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The terrestrial biosphere and atmospheric chemistry interact through multiple feedbacks, but the models of vegetation and chemistry are developed separately. In this study, the Yale Interactive terrestrial Biosphere (YIBs) model, a dynamic vegetation model with biogeochemical processes, is implemented into the Chemical Transport Model GEOS-Chem version 12.0.0. Within the GC-YIBs framework, leaf area index (LAI) and canopy stomatal conductance dynamically predicted by YIBs are used for dry deposition calculation in GEOS-Chem. In turn, the simulated surface ozone (O3) by GEOS-Chem affect plant photosynthesis and biophysics in YIBs. The updated stomatal conductance and LAI improve the simulated daytime O3 dry deposition velocity for major tree species. Compared with the GEOS-Chem model, the model-to-observation correlation for dry deposition velocities increases from 0.76 to 0.85 while the normalized mean error decreases from 35 % to 27 % using the GC-YIBs model. Furthermore, we quantify O3 vegetation damaging effects and find a global reduction of annual gross primary productivity by 2-5 %, with regional extremes of 11-15 % in the eastern U.S. and eastern China. The online GC-YIBs model provides a useful tool for discerning the complex feedbacks between atmospheric chemistry and terrestrial biosphere under global change. [ABSTRACT FROM AUTHOR]

This study focuses on the uncertainties that influence numerical simulation results of meteorological fields (including horizontal resolution, vertical resolution, near-surface scheme, initial and boundary conditions, underlying surface update, and update of model version). By further evaluating and analyzing the uncertainty factors, it is expected to provide relevance for those scholars who are devoted to factor analysis, in order to make the results closer to the observed values. In this study, a total of 12 experiments are set up to analyze the effects of the uncertainties mentioned above, and the following conclusions are drawn: (1) Horizontal resolution has a greater effect than vertical resolution. (2) The simulated effects of temperature and wind speed in the near-surface scheme are smaller than those in the PBL scheme. (3) The initial and boundary conditions of different products have the most remarkable effect on relative humidity, and the simulation results of EC data are the best. (4) The updates with urban and water bodies as the underlying surface have more significant contribution to the meteorological fields, especially on temperature. (5) The update of the model version does not necessarily optimize the model results. In general, the configuration of uncertainties needs to be considered comprehensively according to what you need in order to obtain the best simulation results. [ABSTRACT FROM AUTHOR]

The optimal choice of the planetary boundary layer (PBL) parameterization scheme is of particular interest and urgency to a wide range of scholars, especially for many works involving models. At present, there have been many works to evaluate the PBL schemes. However, little research has been conducted into a more comprehensive and systematic assessment of the performance capability of schemes in key regions of China, especially when it comes to the differences in the mechanisms of the schemes themselves, primarily because there's scarcely sufficient observational data, computer resources, and storage support to complete the work. In addition, there are many factors that influence the selection of schemes, such as underlying surface, initial and boundary conditions, near-surface layer scheme, horizontal/vertical resolution, etc. In this Part (i.e., Part I), four typical schemes (i.e., YSU, ACM2, BL and MYJ) are selected to systematically analyze and evaluate near-surface meteorological parameters, PBL vertical structure, PBL height (PBLH), and turbulent diffusion in five key regions (i.e., North China Plain, NCP; Yangtze River Delta, YRD; Sichuan Basin, SB; Pearl River Delta, PRD and Northwest Semi-arid, NS) of China in different seasons (i.e., January, April, July and October). The differences in the simulated 2-m temperatures between the nonlocal closure schemes are mainly affected by the downward shortwave radiation, but to compare the nonlocal closure schemes with the local closure schemes, the effect of sensible heat flux needs to be further considered. In terms of temporal variation, the simulated results for July are better than the other three months, and the simulated results for nighttime are better than daytime. In terms of regional distribution, the temperature at stations with higher elevation is easily underestimated, while overestimated with lower elevation. The variation of relative humidity corresponds to temperature. The 10-m wind speed is under the influence of factors like the momentum transfer coefficient and the integrated similarity functions at night. The wind speeds are more significantly overestimated in the plains and basin, while less overestimated or even underestimated in the mountains, as a result of the effect on topographic smoothing in the model. Moreover, the overestimation of small wind speeds at night is attributable to the inapplicability of the Monin-Obukhov similarity theory (MOST) at night. The model captures the vertical structure of temperature well, while the wind speed is outstandingly overestimated below 1000 m, largely because of the turbulent diffusion coefficient (TDC). The difference between the MOST and the mixing length theory, PBLH and Prandtl number is cited as the reason for the difference between the TDC of the YSU and ACM2 schemes. The TDCs of the BL and MYJ schemes are affected by the mixing length scale, which of BL is calculated on the basis of the effect of buoyancy, while MYJ calculates it with the consideration of the effect of the total turbulent kinetic energy. The PBLH of the BL scheme is better than the other schemes because of the better simulation results of temperature. The difference in the PBLH by the YSU and ACM2 scheme mainly comes from the Richardson number and the jagged PBLH of the MYJ scheme is due to the coarse vertical resolution and the threshold value. [ABSTRACT FROM AUTHOR]

A major limitation in modeling global ozone (O3) vegetation damage has long been the reliance on empirical O3 sensitivity parameters derived from a limited number of species and applied at the level of plant functional types (PFTs), which ignore the large interspecific variations within the same PFT. Here, we present a major advance in large-scale assessments of O3 plant injury by linking the trait leaf mass per area (LMA) and plant O3 sensitivity in a broad and global perspective. Application of the new approach and a global LMA map in a dynamic global vegetation model reasonably represents the observed interspecific responses to O3 with a unified sensitivity parameter for all plant species. Simulations suggest a contemporary global mean reduction of 4.8% in gross primary productivity by O3, with a range of 1.1%-12.6% for varied PFTs. Hotspots with damages > 10% are found in agricultural areas in the eastern U.S., western Europe, eastern China, and India, accompanied by moderate to high levels of surface O3. Furthermore, we simulate the distribution of plant sensitivity to O3, which is highly linked with the inherent leaf trait trade-off strategies of plants, revealing high risks for fast-growing species with low LMA, such as crops, grasses and deciduous trees. [ABSTRACT FROM AUTHOR]

The study presents a climatology of aerosol composition concentration obtained by a recently developed GRASP/Component (GRASP stands for the Generalized Retrieval of Atmosphere and Surface Properties algorithm) approach applied to the whole archive of POLDER-3 observations. The conceptual specific of the GRASP/Component approach is in direct retrieval of aerosol speciation (component fraction) without an intermediate retrievals of aerosol optical characteristics. Despite a global validation of the derived aerosol component product is challenging, the results obtained are in line with general knowledge about aerosol types in different regions. In addition, we compare the GRASP derived black carbon and dust components with those of the MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications, version 2) product. Quite reasonable general agreement in spatial and temporal distribution of the species provided by GRASP and MERRA-2 was found, the differences however appeared in regions known for strong biomass burning and dust emissions; the reasons for the discrepancies are discussed. The other derived components, such as concentration of absorbing (black carbon, brown carbon, iron oxides content in mineral dust) and scattering (ammonium sulphate and nitrate, organic carbon, non-absorbing dust) aerosol, represent scarce but imperative information for validation and potential adjustment of chemical transport models. The aerosol optical properties derived by GRASP/Component were found to agree well with the AERONET ground reference data and fully consistent with the previous GRASP Optimized, High Precision and Models retrieval versions applied to POLDER-3 data. Thus, the presented extensive climatology product provides an opportunity for understanding variabilities and trends in global and regional distributions of aerosol species. The climatology of the aerosol components obtained in addition to the aerosol optical properties provides additional valuable, qualitatively new inside about aerosol distributions and, therefore, demonstrates advantages of multi-angular polarimetric satellite observations as the next frontier for aerosol inversion from advanced satellite observations. [ABSTRACT FROM AUTHOR]

As the earth's third pole, Qinghai-Tibet Plateau belongs to one of the most sensitive regions to climate change in the world. Based on the observed and the simulated daily precipitation from the Coupled Model Intercomparison Project Phase 5 (CMIP5), we evaluated the simulation performance of daily precipitation from selected CMIP5 models from 1975 to 2005 over the Qinghai-Tibet Plateau. We found that daily precipitation exhibited obvious longrange correlation characteristics using the detrended fluctuation analysis method. The scaling exponents of daily precipitation in summer and autumn are significantly larger than those in spring and winter. MIROC4H with the best performance can reproduce long-range correlation characteristic of daily precipitation series probably because of the higher resolution, which can capture small scale cloud convections. Besides there are seasonal differences in the simulation results among different regions of the Qinghai- Tibet Plateau, simulation effects of all climate models in summer and winter are better than those in spring and autumn. The performance of MIROC4H model works the best in spring. Overall, the scaling exponents of daily precipitation from BCC-CSM1-1-M, CMCC-CM and MIROC4H are close to the observations. CCSM4 and MIROC4H climate models could reproduce the internal dynamics characteristic of daily precipitation in autumn. But for winter, all climate models have exaggerated the scaling value in southeastern Qinghai-Tibet Plateau compared with the observed values. [ABSTRACT FROM AUTHOR]