• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    The Variability of Air-sea O2 Flux in CMIP6: Implications for Estimating Terrestrial and Oceanic Carbon Sinks※

    2022-07-13 06:20:32ChangyuLIJianpingHUANGLeiDINGYuRENLinliANXiaoyueLIUandJipingHUANG
    Advances in Atmospheric Sciences 2022年8期

    Changyu LI , Jianping HUANG , Lei DING , Yu REN , Linli AN , Xiaoyue LIU , and Jiping HUANG

    1College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China

    2Collaborative Innovation Center for Western Ecological Safety, Lanzhou University, Lanzhou 730000, China

    3Enlightening Bioscience Research Center, Mississauga, L4X 2X7, Canada

    ABSTRACT The measurement of atmospheric O2 concentrations and related oxygen budget have been used to estimate terrestrial and oceanic carbon uptake. However, a discrepancy remains in assessments of O2 exchange between ocean and atmosphere(i.e. air-sea O2 flux), which is one of the major contributors to uncertainties in the O2-based estimations of the carbon uptake. Here, we explore the variability of air-sea O2 flux with the use of outputs from Coupled Model Intercomparison Project phase 6 (CMIP6). The simulated air-sea O2 flux exhibits an obvious warming-induced upward trend (~1.49 Tmol yr-2)since the mid-1980s, accompanied by a strong decadal variability dominated by oceanic climate modes. We subsequently revise the O2-based carbon uptakes in response to this changing air-sea O2 flux. Our results show that, for the 1990-2000 period, the averaged net ocean and land sinks are 2.10±0.43 and 1.14±0.52 GtC yr-1 respectively, overall consistent with estimates derived by the Global Carbon Project (GCP). An enhanced carbon uptake is found in both land and ocean after year 2000, reflecting the modification of carbon cycle under human activities. Results derived from CMIP5 simulations also investigated in the study allow for comparisons from which we can see the vital importance of oxygen dataset on carbon uptake estimations.

    Key words: air-sea O2 flux,carbon budget,land and ocean carbon sinks,CMIP6

    1.Introduction

    Human beings are now faced with continuous growth of the climate risk in the warming world. The climate change, occurring mainly as a consequence of anthropogenic CO2emissions, is already wielding its influences on ecosystems, economic sectors and people's health (Bopp et al.,2013; Huang et al., 2016; Fr?licher et al., 2018; Wei et al.,2021). An increasing number of evidence warns us that actions should be taken urgently to minimize dangerous anthropogenic interference with the climate system, limiting global warming to 2 degrees - a threshold laid down by the Paris Agreement (Seneviratne et al., 2016; Huang et al.,2017b). Under this circumstance, the carbon neutrality,which refers to the balance of emissions of carbon dioxide with its removal, has become one of the most essential things human society needs to achieve in the mid-late 21st century (Dhanda and Hartman, 2011; Niu et al., 2021).

    The land and ocean play an important role in the storage of atmospheric CO2(Dai et al., 2013; DeVries et al., 2019).It has been reported that the land and ocean have sequestered approximately half of the anthropogenic CO2emitted to the atmosphere in the past decades, which helps greatly buffer climate change (Friedlingstein et al., 2019;Gao et al., 2019, 2020). Thus, for a reasonable design of global warming mitigation and carbon neutrality strategies,there is a pressing need to address the effectiveness of terrestrial and oceanic carbon uptake and their susceptibility to climate change. According to this view, the measurement of atmospheric O2concentrations and related oxygen budget could provide us a concise and effective method to estimate carbon-uptake capacity of land and ocean on the basis of the close relationship between oxygen and carbon (Huang et al.,2018, 2021; Han et al., 2021; Li et al., 2021).

    The accuracy of this O2-based carbon uptake estimation largely depends on how the oxygen data, especially the airsea O2exchange, is processed in the calculation. Early studies used to assume that there was no long-term oceanic effect of O2on the atmosphere (Keeling and Shertz, 1992; Battle et al., 2000). However, a number of indications have revealed the huge oceanic heat uptake under climate change(Willis et al., 2004; Cheng et al., 2018; Cheng and Zhu,2018; Li et al., 2019), which implies the air-sea O2exchange could vary as a consequence of warming-induced solubility and circulation changes (Bopp et al., 2002; Li et al., 2020). Later studies have thus taken air-sea O2flux into consideration (Manning and Keeling, 2006; Tohjima et al.,2019), where the oceanic O2outgassing to the atmosphere is approximately estimated by a linear regression with ocean heat content, assuming the relationship between gas flux and heat flux bears a proportional relationship at the air-sea interface. In fact, mechanisms that control the variability of air-sea O2flux are rather complicated. Its temporal and spatial variations could be affected by changes in ocean primary production, ventilation and stratification, as well as oceanic internal modes such as El Ni?o-Southern Oscillation(ENSO) (Resplandy et al., 2015; Yang et al., 2017). The intensified ocean heat uptake in the past few decades (Trenberth et al.,2014; Cheng et al., 2017) also wields its influences in the long-term period. How to accurately quantify the air-sea O2flux has therefore been one of the most important questions in the field of O2-based carbon uptake estimations.

    Here, based on recent CMIP6 model simulations, we systematically investigate the characteristics of air-sea O2flux and from it, we subsequently calculate the terrestrial and oceanic carbon sinks. We hope to provide a better understanding of air-sea O2flux under ongoing climate change. We also hope the applications of process-based air-sea O2flux from CMIP6 model simulations can provide a more comprehensive and reliable carbon sink estimation, compared with results from previous studies where the air-sea O2flux is not considered or simply approximated by a linear relationship between O2outgassing and heat content.

    The paper is arranged as follows. Section 2 describes the detailed method of O2-based carbon sink estimations and the datasets, especially air-sea O2flux, used in this study. The climatology characteristics of air-sea O2flux and its variability under climate change in CMIP6 are shown in section 3.1. Section 3.2 provides our estimations of terrestrial and oceanic carbon sinks with the use of this air-sea O2flux.Discussion and conclusion are presented in section 4.

    2.Data and methods

    2.1.O2-based estimations of terrestrial and oceanic carbon sinks

    2.1.1.Mass balanced equations for global oxygen and carbon budgets

    The assessments of land and ocean carbon sinks in this study are based on the strong relationship between oxygen and carbon, which can be written as follows (Keeling and Manning, 2014; Li et al., 2021):

    where ΔCO2and ΔO2represent changes in atmospheric CO2and O2; Ffossilis the industrial CO2emissions, which mainly comes from fossil fuel combustion; Fair-searepresents the air-sea O2flux;αFandαBare dimensionless parameters which represent the globally averaged O2: CO2mole exchange ratios for fossil fuel burning and biological process; Slandand Soceanrepresent the net land carbon sink and ocean carbon sink, respectively. These two equations briefly describe the human impacts on the oxygen and carbon cycles. All variables in the equations mentioned above use the units of mole.

    2.1.2.Observed atmospheric CO2and O2concentrations

    The concentrations of CO2in the atmosphere () are meas ured using the unit of “ppm” (parts per million). Its change can be expressed as

    where Mairrepresents the global total number of moles of dry air (Mair=1.769×1020). The change of atmospheric O2concentrations, however, is typically measured as the mole ratio changes of O2/N2rather than the mole fraction such as ppm, due to its high abundance in the atmosphere. Following Keeling and Shertz (1992), the O2content of an air sample can be defined as

    where (O2/N2)sampleis the mole ratio of O2to N2in the sample air and (O2/N2)refis the ratio in an arbitrary reference gas.Note thatδ(O2/N2) is typically multiplied by 106and expressed as “per meg” unit. The observed changes ofδ(O2/N2) in the atmosphere could thus be written as

    where ΔO2and ΔN2are changes in moles of atmospheric O2and N2;andare the standard mole fraction of O2and N2in the atmosphere (= 0.2094 and= 0.7808).

    According to Eqs. (1)-(5), the land and ocean carbon sink can be written as

    The observed timeseries of atmospheric CO2and O2concentrations [i.e.andδ(O2/N2)] can be downloaded from Scripps O2Program (https://scrippso2.ucsd.edu/),which provides records of both CO2and O2concentrations at 12 stations. In this study, we choose the longest three timeseries, at Alert (82.5°N, 62.3°W), La Jolla (32.9°N, 277.3°W), and Cape Grim (40.7°S, 144.7°E), respectively, and calculate the average with weights of 0.25, 0.25, 0.5 (given the equal weight in both hemispheres).

    2.1.3.Global fossil-fuel combustion and the oxidative ratio

    The global CO2emissions (Ffossil) are derived from Carbon Dioxide Information Analysis Center (CDIAC, Andres et al., 2016), which counts the consumptions of each type of fossil fuel. It should be noted that each fuel type has its own combustion ratio (αF), as shown in Table 1 (Liu et al., 2020).The global averaged αFtherefore slightly varies with time due to changes of global energy sources [Fig. S1 in the Electronic Supplementary Material, (ESM)]. The oxidative ratioαBalso exhibits temporal variations due to modifications to global vegetation cover by human activities, however, it is generally believed the decrease of αBis less than 0.01 over 100 years (Randerson et al., 2006). We thus set the typical value ofαBas 1.10 according to previous studies (Keeling and Manning, 2014; Battle et al., 2019).

    2.2.The air-sea O2 flux

    Due to the importance of O2flux (Fair-sea) in estimating the carbon uptake, here we discuss it in greater detail. The air-sea O2flux evaluated in this study builds on the processbased ocean physical and biochemical models developed as part of Coupled Model Intercomparison Project phase 6(CMIP6), which can be downloaded from https://esgf-node.llnl.gov/search/cmip6/. The detailed descriptions of these models are presented in Table 2. Here we choose the historical experiments of these models to match the timeseries of O2observations. Note that the air-sea O2flux is calculated by the model in mol m-2s-1, so we convert to mol of oxygen per year (mol m-2yr-1). For sake of comparisons and analysis, all the model results are gridded to 1°×1° resolution.

    Furthermore, it should be noted that, due to import of N2in the atmospheric O2observations, oceanic N2outgassing must be considered in the calculations. The total effect of the ocean on carbon sinks could thus be expressed as Eq.(8). Here we apply the tuning parameterβ=0.88 to represent the negative effect of N2outgassing (Keeling and Manning,2014); it can be shown that the equation can be written as

    The related ocean physics variables such as sea temperature, salinity, and mixed layer depth in CMIP6 are also used in this study to analyze mechanisms of O2flux change.

    2.3.The EEMD method

    We use the ensemble empirical mode decomposition(EEMD) method to separate the human-induced long-term signals from natural decadal variability in the time series of airsea O2flux. This noise-assisted method can separates scales naturally without any prior subjective criterion (Ji et al.,2014; Huang et al., 2017a). EEMD performs operations that partition a series into different “modes” (Intrinsic Mode Functions, IMFs), which are expressed by the following equation:

    Table 1. Typical oxidative ratio for each fuel type.

    Table 2. The CMIP6 models used in this study to obtain the air-sea O2 fluxa.

    where IMFi(t) is the ith IMF, and rn(t) is the residual of data X(t). The detailed descriptions of the steps on how to execute EEMD method can be found in Text S1 in the ESM. In this study, the noise added to the data has an amplitude that is 0.2 times the standard deviation of the raw data, and the ensemble number is 400. The number of IMFs is 6. A python version of EEMD is available at https://www.github.com/laszukdawid/PyEMD (Laszuk, 2017).

    3.Results

    3.1.The characteristics of air-sea O2 exchange in CMIP6

    3.1.1.Climatological status of air-sea O2flux in 1985-2014 and evaluation against available studies

    The transfer of gases across the air-sea interface is controlled by several physical, biological and chemical processes in the atmosphere and ocean, which could influence not only the partial pressure differences but also the efficiency of transfer processes (Wanninkhof, 1992; Liang et al., 2013).The air-sea O2flux thus varies considerably among the ocean regions. Figure 1a presents the model-ensemble-mean of annual air-sea O2flux averaged from 1985 to 2014 in CMIP6 historical experiments (positive means a flux to the atmosphere). Spatial distributions of O2flux in each individual model can be found in Fig. S2 in the ESM. The results show an overall net O2outgassing from ocean to the atmosphere at low latitudes, while a significant influx of O2occurs at high latitudes. The tropical and subtropical ocean(30°S-30°N) emits approximately 250.8±38.4 Tmol O2per year (1 Tmol = 1012mol), which is partly compensated by O2absorption in the high-latitude ocean, about -105.2±24.8 and -87.2±41.4 Tmol yr-1in the Northern (>30°N) and Southern Hemisphere (>30°S), respectively, eventually leading to a net O2outgassing of ~58.5±9.6 Tmol yr-1over the global ocean. This pattern highlights the solubility effect driven by meridional temperature gradients, as well as combinations of the dynamical and biological effects, which lead to a surplus of oceanic O2production in low latitudes (Bopp et al.,2002).

    Furthermore, the simulated O2flux is evaluated against results derived from previous studies (Gruber et al., 2001;Resplandy et al., 2015), which are found in Fig. 1b . The ocean is divided into 13 regions for sake of comparison (Fig.S3 in the ESM). The patterns presented by the ensemblemean of the suite of models in CMIP6 correspond well with estimations based on ocean inversions (Gruber et al., 2001),except for the Sothern Ocean. The results derived from Gruber et al. (2001) exhibit a much stronger O2outgassing in the subpolar South Atlantic [95.0 Tmol yr-1differences between this study and Gruber et al. (2001)]. However, this difference could roughly cancel out when we integrate the whole Southern Ocean regions, as it also exists a larger O2influx in subpolar Indian-Pacific Ocean and Oceans >58°S (differences of-58.1 and -26.2 Tmol yr-1, respectively). Besides, the spatial distribution shows a remarkable consistency with preindustrial experiments presented by Resplandy et al. (2015), indicating the robust of models in simulating O2flux.

    3.1.2.Modifications of air-sea O2flux under global warming

    Temporal evolution of the air-sea O2flux reveals that significant modifications have been occurring in response to ongoing climate change (Fig. 2). In Fig. 2a, we can see sizable oscillations of air-sea O2flux during the period 1950-85.Also obvious is the increase of oceanic O2outgassing found since the mid-1980s, with an upward trend of ~1.49 Tmol yr-2(significant at 0.01 level). Based on EEMD method,here we split the evolution of air-sea O2flux into decadal variability (i.e. sum of IMFs 2-5 from EEMD) and the longterm trend (i.e. IMF 6). As shown in Fig. 2b, the time series of air-sea O2flux from 1950 to 1985 is primarily dominated by natural decadal variability, while the human-induced long-term changes gradually wields its influence after 1985.The combination of the two terms eventually lead to an overall upward trend since the 1980s, with natural variability modulating the long-term trend.

    The EOF analysis was applied to the de-trended global air-sea O2flux over the 1985-2014 period to explore the spatio-temporal distributions of decadal variability (Fig. 3).The first two modes explain approximately 58% of the total variance. The highest decadal variability of O2flux is found in the North Pacific, the North Atlantic and the Southern Ocean (Figs. 3a, 3b). The most significant changes in the Atlantic are mainly in the high-latitude areas where the sinking branch of the Atlantic Meridional Overturning Circulation(AMOC) is located, the changes of which could significantly influence climate (Yang et al., 2016; Wen et al., 2018; Yang and Wen, 2020). In the Southern Ocean, the spatial pattern exhibits opposite phase between 40°S and 65°S, suggesting the potential relationship with the Southern Annular Mode(SAM). Time series associated with EOF modes reveal a cycle of ~15 years with different phases in PC1 and PC2(Fig. 3c). The standard deviation of the decadal variability derived from EEMD also shows a similar spatial distribution compared with the EOF analysis (Fig. S4 in the ESM).

    The long-term changes of air-sea O2flux, which are generally considered as modifications to anthropogenic forcing,is presented in Fig. 4. Positive values are mainly found in the high latitude areas (Fig. 4a), where strong O2uptake in the climatological state is seen (Fig. 1a), revealing the weakening of the oceanic O2absorption capacity from the atmosphere. The maximum increase of the flux occurs in the Southern Ocean (SO>58°S), where it reaches 5.39±0.34 Tmol yr-1. The next two highest increases occur in the North Pacific (Temp NPac) and North Atlantic (N NAtl), with an increase about 4.39±0.17 and 3.25±0.11 Tmol yr-1, respectively (Fig. 4b). This long-term change could be attributed to human-induced solubility and circulation changes. The solubility of dissolved O2has been decreasing in the warming ocean. This effect could be written as:

    Fig. 1 The spatial distributions of annual mean air-sea O2 flux (a) averaged from 1985 to 2014 in CMIP6 historical simulations, and (b) compared with two other studies. Positive flux in Fig. 1a means O2 outgassing from ocean to the atmosphere.For sake of comparisons, the ocean is partitioned into 13 regions as shown in Fig. S3 in the ESM. The results from Li et al (2020) are similar with Resplandy et al 2015,which are not shown here.

    where Q is the total sea-surface downward heat flux; Cprepresents the heat capacity of sea water; ?O2/?T is the temperature dependence of O2solubility which could be derived from Garcia and Gordon (1992). Our calculations reveal that roughly one quarter of the increase is directly associated with reduced solubility in the warming ocean, which is consistent with results found by Li et al. (2020) and Plattner et al. (2002). Warming-induced ocean stratification also plays an important role in the modifications of air-sea O2flux. Strong shoaling of the mixed layer is found in the North Atlantic and widespread areas in the Southern Ocean(Fig. S5 in the ESM), which prevents oxygen supplies from reaching the deeper layers and eventually result in a positive contribution to the air-sea O2flux.

    3.1.3.Comparisons with CMIP5: What’s new about the air-sea O2flux we can learn in CMIP6

    In Li et al. (2020), the air-sea O2flux derived from CMIP5 is applied to investigate the terrestrial and oceanic carbon sinks. It is therefore necessary to clarify the difference of the flux between the CMIP5 and CMIP6 as well as its influences on carbon sink estimations.

    Fig. 2 Time series in the historical period (1950-2014) of (a) air-sea O2 flux and (b)its EEMD decomposition. The red dashed line in (a) represents linear regression from 1980 to 2014, significant at the 0.01 level. Shaded area is the uncertainty of the flux represented by the standard deviation of these models. The decadal variability in (b)(the blue solid line) is the sum of IMF2-5 from the EEMD and the long-term trend(the red solid line) is the IMF6. Positive values in both panels indicate oceanic O2 outgassing to the atmosphere.

    For a simulated historical period from 1975 to 2005,the comparisons between CMIP6 (this study) and CMIP5[derived from Li et al. (2021)] reveal pronounced temporally varying differences of air-sea O2flux (Fig. 5). Except for a short period of time around year 1990, the ocean in CMIP6 exhibits an overall smaller oceanic O2outgassing, up to -22 Tmol yr-1, than in CMIP5. Spatial patterns shown in Fig. 5b reveal that this difference is mainly caused by the intensified high-latitude oceanic O2uptake in CMIP6, especially in the North Atlantic and Southern Ocean. Although there still exists relatively large uncertainties, this intensified uptake in CMIP6 is more consistent with the regional observations in the Southern Ocean (Bushinsky et al., 2017), reflecting the improvement of simulations in CMIP6. Furthermore,slight difference also exists in the long-term trend of air-sea O2flux. An upward linear trend of ~1.52 Tmol yr-2has been found in CMIP6 during the period 1985 to 2005, while the trend is approximately 1.12 Tmol yr-2in CMIP5. This indicates an accelerated oceanic O2outgassing in CMIP6,which is tightly associated with ocean deoxygenation (Bopp et al., 2013; Palter and Trossman, 2018; Li et al., 2020).

    According to Eqs. (6)-(8), this difference in O2flux could lead to a total fluctuation as large as 0.4 GtC yr-1in the estimated carbon sink. It should be noted that, besides the air-sea O2flux, the estimated carbon sink could also be influenced by the choice of other oxygen datasets in the study, which is therefore rather complicated. Comparisons of O2-based carbon sinks between this study and Li et al.(2021), as well as other previous studies, will be discussed in detail in the following section.

    3.2.Estimates of terrestrial and oceanic carbon sinks

    3.2.1.O2-CO2diagram from 1990 to 2014

    Simulations of the air-sea O2flux in CMIP6 provide a valuable complement for the O2-based carbon uptake estimations. With the use of air-sea O2flux as well as other O2-related variables, the global terrestrial and oceanic carbon sinks could be calculated based on Eqs. (1)-(9). The processes are briefly diagrammed in Fig. 6.

    Fig. 3 EOF analysis of de-trended global air-sea O2 flux over the 1985-2014 period.The spatial patterns of the first and second EOF mode are presented in panel (a) and(b), respectively. The black and blue lines in (a) represent the temporal coefficient of the two modes. Note that the original timeseries is pre-processed with a pentad running average to remove the influence of the high-frequency oscillations.

    The dots in Fig. 6 are the observed anomalies of global atmospheric CO2(horizontal axis) and O2/N2concentrations(vertical axis) from 1990 to 2014. Here we set the concentrations in year 1990 as the base point (0 ppm, 0 per meg).These dots show an increase of CO2concentration and a simultaneous decline in O2/N2concentration with time. For example, the concentrations in 2014 could be written as (44 ppm, -465 per meg) in this coordinate system, which means a 44 ppm increase of CO2concentration and a 465 per meg decrease of O2/N2concentration in the atmosphere since year 1990. The arrows in Fig. 6 reveal the effect of related processes on atmospheric CO2and O2/N2concentration changes. For example, the fossil fuel combustion is marked by the black arrow in Fig. 6, starting at (0, 0) and ending at(89.0, -584.7), meaning that the fossil fuel burning would have contributed to a total 89.0 ppm increase of CO2(that is,a release of 189.0 GtC CO2, 1 Gt = 1015g, 1 ppm = 2.12 GtC)and 584.7 per meg decrease of O2/N2concentration during 1990-2014, if no other processes were involved. This is to say, the observed decline of O2/N2(~465.1 per meg) is a bit smaller compared with the decline directly derived from fossil fuel combustion (584.7 per meg) during 1990-2014.More importantly, the observed atmospheric CO2concentration only increases by about half of the value derived from fossil fuel combustion (that is, ~44 ppm, as shown in Fig. 6 and Fig. 7), from which we can thus infer huge land and ocean carbon sinks, absorbing a total of 96.6 GtC carbon.The projections of these arrows on the x- axis are also drawn in Fig. 6, which reflect how the atmospheric CO2concentrations are influenced by the related processes. The land and ocean carbon sinks can be separated from the total carbon uptake according to Eq. (6) and Eq. (7), as 33.5 GtC and 63.2 GtC, respectively, during this period.

    Fig. 4 15-year changes in the long-term trend of air-sea O2 flux since 1985. The error bars in panel (b) represent the uncertainty of flux change.

    It should be especially noted that the air-sea O2flux plays an important role in the carbon uptake estimations.The ocean emits ~1.54 Pmol O2(1 Pmol = 1015mol) to the atmosphere (sum of the air-sea O2flux from 1990 to 2014 in Fig. 2a), making a positive contribution of about 36.7 per meg to the atmospheric O2/N2concentration (red vector in Fig. 6). Despite this air-sea O2flux being relatively small, it plays an important role in the estimation of land and ocean carbon sinks. Figure 8 describes the situation assuming that the air-sea O2flux is negligible on a multiannual-to-decadal timescale, as proposed in the early studies (Bender and Battle, 1999; Battle et al., 2000). If the air-sea O2flux is not considered in the O2budget, the ocean carbon sink would be apparently underestimated by approximately 14.8 GtC during 1990-2014, while the land carbon uptake would be largely overestimated (bar charts in the top right of Fig. 8).

    3.2.2.Averaged terrestrial and oceanic carbon sinks in different periods

    We subsequently calculated the averaged terrestrial and oceanic carbon uptake over several different periods and compared them with previous O2-based carbon uptake estimations(Table 3). Here, we use the linear trend of atmospheric O2/N2and CO2concentrations in the period to represent the O2/N2and CO2changes in Eqs. (6)-(7) (Δδ(O2/N2) and ΔCO2).For observed atmospheric concentration changes and fossil fuel consumption (Ffossil), our results are relatively consistent with Keeling et al. (2014) (differences less than 0.06 ppm yr-1in ΔCO2and 0.12 GtC yr-1in Ffossil). The effect of airsea flux in our study (which are derived from process-based CMIP6 model simulations, as described above) shows a relatively large discrepancy with that in Keeling et al. (2014)(which is calculated based on the linear regression between O2flux and net changes of ocean heat content). Our results show an averaged ocean and land carbon sink of 2.10±0.43 and 1.14±0.52 GtC yr-1, respectively, during 1990-2000.An increase is found in both ocean and land carbon sinks during 2000-10, while results from Keeling et al. (2014) show an increase in ocean sink but a decline in land sink. Furthermore, the averaged carbon sinks from 2004 to 2008 in our study (2.64±0.66 GtC yr-1for ocean and 1.84±0.79 GtC yr-1for land) are generally larger than that in Tohjima et al.(2019) (1.97±0.62 GtC yr-1for ocean and 2.17±0.82 GtC yr-1for land), which could also be partly attributed to the discrepancy in the air-sea flux (Table 3).

    Fig. 5 Differences of air-sea O2 flux between CMIP6 and CMIP5 during period 1975-2005 (i.e.FLUXCMIP6 minus FLUXCMIP5). The black line in (a) is the time series of the difference and (b)shows the spatial distribution of the difference averaged from 1975-2005.

    To further explore the temporal changes of ocean and land carbon sinks over the past two decades, the averaged ocean and land carbon sinks were calculated for several representative periods: 1991-97, 1994-2000 and 2004-10 were selected for the estimates of averaged ocean sinks; meanwhile, 1994-2000, 2002-08 and 2008-14 were selected for the estimates of averaged land sinks. These results are shown as the asterisks in Fig. 9, accompanied by time-continuous estimations from the Global Carbon Project (GCP,Friedlingstein et al., 2019), Landschützer et al 2016 and Carbon Tracker (CT, Jacobson et al., 2020). The estimates by GCP clearly show a quasi-monotonous increase of the oceanic carbon sink over the past few decades (Fig. 9a, red line). However, the oceanic uptake in our results show a decline from 2.04±0.47 GtC yr-1in 1991-97 to 1.85±0.45 GtC yr-1in 1994-2000. A significant upward trend is subsequently found in the 21st century, with ocean uptake increasing to 2.87±0.47 GtC yr-1in 2004-10. This temporal pattern is generally consistent with results derived from observed surface partial pressure of CO2in Landschützer et al. (2016)(Fig. 9a, green line), which may occur as consequences of the combined influence of anthropogenic forcing and oceanic internal modes. The net terrestrial carbon uptake estimated in this study corresponds well with the results derived from GCP. An increase of land carbon uptake (from 1.23±0.60 GtC yr-1to 1.91±0.50 GtC yr-1according to our estimations) could be found in the 2000s (Fig. 9b) which has been reported by several atmospheric inversion and model-based studies (Keenan et al., 2016; Ballantyne et al.,2017; Piao et al., 2018). Despite the fact that the mechanisms behind this increase are still under discussion, it is generally believed that the changes in land use, modifications of terrestrial productivity and respiration, as well as climatic variations of temperature and moisture are responsible for changes in terrestrial carbon uptake (Chen et al., 2020; Piao et al., 2020a, b; Yue et al., 2020).

    Fig. 6 Changes in observed atmospheric concentrations of O2/N2 and CO2 from 1990 to 2014. The blue dots represent the annual averaged O2 and CO2 anomaly (here we choose the concentrations in 1990 as the reference value). The vectors in the diagram schematically illustrate the contribution of each process related to the changes in O2 (vertical axis) and CO2(horizontal axis) during this period. The effect of air-sea O2 flux is highlighted in red.

    Fig. 7 The observed time series of atmospheric O2/N2 and CO2 concentrations. The blue, green and red lines represents observations in La Jolla (32.9°N, 277.3°W), Alert (82.5°N,62.3°W), and Cape Grim (40.7°S, 144.7°E), respectively. The black line is the annual mean concentrations averaged among the three stations with a weight of 0.25, 0.25 and 0.5.

    Fig. 8 Role of air-sea O2 flux in O2-based carbon sinks estimations. The diagram is same as Fig. 6, except for no airsea O2 flux considered in the calculation. The bar charts in the top right show the comparisons between estimated ocean/land carbon sink with and without O2 flux correction.

    3.2.3.Influence of oxygen datasets on estimated carbon uptake

    In this section, we specifically investigate the differences of the carbon sinks from that in Li et al. (2021). As mentioned in section 3.1.3, the air-sea O2flux used in Li et al. (2021) is derived from CMIP5, while CMIP6 simulation of the flux is used in this study. Meanwhile, the other O2-related variables(such as atmospheric O2decline) in Li et al. (2021) are derived from the oxygen budget proposed by Huang et al.(2018), which is also different from this study. Terrestrial and oceanic carbon uptakes estimated by Li et al. (2021) are depicted by the triangles in Fig. 9. From the comparisons between this study and Li et al. (2021), we can discern the role of oxygen data in carbon sink estimations.

    For the terrestrial carbon sink, both of the two studies corresponds well with GCP in the 21st century, which exhibit an enhanced uptake mentioned in section 3.2.2. However,the result from Li et al. (2021) seems to present an unrealistically high land carbon uptake (1.50 GtC yr-1) in the 1990s,while the current study behaves in good agreement with GCP during this period (1.06 GtC yr-1). The oceanic carbon uptake in both this study and Li et al. (2021) exhibits a similar variability with that in Landschützer et al. (2016) (that is, adownward trend in the 1990s subsequently followed by an upward trend in the 2000s). Despite this, discrepancy occurs around year 2010, as shown in Fig. 9a. The estimated oceanic carbon uptake in this study (2.87 GtC yr-1) is relatively larger than it in Li et al. (2021) (2.45 GtC yr-1) and GCP (2.36 GtC yr-1).

    Table 3. Estimations of O2-based carbon sinks in different periods.

    Fig. 9 Estimated ocean and land carbon sinks in different studies. The asterisks and triangles are seven-year averaged carbon sinks in this study and Li et al 2021, with error bars representing uncertainties of the estimations.The time series of carbon sinks derived from Global Carbon Project 2019, Landschützer et al 2016 and Carbon Tracker 2019 are colored in red, green and blue, respectively. The thin dashed lines and the thick solid lines are annual and seven-year running averaged carbon sinks, respectively.

    Overall, both of the two studies reveal an enhanced carbon uptake in the 21st century. This study provides a more reliable estimate of the terrestrial carbon uptake in the 1990s, while the oceanic carbon sink in Li et al. (2021) is more consistent with the Global Carbon Project after year 2010. Our calculations show that the differences in air-sea O2flux (Fair-sea) and atmospheric O2change (Δ O2) are the main contributors to the discrepancies. If the difference in O2flux is expressed as ΔFair-sea(the other variables remain unchanged), its influence on the terrestrial and oceanic carbon uptake could then be respectively expressed as ΔB=-β/αBΔFair-seaand ΔO=β/αBΔFair-sea,according to Equations 6-8. This implies that a weakened oceanic O2outgassing, approximately -22 Tmol O2yr-1, would lead to an increase of 0.21 GtC yr-1land carbon sink and a simultaneous opposite effect on ocean carbon sink. For the period 1990-95, Li et al. (2021) shows a smaller declining trend of atmospheric O2and oceanic outgassing in 1990-95, which could eventually lead to a larger land uptake in Li et al.(2021) during this period. These results highlight the vital importance of oxygen datasets on carbon sink estimations.

    4.Summary and discussion

    We use the coupled ocean biogeochemistry models in CMIP6 to investigate the modifications of air-sea O2flux under climate change and its influences on the estimations of global terrestrial and ocean carbon uptake. Our results show an enhanced global oceanic O2outgassing to the atmosphere since the 1980s, accompanied by a strong decadal variability dominated by oceanic internal modes. Consistent with Li et al. (2020), this study shows maximum changes of flux mainly occurring in the high latitudes, with roughly one quarter of the outgassing directly associated with reduced solubility in the warming ocean, and the rest mainly linked with circulation changes and ocean stratification. This modification of air-sea O2flux plays an important role in estimating carbon uptake, as described in section 3.2.

    The application of air-sea O2flux in CMIP6 provides a valuable complement for studies of O2-based global carbon sinks estimations under climate change. Our results reveal the significant increases of terrestrial and oceanic carbon sinks in the 21st century, reflecting the human impacts on the carbon cycle and Earth’s environments. The model biases of air-sea O2flux between CMIP5 and CMIP6 are also investigated in this study, which could lead to a total discrepancy up to 0.4 GtC yr-1in the estimations, indicating the importance of improvement of air-sea O2flux parameterizations in the model.

    Some limitations should also be acknowledged. Our estimation of carbon sinks still suffers from relatively large uncertainties (0.4-0.8 GtC yr-1) due to the accumulations of uncertainty of each term in the calculations. Furthermore, the earliest observations of O2/N2we could obtain are from the late 1980s, which greatly limits the lengths of estimated time series. The comparisons between this study and Li et al.(2021) also reveal the importance of the accuracy of oxygen datasets on the carbon uptake estimations. Presently, we are working on structuring the global oxygen budget (Huang et al., 2018) under the constrain of O2/N2observations, from which we hope to extend the time series of atmospheric O2changes back to the 1900s as well as provide a more reliable oxygen dataset. Further explorations and investigations of the O2-based carbon uptake estimations should be done in the future.

    Acknowledgements.The authors acknowledge the Scripps O2Program for providing the observations of atmospheric O2and CO2data. The authors also acknowledge the World Climate Recruitment Programme’s (WCRP) Working Group on Coupled Modelling(WGCM), and the Global Organization for Earth System Science Portals (GO-ESSP) for producing outputs of CMIP6 model simulations. This work was jointly supported by the National Science Foundation of China (Grant Nos. 41991231, 91937302) and the China 111 project (Grant No. B13045). The data processes and analysis are supported by Supercomputing Center of Lanzhou University.

    Electronic supplementary material:Supplementary material is available in the online version of this article at https://doi.org/10.1007/s00376-021-1273-x.

    Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing,adaptation, distribution and reproduction in any medium or format,as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material.If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence,visit http://creativecommons.org/licenses/by/4.0/.

    他把我摸到了高潮在线观看| 久久久色成人| 亚洲熟女毛片儿| 香蕉久久夜色| 亚洲成人久久爱视频| 床上黄色一级片| 国产精品香港三级国产av潘金莲| 在线播放国产精品三级| a在线观看视频网站| 国产精品久久久久久亚洲av鲁大| 国产精品永久免费网站| 日韩av在线大香蕉| 亚洲午夜理论影院| 国产极品精品免费视频能看的| 国产淫片久久久久久久久 | 免费电影在线观看免费观看| 在线国产一区二区在线| 无人区码免费观看不卡| 手机成人av网站| 国产美女午夜福利| 亚洲av免费在线观看| 每晚都被弄得嗷嗷叫到高潮| 看黄色毛片网站| 精品午夜福利视频在线观看一区| 欧美xxxx黑人xx丫x性爽| 国产精品一及| www.自偷自拍.com| 欧美不卡视频在线免费观看| 最新美女视频免费是黄的| 一级作爱视频免费观看| 极品教师在线免费播放| 亚洲欧美日韩无卡精品| 白带黄色成豆腐渣| 欧美一级a爱片免费观看看| 99久久国产精品久久久| 长腿黑丝高跟| 亚洲乱码一区二区免费版| 国产精品亚洲一级av第二区| 亚洲成a人片在线一区二区| 国产成年人精品一区二区| 国产爱豆传媒在线观看| 小说图片视频综合网站| 日本撒尿小便嘘嘘汇集6| 天天躁日日操中文字幕| 婷婷六月久久综合丁香| 亚洲专区中文字幕在线| 亚洲欧美精品综合久久99| 一区二区三区激情视频| 欧美中文日本在线观看视频| 亚洲欧美一区二区三区黑人| xxx96com| 在线免费观看不下载黄p国产 | 两性午夜刺激爽爽歪歪视频在线观看| 成人午夜高清在线视频| 欧美+亚洲+日韩+国产| 国产精品 国内视频| 成人国产一区最新在线观看| 国产免费男女视频| 99在线视频只有这里精品首页| 日韩 欧美 亚洲 中文字幕| 日韩国内少妇激情av| 亚洲男人的天堂狠狠| 免费电影在线观看免费观看| 高清毛片免费观看视频网站| 男人舔奶头视频| 人人妻人人看人人澡| 97超级碰碰碰精品色视频在线观看| 国内毛片毛片毛片毛片毛片| 人妻夜夜爽99麻豆av| 啦啦啦观看免费观看视频高清| 嫩草影院入口| 久久久国产欧美日韩av| 欧美绝顶高潮抽搐喷水| 成熟少妇高潮喷水视频| 嫩草影院入口| 色综合亚洲欧美另类图片| 亚洲精品在线美女| 中文字幕最新亚洲高清| 免费搜索国产男女视频| 我的老师免费观看完整版| 免费在线观看亚洲国产| 99国产综合亚洲精品| 一区二区三区高清视频在线| 91麻豆av在线| 真人一进一出gif抽搐免费| 日本免费a在线| 大型黄色视频在线免费观看| 国产午夜精品论理片| 国产视频内射| 欧美黑人巨大hd| 日韩 欧美 亚洲 中文字幕| 日本黄大片高清| 亚洲国产日韩欧美精品在线观看 | 免费人成视频x8x8入口观看| 国产成人精品久久二区二区免费| 久久久久性生活片| 久久亚洲精品不卡| 日本三级黄在线观看| 最近最新免费中文字幕在线| 男女午夜视频在线观看| 亚洲欧美日韩东京热| 伦理电影免费视频| 午夜福利欧美成人| 一本精品99久久精品77| 国产成人aa在线观看| 狂野欧美白嫩少妇大欣赏| 欧美日韩一级在线毛片| 99热只有精品国产| 精品国产超薄肉色丝袜足j| 国产av一区在线观看免费| 久久草成人影院| 村上凉子中文字幕在线| 午夜两性在线视频| 欧美日韩综合久久久久久 | 亚洲精品粉嫩美女一区| 变态另类丝袜制服| av天堂在线播放| 97人妻精品一区二区三区麻豆| 在线观看免费视频日本深夜| 国产av麻豆久久久久久久| 日本撒尿小便嘘嘘汇集6| av女优亚洲男人天堂 | 午夜日韩欧美国产| 啦啦啦观看免费观看视频高清| 特大巨黑吊av在线直播| 国产成人一区二区三区免费视频网站| 在线观看午夜福利视频| 91在线精品国自产拍蜜月 | 18禁黄网站禁片免费观看直播| 亚洲国产高清在线一区二区三| 中文字幕av在线有码专区| 欧美3d第一页| 欧美黄色淫秽网站| 一级作爱视频免费观看| 免费观看人在逋| 成在线人永久免费视频| АⅤ资源中文在线天堂| 成年女人永久免费观看视频| 国产精品av久久久久免费| 国产91精品成人一区二区三区| 国产高清激情床上av| 18禁国产床啪视频网站| 亚洲熟妇中文字幕五十中出| 国产精品久久久av美女十八| 精品一区二区三区av网在线观看| bbb黄色大片| 亚洲五月婷婷丁香| 美女cb高潮喷水在线观看 | 美女cb高潮喷水在线观看 | 一本久久中文字幕| 免费电影在线观看免费观看| 他把我摸到了高潮在线观看| 一二三四社区在线视频社区8| av国产免费在线观看| 免费一级毛片在线播放高清视频| 可以在线观看毛片的网站| 亚洲 欧美一区二区三区| 亚洲精品456在线播放app | 成人三级黄色视频| 欧美激情久久久久久爽电影| 特级一级黄色大片| 一级毛片女人18水好多| 免费在线观看亚洲国产| 国产日本99.免费观看| 亚洲一区高清亚洲精品| 国产精品 国内视频| 日日干狠狠操夜夜爽| 成年女人永久免费观看视频| 精品国产三级普通话版| 在线免费观看的www视频| 999久久久国产精品视频| 免费看光身美女| 午夜精品一区二区三区免费看| 国产精品一区二区免费欧美| 中文在线观看免费www的网站| 99久久成人亚洲精品观看| 又爽又黄无遮挡网站| 老司机午夜十八禁免费视频| 午夜精品在线福利| a在线观看视频网站| cao死你这个sao货| 俺也久久电影网| 中文字幕熟女人妻在线| 国产蜜桃级精品一区二区三区| 亚洲真实伦在线观看| 在线十欧美十亚洲十日本专区| 欧美乱色亚洲激情| 啦啦啦观看免费观看视频高清| www.熟女人妻精品国产| 亚洲欧美日韩高清在线视频| 天天一区二区日本电影三级| 三级国产精品欧美在线观看 | 日韩欧美国产一区二区入口| 色哟哟哟哟哟哟| 欧美又色又爽又黄视频| 91av网一区二区| 亚洲av美国av| 黄频高清免费视频| 亚洲国产精品sss在线观看| 亚洲成人免费电影在线观看| 丰满人妻熟妇乱又伦精品不卡| 最近视频中文字幕2019在线8| 淫秽高清视频在线观看| 俄罗斯特黄特色一大片| 午夜亚洲福利在线播放| 国产不卡一卡二| 欧美日韩国产亚洲二区| 免费一级毛片在线播放高清视频| 九色国产91popny在线| 国产aⅴ精品一区二区三区波| 精品久久久久久久久久免费视频| 波多野结衣高清无吗| 99久久99久久久精品蜜桃| 亚洲欧美日韩高清在线视频| 两个人看的免费小视频| 成人永久免费在线观看视频| 欧美不卡视频在线免费观看| 国产熟女xx| 在线十欧美十亚洲十日本专区| 婷婷精品国产亚洲av在线| 久久久久亚洲av毛片大全| 久久久久亚洲av毛片大全| av欧美777| 99精品欧美一区二区三区四区| 嫩草影院精品99| 欧美zozozo另类| 亚洲国产精品成人综合色| 露出奶头的视频| 国产精品 国内视频| 国模一区二区三区四区视频 | 精品99又大又爽又粗少妇毛片 | 日本撒尿小便嘘嘘汇集6| 欧美色欧美亚洲另类二区| 99久国产av精品| 精品99又大又爽又粗少妇毛片 | 欧美成人免费av一区二区三区| 丰满人妻熟妇乱又伦精品不卡| 天堂网av新在线| 9191精品国产免费久久| 超碰成人久久| 亚洲色图av天堂| 中文亚洲av片在线观看爽| 成人国产一区最新在线观看| 美女免费视频网站| 村上凉子中文字幕在线| 亚洲乱码一区二区免费版| 国产伦精品一区二区三区视频9 | 天堂网av新在线| 成人精品一区二区免费| 国产午夜精品论理片| 在线十欧美十亚洲十日本专区| 成人精品一区二区免费| 亚洲一区二区三区不卡视频| 国产免费男女视频| 国产亚洲精品久久久久久毛片| 国产乱人视频| 久久久久久九九精品二区国产| 久久精品aⅴ一区二区三区四区| 国产精品免费一区二区三区在线| 99久久精品热视频| 久久精品影院6| 男女做爰动态图高潮gif福利片| 精品乱码久久久久久99久播| 九色成人免费人妻av| 1024香蕉在线观看| 黄色视频,在线免费观看| 十八禁网站免费在线| 美女免费视频网站| 午夜视频精品福利| 午夜影院日韩av| 国产主播在线观看一区二区| 19禁男女啪啪无遮挡网站| 欧美黑人巨大hd| 首页视频小说图片口味搜索| 国产久久久一区二区三区| 黑人欧美特级aaaaaa片| 亚洲专区字幕在线| 成年女人看的毛片在线观看| 日韩精品青青久久久久久| 久久婷婷人人爽人人干人人爱| 波多野结衣高清作品| 免费观看人在逋| 国产一区在线观看成人免费| 99视频精品全部免费 在线 | 69av精品久久久久久| 又大又爽又粗| 性欧美人与动物交配| 啦啦啦观看免费观看视频高清| 免费看光身美女| 欧美+亚洲+日韩+国产| 香蕉av资源在线| 香蕉丝袜av| av女优亚洲男人天堂 | 久久久久亚洲av毛片大全| 欧美午夜高清在线| 18禁国产床啪视频网站| 黄色视频,在线免费观看| 中亚洲国语对白在线视频| 俺也久久电影网| 99在线视频只有这里精品首页| 99热6这里只有精品| 久久精品国产99精品国产亚洲性色| 国产亚洲欧美98| 亚洲国产精品久久男人天堂| 中文字幕最新亚洲高清| 久久精品亚洲精品国产色婷小说| 小说图片视频综合网站| 香蕉av资源在线| 熟女电影av网| 精品午夜福利视频在线观看一区| 狂野欧美白嫩少妇大欣赏| 久9热在线精品视频| xxx96com| 啦啦啦韩国在线观看视频| 男女那种视频在线观看| 男女视频在线观看网站免费| 久久久久性生活片| 好男人在线观看高清免费视频| 国产精品九九99| 久久久久久久久中文| 法律面前人人平等表现在哪些方面| 中文字幕av在线有码专区| 国产亚洲精品久久久久久毛片| 国产伦精品一区二区三区视频9 | 99热精品在线国产| 国产精品乱码一区二三区的特点| 国产精品久久久av美女十八| 久久中文字幕人妻熟女| 国内精品久久久久久久电影| 91老司机精品| 黄色日韩在线| 亚洲乱码一区二区免费版| 三级国产精品欧美在线观看 | 精品久久久久久,| 国产爱豆传媒在线观看| 男人舔奶头视频| 国产精品爽爽va在线观看网站| 色综合站精品国产| 琪琪午夜伦伦电影理论片6080| 精华霜和精华液先用哪个| 久久久国产精品麻豆| 亚洲性夜色夜夜综合| 久久九九热精品免费| 午夜精品一区二区三区免费看| 国产精品亚洲美女久久久| 国产精品影院久久| 久久亚洲精品不卡| 日韩欧美三级三区| 黄色视频,在线免费观看| 91av网站免费观看| 男女视频在线观看网站免费| 后天国语完整版免费观看| 国产成人欧美在线观看| 精品免费久久久久久久清纯| 亚洲av熟女| 非洲黑人性xxxx精品又粗又长| 精品一区二区三区视频在线 | 我的老师免费观看完整版| 国产野战对白在线观看| 亚洲 国产 在线| 90打野战视频偷拍视频| 国产伦一二天堂av在线观看| 91字幕亚洲| 国产亚洲欧美在线一区二区| 精品国产超薄肉色丝袜足j| 两个人的视频大全免费| 久久精品国产亚洲av香蕉五月| 九九热线精品视视频播放| 欧美在线一区亚洲| 精品欧美国产一区二区三| 欧美乱色亚洲激情| 成人国产一区最新在线观看| 亚洲av五月六月丁香网| 三级男女做爰猛烈吃奶摸视频| 国产爱豆传媒在线观看| 99精品欧美一区二区三区四区| 亚洲七黄色美女视频| 麻豆国产av国片精品| 久久久久国产一级毛片高清牌| 欧美色欧美亚洲另类二区| 亚洲国产欧美网| 久久久久免费精品人妻一区二区| 免费无遮挡裸体视频| 老熟妇乱子伦视频在线观看| 九九在线视频观看精品| 亚洲av电影不卡..在线观看| 精品无人区乱码1区二区| 欧美国产日韩亚洲一区| 一区二区三区国产精品乱码| 小蜜桃在线观看免费完整版高清| 亚洲av片天天在线观看| 亚洲中文日韩欧美视频| 亚洲成av人片在线播放无| 三级男女做爰猛烈吃奶摸视频| 午夜影院日韩av| 婷婷六月久久综合丁香| 欧美一区二区国产精品久久精品| 舔av片在线| 亚洲精品美女久久av网站| 又大又爽又粗| 欧美色欧美亚洲另类二区| 国产高清videossex| 免费看光身美女| 久久国产精品人妻蜜桃| 黄色丝袜av网址大全| 国产毛片a区久久久久| 一进一出抽搐gif免费好疼| 88av欧美| 99久久国产精品久久久| 国产激情偷乱视频一区二区| 欧美精品啪啪一区二区三区| 国产91精品成人一区二区三区| 九九热线精品视视频播放| 九九热线精品视视频播放| 男人和女人高潮做爰伦理| 国产v大片淫在线免费观看| av天堂中文字幕网| 色综合站精品国产| 国模一区二区三区四区视频 | 性欧美人与动物交配| 在线十欧美十亚洲十日本专区| 久久久国产欧美日韩av| 五月玫瑰六月丁香| 99热6这里只有精品| 一级毛片精品| 女人高潮潮喷娇喘18禁视频| 国产一区二区激情短视频| 男人和女人高潮做爰伦理| 欧美大码av| 国产精品99久久99久久久不卡| 久久久久久久久久黄片| 中亚洲国语对白在线视频| 精品久久蜜臀av无| 精品久久久久久久人妻蜜臀av| 变态另类成人亚洲欧美熟女| 亚洲成人久久性| 中文字幕熟女人妻在线| 99热这里只有精品一区 | 欧美色视频一区免费| 国产成人精品久久二区二区免费| av中文乱码字幕在线| 国内毛片毛片毛片毛片毛片| 最新在线观看一区二区三区| 国产精品99久久99久久久不卡| 午夜免费成人在线视频| 成人特级av手机在线观看| 一本一本综合久久| 两个人看的免费小视频| 国产亚洲精品久久久久久毛片| 久久中文看片网| 久久九九热精品免费| 真实男女啪啪啪动态图| 他把我摸到了高潮在线观看| 欧美日韩中文字幕国产精品一区二区三区| 老司机午夜福利在线观看视频| 欧美激情久久久久久爽电影| 美女免费视频网站| 成人午夜高清在线视频| 午夜精品一区二区三区免费看| 一进一出抽搐gif免费好疼| 亚洲av日韩精品久久久久久密| 国产精品美女特级片免费视频播放器 | 深夜精品福利| 99国产精品一区二区蜜桃av| 99久国产av精品| 国产亚洲精品综合一区在线观看| 久久久国产欧美日韩av| 午夜福利免费观看在线| 色综合欧美亚洲国产小说| 国产伦在线观看视频一区| 国产男靠女视频免费网站| 欧美午夜高清在线| 一夜夜www| 久久这里只有精品19| 曰老女人黄片| 好男人电影高清在线观看| 欧美性猛交╳xxx乱大交人| 一本一本综合久久| 丁香六月欧美| 国产主播在线观看一区二区| 日本a在线网址| 色综合欧美亚洲国产小说| 亚洲熟女毛片儿| 欧美黑人欧美精品刺激| 免费看十八禁软件| 一边摸一边抽搐一进一小说| netflix在线观看网站| 天天躁狠狠躁夜夜躁狠狠躁| 免费看美女性在线毛片视频| 精品无人区乱码1区二区| 日本成人三级电影网站| 97超视频在线观看视频| 一级作爱视频免费观看| 成人高潮视频无遮挡免费网站| 成人三级黄色视频| 啪啪无遮挡十八禁网站| 成年女人毛片免费观看观看9| 日日夜夜操网爽| 搡老岳熟女国产| 99国产精品一区二区蜜桃av| 色尼玛亚洲综合影院| 在线观看免费视频日本深夜| 日韩欧美 国产精品| 波多野结衣高清作品| 亚洲人成电影免费在线| 看黄色毛片网站| 午夜免费成人在线视频| 一个人免费在线观看电影 | 亚洲中文日韩欧美视频| 日韩精品青青久久久久久| 久久中文字幕一级| 欧美日韩亚洲国产一区二区在线观看| 在线十欧美十亚洲十日本专区| 他把我摸到了高潮在线观看| 精品久久久久久久末码| 免费在线观看日本一区| 又粗又爽又猛毛片免费看| 观看美女的网站| svipshipincom国产片| 全区人妻精品视频| 国产成年人精品一区二区| 操出白浆在线播放| 不卡av一区二区三区| 日韩成人在线观看一区二区三区| 观看美女的网站| 最新在线观看一区二区三区| 好看av亚洲va欧美ⅴa在| 久久99热这里只有精品18| 18禁美女被吸乳视频| 亚洲成a人片在线一区二区| 久久精品国产综合久久久| 成年女人看的毛片在线观看| 国产av不卡久久| 很黄的视频免费| www日本在线高清视频| 天堂√8在线中文| 成年免费大片在线观看| 99国产精品一区二区三区| 热99在线观看视频| 久久午夜亚洲精品久久| 亚洲成av人片在线播放无| 久久这里只有精品中国| a在线观看视频网站| 欧美高清成人免费视频www| 亚洲自拍偷在线| 亚洲,欧美精品.| 国产精华一区二区三区| 精品久久久久久成人av| 欧美绝顶高潮抽搐喷水| 亚洲激情在线av| 黄色片一级片一级黄色片| 91九色精品人成在线观看| 男人舔女人下体高潮全视频| 美女cb高潮喷水在线观看 | 亚洲成人免费电影在线观看| 午夜福利免费观看在线| 国产97色在线日韩免费| 精品不卡国产一区二区三区| 在线视频色国产色| 久久九九热精品免费| 美女被艹到高潮喷水动态| 日本黄大片高清| 欧美性猛交黑人性爽| 成人18禁在线播放| 亚洲av成人不卡在线观看播放网| 成年女人永久免费观看视频| 97超级碰碰碰精品色视频在线观看| 伦理电影免费视频| 一区二区三区高清视频在线| 午夜免费观看网址| e午夜精品久久久久久久| 麻豆一二三区av精品| 日韩 欧美 亚洲 中文字幕| 真人一进一出gif抽搐免费| 亚洲国产日韩欧美精品在线观看 | 首页视频小说图片口味搜索| 亚洲欧美精品综合一区二区三区| 国产一区二区在线av高清观看| 特大巨黑吊av在线直播| 亚洲成人免费电影在线观看| 舔av片在线| 日韩欧美国产在线观看| 动漫黄色视频在线观看| 亚洲一区高清亚洲精品| 欧美精品啪啪一区二区三区| 亚洲熟妇熟女久久| 精品久久久久久成人av| 国产高清视频在线播放一区| 亚洲七黄色美女视频| 欧洲精品卡2卡3卡4卡5卡区| 1000部很黄的大片| 91在线精品国自产拍蜜月 | 欧美日韩中文字幕国产精品一区二区三区| 成年女人毛片免费观看观看9| 久久久久久九九精品二区国产| 国产成人精品久久二区二区91| 天堂影院成人在线观看| 欧美日韩黄片免| 少妇裸体淫交视频免费看高清| 成人亚洲精品av一区二区| 老汉色∧v一级毛片| 久久香蕉国产精品| 国产成人啪精品午夜网站| 久久精品人妻少妇| 性色avwww在线观看| 伦理电影免费视频| 国产一区二区三区视频了| 亚洲性夜色夜夜综合| 精品久久久久久久久久久久久| 国语自产精品视频在线第100页| 1024香蕉在线观看| 又爽又黄无遮挡网站| 1000部很黄的大片| 中亚洲国语对白在线视频| 搡老熟女国产l中国老女人|