A warm-season comparison of WRF coupled to the CLM4.0, Noah-MP,and Bucket hydrology land surface schemes over the central USA     

Matthew?S.?Van Den BroekeEmail authorView author&#;s OrcID profile  Andrew?Kalin  Jose?Abraham?Torres?Alavez  Robert?Oglesby  Qi?Hu 《Theoretical and Applied Climatology》2018,134(3-4):801-816

In climate modeling studies, there is a need to choose a suitable land surface model (LSM) while adhering to available resources. In this study, the viability of three LSM options (Community Land Model version 4.0 [CLM4.0], Noah-MP, and the five-layer thermal diffusion [Bucket] scheme) in the Weather Research and Forecasting model version 3.6 (WRF3.6) was examined for the warm season in a domain centered on the central USA. Model output was compared to Parameter-elevation Relationships on Independent Slopes Model (PRISM) data, a gridded observational dataset including mean monthly temperature and total monthly precipitation. Model output temperature, precipitation, latent heat (LH) flux, sensible heat (SH) flux, and soil water content (SWC) were compared to observations from sites in the Central and Southern Great Plains region. An overall warm bias was found in CLM4.0 and Noah-MP, with a cool bias of larger magnitude in the Bucket model. These three LSMs produced similar patterns of wet and dry biases. Model output of SWC and LH/SH fluxes were compared to observations, and did not show a consistent bias. Both sophisticated LSMs appear to be viable options for simulating the effects of land use change in the central USA.  相似文献   

Application of physical scaling towards downscaling climate model precipitation data     

Abhishek?GaurEmail authorView author&#;s OrcID profile  Slobodan?P.?Simonovic 《Theoretical and Applied Climatology》2018,132(1-2):287-300

Physical scaling (SP) method downscales climate model data to local or regional scales taking into consideration physical characteristics of the area under analysis. In this study, multiple SP method based models are tested for their effectiveness towards downscaling North American regional reanalysis (NARR) daily precipitation data. Model performance is compared with two state-of-the-art downscaling methods: statistical downscaling model (SDSM) and generalized linear modeling (GLM). The downscaled precipitation is evaluated with reference to recorded precipitation at 57 gauging stations located within the study region. The spatial and temporal robustness of the downscaling methods is evaluated using seven precipitation based indices. Results indicate that SP method-based models perform best in downscaling precipitation followed by GLM, followed by the SDSM model. Best performing models are thereafter used to downscale future precipitations made by three global circulation models (GCMs) following two emission scenarios: representative concentration pathway (RCP) 2.6 and RCP 8.5 over the twenty-first century. The downscaled future precipitation projections indicate an increase in mean and maximum precipitation intensity as well as a decrease in the total number of dry days. Further an increase in the frequency of short (1-day), moderately long (2–4 day), and long (more than 5-day) precipitation events is projected.  相似文献   

Field significance of performance measures in the context of regional climate model evaluation. Part 1: temperature     

Martin?IvanovEmail authorView author&#;s OrcID profile  Kirsten?Warrach-Sagi  Volker?Wulfmeyer 《Theoretical and Applied Climatology》2018,132(1-2):219-237

A new approach for rigorous spatial analysis of the downscaling performance of regional climate model (RCM) simulations is introduced. It is based on a multiple comparison of the local tests at the grid cells and is also known as “field” or “global” significance. New performance measures for estimating the added value of downscaled data relative to the large-scale forcing fields are developed. The methodology is exemplarily applied to a standard EURO-CORDEX hindcast simulation with the Weather Research and Forecasting (WRF) model coupled with the land surface model NOAH at 0.11 ^° grid resolution. Monthly temperature climatology for the 1990–2009 period is analysed for Germany for winter and summer in comparison with high-resolution gridded observations from the German Weather Service. The field significance test controls the proportion of falsely rejected local tests in a meaningful way and is robust to spatial dependence. Hence, the spatial patterns of the statistically significant local tests are also meaningful. We interpret them from a process-oriented perspective. In winter and in most regions in summer, the downscaled distributions are statistically indistinguishable from the observed ones. A systematic cold summer bias occurs in deep river valleys due to overestimated elevations, in coastal areas due probably to enhanced sea breeze circulation, and over large lakes due to the interpolation of water temperatures. Urban areas in concave topography forms have a warm summer bias due to the strong heat islands, not reflected in the observations. WRF-NOAH generates appropriate fine-scale features in the monthly temperature field over regions of complex topography, but over spatially homogeneous areas even small biases can lead to significant deteriorations relative to the driving reanalysis. As the added value of global climate model (GCM)-driven simulations cannot be smaller than this perfect-boundary estimate, this work demonstrates in a rigorous manner the clear additional value of dynamical downscaling over global climate simulations. The evaluation methodology has a broad spectrum of applicability as it is distribution-free, robust to spatial dependence, and accounts for time series structure.  相似文献   

Clashing interpretations of REDD+ “results” in the Amazon Fund     

Richard van der Hoff  Raoni Rajão  Pieter Leroy 《Climatic change》2018,150(3-4):433-445

Results-based funding (RBF) is a governance concept that is rapidly becoming the mainstream paradigm for international collaborations in the environmental sector. While portrayed as a compromise solution between market-based mechanisms and unconditional donations, the implementation of RBF is revealing new conflicts and contradictions of its own. This paper explores the application of RBF for Reducing Emissions from Deforestation and Forest Degradation (REDD+) by describing the discursive conflicts between recipient (i.e., Brazil) and donor (i.e., Norway and Germany) countries of the Amazon Fund about what constitutes “results” or “performance.” Although all parties agree that the financial transfers to RBF should be based on past emission reductions in relation to a historical baseline, they hold clashing interpretations about temporal (i.e., past or future) and epistemological (i.e., how to measure) aspects of the results these payments are intended for. Firstly, while Brazil emphasizes that it deserves a reward of USD 21 billion for results achieved between 2006 and 2016, donor countries have indicated an interest in paying only for most recent results as a way to incentivize further reductions. Secondly, while all parties believe that Amazon Fund should support policies to reduce deforestation, donor countries have revealed concerns that the performance of the Amazon Fund projects in generating further reductions has not been measured in a rigorous manner. This suggests that donor countries may consider making changes to current RBF mechanisms or getting involved in new forms of finance.  相似文献   

Geometry of the hemispherical radiometric footprint over plant canopies     

B.?Marcolla  A.?CescattiEmail authorView author&#;s OrcID profile 《Theoretical and Applied Climatology》2018,134(3-4):981-990

Radiometric measurements of hemispherical surface reflectance and long-wave irradiance are required to quantify the broadband albedo and the outgoing thermal radiation. These observations are typically integrated with eddy covariance measurements of sensible and latent heat fluxes to characterize the surface energy budget. While the aerodynamic footprint has been widely investigated, the geometry of the hemispherical radiometric footprint over plant canopies has been rarely tackled. In the present work, the size and shape of the hemispherical radiometric footprint are formalized for a bare surface and in presence of a vegetation cover. For this purpose, four idealized canopies are analyzed and the dependency of the radiometric footprint on leaf area index and canopy height is explored. Besides, the radiometric footprint is compared with the aerodynamic footprint in conditions of neutral stability. It was observed that almost 100% of the hemispherical radiometric signal originates within a distance of a few radiometer heights, while only about 50–80% of the cumulative aerodynamic signal is generated within a distance of about 20 sensor heights. In order to achieve comparable extensions of the footprint areas, hemispherical radiometric measurements should therefore be taken about 6–15 times higher than turbulent flux ones, depending on the vegetation type. The analysis also highlights that the size of the radiative footprint decreases at increasing leaf area index, whereas the aerodynamic footprint shows an opposite behavior. For the abovementioned reasons, this work may support the interpretation of energy flux measurements and the optimal design of eddy covariance stations located in heterogeneous sites.  相似文献   

A formal framework for the representation of stack-based terrains     

Alejandro Graciano  Antonio Jesús Rueda  Francisco Ramón Feito 《International journal of geographical information science》2018,32(10):1999-2022

This paper presents a formal framework for the representation of three-dimensional geospatial data and the definition of common geographic information system (GIS) spatial operations. We use the compact stack-based representation of terrains (SBRT) in order to model geological volumetric data, both at the surface and subsurface levels, thus preventing the large storage requirements of regular voxel models. The main contribution of this paper is fitting the SBRT into the geo-atom theory in a seamless way, providing it with a sound formal geographic foundation. In addition we have defined a set of common spatial operations on this representation using the tools provided by map algebra. More complex geoprocessing operations or geophysical simulations using the SBRT as representation can be implemented as a composition of these fundamental operations. Finally a data model and an implementation extending the coverage concept provided by the Geography Markup Language standard are suggested. Geoscientists and GIS professionals can take advantage of this model to exchange and reuse geoinformation within a well-specified framework.  相似文献   

Sedimentary provenance in the central Ribeira belt based on laser-ablation ICPMSPb/Pb zircon ages     

Claudia Sayo Valladares  Nuno Machado  Monica Heilbron  Beatriz Paschoal Duarte  Gilles Gauthier 《Gondwana Research》2008,13(4):516-526

²⁰⁷Pb/²⁰⁶Pb ages from 420 zircons from 9 upper amphibolite and granulite facies quartzites of the post-1.8 Ga metasedimentary cover from the Occidental and Oriental terranes from the Neoproterozoic central Ribeira belt, in eastern Brazil, are discussed. Ages from the Occidental terrane show that Proterozoic ages predominate with a modal class at 2.1–2.2 Ga and that Archean ages are less common and lie within the 2.5–3.6 Ga range. A wider dispersion on Proterozoic ages down to 1.1 Ga and youngest Neoproterozoic ages (550–700 Ma) were also observed and could be related to the Brasiliano/PanAfrican metamorphic events. The data show that detrital sediments of the Occidental terrane were derived predominantly from erosion of a 1.8–2.2 Ga Paleoproterozoic terrane with a small proportion of a 2.6–3.6 Ga Archean crust. Ages from the Oriental terrane are greatly dispersed, but show a significant proportion of ages between 1.7 and 2.1 Ga, although the great majority are between 0.5 and 1.6 Ga. Only 3 out of 144 grains yield Archean ages, between 2.5 and 2.9 Ga. Based on the greatest errors observed on the data from the Oriental Terrane (100–300 Ma), and a continuum of obtained ages between 2072 Ma (Paleoproterozoic) and 517 Ma (Cambrian), the more plausible interpretation is that the dispersion of ages results from partial resetting of the U–Pb system by Brasiliano metamorphism in Proterozoic–Archean zircons, although a Mesoproterozoic source could not be discarded.  相似文献   

The nature and tropospheric formation of iberulites: Pinkish mineral microspherulites     

José L. Díaz-Hernández  Jesús Párraga 《Geochimica et cosmochimica acta》2008,72(15):3883-3906

The circum-Mediterranean area has one of the highest dust accretion rates in the world. We have found pinkish mineral microspherulites (here referred to as iberulites), a new type of aerosol particle formed under special atmospheric conditions in periods corresponding to the highest levels of solid additions (summer). Because these particles are labile, they have gone unnoticed until now.Image analysis shows that these particles are spherical in shape, most commonly 60-90 μm in diameter, and show a typical depression (vortex). Iberulites are considered complex mineral assemblages with different hygroscopic characteristics and also contain biological remains (plants, silica shells, plankton and probably viruses). Their bulk mineralogy includes silicates, carbonates, sulfates, halides, oxides and phosphate-vanadates. This mineralogical composition indicates that likely source areas are the Sahara and Sahel for primary minerals (inherited), while other minerals are the result of atmospheric neoformation (gypsum and alunite-jarosite).We thus define an iberulite as a coassociation with axial geometry, constituted by well-defined mineral grains together with non-crystalline compounds, structured on a coarse-grained core and a smectite rind, with only one vortex and pinkish color, formed in the troposphere by complex aerosol-water-gas interactions.We suggest the aqueous interphase hypothesis as the mechanism for tropospheric formation of iberulites, mainly in summer: interactions between water droplets and aerosols create complex hydrodynamic conditions, causing possible collisions (wake and front capture) that produce the “precursor water droplets” of iberulites. Atmospheric processing is required from this stage to iberulite maturation.To date, we do not know to what extent these iberulites are present in time and space or whether they can serve as markers for environmental or paleoclimatic analyses or even lead to uncertainty in radiative transfer models.  相似文献   

Thermoluminescence, electron paramagnetic resonance and optical absorption in natural and synthetic rhodonite crystals     

J. R. B. Paião  S. Watanabe 《Physics and Chemistry of Minerals》2008,35(9):535-544

Thermoluminescence, electron paramagnetic resonance and optical absorption properties of rhodonite, a natural silicate mineral, have been investigated and compared to those of synthetic crystal, pure and doped. The TL peaks grow linearly for radiation dose up to 4 kGy, and then saturate. In all the synthetic samples, 140 and 340°C TL peaks are observed; the difference occurs in their relative intensities, but only 340°C peak grows strongly for high doses. Al₂O₃ and Al₂O₃ + CaO-doped synthetic samples presented several decades intenser TL compared to that of synthetic samples doped with other impurities. A heating rate of 4°C/s has been used in all the TL readings. The EPR spectrum of natural rhodonite mineral has only one huge signal around g = 2.0 with width extending from 1,000 to 6,000 G. This is due to Mn dipolar interaction, a fact proved by numerical calculation based on Van Vleck dipolar broadening expression. The optical absorption spectrum is rich in absorption bands in near-UV, visible and near-IR intervals. Several bands in the region from 540 to 340 nm are interpreted as being due to Mn³⁺ in distorted octahedral environment. A broad and intense band around 1,040 nm is due to Fe²⁺. It decays under heating up to 900°C. At this temperature it is reduced by 80% of its original intensity. The pink, natural rhodonite, heated in air starts becoming black at approximately 600°C.  相似文献   

A genetic classification of sinkholes illustrated from evaporite paleokarst exposures in Spain   总被引：2，自引：0，他引：2  

Francisco Gutiérrez  Jesús Guerrero  Pedro Lucha 《Environmental Geology》2008,53(5):993-1006

This contribution analyses the processes involved in the generation of sinkholes from the study of paleokarst features exposed in four Spanish Tertiary basins. Bedrock strata are subhorizontal evaporites, and in three of the basins they include halite and glauberite in the subsurface. Our studies suggest that formation of dolines in these areas results from a wider range of subsidence processes than those included in the most recently published sinkhole classifications; a new genetic classification of sinkholes applicable to both carbonate and evaporite karst areas is thus proposed. With the exception of solution dolines, it defines the main sinkhole types by use of two terms that refer to the material affected by downward gravitational movements (cover, bedrock or caprock) and the main type of process involved (collapse, suffosion or sagging). Sinkholes that result from the combination of several subsidence processes and affect more than one type of material are described by combinations of the different terms with the dominant material or process followed by the secondary one (e.g. bedrock sagging and collapse sinkhole). The mechanism of collapse includes any brittle gravitational deformation of cover and bedrock material, such as upward stoping of cavities by roof failure, development of well-defined failure planes and rock brecciation. Suffosion is the downward migration of cover deposits through dissolutional conduits accompanied with ductile settling. Sagging is the ductile flexure of sediments caused by differential corrosional lowering of the rockhead or interstratal karstification of the soluble bedrock. The paleokarsts we analysed suggest that the sagging mechanism (not included in previous genetic classifications) plays an important role in the generation of sinkholes in evaporites. Moreover, collapse processes are more significant in extent and rate in areas underlain by evaporites than in carbonate karst, primarily due to the greater solubility of the evaporites and the lower mechanical strength and ductile rheology of gypsum and salt rocks.  相似文献