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wdc-climate.de:3501913 eng; USA collection TRIM-NP-2d-PCA_ResCurr Dr. Ulrich Callies Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH not filled pointOfContact Dr. Ulrich Callies Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH not filled pointOfContact 2015-12-11T10:23:25 ISO 19115 ISO 19115-2:2009 coastDat-2 Hydrodynamic Model TRIM-NP Principal Component Analysis Residual Currents 2016-03-15 publication 1 TRIM-NP-2d-PCA_ResCurr doi:10.1594/WDCC/TRIM-NP-2d-PCA_ResCurr Dr. Ulrich Callies Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH not filled Email: ulrich.callies@hzg.de principalInvestigator Dr. Ulrich Callies Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH not filled Email: ulrich.callies@hzg.de author WDC Climate at DKRZ publisher Simulated 2D residual velocity fields in the inner German Bight were subjected to Principal Component Analysis (PCA). Residual currents were obtained from coastDat2 barotropic 2D simulations with the hydrodynamic model TRIM-NP V2.1.22 in barotropic 2D mode on a Cartesian grid (1.6km spatial resolution) stored on an hourly basis for the years 1948 - 2012 (doi:10.1594/WDCC/coastDat-2_TRIM-NP-2d) and later extended until August 2015. The present analysis refers to the period Jan 1958 - Aug 2015. The spatial domain considered is the region to the east of 6 degrees east and to the south of 55.6 degrees north. All grid nodes with a bathymetry of less than 10m were excluded. Residual velocities were calculated in two different ways: 1.) as 25h means, 2.) as monthly means. Both types of residual current data are available from * RESIDUAL_CURRENTS_195801_201508 The directory contains sub-directories for years and months. Daily residual currents for the 13th of September 1974, for instance, are stored in * RESIDUAL_CURRENTS_195801_201508/YEAR_1974/MONTH_09/TRIM2D_1974_09_13_means.nc while monthly mean residual currents for September 1974 are stored in: * RESIDUAL_CURRENTS_195801_201508/YEAR_1974/TRIM2D_1974_09_means.nc All current fields provided were interpolated from the original Cartesian model grid to a more convenient regular geographical grid (116x76 nodes). Mean residual currents are stored in: * mean_residual_currents.nc This data set contains residual velocities both on original Cartesian grid nodes and interpolated to the geographical grid. An example plot is provided: * mean_residual_currents.png For PCA, two residual velocity components from each of 12133 Cartesian grid nodes were combined into one data vector (length 2x12133), referring to 21061 daily or 692 monthly time levels. Results of two independent PCAs for either daily or monthly mean fields are stored in: * PCA_daily_residual_currents.nc * PCA_monthly_residual_currents.nc Files contain three leading Principal Components (PCs) and corresponding Emipirical Orthogonal Functions (EOFs). Again EOFs were also interpolated to a regular geographical grid. PC time series are also stored in plain ASCII format: * PCs_daily.txt * PCs_monthly.txt For monthly fields the number N of variables (N=2x12133) is much larger than the number T of time levels (T=692). Therefore, to reduce computational demands, the roles of time and space were formally interchanged. Having conducted the PCA the EOFs were then transformed back to the original spatial coordinates (cf. Section 12.2.6 in von Storch and Zwiers (1999), Statistical Analysis in Climate Research, Cambridge University Press). A much larger number of time levels made even this approach prohibitive for the full set of daily data. Therefore, PCAs were performed for six sub-periods (1958-1965, 1966-1975, 1976-1985, 1986-1995, 1996-2005, 2006-2015(Aug)) independently. EOFs obtained from these six sub-periods were then averaged to obtain EOFs representative for the whole period. Corresponding PCs were calculated by projecting daily fields onto these average EOFs. IMPORTANT: In contrast with PCA of monthly data, the PCA of daily data INVOLVES SOME APPROXIMATIONS! EOFs on the original nodes were normalized to have unit lengths. The following figures, * daily_EOF1.png * daily_EOF2.png * daily_EOF3.png show the first three EOFs obtained from daily data, assuming that corresponding PCs have the value of one standard deviation. The following two plots, * monthly_EOF1.png * monthly_EOF2.png show the leading EOFs for monthly mean data. EOF3 is omitted as it represents just a very small percentage of overall variance (1.7%). Dr. Ulrich Callies Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH not filled pointOfContact zip-file ascii NetCDF climate simulation coastdat hindcasting regional modelling scientific use: For scientific use only eng; USA 6.0 9.0 53.3 55.6 gregorian 1958-01-01 2015-08-31 10 variables: sea_floor_depth_below_geoid; PC1; EOF1_u_grd; EOF1_v_grd; PC2; EOF2_u_grd; EOF2_v_grd; PC3; EOF3_u_grd; EOF3_v_grd 10 variables: sea_floor_depth_below_geoid; PC1; EOF1 residual current, eastward component; EOF1 residual current, northward component; PC2; EOF2 residual current, eastward component; EOF2 residual current, northward component; PC3; EOF3 residual current, eastward component; EOF3 residual current, northward component; unit: n/a PC1, PC2, PC3 not filled; unit: n/a 3 variables: sea_floor_depth_below_geoid; Mean residual current, eastward component; Mean residual current, northward component not filled; unit: n/a 2 variables: Mean residual current, eastward component; Mean residual current, northward component not filled; unit: n/a zip-file ascii NetCDF 895 https://www.wdc-climate.de/ui/entry?acronym=TRIM-NP-2d-PCA_ResCurr information collection n/a None n/a None n/a None