Gcm outputs, typically at a spatial resolution of around 3 latitude and 4 longitude, are currently not considered reliable at time scales shorter than 1 month. Description downscaling of climate change models is the procedure of using largescale climate models to make climate predictions at finer temporal and spatial scales to fit the purpose of local level analysis and planning. Regional climate model assessment using upscaling and downscaling techniques veronica j. Statistical downscaling and bias correction for climate. Forecasts expressed in terms of deviations from the model s climate. Agilan, impact of climate change on flood frequency of the trian reservoir in vietnam using rcms, journal of hydrologic engineering, 2018, 23, 2, 05017032crossref. Keith dixon lucas harris tom knutson related areas of research. First, the 2 degree gcm output is reduced to a 12 kilometer grid using a constructed analogues method. Statistical downscaling regional climate model evaluation. Downscaling climate modelling for highresolution climate. Berrocal university of michigan department of biostatistics joint work with peter craigmile university of glasgow and peter guttorp university of washington veronica j. Statistical downscaling techniques for global climate. However sophisticated the downscaling method is, simulations of regional climate change are strongly dependent on the simulation of present conditions joubert and hewitson, 1997. Their design is focused on the global scale, and their main scope consists in capturing the sensitivity of the global climate to changes in external natural and anthropogenic forcing.
Downscaling does, however, lead to further uncertainty and limitations of results, which must be made explicit to endusers. Projections based on downscaling pacific climate change science. In this study a regional climate model is used to downscale a global climate model to develop meteorological. Explicitly solve for the processbased physical dynamics of the regional climate system and incorporate essential historical observations into future projections gridded average to a single location key challenge remains translating climate projections generated by the downscaling into. The delta method decision and policy analysis working paper no. Four sets of downscaling simulations based on the eta regional climate model forced by two global climate models, the hadgem2es and the miroc5, and two rcp scenarios8. The downscaling method makes minimal, physically based corrections to the global simulation while preserving much. If the models were doing a good job, their predictions would cluster symmetrically around the actual measured temperatures. The california basin characterization model uses several stages of downscaling to produce climate projection maps at a 270meter resolution. A methodology is developed for testing the downscaling ability of nested regional climate models rcms. Assessing the fidelity of dynamical downscaling with the nasa unifiedweather and research forecasting nuwrf model focuses on determining the credibility of a dynamical downscaling technique using a regional climate model. The paper describes the application of sdsm statistical downscaling model and anns artificial neural networksmodels for prediction of the hydrological trend due to the climate change.
While dynamic downscaling involves nesting a highresolution regional climate model within coarser grids of the gcm jones et al. Statistical downscaling techniques for global climate model simulations of temperature and precipitation with application to water resources planning. Liang xz, pan j, zhu j, kunkel ke, wang jxl, dai a 2006 regional climate model downscaling of the us summer climate and future change. Downscaling climate models are an attempt to bridge the gap between global and local effects by layering locallevel data over largerscale climate models. The application of downscaling can involve several different approaches. The rcm tries to represent the transfer function f through the same 1st principle solution methods as the gcm using higher resolution over a limited geographical region. In the second step, the 12kilometer output is interpolated down to a 4kilometer scale using inverse. The inability of climate models to credibly project precipitation extremes in india has not been helpful to longer. Climate model downscaling contacts, for more information. Global climate models are our best tools for computing future temperature. Global climate change is typically understood and modeled using global climate models gcms, but the outputs of these models in terms of hydrological variables are only available on coarse or large spatial and time scales, while finer spatial and temporal resolutions are needed to reliably assess the hydroenvironmental impacts of climate change. Statistical downscaling of global climate model outputs to monthly.
For a given forecast, the deviation of the model from its own climate provides a forecast of how the real climate is expected to deviate from the real localregional longterm climate. Reliability of regional and global climate models to. While previous studies have demonstrated that rcms can add value to. Introduction studies of the regional impacts of climate change must confront the problem of choosing climatechange scenarios.
Dynamical downscalingdynamical downscaling use global climate models with horizontal resolution of 100200 km to drive regional cli t d l ith l ti f 50 klimate models with resolution of 50 km or better. Describes downscaling techniques where gcm outputs are interpolated to the scale of hydrological modeling or local scale requirement. Downscaling techniques in climate modeling springerlink. A climate model is a mathematical representation of the climate system. Climate model downscaling geophysical fluid dynamics laboratory.
Regional climate model version 3 remo german regional climate model stardex statistical and regional dynamical downscaling of extremes for european regions som selforganizing map. The added value to global model projections of climate. For the very first time, this book provides updated, integrated and organized, theoretical. The proposed methodology, nicknamed the bigbrother experiment bbe, is based on a perfectprognosis approach and hence does not suffer from model errors nor from limitations in observed climatologies. The objective of this work is to assess the climate change over south america based on the eta simulations.
The ultimate test for a climate model is the accuracy of its predictions. The task of downscaling global climate model simulations is often so demanding that only a limited selection of models and greenhouse gas emission scenarios. Oct 27, 2012 in statistical downscaling, a model is developed for the region of interest, which statistically relates large. Statistical and dynamical mesoscale climate downscaling.
Downscaling simulations of future global climate with. This book provides a comprehensive reference to widelyused approaches, and additionally covers the relevant user context and technical background, as well as a synthesis and guidelines for practitioners. Surface air temperature predictions from the regional climate model wrf the outer domain d1. At the moment, there exists no universal downscaling method for all situations, and all are still at the stage of development and testing xu, 1999. A nonparametric kernel regression model for downscaling. Pdf statistical downscaling for climate change scenarios of. The downscaling method makes minimal, physically based corrections to the global simulation while preserving much of the statistics of interannual variability in the climate model. The excel spreadsheet includes the downscaling location, months indicated, observational data, model data, and downscaled data. Statistical downscaling for hydrological and environmental. The technique uses broadscale climate data from global climate models as input data for a finer resolution atmospheric model see. The present article explores the impacts of climate change on precipitation at station scale in the minab basin, iran. Statistical downscaling of regional climate model output to. Statistical downscaling of regional climate model output.
But the models predicted that there would be much greater warming between 1998 and 2014 than actually happened. The added value to global model projections of climate change. Climate model based consensus on the hydrologic impacts of climate change to the rio lempa basin of central america, hydrology and earth system sciences, 183194, 2009 connect to online version. Assessment of climate change over south america under rcp 4. Regional climate model assessment using upscaling and. All of these projects have a component in creating or using downscaled climate information. The bbe consists in first establishing a reference climate by performing a large. The spreadsheet should add a new sheet with the different method information. Statistical downscaling and bias correction are becoming standard tools in climate impact studies. Dynamical downscaling precis method description a regional climate model rcm is a high resolution climate model that covers a limited area of the globe, typically 5,000 km x 5,000 km, with a typical horizontal resolution of 50 km. Regional climate models downscaling analysis of general.
T1 downscaling global circulation model projections of climate change for the united arab emirates. The issues of downscaling the results from global climate models gcms to a scale relevant for hydrological impact studies are examined. Regional climate downscaling with prior statistical. Statistical downscaling techniques for global climate model simulations of temperature and precipitation with application to water resources planning studies alan f. Use regression, quantile mapping or other mathematical techniques to replicate past. Mathematical equations are solved on a supercomputer at points on a 3dimensional grid in the ocean and atmosphere, over a number of timesteps. In section 2 we identify a set of generic end user needs. Goal is to obtain highresolution climate climate model is input to this statistical model to approximate the corresponding regional and local. The downscaling method process is still in development within the research community, and because of this, endusers must be able to read highly technical and specialized explanations andor assessments to apply the. A search on amazon for textbooks on regional climate modeling or downscaling does not. Global climate models provide initial andglobal climate models provide initial and boundary conditions. A regional climate model rcm solving the same equation set as a gcm is driven at the lateral and surface boundaries by temporally evolving fields simulated by the gcm. An improved climate dynamical downscaling at regional scales.
The stateoftheart in dynamical and statistical downscaling is presented in sections 3 and 4, respectively, and in section 5, validation techniques are introduced. The rcms downscaling reduces significantly driving gcms present. Downscaling climate information oxford research encyclopedia. Statistical downscaling techniques for global climate model. Salathe 1 pablo carrasco 2 1 center for science of the earth system, climate impacts group, university of washington.
Downscaling of global climate change estimates to regional scales. Climate impacts weather and climate extremes global climate models gcms continue to yield important scientific insights into the dynamics and evolution of the climate system o. The paper describes the application of sdsm statistical downscaling model and anns artificial neural networksmodels for prediction of the hydrological trend due to the climatechange. Downscaling climate models for ecological forecasting in. Downscaling ability of oneway nested regional climate models. Dynamical and statistical regional climate modeling. Climate impacts weather and climate extremes global climate models gcms continue to yield important scientific insights into the. Globally downscaled climate data santa clara university. Global climate models gcms are our best tools for providing climate projections.
Regional climate modeling is still a challenge due much to uncertainties in the model physics and forcing data boundary conditions in this study, we attempt to improve precipitation simulations and forecasts for the western united states with an advanced regional climate model by calibrating its physics and correcting the biases in the. Detecting and modelling regional climate change manola brunet. Each component of the mod25 eling system is described below along with the downscaling and evaluation methods used. Deviations can be categorical terciles, quintile shifts or pdf shifts. Downscaling global circulation model projections of climate. A global climate model typically contains enough computer code to fill 18,000 pages of printed text. Cambridge core statistics for environmental sciences statistical downscaling and bias correction for climate research by douglas maraun. Statistical downscaling techniques that facilitate statistical relationships that metamorphose largescale atmospheric variablespredictors simulated by gcms to local scale variablespredictand are discussed in detail. Their dynamic downscaling approach was intended to fill the gap between the global but coarse estimates of global climatecirculation models gcms, which. Statistical and dynamical mesoscale climate downscaling background climate downscaling is a practice whereby coarseresolution climate data which comes from global atmospheric reanalyses e. Regional climate downscaling with prior statistical correction of the. Nonparametric statistical downscaling of precipitation from global climate models.
Projections based on downscaling pacific climate change. Nonparametric statistical downscaling of precipitation from global. Statistical downscaling is a twostep process consisting of i the development of statistical relationships between local climate variables e. They are also computationally expensive and may not simulate precipitation well cubash et al. Climate model downscaling geophysical fluid dynamics. Skip to main content accessibility help we use cookies to distinguish you from other users and to provide you with a better experience on our websites. Pdf statistical downscaling for climate change scenarios. Regional overview dynamical downscaling is a methodology for providing more detailed climate projection information for a specific region. The future changes are shown in timeslices of 30 years.
Global climate models gcms continue to yield important scientific insights into the dynamics and evolution of the climate system on time scales ranging from. Extract global climate model historical and future projections for same location 3. Assessment of climate change over south america under rcp. Jul 12, 2015 dynamically downscaling climate models july 12, 2015 by staff jim collins writes that a research team from argonne national laboratory and the university of chicago is using the mira supercomputer to investigate the effectiveness of dynamically downscaled climate models.
Here a new approach to downscaling is introduced that consists of generating a large set of synthetic storm tracks whose statistics are consistent with the largescale general circulation of the climate model, and then running a deterministic, coupled tropical cyclone model along each track, with atmospheric and upperocean thermodynamic. Goal is to obtain highresolution climate global climate derives statistical relationships between observed variables and larger gcm scale variables various methods proposed but bcsd biascorrection and spatial disaggregation is widely adopted. Regional climate model rcm output is used for largescale precipitation data, both current and projected, or x c and x p from eq. Introduction 2 global climate models gcm improved notably in their representation of the climate system over the past couple of decades intergovernmental panel on climate change, 2007a. Downscaled modeling examines relatively small areas in detailin some cases down to 25 square kilometers, 3 a far higher resolution than that offered by global climate model simulations. Downscaling of global climate models for flood frequency. This study approaches the problem of downscaling global climate model simulations with an emphasis on validating and selecting global models. Coordinated regional climate downscaling experiment. Readers are introduced to stateoftheart research in downscaling and gcms. Rcms are based on physical laws represented by mathematical equations that are solved using a threedimensional. One of the most widely known climate projection tools is the general circulation model gcm, a computer model that mathematically represents various physical processes of the global climate system.
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