Kinetic Energy Budgets during the Rapid Intensification of Typhoon Rammasun (2014)

In this study,Typhoon Rammasun(2014)was simulated using the Weather Research and Forecasting model to examine the kinetic energy during rapid intensification(RI).Budget analyses revealed that in the inner area of the typhoon,the conversion from symmetric divergent kinetic energy associated with the collocation of strong cyclonic circulation and inward flow led to an increase in the symmetric rotational kinetic energy in the lower troposphere.The increase in the symmetric rotational kinetic energy in the mid and upper troposphere resulted from the upward transport of symmetric rotational kinetic energy from the lower troposphere.In the outer area,both typhoon and Earth’s rotation played equally important roles in the conversion from symmetric divergent kinetic energy to symmetric rotational kinetic energy in the lower troposphere.The decrease in the symmetric rotational kinetic energy in the upper troposphere was caused by the conversion to asymmetric rotational kinetic energy through the collocation of symmetric tangential rotational winds and the radial advection of asymmetric tangential rotational winds by radial environmental winds.

RO_(x) Budgets and O_(3) Formation during Summertime at Xianghe Suburban Site in the North China Plain

Photochemical smog characterized by high concentrations of ozone(O_(3)) is a serious air pollution issue in the North China Plain(NCP)region,especially in summer and autumn.For this study,measurements of O_(3),nitrogen oxides(NO_(x)),volatile organic compounds(VOCs),carbon monoxide(CO),nitrous acid(HONO),and a number of key physical parameters were taken at a suburban site,Xianghe,in the NCP region during the summer of 2018 in order to better understand the photochemical processes leading to O_(3)formation and find an optimal way to control O_(3)pollution.Here,the radical chemistry and O_(3)photochemical budget based on measurement data from 1−23 July using a chemical box model is investigated.The daytime(0600−1800 LST)average production rate of the primary radicals referred to as RO_(x)(OH+HO2+RO2)is 3.9 ppbv h−1.HONO photolysis is the largest primary RO_(x)source(41%).Reaction of NO2+OH is the largest contributor to radical termination(41%),followed by reactions of RO2+NO2(26%).The average diurnal maximum O_(3)production and loss rates are 32.9 ppbv h−1 and 4.3 ppbv h−1,respectively.Sensitivity tests without the HONO constraint lead to decreases in daytime average primary RO_(x)production by 55%and O_(3)photochemical production by 42%,highlighting the importance of accurate HONO measurements when quantifying the RO_(x)budget and O_(3)photochemical production.Considering heterogeneous reactions of trace gases and radicals on aerosols,aerosol uptake of HO2 contributes 11%to RO_(x)sink,and the daytime average O_(3)photochemical production decreases by 14%.The O_(3)-NO_(x)-VOCs sensitivity shows that the O_(3)production at Xianghe during the investigation period is mainly controlled by VOCs.

Estimating the Budgets of Nutrients for Phytoplankton Bloom inthe Central Yellow Sea Using a Modified LowerTropic Ecosystem Model

A modified lower trophic ecosystem model （NEMURO） is coupled with a three-dimensional hydrodynamic model for anapplication in the central Yellow Sea. The model is used to simulate the horizontal distributions and annual cycles of chlorophyll-aand nutrients with results consistent with historical observations. Generally, during the winter background and spring bloom periods,the exchange with neighboring waters constitutes the primary sources of nutrients. Howerver, during the winter background period,the input of silicate from the layer deeper than 50 m is the most important source that contributes up to 60% to the total sources. Dur-ing the spring bloom period, the transport across the thermocline makes significant contribution to the input of phosphate and silicate.During the post spring bloom period, the relative contribution of relevant processes varies for different nutrients. For ammonium,atmospheric deposition, excretion of zooplankton and decomposition of particulate and dissolved nitrogen make similar contributionsFor phosphate and silicate, the dominant input is the transport across the thermocline, accounting for 62% and 68% of the totalsources, respectively. The N/P ratio averaged annually and over the whole southern Yellow Sea is up to 51.8, indicating the potentialof P limitation in this region. The important influence of large scale sea water circulation is revealed by both the estimated fluxes andthe corresponding N/P ratio of nutrients across a section linking the northeastern bank of the Changjiang River and Cheju Island.During the winter background period, the input of nitrate, ammonium, phosphate and silicate by the Yellow Sea Warm Current isestimated to be 4.6~ 101~, 2.3x 101~, 2.0x 109 and 1.2x 101~ mol, respectively.

Modeling Carbon and Water Budgets in the Lushi Basin with Biome-BGC

In this article, annual evapotranspiration(ET) and net primary productivity (NPP) of fourtypes of vegetation were estimated for the Lushi basin,a subbasin of the Yellow River in China. These fourvegetation types include: deciduous broadleaf forest,evergreen needle leaf forest, dwarf shrub and grass.Biome-BGC--a biogeochemical process model wasused to calculate annual ET and NPP for eachvegetation type in the study area from 1954 to 2000.Daily microclimate data of 47 years monitored byLushi meteorological station was extrapolated tocover the basin using MT-CLIM, a mountainmicroclimate simulator. The output files of MT-CLIM were used to feed Biome-BGC. We usedaverage ecophysiological values of each type ofvegetation supplied by Numerical TerradynamicSimulation Group (NTSG) in the University ofMontana as input ecophysiological constants file.The estimates of daily NPP in early July and annualET on these four biome groups were comparedrespectively with field measurements and other studies.Daily gross primary production (GPP) of evergreenneedle leaf forest measurements were very close tothe output of Biome-BGC, but measurements ofbroadleaf forest and dwarf shrub were much smallerthan the simulation result. Simulated annual ET andNPP had a significant correlation with precipitation,indicating precipitation is the major environmentalfactor affecting ET and NPP in the study area.Precipitation also is the key climatic factor for theinterannual ET and NPP variations.

The experimental studies on the carbon and nitrogen budgets of Pseudeuphausia sinica

The carbon and nitrogen budgets were estimated on the adult females, juveniles and post-furcilia larvae of Pseudeuphausia sinica fed on newly hatching nauplii of Artemia salina in the laboratory. It was found that the ingestion rate was linearly related to the food concentration, suggesting high feeding potential. The linear correlation could be established between the respirating rate (carbon consumption rate) and carbon ingestion rate, as well as carbon assimilation rate. The regression coefficients (i.e.specific dynamic action coefficients) were in the range from 9% to 16% (ingested C) or 10% to 17% (assimilated C) respectively, with lower in the post-furcilia larvae. There also existed a linear correlation equation between estimated total nitrogen excretion rate and the rates of nitrogen ingestion and assimilation separately, except for the juveniles. The defecation rates increased with the increase of the ingestion rate; as a result, assimilation efficiency was not related to the ingestion rate, ranging from 0.84 to 0.95. The results inducated that the nitrogen content in food particles was a key factor limiting the growth of P. sinica. The critical ingestion rate was 10 μgN·mg-1 body dry weight per day. Assimilated N was lost mostly by excretion, following allocated to somatic growth. The nitrogen loss by moult only accounted for a minor part. As for carbon budget, respiration and somatic growth also accounted for most of assimilation, but varied with ingestion rates. Moult loss was minor. Estimated reproductive growth (C&N) in the adult females accounted for somewhat higher percent of assimilation than the moult growth. The net growth efficiency (K2) increased with the increase of the ingestion rates, but decreased slightly for juvenile and post-furcilia larvae after the rates up to a certain value.

Water budgets for freshwater aquaculture ponds with reference to effluent volume

This paper presents the consumptive water use for freshwater pond aquaculture for semi-intensive carps farming practices. The consumptive use of water includes evaporation loss, seepage loss and water exchanges requirements. The water requirement has been estimated to be10.3 m3/Kg of fish production under present study for semi-intensive culture and with supplemental feeding. Out of which7.6 m3/Kg of fish production is system associated requirement. On an average the evaporation loss from the pond is1498.3 mm/year and seepage loss per year is about1182.60 mm/year. Seepage and water exchange losses recharge the ground water aquifers and if they are treated and recycled, the water use in aquaculture can be reduced significantly. A further reduction in fresh water use in pond aquaculture is possible through development of intensive and superintensive culture systems and aqua feeds.

Characteristics of Central Southwest Asian Water Budgets and Their Impacts on Regional Climate

Water budgets terms, evapotranspiration (E), precipitation (P), runoff (N), moisture convergence (MC) and both surface as well as atmospheric residual terms have been computed with National Centers for Environmental Prediction (NCEP) (1948-2007) and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-40 (1958-2001) reanalysis data sets for Central Southwest Asia (CSWA).The domain of the study is 45° - 75°E & 25° - 40°N. Only the land area has been used in these calculations. It is noted in the comparison of both reanalysis data sets with Global Precipitation Climatology Centre (GPCC) that all three data sets record different precipitation before 1970. The maximum is from NCEP and the minimum with ERA-40. However, after 1970 all the data sets record almost the same precipitation. ERA-40 computes two phases of MC. Before 1975, the domain acts as a moisture source, whereas after 1975 it behaves as a moisture sink. The region CSWA is divided into six sub areas with rotational principle factor analysis and we distinguish them by different approached weather systems acting on each area. Finally, NCEP yearly precipitation is further divided into seasons;winter (November to April) and summer (May to October) and two phases have been noted. The variation in winter precipitation is more than summer during last 60-year analysis.

Differences between Convective and Stratiform Precipitation Budgets in a Torrential Rainfall Event

Differences in rainfall budgets between convective and stratiform regions of a torrential rainfall event were investigated using high-resolution simulation data produced by the Weather Research and Forecasting(WRF) model. The convective and stratiform regions were reasonably separated by the radar-based convective–stratiform partitioning method, and the threedimensional WRF-based precipitation equation combining water vapor and hydrometeor budgets was further used to analyze the rainfall budgets. The results showed that the magnitude of precipitation budget processes in the convective region was one order larger than that in the stratiform region. In convective/stratiform updraft regions, precipitation was mainly from the contribution of moisture-related processes, with a small negative contribution from cloud-related processes. In convective/stratiform downdraft regions, cloud-related processes played positive roles in precipitation, while moisture-related processes made a negative contribution. Moisture flux convergence played a dominant role in the moisture-related processes in convective or stratiform updraft regions, which was closely related to large-scale dynamics. Differences in cloud-related processes between convective and stratiform regions were more complex compared with those in moisture-related processes.Both liquid-and ice-phase microphysical processes were strong in convective/stratiform updraft regions, and ice-phase processes were dominant in convective/stratiform downdraft regions. There was strong net latent heating within almost the whole troposphere in updraft regions, especially in the convective updraft region, while the net latent heating(cooling) mainly existed above(below) the zero-layer in convective/stratiform downdraft regions.

Historic changes in flux of matter and nutrient budgets in the Bohai Sea

Over the past four periods （ 1959--1960, 1982--1983, 1992--1993, and 1998--1999）, the ecosystem of the Bohai Sea changed due to both a significant decrease of river water discharge from the Huanghe River and a reduction of precipitation. The shifts in nutrient chemistry could result in changes in the phytoplankton composition with an increased potential for non-diatom algal blooms. Simple box model was used to estimate the water - mass balance and nutrient budgets for the Bohai Sea. Water budgets indicate that the residual flow changed from out of the Bohai Sea before 1993, but became inflow to the Bohai Sea after then. The nutrient budgets developed indicate that the Bohai Sea was a sink for nutrients except for phosphate in 1959--1960 and 1982-- 1983 and for silicate in 1982--1983. Net water flow transports nutrients out of the Bohai Sea in 1959--1960, 1982--1983 and 1992--1993, but into the sea in 1998--1999 due to climate changes, such as precipitation and subsequent freshwater discharge. The residual fluxes of nutrients are minor relative to atmospheric deposition and riverine inputs. Conversions of phosphate values to carbon by stoichiometric ratios were used to predict that the system was net heterotrophic before 1982--1983 and net autotrophic after then. Nutrient budgets can explain the change of nutrient concentrations in the Bohai Sea except nitrates, which should include the surface runoff.

Water Vapor,Cloud,and Surface Rainfall Budgets Associated with the Landfall of Typhoon Krosa(2007):A Two-Dimensional Cloud-Resolving Modeling Study

Water vapor, cloud, and surface rainfall budgets associated with the landfall of Typhoon Krosa on 6-8 October 2007 are analyzed based on a two-dimensional cloud-resolving model simulation. The model is integrated with imposed zonally-uniform vertical velocity, zonal wind, horizontal temperature, and vapor advection from NCEP/Global Data Assimilation System （GDAS） data. The simulation data that are validated with observations are examined to study physical causes associated with surface rainfall processes during the landfall. The time- and domain-mean analysis shows that when Krosa approached the eastern coast of China on 6 October, the water vapor convergence over land caused a local atmospheric moistening and a net condensation that further produced surface rainfall and an increase of cloud hydrometeor concentration. Meanwhile, latent heating was balanced by advective cooling and a local atmospheric warming. One day later, the enhancement of net condensation led to an increase of surface rainfall and a local atmospheric drying, while the water vapor convergence weakened as a result of the landfall-induced deprivation of water vapor flux. At the same time, the latent heating is mainly compensated the advective cooling. Further weakening of vapor convergence on 8 October enhanced the local atmospheric drying while the net condensation and associated surface rainfall was maintained. The latent heating is balanced by advective cooling and a local atmospheric cooling.

Surface Rainfall and Cloud Budgets Associated with Mei-yu Torrential Rainfall over Eastern China during June 2011

Surface rainfall and cloud budgets associated with three heavy rainfall events that occurred over eastern China during the mei-yu season in June 2011 were analyzed using 2D cumulus ensemble model simulation data.Model domain mean rainfall showed three peaks in response to three prescribed ascending motion maxima,primarily through the mean moisture convergence during the torrential rainfall period.Prescribed ascending motion throughout the troposphere produced strong convective rainfall during the first （9 June） and third （17-18 June） rainfall events,whereas strong prescribed ascending motion in the mid and upper troposphere and weak subsidence near the surface generated equally important stratiform and convective rainfall during the second rainfall event （14 June）.The analysis of surface rainfall budgets reveals that convective rainfall was associated with atmospheric drying during the first event and moisture convergence during the third event.Both stratiform and convective rainfall responded primarily to moisture convergence during the second event.An analysis of grid data shows that the first and third mean rainfall maxima had smaller horizontal scales of the precipitation system than the second.

INVESTIGATIONS ON MOISTURE TRANSPORTS, BUDGETS AND SOURCES RESPONSIBLE FOR THE DECADAL VARIABILITY OF PRECIPITATION IN SOUTHERN CHINA

In the context of global warming,apparent decdal-interdecdal variabilities can be detected in summer precipitation in southern China.Especially around the 1990 s,precipitation in South China experienced a phase transition from a deficiency regime to an abundance regime in the early 1990 s,while the Yangtze River Valley witnessed a phase shift of summer precipitation from abundance to deficiency in the late 1990 s.Pertinent analyses reveal a close relationship between such decadal precipitation shifts and moisture budgets,which is mainly modulated by the meridional component.This relationship can be attributed to large-scale moisture transport anomalies.Further,the HYSPLIT model is utilized to quantitatively evaluate relative moisture contributions from diverse sources during different regimes.It can be found that during the period with abundant precipitation in South China,the moisture contribution from the source of Indochina Peninsula-South China Sea increased significantly,while during the deficient precipitation regime in the Yangtze River Valley,moisture from local source,western Pacific and Indochina Peninsula-South China Sea contributed less to precipitation.It means some new features of relative moisture contributions from diverse sources to precipitation anomaly in southern China took shape after 1990 s.

DISCREPANCY OF THE GLOBAL AIR MASS AND WATER BUDGETS AMONG 20 CMIP5 CLIMATE MODELS

The consistency of global atmospheric mass and water budget performance in 20 state-of-the-art ocean-atmosphere Coupled Model Intercomparison Project Phase 5(CMIP5) coupled models has been assessed in a historical experiment. All the models realistically reproduce a climatological annual mean of global air mass(AM) close to the ERA-Interim AM during 1989-2005. Surprisingly, the global AM in half of the models shows nearly no seasonal variation,which does not agree with the seasonal processes of global precipitable water or water vapor, given the mass conservation constraint. To better understand the inconsistencies, we evaluated the seasonal cycles of global AM tendency and water vapor source(evaporation minus precipitation). The results suggest that the inconsistencies result from the poor balance between global AM tendency and water vapor source based on the global AM budget equation. Moreover, the cross-equatorial dry air mass flux, or hemispheric dry mass divergence, is not well represented in any of the 20 CMIP5 models, which show a poorly matched seasonal cycle and notably larger amplitude, compared with the hemispheric tendencies of dry AM in both the Northern Hemisphere and Southern Hemisphere. Pronounced erroneous estimations of tropical precipitation also occur in these models. We speculate that the large inaccuracy of precipitation and possibly evaporation in the tropics is one of the key factors for the inconsistent cross-equatorial mass flux. A reasonable cross-equatorial mass flux in well-balanced hemispheric air mass and moisture budgets remains a challenge for both reanalysis assimilation systems and climate modeling.

Water Budgets of Tropical Cyclones： Three Case Studies

In this study, three tropical cyclones （TCs） that passed through the Taiwan Strait were analyzed; our results show that precipitation is not directly related to the intensity of TCs. From the perspective of water budget, moisture flux convergence was dominant and contributed -70% of the moisture for TC precipitation over the ocean and almost all over the land, especially inside the TC circulation. Their spatial distributions were also similar. Evaporation contributed -30% of the moisture for precipitation over the ocean but changed little with the time. Moisture flux convergence can be divided into two parts： wind convergence and moisture advection. Moisture flux convergence was mostly due to wind convergence, which was dominant in the southwestern quadrants of the TCs. Moisture advection was located in the northern area, and becomes relatively important when the TCs approached the land. The moisture flux convergence and its two parts varied during TC movement, with strengthening and contraction of moisture convergence present near landfall. The vertical structure of the three TC eases all indicated that the moisture convergence was mainly confined to the lower atmosphere under 800 hPa and a weak divergence region was present in the middle troposphere around 550 hPa.

Are diurnal time-budgets and activity patterns density-dependent in the Shelduck (Tadorna tadorna) wintering in Algeria? An analysis across multiple temporal scales

Background: The Shelduck (Tadorna tadorna) is a characteristic waterbird species of inland wetlands in northeastern Algeria. Its wintering behavior in relation to changes of local abundances and foraging group density is poorly known. Objectives: This study aims at monitoring patterns of diurnal activities and the variation of behavioral time-budgets in relation to numbers of wintering Shelducks. We investigate temporal variations of diurnal activities across multipletime scales and consider their interrelationships. Methods: Assessments of local population abundance were weekly surveyed during two wintering seasons (2010– 2012), whereas diurnal activities (feeding, sleeping, swimming, preening, loafing, flying, courtship, and antagonism) were studied three times a month during seven hours (08:00–16:00) using the Scan method. Time budget variations of each behavioral activity were tested using nested ANOVAs following multiple time scales. Generalized linear mixedeffects models (GLMM) tested whether variations in diurnal activities were density-dependent. Results: During the wintering season, Shelduck’s numbers followed a bell-shaped trend, which indicated that the species was typically a wintering migrant in Sabkha Djendli. The first individuals arrived onsite in October–November then numbers reached a peak in January (up to 2400 individuals in 2012) with steady density during December–February, afterward individuals left the site progressively until late April when the site is deserted. During both wintering seasons, diurnal activities were dominated by feeding (60%), followed by sleeping (12%) then swimming and preening with 9% and 8%, respectively. The rest of the activities (loafing, flying, courtship and antagonistic behaviors) had low proportions of time budget. ANOVAs showed that activity time budgets varied significantly following multiple time scales (year, season, month, day, semi-hour). Time budgets of diurnal activities during each wintering season were significantly interrelated. Correlations patterns between the two seasons were similar. GLMMs revealed that the variations of diurnal activities were not density-dependent, except for preening and swimming. Conclusion: During the wintering season, habitats of Sabkha Djendli are important for waterbirds, including the Shelduck that used the lake mainly for food-foraging and resting. The 2400 individuals censused in mid-winter are important locally and at the North African scale. This stresses the need to strengthen the protection status of this wetland and mitigate degradation sources that threaten wintering waterfowl.

Effect of Temperature on the Carbon, Nitrogen, and Phosphorus Nutrient Budgets of Steelhead Trout (Oncorhynchus mykiss) with Different Sizes

This study was performed to evaluate the effect of temperature on the carbon(C),nitrogen(N),and phosphorus(P)nu-trient budgets of adult steelhead trout(Oncorhynchus mykiss)with different body sizes.A complete two-factor experiment was con-ducted at four temperatures,i.e.,9(T9),13(T13),16(T1℃℃℃6),and 19(T19);and three body sizes,℃i.e.,0.65 kg±0.02 kg(S1),1.22 kg±0.06 kg(S2),and 2.05 kg±0.09 kg(S3).The following properties of steelhead trout were determined:C,N,and P nutrient budgets;feed intake rate;fecal production rate;oxygen consumption rate;ammonia excretion rate;phosphorus excretion rate;scope of the growth of C,N,and P;and absorption efficiency of C,N,and P.Results showed no significant interaction between temperature and body size in terms of the nutrient budgets of steelhead trout.However,temperature and body size played important separate roles in the nutrient budgets except for the absorption efficiency of nitrogen.The feed intake rate,fecal production rate,ammonia excretion rate,phosphorus excretion rate,and scope of the growth of C,N,and P were the highest in the T16 treatments.The absorption effi-ciency of C and P decreased as temperature increased.Nonlinear multiple regression results indicated that 15 was the approximate℃optimal temperature for the feeding and growth of steelhead trout.The feed intake rate,fecal production rate,oxygen consumption rate,ammonia excretion rate,phosphorus excretion rate,and scope of the growth of C,N,and P per unit of the body weight of fish decreased as body size increased.The absorption efficiency of C increased as body weight increased,and the absorption efficiencies of P in the S2 and S3 treatments were significantly higher than those in the S1 treatment.During the culture of steelhead trout,the daily ratio should be adjusted with changes in the temperature and body size of fish.Furthermore,managers should focus on the risk of hypoxia at high water temperatures.

A Case Study of the Impacts of Dust Aerosols on Surface Atmospheric Variables and Energy Budgets in a Semi-Arid Region of China

The authors present a case study investigating the impacts of dust aerosols on surface atmospheric variables and energy budgets in a semi-arid region of China. Enhanced observational meteorological data, radiative fluxes, near-surface heat fluxes, and concentrations of dust aerosols were collected from Tongyu station, one of the reference sites of the International Coordinated Energy and Water Cycle Observations Project (CEOP), during a typical dust storm event in June 2006. A comprehensive analysis of these data show that in this semi-arid area, higher wind velocities and a continuously reduced air pressure were identified during the dust storm period. Dust storm events are usually associated with low relative humidity weather conditions, which result in low latent heat flux values. Dust aerosols suspended in the air decrease the net radiation, mainly by reducing the direct solar radiation reaching the land surface. This reduction in net radiation results in a decrease in soil temperatures at a depth of 2 cm. The combination of increased air temperature and decreased soil temperature strengthens the energy exchange of the atmosphere-earth system, increasing the surface sensible heat flux. After the dust storm event, the atmosphere was dominated by higher pressures and was relatively wet and cold. Net radiation and latent heat flux show an evident increase, while the surface sensible heat flux shows a clear decrease.

Large porewater exchange reshapes saltmarsh carbon and greenhouse gas budgets on local and global scales

Saltmarshes are carbon-rich ecosystems that play a role in climate regulation by efficiently sequestrating atmospheric CO_(2).Climate change is a major threat to saltmarshes and will impact saltmarsh carbon sequestration.Notably,porewater-derived carbon outwelling emerges as a crucial pathway for carbon sequestration,but it has been largely overlooked in saltmarshes.Here,we assessed the drivers of dissolved carbon exports and greenhouse gas emissions in a saltmarsh and placed those observations into a global context.In our study site,porewater exchange(PEX)was the major process controlling dissolved carbon and greenhouse gas dynamics.Combining our results with 33 other studies in saltmarshes worldwide,porewater-derived carbon fluxes were equivalent to~48% of average global saltmarsh primary productivity and 2.2 times greater than global organic carbon burial.Hence,our local observations and global upscaling demonstrate the major role played by PEX in saltmarsh carbon budgets.While part of dissolved inorganic carbon returns to the atmosphere as CO_(2),the remaining bicarbonate fraction is stored in the ocean over long time scales.Our findings strengthen global blue carbon assessments and build arguments for the use of saltmarshes as nature-based solutions for global climate change.

Understanding equityeefficiency interaction in the distribution of global carbon budgets

Equity and efficiency are two important factors guiding the mitigation of anthropogenic emissions to achieve the Paris climate goals.Previous studies have proposed a range of allocations of global carbon budgets,but few have quantified the equity-efficiency interaction.Based on an investigation of the existing allocation literature,this study conducts a novel analysis using a‘mixed’allocation‘big-data’framework to understand the equityeefficiency interaction in the distribution of global carbon budgets under 2℃ and 1.5℃ warming targets.At a global scale,a carbon Gini coefficient and aggregate abatement costs are used as quantitative metrics to reflect equity and efficiency,respectively.Results show an equity-efficiency frontier that reflects the opportunity for the international community to co-improve equity and efficiency on top of existing allocations.However,the frontier also features strong trade-offs to further improve equity and efficiency if national allocations are to be achieved individually.Our analysis verifies that such trade-offs are sensitively dependent on the level of global connection and integration.Linking national mitigation actions and potentials can help promote equity-efficiency synergies and contribute to the efficient achievement of the Paris Agreement's temperature and equity goals.

Hydrochemistry and carbon isotope characteristics of Nujiang River water:Implications for CO_(2) budgets of rock weathering in the Tibetan Plateau

The Tibetan Plateau is one of the most complicated geographical units worldwide in terms of its tectonic and environmental background.Although a hotspot for continental weathering and carbon cycling studies,accurate determination of the weathering carbon budget is challenging in this area,especially sink and source flux quantification and the controlling mechanisms.Compared with other major rivers on the plateau,the Nujiang River is characterized by less human disturbance and maintains a relatively pristine state.This study investigates the high spatiotemporal resolution hydrochemistry and dual-carbon isotope composition(δ~(13)C_(DIC)andΔ~(14)C_(DIC))of river water in the Nujiang River Basin.The results revealed that the solutes and dissolved inorganic carbon in the river water are predominantly derived from rock weathering by carbonic and sulfuric acids,mainly due to the carbonate weathering process,and significantly enhanced by deep carbon sourcing from hot springs in the fault zone.The average contributions of geological and modern carbon in the main stream of the Nujiang River are 35.2%and 64.8%,respectively,and sulfide oxidation contributes>90%of sulfate ions in the river water.After considering the involvement of sulfuric acid generated by sulfide oxidation during rock weathering,the calculated consumption fluxes of atmospheric CO_(2) by silicate and carbonate weathering in the watershed were decreased by approximately 52.0%and 37.4%,respectively,compared with those calculated ignoring this process.Rock weathering of the Nujiang River Basin is a“CO_(2) sink”on a short time scale,while the participation of sulfuric acid makes it a“CO_(2) source”on a geological time scale.The high-frequency observations of ion concentrations,elemental ratios,and calculated contributions of different rock weathering materials indicate that carbonate rock weathering is more sensitive to temperature and runoff variations than silicate rock weathering,with the solute contribution from carbonate weathering increasing significantly during monsoon period.The material input from different rock types is dominated by the hydrological pathways and water-rock reaction times in the basin.This study reveals the river solute origins and weathering CO_(2) sequestration effect in response to a monsoonal climate in one of the most representative pristine plateau watersheds in the world,which is of great importance for elucidating the weathering control mechanisms and CO_(2) net sourcesink effect in plateau watersheds.