Ancillary File Tutorial Keir Bovis June 2013 © Crown copyright Met Office
Overview of the tutorial • What is an ancillary file ? • Review and summarise some important ancillary files used in NWP. • Creating ancillary files using the Central Ancillary Program (CAP) • Creating ancillary files from PP formatted data and Net. CDF. © Crown copyright Met Office
What is an ancillary file ? • Ancillary files are the mechanism by which external data sources are entered into the Unified Model (UM). • Ancillaries files typically comprise static data held on disk in UM fields file format. • Ancillary files may hold data relating to model orography, soil and vegetation types, and climatologies for sea surface temperature and sea ice amongst others. • At the UK Met Office, the Central Ancillary Program (CAP) creates ancillary files by reading post-processed source data and writing them in UM fields file format. © Crown copyright Met Office
Ancillary files SST/ice climatology Soil moisture/snow climatology Vegetation surface type and LAI Soil parameters Model orography (topography) Land-sea mask © Crown copyright Met Office Assumed underpinning hierarchy
Land-sea mask • Name: qrparm. mask • Key field: • Land mask stored as a logical field (1=land, 0=sea) • Application: • Key ancillary used to differentiate between land sea points. • The field is usually stored in model start dumps. • Source: • International Geophysical Biosphere Programme (IGBP). http: //edc 2. usgs. gov/glcc/globe_int. php • 1 km resolution obtained from Advanced Very High Resolution Radiometer (AVHRR) data spanning April 1992 to March 1993. © Crown copyright Met Office
Land-sea mask Sea points Land points Note the absence of inland lakes. Majority of these are defined as land points with a surface type of inland water and not as sea points. © Crown copyright Met Office
Land-sea mask: post-processing • The default land-sea mask generated by the Central Ancillary Program (CAP) may not be suitable for use in NWP models. • For example, very small lakes and islands may lead to numerical instabilities and run-time failures in NWP models. Alternatively, some land points are missing in the IGBP data set, e. g. Hawaii, Chatham Islands, etc. • A facility exists with the CAP to allow the user to override the default mask and reassign land to sea point and vice-versa. • The overrides may be manually created using a facility in the CAP or by using the graphical IDL-based tool ‘edit_lsm’ (we will see both approaches in the workshop later). © Crown copyright Met Office
Model orography (topography) • Name: qrparm. orog • Key fields: • Mean orography in grid box (metres above sea level), standard deviation and three gradient orography fields. • Application: • These fields are used in gravity wave drag scheme, radiation scheme and hydrological inundation models. Stored in model start dumps. • Source: • Global models use the GLOBE dataset at 1 km resolution. http: //www. ngdc. noaa. gov/mgg/topo/globe. html • UK regional models use restricted military DTED dataset. • Alternative data sets include the Shuttle Radar Topography Mission (SRTM) data set http: //www 2. jpl. nasa. gov/srtm/cbanddataproducts. html © Crown copyright Met Office
Model orography – mean field © Crown copyright Met Office
Orography: post-processing • Filtering is applied to remove scales shorter than 6 km so that features too small to generate flow blocking and gravity waves are not included. • Inland lakes are automatically detected and given values as if they were land points. If a high lake such as Lake Victoria is given a height of zero then it is likely that the model will fail. © Crown copyright Met Office
Soil parameters • Name: qrparm. soil • Key fields: • Soil moisture volume content at critical, wilting and saturation points. • Application: • Describe the physical properties of the soil and are important in correctly determining the surface energy / soil moisture balance and the exchange of moisture and heat between the atmosphere and land surface. • Source: • NWP previously used Wilson & Henderson-Sellers (WHS) at resolution 1° latitude X 1° longitude originally designed for climate models. • More up-to-date Harmonised World Soils Database (HWSD) at 1 km resolution is now used operationally. As quality is variable it is supplemented with other regional soils datasets using an optimal interpolation scheme. http: //www. fao. org/nr/water/news/soil-db. html © Crown copyright Met Office
Soil parameters – key soil fields Critical point Saturation point Soil pores filled with water and soil is said to be saturated. There is no air left in the soil. Accurate specification of these fields is important as they are used in calculating the movement of water through the implemented soil hydraulic scheme Irrigation Water Management: Introduction to irrigation, FAO. © Crown copyright Met Office After drainage has stopped, large pores in soil are full of air and smaller are full of water. Wilting point The point at which a plant wilts, there is not enough water in the soil for the plant root to extract.
Soil parameters – soil hydraulics • Soil hydraulic schemes are used to parameterise the rate of infiltration of water through the soil by describing the relationship between volumetric soil moisture and soil suction. • Two different schemes have been implemented in Met Office models, Clapp and Hornberger and van Genuchten each requiring there own soil ancillaries. • Correct parameterisation of each scheme will ensure correct water ponding and run-off over the ground surface. © Crown copyright Met Office
Vegetation fraction • Name: qrparm. veg. frac • Key fields: • Fraction of surface type expressed as a value (0 -1). • Application: • Describe the fraction of each grid box that occupies each surface type defined within the land-surface model. • Used in land-surface model and surface analysis. • Source: • International Geophysical Biosphere Programme (IGBP). http: //edc 2. usgs. gov/glcc/globe_int. php © Crown copyright Met Office
Vegetation fraction types land-surface scheme implemented in the UM recognises 9 surface types: Broad leaf tree Shrub © Crown copyright Met Office Needle leaf tree Urban C 3 grass Inland water Bare soil C 4 grass Land ice
Vegetation fraction types The impact of incorrect specification of surface types affects evapotranspiration in NWP models. © Crown copyright Met Office
Veg fraction: post-processing • Source IGBP data is interpolated onto the model grid and the fraction of each of the IGBP classes present is calculated. • Not every IGBP grid point has a defined class and final totals are adjusted to remove any areas of missing data. IGBP classes consisting of less than 1% of the grid box are eliminated, the area reallocated to other classes. • The fraction totals of the 9 UM surface types are calculated by mapping IGBP classes to UM surface types using mapping weights. © Crown copyright Met Office
Veg fraction: post-processing 17 IGBP vegetation classes 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. Evergreen Needleleaf Forest Evergreen Broadleaf Forest Deciduous Needleleaf Forest 9 fractional UM classes Deciduous Broadleaf Forest Mixed Forest Closed Shrublands are to Open Shrublands mapped Woody Savannas Grasslands Permanent Wetlands Croplands Urban and Built-Up Cropland/Natural Vegetation Mosaic Snow and Ice Barren or Sparsely Vegetated Water Bodies © Crown copyright Met Office be on to 1. 2. 3. 4. 5. 6. 7. 8. 9. Fraction of broadleaf trees Fraction of needleleaf trees Fraction of C 3 grass Fraction of C 4 grass Fraction of shrub Fraction of urban Fraction of water Fraction of bare soil Fraction of ice
IGBP -> UM mapping weights for vegetation fraction totals UM surface types Broadleaf Needleleaf C 3 Grass C 4 Grass Shrub Urban Water Bare soil Ice Evergreen needleleaf 0. 0 70. 0 20. 0 0 0. 0 10. 0 Evergreen broadleaf 85. 0 0. 0 10. 0 5. 0 0. 0 Deciduous needleleaf 0. 0 65. 0 25. 0 0. 0 10. 0 Deciduous broadleaf 60. 0 5. 0 10. 0 5. 0 0. 0 20. 0 Mixed forest 35. 0 20. 0 0. 0 10. 0 Close shrub 0. 0 25. 0 0. 0 60. 0 15. 0 0. 0 Open shrub 0. 0 5. 0 10. 0 35. 0 0. 0 50. 0 Woody savanna 50. 0 15. 0 0. 0 25. 0 0. 0 10. 0 Savanna 20. 0 75. 0 0. 0 5. 0 0. 0 Grassland 0. 0 66. 0 15. 7 4. 9 0. 0 13. 5 0. 0 Permanent wetland 0. 0 80. 0 20. 0 Cropland 0. 0 75. 0 0. 0 20. 0 Urban 0. 0 0. 0 100. 0 Cropland/natural mosaic 5. 0 55. 0 10. 0 Snow and ice 0. 0 0. 0 100. 0 Barren 0. 0 0. 0 100. 0 Inland water 0. 0 0. 0 100. 0 IGBP class © Crown copyright Met Office Composite mapping 1 -to-1 mapping
Leaf Area Index (LAI) • Name: qrparm. veg. func • Key field: • The Leaf Area Index (LAI) is a measure of leaf area on each of the vegetative surface types. • Application: • LAI used in land-surface model in the determination of surface moisture and heat fluxes, through impact on transpiration, controlling the partitioning between surface sensible and latent heat fluxes. • Source: • Seasonal climatology derived from monthly means of the Moderate Resolution Imaging Spectroradiometer (MODIS) global 4 km LAI product, from 2005 -2009. ftp: //primavera. bu. edu/pub/datasets/MODIS/MOD 15_BU/C 5/LAI/data/monthly/ 4 km/ © Crown copyright Met Office
Leaf Area Index (LAI) LAI is the total one-sided area of leaves in a vertical column, within a unit area of ground © Crown copyright Met Office
MODIS Broadleaf trees LAI July climatology Time-varying zonal mean Boreal forest growth December climatology SH NH summer © Crown copyright Met Office NH
MODIS needleleaf trees LAI July climatology Time-varying zonal mean Boreal forest growth December climatology SH © Crown copyright Met Office NH summer NH
SST & sea-ice climatologies • Name: qrclim. sst, qrclim. seaice • Key fields: • The skin SST is the temperature of the top few micrometres over sea points at 12 monthly intervals. • Fraction of sea-ice in sea over at 12 monthly intervals. • Application: • Both fields used in land-surface model and in construction of surface analyses. • Source: • The Met Office Hadley Centre's sea-ice and Sea Surface Temperature (SST) data set, Had. ISST 1, created from monthly globally-complete fields of SST and sea-ice concentration on a 1 degree latitude-longitude grid from 1870 to-date http: //www-hc/~hadobs/www. hadobs. org/hadisst/ © Crown copyright Met Office
Sea surface temperature climatology Zonal mean of 12 month climatology SH NH summer © Crown copyright Met Office NH Monthly climatology for July
Sea-ice climatology Zonal mean of 12 month climatology Monthly climatology for January The sea ice thickness field is arbitrarily assigned values of 2 m in the Arctic and 1 m in the Antarctic. However, a separate dataset exists for models that have variable sea-ice thickness. © Crown copyright Met Office
Soil moisture climatology • Name: qrclim. smow • Key fields: • The soil moisture content in each soil layer at 12 monthly intervals. • Application: • The soil moisture climatology is used during the creation of a soil moisture analysis. • Different climatologies will exist depending on soil parameters and soil hydraulic scheme used. • Source: • The climatology is created by running the Joint UK Land Environment Simulator JULES model (standalone land-surface model) off-line for 10 years following a 6 year spin-up period. http: //www. jchmr. org/jules/ © Crown copyright Met Office
Soil moisture climatology Created using WHS soil parameters Created using HWSD soil parameters We hope the new climatologies are more realistic in the climatologies derived from the HWSD soil parameters. For example we see drier response over sandy soils in Portugal and finer structures as a result of increased HWSD resolution. © Crown copyright Met Office
Snow climatology • Name: qrclim. smow • Key fields: • The snow amount over land (kg/m-2) at 12 monthly intervals. • Application: • This ancillary is available for model initialisation. • Source: • Climatology created by constructed from Willmott and Rowe (WR) and source climatologies from the Atmospheric Model Intercomparison Project (AMIP) at 1° X 1° resolution. © Crown copyright Met Office
Snow climatology Zonal mean of 12 month climatology SH NH winter © Crown copyright Met Office NH Monthly climatology for February
Implementation of ancillary files • We’ve looked at the different types of ancillary files used in the unified model and now we move onto examine how these files are stored and used. • Specifically we will look at: • How they are created using the CAP • Other methods of creating them • Briefly how to visualise them © Crown copyright Met Office
Creating ancillary files • There are two methods used to create ancillary files: 1. Create them using the Central Ancillary Program (CAP). 2. Importing processed data into ancillary fieldsfile format from • a PP (Post-processed) format • A Net. CDF format. • We’ll look at the CAP first and then other methods of importing data. © Crown copyright Met Office
The Central Ancillary Program (CAP) • The CAP comprises a suite of FORTRAN, C and UNIX shell scripts that are run to construct ancillary files from a postprocessed data source. • Ancillary file content is generated according to a predetermined list of fields implemented in the code. • It is has been previously ported to IBM, NEC and Cray platforms. • Can also run on LINUX for use in the workshop that follows. • All code is version controlled using an subversion repository and FCM. © Crown copyright Met Office
pptoanc • This UM utility may be used to create an UM ancillary format fieldsfile from a PP data source. • PP files may have been used in IDL to carry out processing on ancillary file data. • The PP file must be converted back to fieldsfile format before it can be used in the UM. • It is run from the command line • pptoanc -hpf -n <namelist. File> <PPinput. File> <ancillary. File> • An example namelist file is shown in the next slide. © Crown copyright Met Office
pptoanc namelist &SIZES field_types=1, n_times=1, nlevels=70, n_pp_files=1, field_code=287, stash_code=57, nlevs_code=70, len_intc=15, len_realc=6 / &LOGICALS single_time=. true. pack 32=. true. , pphead=. true. field_order=. true. lwfio=. true. / &FIRST_VT fvhh=0, fvdd=0, fvmm=0, fvyy=0 / &INTERVAL year 360=f, ivhh=0, ivdd=0, ivmm=0, ivyy=0 / &LAST_VT lvhh=0, lvdd=0, lvmm=0, lvyy=0 / &HEADER_DATA fixhd(2)=1 fixhd(3)=1 fixhd(12)=600 / © Crown copyright Met Office Number of field types, times and max levels in PP file. Mapping of UM stash codes to PP field codes. Number of levels for each code. Length of integer and real constants array (15 & 6 for ancillaries) All input fields valid at a single time, pack real fields using 32 bit numbers print out pp headers read in, fields are ordered by time, output ancillary file or dump well-formed. Defines the first validity time of the ancillary data. Defines the time interval between the validity times. Defines the last validity time of the ancillary data. Used to overwrite values in the fieldsfile header: submodel=atmosphere; vertical coordinate. type=hybrid; model version number x 100 + release.
Xancil – creates ancillary files from Net. CDF sources • Written by Jeff Cole at the Department of Meteorology, University of Reading. • Xancil takes Net. CDF data and converts it into UM ancillary format. • Comprises a front-end Tcl/Tk GUI with the same look and feel as xconv. • Back-end processing is a compiled FORTRAN source single executable. • Xancil contains none of the CAP functionality and cannot operate on un-processed source data for the purpose ancillary file creation. © Crown copyright Met Office
Xancil overview Pre-defined set of known ancillary files to create Selected ancillary file has a predefined set of known fields Symbolic mapping to fields in Net. CDF source © Crown copyright Met Office
Viewing ancillary files • They can be viewed graphically using xconv or using in-house IDL routines such as pp_contour. • Contents can be dumped using the UM ‘pumf’ (print UM file) utilities. • Different versions of ancillary files can be compared using the UM ‘cumf’ (compare UM file) utility. © Crown copyright Met Office
Practical session • By the end of the practical session you should be able to: • Compile the CAP on a LINUX platform. • Create a default land-sea mask for use in a global NWP model. • Be able to manually edit the default land-sea mask to reassign land sea points. • Experiment in modifying a land-sea mask using the graphical edit_lsm tool. • Please copy the pdf below to access the tutorial: /home/h 01/frke/CAPworkshop. pdf (use evince to view it). • Please ask if you get stuck or have any questions. . © Crown copyright Met Office
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