₂ stabilization profiles. The uptake of atmospheric CO₂ by the ocean is reduced between 7 to 10% by year 2100 compared to simulations without global warming. The reduction is of similar size in the Southern Ocean and in low‐latitude regions (32.5°S‐32.5°N) until 2100, whereas low‐latitude regions dominate on longer time scales. In the North Atlantic the CO₂ uptake is enhanced, unless the Atlantic thermohaline circulation completely collapses. At high latitudes, biologically mediated changes enhance ocean CO₂ uptake, whereas in low‐latitude regions the situation is reversed. Different implementations of the marine biosphere yield a range of 5 to 16% for the total reduction in oceanic CO₂ uptake until year 2100. Modeled oceanic O₂ inventories are significantly reduced in global warming simulations. This suggests that the terrestrial carbon sink deduced from atmospheric O₂/N₂ observations is potentially overestimated if the oceanic loss of O₂ to the atmosphere is not considered.  相似文献   

Vertical profiles of biospheric and fossil fuel-derived CO₂ and fossil fuel CO₂ : CO ratios from airborne measurements of Δ¹⁴C, CO₂ and CO above Colorado, USA     

By HEATHER D. GRAVEN †  BRITTON B. STEPHENS  THOMAS P. GUILDERSON  TERESA L. CAMPOS  DAVID S. SCHIMEL  J. ELLIOTT CAMPBELL  RALPH F. KEELING 《Tellus. Series B, Chemical and physical meteorology》2009,61(3):536-546

Measurements of  Δ¹⁴C  in atmospheric CO₂ are an effective method of separating CO₂ additions from fossil fuel and biospheric sources or sinks of CO₂. We illustrate this technique with vertical profiles of CO₂ and  Δ¹⁴C  analysed in whole air flask samples collected above Colorado, USA in May and July 2004. Comparison of lower tropospheric composition to cleaner air at higher altitudes (>5 km) revealed considerable additions from respiration in the morning in both urban and rural locations. Afternoon concentrations were mainly governed by fossil fuel emissions and boundary layer depth, also showing net biospheric CO₂ uptake in some cases. We estimate local industrial CO₂:CO emission ratios using in situ measurements of CO concentration. Ratios are found to vary by 100% and average 57 mole CO₂:1 mole CO, higher than expected from emissions inventories. Uncertainty in CO₂ from different sources was ±1.1 to ±4.1 ppm for addition or uptake of −4.6 to 55.8 ppm, limited by  Δ¹⁴C  measurement precision and uncertainty in background  Δ¹⁴C  and CO₂ levels.  相似文献   

Tropospheric carbon dioxide concentrations at a northern boreal site in Finland: basic variations and source areas     

T. AALTO  J. HATAKKA  I. PAATERO  J.-P. TUOVINEN  M. AURELA  T. LAURILA  K. HOLMÉN  N. TRIVETT  Y. VIISANEN 《Tellus. Series B, Chemical and physical meteorology》2002,54(2):110-126

Diurnal and annual variations of CO₂, O_3, SO₂, black carbon and condensation nuclei and their source areas were studied by utilizing air parcel trajectories and tropospheric concentration measurements at a boreal GAW site in Pallas, Finland. The average growth trend of CO₂ was about 2.5 ppm yr⁻¹ according to a 4-yr measurement period starting in October 1996. The annual cycle of CO₂ showed concentration difference of about 19 ppm between the summer minimum and winter maximum. The diurnal cycle was most pronounced during July and August. The variation between daily minimum and maximum was about 5 ppm. There was a diurnal cycle in aerosol concentrations during spring and summer. Diurnal variation in ozone concentrations was weak. According to trajectory analysis the site was equally affected by continental and marine air masses. During summer the contribution of continental air increased, although the southernmost influences decreased. During daytime in summer the source areas of CO₂ were mainly located in the northern parts of the Central Europe, while during winter the sources were more evenly distributed. Ozone showed similar source areas during summer, while during winter, unlike CO₂, high concentrations were observed in air arriving from the sea. Sulfur dioxide sources were more northern (Kola peninsula and further east) and CO₂ sources west-weighted in comparison to sources of black carbon. Source areas of black carbon were similar to source areas of aerosols during winter. Aerosol source area distributions showed signs of marine sources during spring and summer.  相似文献   

Determination of microbial versus root‐produced CO₂ in an agricultural ecosystem by means of δ¹³CO₂ measurements in soil air     

WOLFRAM SCHÜßLER  ROLF NEUBERT  INGEBORG LEVIN  NATALIE FISCHER  CHRISTIAN SONNTAG 《Tellus. Series B, Chemical and physical meteorology》2000,52(3):909-918

The amounts of microbial and root‐respired CO₂ in a maize/winter wheat agricultural system in south western Germany were investigated by measurements of the CO₂ mixing ratio and the ¹³C/¹²C ratio in soil air. CO₂ fluxes at the soil surface for the period of investigation (1993–1995) were also determined. Root respired CO₂ shows a strong correlation with the plant mass above ground surface of the respective vegetation (R²≥0.88); the maximum CO₂ release from roots was in August for the maize (2.0±0.5 mmol m⁻² h⁻¹) and in June for winter wheat (1.5±0.5 mmol m⁻² h⁻¹). Maximum CO₂ production by roots correlate well with the maximum amount of plant root matter. Integrating the CO₂ production over the whole growing season and normalizing to the dry root matter yields, the CO₂ production per gram dry organic root matter (DORM) of maize was found to be 0.14±0.03 gC (g DORM)⁻¹. At the sites investigated, root‐produced CO₂ contributed (16±4)% for maize, and (24±4)% for winter wheat, respectively, to the total annual CO₂ production in the soil (450±50 gC m⁻² for maize, 210±30 gC m⁻² for winter wheat).  相似文献   

Aircraft observation of carbon dioxide at 8–13 km altitude over the western Pacific from 1993 to 1999     

HIDEKAZU MATSUEDA  HISAYUKI YOSHIKAWA INOUE  MASAO ISHII 《Tellus. Series B, Chemical and physical meteorology》2002,54(1):1-21

Abstract The spatial and temporal variations of atmospheric CO₂ at 8–13 km from April 1993 to April 1999 were observed by measuring CO₂ mixing ratios in samples collected biweekly from a commercial airliner between Australia and Japan. The CO₂ growth rate showed a considerable interannual variation, with a maximum of about 3 ppm yr⁻¹ during late 1997. This variation is related to the El Niño/Southern Oscillation (ENSO) events. A year-to-year change related to the ENSO events was also found in the latitudinal distribution pattern of the CO₂ annual mean between 30°N and 30°S. The averaged CO₂ seasonal cycle in the Northern Hemisphere gradually decayed toward the equator, and a relatively complicated variation with a double seasonal maximum appeared in the Southern Hemisphere. A significant yearly change of the seasonal cycle pattern was observed in the Southern Hemisphere. The impact of a tropical biomass-burning injection on the upper tropospheric CO₂ was estimated on the basis of the CO data from the same airliner observation.  相似文献   

Climate effects on atmospheric carbon dioxide over the last century   总被引：1，自引：0，他引：1  

By LAUREN ELMEGREEN RAFELSKI  STEPHEN C. PIPER  RALPH F. KEELING 《Tellus. Series B, Chemical and physical meteorology》2009,61(5):718-731

The buildup of atmospheric CO₂ since 1958 is surprisingly well explained by the simple premise that 57% of the industrial emissions (fossil fuel burning and cement manufacture) has remained airborne. This premise accounts well for the rise both before and after 1980 despite a decrease in the growth rate of fossil fuel CO₂ emissions, which occurred at that time, and by itself should have caused the airborne fraction to decrease. In contrast, the buildup prior to 1958 was not simply proportional to cumulative fossil fuel emissions, and notably included a period during the 1940s when CO₂ growth stalled despite continued fossil fuel emissions. Here we show that the constancy of the airborne fraction since 1958 can be in part explained by decadal variations in global land air temperature, which caused a warming-induced release of CO₂ from the land biosphere to the atmosphere. We also show that the 1940s plateau may be related to these decadal temperature variations. Furthermore, we show that there is a close connection between the phenomenology producing CO₂ variability on multidecadal and El Niño timescales.  相似文献   

Assessment of the soil CO₂ gradient method for soil CO₂ efflux measurements: comparison of six models in the calculation of the relative gas diffusion coefficient     

By NATCHAYA PINGINTHA  MONIQUE Y. LECLERC  JOHN P. BEASLEY Jr.  GENGSHENG ZHANG  CHUCKREE SENTHONG 《Tellus. Series B, Chemical and physical meteorology》2010,62(1):47-58

This paper uses a refined soil gradient method to estimate soil CO₂ efflux. Six different models are used to determine the relative gas diffusion coefficient (ξ). A weighted harmonic averaging is used to estimate the soil CO₂ diffusion coefficient, yielding a better estimate of soil CO₂ efflux. The resulting soil CO₂ efflux results are then compared to the soil CO₂ efflux measured with a soil chamber. Depending on the choice of ξ model used, the estimated soil CO₂ efflux using the gradient method reasonably approximates the efflux obtained using the soil chamber method. In addition, the estimated soil CO₂ efflux obtained by this improved method is well described by an exponential function of soil temperature at a depth of 0.05 m with the temperature sensitivity ( Q ₁₀) of 1.81 and a linear function of soil moisture at a depth of 0.12 m, in general agreement with previous findings. These results suggest that the gradient method is a practical cost-effective means to measure soil CO₂ emissions. Results from the present study suggest that the gradient method can be used successfully to measure soil CO₂ efflux provided that proper attention is paid to the judicious use of the proper diffusion coefficient.  相似文献   

The YAK-AEROSIB transcontinental aircraft campaigns: new insights on the transport of CO₂, CO and O₃ across Siberia     

J.-D. PARIS  P. CIAIS  P. NÉDÉLEC  M. RAMONET  B. D. BELAN  M. YU. ARSHINOV  G. S. GOLITSYN  I. GRANBERG  A. STOHL  G. CAYEZ  G. ATHIER  F. BOUMARD  J.-M. COUSIN 《Tellus. Series B, Chemical and physical meteorology》2008,60(4):551-568

Two airborne campaigns were carried out to measure the tropospheric concentrations and variability of CO₂, CO and O₃ over Siberia. In order to quantify the influence of remote and regional natural and anthropogenic sources, we analysed a total of 52 vertical profiles of these species collected in April and September 2006, every ∼200 km and up to 7 km altitude. CO₂ and CO concentrations were high in April 2006 (respectively 385–390 ppm CO₂ and 160–200 ppb CO) compared to background values. CO concentrations up to 220 ppb were recorded above 3.5 km over eastern Siberia, with enhancements in 500–1000 m thick layers. The presence of CO enriched air masses resulted from a quick frontal uplift of a polluted air mass exposed to northern China anthropogenic emissions and to fire emissions in northern Mongolia. A dominant Asian origin for CO above 4 km (71.0%) contrasted with a dominant European origin below this altitude (70.9%) was deduced both from a transport model analysis, and from the contrasted ΔCO/ΔCO₂ ratio vertical distribution. In September 2006, a significant O₃ depletion (∼–30 ppb) was repeatedly observed in the boundary layer, as diagnosed from virtual potential temperature profiles and CO₂ gradients, compared to the free troposphere aloft, suggestive of a strong O₃ deposition over Siberian forests.  相似文献   

Transport of SF₆ and ¹⁴CO₂ in the atmospheric general circulation model ECHAM4     

ERIK KJELLSTRÖM  JOHANN FEICHTER  GEORG HOFFMAN 《Tellus. Series B, Chemical and physical meteorology》2000,52(1):1-18

  相似文献   

Seasonal variation of the molecular hydrogen uptake by soils inferred from continuous atmospheric observations in Heidelberg, southwest Germany   总被引：1，自引：0，他引：1  

By SAMUEL HAMMER  INGEBORG LEVIN 《Tellus. Series B, Chemical and physical meteorology》2009,61(3):556-565

The dominant sink of atmospheric molecular hydrogen (H₂) is its enzymatic destruction in soils. Quantitative estimates of the global sink strength, as derived from bottom-up process studies, are, however, still associated to large uncertainties. Here we present an alternative way to estimate atmosphere-to-soil flux densities, respectively deposition velocities of H₂, based on atmospheric H₂ and ²²²Rn observations in the boundary layer. Two and a half years of continuous measurements from a polluted site in the Rhine-Neckar area have been evaluated and night-time flux densities were calculated for situations of strong nocturnal boundary layer inversions using the Radon-Tracer Method. The influences from local anthropogenic combustion sources could be detected and successfully separated by parallel measurements of carbon monoxide. Inferred daily uptake fluxes in the Heidelberg catchment area range from 0.5 to 3 × 10⁻⁸ g H₂ m⁻² s⁻¹ with a mean value of (1.28 ± 0.31) × 10⁻⁸ g H₂ m⁻² s⁻¹. Uptake rates are about 25% larger during summer than during winter, when soil moisture is high, and diffusive transport of H₂ into the soil is inhibited. The mean deposition velocity is 3.0 ± 0.7 × 10⁻² cm s⁻¹_, which is very well in line with direct measurements on similar soil types in Europe and elsewhere.  相似文献   

雅鲁藏布大峡谷地区近地面-大气间水热交换特征分析     

张强  文军  武月月  陈亚玲  李悦绮  刘正 《高原气象》2022,(1):153-166

利用欧洲中期天气预报中心第五代再分析数据产品,归类分析了藏东南雅鲁藏布大峡谷地区水汽输送类别.选取大峡谷地区排龙站、墨脱站两个站点2019年涡动相关系统观测数据,分析不同水汽条件下雅鲁藏布大峡谷地区不同位置近地面水热交换通量的日变化特征.结果表明:高原季风期对应大峡谷地区水汽强输送期和温湿期,高原非季风期则相反.墨脱站...  相似文献   

Is the recent build-up of atmospheric CO₂ over Europe reproduced by models. Part 2: an overview with the atmospheric mesoscale transport model CHIMERE     

By C. AULAGNIER  P. RAYNER  P. CIAIS  R. VAUTARD  L. RIVIER  M. RAMONET 《Tellus. Series B, Chemical and physical meteorology》2010,62(1):14-25

In this issue, Ramonet et al. revealed a positive trend in European, atmospheric CO₂ concentrations relative to a marine, North Atlantic reference baseline, for the years 2001–2006. The observed build up mainly occurred during the cold season where it reaches a 0.8 ppm yr⁻¹ at low-altitude stations to a 0.3 ppm yr⁻¹ at mid-altitude stations. We explore the cause of this build-up using the mesoscale model CHIMERE. We first model the observed trends, using interannually varying fluxes and transport, then suppress the interannual variability in fluxes or aspects of transport to elucidate the cause. The run with no interannual variability in fluxes still matches observed trends suggesting that transport is the major cause. Separate runs varying either boundary layer height or winds show that changes in boundary layer height explain the trends at low-altitude stations within the continents while changes in wind regimes drive changes elsewhere.  相似文献   

Potential impact of climate change on marine dimethyl sulfide emissions   总被引：1，自引：0，他引：1  

LAURENT BOPP  OLIVIER AUMONT  SAUVEUR BELVISO  PATRICK MONFRAY 《Tellus. Series B, Chemical and physical meteorology》2003,55(1):11-22

Dimethyl sulfide (DMS) is a biogenic compound produced in sea-surface water and outgased to the atmosphere. Once in the atmosphere, DMS is a significant source of cloud condensation nuclei in the unpolluted marine atmosphere. It has been postulated that climate may be partly modulated by variations in DMS production through a DMS-cloud condensation nuclei-albedo feedback. We present here a modelled estimation of the response of DMS sea-water concentrations and DMS fluxes to climate change, following previous work on marine DMS modeling ( Aumont et al., 2002 ) and on the global warming impact on marine biology ( Bopp et al., 2001 ). An atmosphere–ocean general circulation model (GCM) was coupled to a marine biogeochemical scheme and used without flux correction to simulate climate response to increased greenhouse gases (a 1% increase per year in atmospheric CO₂ until it has doubled). The predicted global distribution of DMS at  1 × CO₂  compares reasonably well with observations; however, in the high latitudes, very elevated concentrations of DMS due to spring and summer blooms of Phaeocystis can not be reproduced. At  2 × CO₂  , the model estimates a small increase of global DMS flux to the atmosphere (+2%) but with large spatial heterogeneities (from −15% to +30% for the zonal mean). Mechanisms affecting DMS fluxes are changes in (1) marine biological productivity, (2) relative abundance of phytoplankton species and (3) wind intensity. The mean DMS flux perturbation we simulate represents a small negative feedback on global warming; however, the large regional changes may significantly impact regional temperature and precipitation patterns.  相似文献   

峨眉山地区近地层微气象特征研究     

常娜  李茂善  王灵芝  龚铭  伏薇  舒磊 《高原气象》2022,(1):226-240

基于2019年12月至2020年11月峨眉山站梯度塔资料、辐射观测资料和地表通量资料,采用涡动相关法对峨眉山地区近地层的地表通量和蒸散发量的变化进行分析,并估算了零平面位移、空气动力粗糙度、空气热力粗糙度、动量通量输送系数和感热通量输送系数等重要的空气动力学和热力学参数.研究表明:近地面风速呈现高层高、低层低的特征,且...  相似文献