Click here to load reader
Click here to load reader
Dec 31, 2015
Crown copyright Met OfficeRegional Climate Modelling and Dynamical DownscalingClimate Data for Agricultural Modelling Workshop, Kasetsart University, 26th February -1st March 20131 Crown copyright Met OfficeTo introduce the PRECIS regional climate modelling system
To review the method for obtaining fine-scale climate information from global climate models (GCMs) from regional climate models (RCMs) such as PRECIS.
Objectives of the session2 Crown copyright Met OfficeWhat is PRECIS?Providing REgional Climates for Impact StudiesRegional climate modelling (RCM) system that can be applied to any area of the globeUsed to generate detailed projections of future climate3PRECIS is a regional climate modelling system developed at the Hadley Centre that can run on a PC and comprises:An RCM that can be applied easily to any area of the globe to generate detailed climate change predictions, A simple user interface to allow the user to set up and run the RCM, andA visualisation and data processing package to allow display and manipulation of RCM output. Crown copyright Met OfficeWhy was PRECIS developed?UNFCCC requirement to assess national vulnerability and plans for adaptationNational CommunicationsBoth need estimates of impactsImpacts need detailed scenarios of future climatePRECIS can provide these detailed scenarios of future climateUNFCCC requirement on the UK to assist capacity building and technology transfer
4Regional Climate Models (RCM) provide climate information with useful local detail including realistic extreme events. Developing countries are the most vulnerable to climate change. Hence the need for detailed climate change scenarios to assess their national vulnerability. The development of a PC version of the Hadley Centres RCM is addressing this need by allowing developing countries to generate their own national scenarios of climate change for use in impact studies. This will lead to technology transfer and capacity building within developing countries.
Crown copyright Met OfficeWho is PRECIS for?Anyone interested in understanding climate change and its potential impactsHighly relevant for scientists involved in vulnerability and adaptation studies (particularly for National Communications documents)
5PRECIS is mainly aimed at government scientists from developing countries involved in vulnerability and adaptation studies, thus in general with either a background in meteorology/climate or climate impacts. As RCM domains generally include several countries it is hoped that PRECIS would be co-operatively used by neighbouring countries. Involving scientists within the region in the use of PRECIS is expected to increase the value of resulting climate scenarios by using their expertise to provide appropriate assessment and interpretation of the scenarios. Crown copyright Met Office
Predicting impacts6To predict future climate change, we first need projections of emissions of greenhouse gases and other constituents. These emission scenarios have been developed in the IPCC Special Report on Emission Scenarios (SRES) and reflect a number of different ways in which the world might develop. The concentrations of these gases is calculated using carbon cycle and chemistry models taking as input the above emission scenarios. The concentration scenarios are used as input into the Global coupled climate models to compute global climate projections. The current resolution of the atmospheric part of a typical GCM is about 250 km in the horizontal, and of the ocean is 125 to 250 km. This resolution is not high enough to represent the fine-scale detail that characterises the climate in many regions of the world. Also, it will be insufficient for the requirements of most impacts models. Hence there is the need to add regional detail and here the technique shown is via regional climate models (as this is what PRECIS uses) though there are other regionalization techniques. Finally the impacts models require climate scenarios as inputs. The climate scenario will be constructed by combining the climate change prediction (from the RCM) with a description of the current climate as represented by the observational data (the observed baseline climate) or by using RCM predictions of current climate as the baseline and of future climate as the scenario..
Crown copyright Met OfficeWhat is a Regional Climate Model? Mathematical model of the atmosphere and land surface (and sometimes the ocean)High resolution: Produces data in grid cells < 50km in sizeSpans a limited area (region) of the globe
Contains representations of many of the important physical processes within the climate systemCloudRadiationRainfallAtmospheric aerosolsSoil hydrologyetc.
7A 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. RCMs are based on physical laws represented by mathematical equations that are solved using a three-dimensional grid. The typical horizontal resolution of an RCM is 50 km. Hence RCMs are comprehensive physical models, usually including the atmosphere and land surface components of the climate system, and containing representations of the important processes within the climate system (e.g., cloud, radiation, rainfall, soil hydrology). Many of these physical processes take place on much smaller spatial scales than the model grid and cannot be modelled and resolved explicitly. Their effects are taken into account using parametrizations by which the process is represented by relationships between the area or time averaged effect of such sub-grid scale process and the large scale flow. Crown copyright Met OfficeThe components of PRECISThe RCMUser interface to design and configure RCM experimentsDisplay and data processing softwareLateral boundary conditions (the input data)Training course and materialsTechnical and Scientific Support (by internet forum and email)Website (http://www.metoffice.gov.uk/precis)8In addition to the main software components, the first three items listed here, there are three other important components. The first is the set of boundary conditions which is needed to run the PRECIS RCM and is derived from an archive of global data at the Hadley Centre. The second is this training course and associated materials which provide the background to make most appropriate and best use PRECIS. The third is the PRECIS website which is a source of these and other materials, hosts an interface to request boundary data and provides a forum for requesting advice and sharing experiences with PRECIS. Crown copyright Met OfficeThe PRECIS user interface
9The first panel on the interface allows the region the PRECIS RCM will be run over to be defined. It also allows the land-sea mask, important initial information for the PRECIS RCM, to be modified should the automatically generated land-sea mask have errors for important, land, island, sea or lake areas.The second panel allows the user to choose whether to use present day or projected future concentrations of greenhouse gases and emissions of SO2 and other chemicals involved in the sulphur cycle.The third panel allows the specification of the start and length of the RCM experiment.The fourth panel allows the choice of output the RCM.The model is started with the Run PRECIS button and can be stopped or interrupted using the Stop PRECIS button. Crown copyright Met OfficeRegion specificationChoice of domainLand surface configurationRCM and Emissions scenarioPeriod of the simulationOutput dataRunPRECIS user interface: Main functionality10 Crown copyright Met OfficeExample of graphical runtime monitoringPRECIS user interface
11The display shows combined pressure at mean sea level (contours) and precipitation (colours) at 6 hourly intervals for three days of an integration of the PRECIS RCM (in this instance being run over the Arctic). The bottom of the display gives information on the status of the experiment, e. g. how long it has run for.
Crown copyright Met OfficeHow fast does it go?1 core:~ 2.5 months4 cores:~ 2.75 weeks8 cores:~ 12.5 days 30 year integration, 100x100, 50km grid pointsMinimum hardware requirementsComputer: PC running under the Linux operating systemMemory : 512MB minimum; 1+ GB recommendedMinimum 250GB disk space + offline storage for archiving dataSimulation speed proportional to CPU speed 12The hardware specification provided here is a minimum for convenient operation of PRECIS though less online disk space would be acceptable if offline tape storage was available for storing of PRECIS output and PRECIS boundary conditions. (This would require experiments to be run in shorter segments, e.g. 1-2 years at a time). In terms of processor speed, it is advisable to obtain the fastest processor available. Crown copyright Met OfficeSupport and follow-upSupportE-mail to the Hadley Centre ([email protected])Online discussion forum hosted by http://climateprediction.netWeb sitehttp://www.metoffice.gov.uk/precisnewsupdatesresourcesCollaboration/workshops13PRECIS users will be able to get assistance from Hadley Centre staff by email or phone and also via a web-based discussion group. The website will provide information on what PRECIS is being used for, future plans, any updates to PRECIS, relevant datasets which users may find useful (small enough to be downloaded) and a list of resources, such as relevant papers and reports. Finally, Hadley Centre staff will be keen to collaborate on research and scientific publications involving PRECIS and to attend, and possibly help organise, workshops where collaborators are presenting and discussing results from PRECIS. Crown copyright Met OfficeWhat PRECIS can deliverPRECIS can provide:climate scenarios for any regionan estimate of uncertainty due to different emissionsan estimat