Welcome to the PRECIS training workshop Tanzania Meteorological Agency, 29th June – 3rd July 2015

Objectives of this workshop… During the next four days, we will be learning about the science of climate modelling and climate change with an emphasis on regional climate modelling using PRECIS. We’ll cover: Modelling the Earth’s climate Downscaling Techniques Uncertainties, and ways to address them Designing Experiments Validating Experiments Addressing extreme events Model Formulation We’ll spend time learning about the output data from PRECIS and how to analyse it. You’ll do this by working through tutorial worksheets in a Linux environment. Other needs? Let us know, and we will try our best to help.

Contents Table of Contents What is PRECIS? Why was PRECIS developed? Who is PRECIS for? Where PRECIS fits in What is an RCM and what information does it need as input? PRECIS 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, and A visualisation and data processing package to allow display and manipulation of RCM output.

What is PRECIS? Providing REgional Climates for Impact Studies It’s not just a regional model – it’s a whole product *system* PRECIS can be applied to any area of the globe PRECIS can be used to generate detailed projections of future climate PRECIS has a simple user interface to set up and run a regional climate model (RCM) PRECIS also provides utilities for users to manipulate RCM output PRECIS is a regional climate modelling system developed at the Hadley Centre that can run on a PC and comprises:

Why was PRECIS developed? There’s a UNFCCC requirement for countries to assess national vulnerability to climate change and to make plans for adaptation Annex II countries are called on to transfer technology to non-Annex II countries to help them fulfil this requirement. PRECIS allows non-Annex II countries to resolve local details and provide realistic extreme events for impact studies generate their own national scenarios of climate change for use in impact studies The PC version of PRECIS addresses the UNFCCC requirement on the UK to assist capacity building and technology transfer UFNCC - United Nations Framework Convention on Climate Change Regional 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 Centre’s 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.

Who is PRECIS for? Anyone interested in understanding climate change and its potential impacts Highly relevant for scientists involved in vulnerability and adaptation studies (particularly for National Communications reports) Very useful for groups of scientist and researchers in a single region to work together and share results PRECIS 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.

Where PRECIS fits in IPCC National research centres PRECIS You! To 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.. You!

What is a Regional Climate Model? An RCM is a mathematical model of the atmosphere and land surface, with a representation of the ocean surface ‘High’ resolution: Produces data in grid cells ≤ 50km in size Spans a limited area (region) of the globe An RCM contains representations of many of the important physical processes within the climate system Cloud Radiation Rainfall Atmospheric aerosols Soil hydrology Etc. 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. 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.

Input (boundary) data Limited area regional models require meteorological information at their edges (lateral boundaries) These data provide the interface between the regional model’s domain and the rest of the planet The climate of a region is always strongly influenced by the global situation These data are necessarily provided by global general circulation models (GCMs) or from observed data sets with global coverage (re-analysis experiments) The nested regional climate modelling technique consists of using initial conditions, time-dependent lateral meteorological conditions and surface boundary conditions to drive high-resolution RCMs. The driving data is derived from GCMs (or analyses of observations) and can include GHG and aerosol forcing. A variation of this technique is to also force the large scale component of the RCM solution throughout the entire domain. To date, this technique has been used only in one-way mode, i.e. with no feedback from the RCM simulation to the driving GCM. The basic strategy is thus to use the global model to simulate the response of the global circulation to large scale forcings and the RCM to a) account for sub-GCM grid scale forcings (e.g. complex topographical features and land cover inhomogeneity) in a physically-based way; and b) enhance the simulation of atmospheric circulations and climatic variables at fine spatial scales.

The components of the PRECIS system The RCM User interface to design and configure RCM experiments Display and data processing software Lateral boundary and initial conditions Training course and materials The PRECIS technical manul and scientific handbook Technical and Scientific Support web forum (http://forum.precisrcm.com) Data sharing website (http://www.precisrcm.com) Main Website (http://www.metoffice.gov.uk/precis) In 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.

The PRECIS user interface The 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.

PRECIS user interface: main functionality Region specification Choice of domain Land surface configuration RCM and Emissions scenario Time period of the simulation Output data Run, Halt and Restart the experiment

Boundary conditions First run a test experiment using the sample data included with PRECIS Then request a full set through precis@metoffice.gov.uk The boundary conditions for the PRECIS RCM are clearly an integral part of the system but as they comprise a very substantial amount of data (20-30 Gigabytes for a 30-year simulation) they have to be supplied separately. They are stored online at the Hadley Centre and will be made available on request through a web-based interface. The data will then be supplied on a storage medium specified by the user.

Minimum hardware requirements Computer: PC running under the Linux operating system Dual core CPU Memory : 512MB minimum; 1+ GB recommended Minimum 250GB disk space + offline storage for archiving data Simulation speed proportional to CPU speed The 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. 30 year integration, 100x100, 50km grid points 4 cores: ~ 2.75 weeks 8 cores: ~ 12.5 days

What PRECIS can deliver PRECIS can provide: climate scenarios for any region an estimate of uncertainty due to different emissions an estimate of uncertainty due to climate variability Data available from PRECIS: Comprehensive and consistent meteorological and physical data for the atmosphere and land-surface Hourly and daily data as well as longer timescale averages In summary, PRECIS can provide climate scenarios for any region, allowing for an estimate of uncertainty from different emissions and due to climate variability (though this is only a small part of the total uncertainty in climate scenarios). The output from PRECIS includes a comprehensive set of data from the atmosphere and land surface, which represent grid-box mean quantities, with a maximum time resolution of one hour.

Future developments Continuously upgraded to reflect new CPUs, new compilers and new versions of Linux Ability to run PRECIS RCM from more GCMs/Reanalyses More IPCC AR5 GCMs will become available during 2015 Output of PRECIS in CF-compliant NetCDF format directly Incorporation of the Met Office IRIS analysis and visualisation software PRECIS is continuously being tested on new processors to ensure it works so enabling the quickest run times to be achieved. The ability to run PRECIS using boundary conditions from different GCMs will be added as these come available. Currently, there are plans to provide an interface to the ECHAM model and discussions are happening with other global modelling centres to obtain access to the necessary data. There is a version of the PRECIS RCM which has been run at 25km and this functionality is included in PRECIS for short integrations or small areas. The Hadley Centre is currently building a new RCM which will be able to be run at resolutions of up to 10km.

Support and follow-up For support: Online discussion forum hosted by http://forum.precisrcm.com E-mail the PRECIS team (precis@metoffice.gov.uk) Website http://www.metoffice.gov.uk/precis Collaboration/workshops PRECIS 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.

Summary PRECIS: The Met Office Hadley Centre’s regional climate modelling system Resolution of 50km (25km for small areas) Runs on a Linux based PC; supplied on a DVD or via download, comes with sample driving data Can be set up by the user to run over any area of the globe Useful for vulnerability and adaptation studies and climate research Provides the capacity to locally produce scenarios of climate change The PRECIS RCM is currently configured to run at 50 and 25km though the computational expense of using higher resolution means it is only appropriate for small areas or short simulations. PRECIS is supplied on two DVD-ROMs which includes over three years of sample boundary conditions for initial testing of the system. In standard configuration PRECIS is used for a region which is typically 5000 square kilometres though smaller or larger regions can be used if appropriate. It can be used for any region of the globe and thus is applicable in countries and regions which currently have no modelling capability thus enabling them to produce their own scenarios of climate change which can then be used in vulnerability and adaptation studies.

About the schedule… Morning session – basic understanding of RCM science i Climate modelling, model evaluation, uncertainties in climate projections, experimental design, extremes Afternoon session – hands-on practical sessions Running PRECIS Manipulate model outputs - the practical worksheets give examples of analyses that people often do with regional model data. Do not expect to finish ALL of the practical work! Think about which exercises are most relevant to you

Questions