For Baltic Sea Physical Analysis and Forecasting Product BALTICSEA_ANALYSIS_FORECAST_PHY_003_006

Transcription

1 For Baltic Sea Physical Analysis and Forecasting Product Contributors: V. Huess Issue: 2.0 CMEMS version scope : Version 4.0 Approval Date by the CMEMS products team : 12 March 2018

2 CHANGE RECORD Issue Date Description of Change Author Validated By 1.0 January 2013 All New product: MYO-BAL-PUM superseding old product (MYO-BAL-PUM ) V. Huess V. Huess 1.1 February March January December 2014 Minor changes V.Huess V. Huess Minor corrections V. Huess V. Huess Update for the V4 upgrade V. Huess V. Huess L. Crosnier Update for the V5 upgrade V. Huess L. Crosnier 1.5 May all Change format to fit CMEMS graphical rules L. Crosnier 1.6 January 2016 all Update for the CMEMS V2.0 upgrade V. Huess 1.7 March 2016 All Include comments from Mercator Ocean V. Huess 1.8 January 2017 all Update for the CMEMS V3.0 upgrade V. Huess 1.9 March 2017 All Design Update for the CMEMS V3.0 upgrade C. Derval, MO V. EU Copernicus Marine Service Public Page 2/ 19

3 2.0 January 2018 All Updated for the CMEMS V4.0/March 2018 system upgrade V. Huess CMEMS products team Table of contents I INTRODUCTION... 5 I.1 Summary... 5 I.2 History of changes... 5 II DESCRIPTION OF THE PRODUCT SPECIFICATION... 8 II.1 General Information... 8 II.2 Details of datasets... 9 II.3 Production System Description II.4 Processing Information II.4.1 Update Time II.4.2 Temporal extend of analysis and forecast stored on delivery mechanism III HOW TO DOWNLOAD A PRODUCT III.1 Download a product through the CMEMS Web Portal IV NOMENCLATURE OF FILES IV.1 Nomenclature of files when downloaded through the CMEMS Web Portal Subsetter Service IV.2 Nomenclature of files when downloaded through the CMEMS Web Portal FTP Service V FILE FORMAT V.1 Netcdf V.2 Reading software... EU Copernicus Marine Service Public Page 3/ 19

4 GLOSSARY AND ABBREVIATIONS MFC BAL NetCDF CF PC PU ftp OpenDAP Subsetter Directgetfile Monitoring and Forecasting Centre Baltic Network Common Data Form Climate Forecast (convention for NetCDF) Production Center Production Unit Protocol to download files Open-Source Project for a Network Data Access Protocol. Protocol to download subset of data from a n-dimensional gridded dataset (ie: 4 dimensions: lon-lat,depth,time) CMEMS service tool to download a NetCDF file of a selected geographical box using values of longitude an latitude, and time range CMEMS service tool (FTP like) to download a NetCDF EU Copernicus Marine Service Public Page 4/ 19

5 PUM for Baltic Sea Physical Analysis and Forecasting Product BALSEA_ANALYSIS_FORECAST_PHY_003_006 Ref:CMEMS-BAL-PUM Date January 2018 I INTRODUCTION I.1 Summary This guide describes the data product from the Copernicus Marine Environment Monitoring Service s (CMEMS) Baltic Monitoring and Forecasting Centre (BAL MFC), what data services are available to access them, and how to use the files and services. The product CMEMS s operational physical product for the Baltic Sea and contains model calculations for the physical condition in the Baltic Sea. Data are served with hourly resolution for the surface parameters: sea surface height variations and sea ice concentrations and thickness, and for the 3D parameters: temperature, salinity and horizontal velocities with 25 vertical levels. A new forecast for the next 5 days (120 hours) is produced twice per day and updated into the CMEMS Catalogue at 10 AM and 10 PM. Model hindcast data are available 2 years back in time in the online CMEMS Catalogue. The product is based on simulations with the HBM ocean model code (HIROMB-BOOS-Model). See the Quality Document CMEMS-BAL-QUID for more information on the products quality. I.2 History of changes On March (V4) the following changes occurred: The HBM ocean code was upgraded by these improvements: o The thermodymic routine has been re-tuned, i.e. a modified near surface heat conduction, a modified insolation and heat absorption in the surface layer as well as a modified heat release through openings in sea ice, has been introduced. This new thermodynamic routine should improve especially the description of sea ice during growing and melting season. In addition some changes in the model description of sea surface temperature are expected. For the data product these changes have been included: EU Copernicus Marine Service Public Page 5/ 19

6 o The forecast product will from the March 2018 upgrade consists of a 5 days forecast (120 hours) produced by forcing the model system HBM-ERGOM with DMI- HARMONIE weather forcing for the first 2.5 days and with forcing data from ECMWF for the next 2.5 days. o The bottom salinity has been included as a variable in the product. Defined as the salinity in the lowest grid cell in the native model calculation grid. o A new dataset with monthly means are included. o A slight change in the daily mean dataset: o The daily means are now calculated as 24 hours means (previous 25 hours means were used). o The products will be served in netcdf4 format. On April (V3) the following changes occurred: The HBM ocean code was upgraded by these improvements: o Sea ice module has been improved by including fast ice. o Turbulence scheme has been further developed and improved o Technical performance of the code has been improved. See the Quality Document CMEMS-BAL-QUID for more information. Further the dataset names have been slightly renamed. On April (V2) the following changes occurred: Two new variables are included in the product: The mixed layer depth: Calculated by the density gradient method by de Boyer Montégut (2004) with a threshold value of 0.03 kg/m 3 for a reference depth of 10 meters. The bottom temperature: Defined as the sea water temperature in the lowest grid cell in the native model calculation grid. Further daily mean values are provided for all variables in addition to the hourly instantaneous values. The daily means are calculated in post-process mode by a simple mean of 25 time steps (midnight EU Copernicus Marine Service Public Page 6/ 19

7 On April (V1) the following changes occurred: o Temporal coverage available online is increased from [3 months ago; ongoing] up to [2 years ago; ongoing] o The HBM code is improved : The baroclinic pressure gradient has been improved by handling aliasing between the barotropic and baroclinic pressure calculations. Allowing automatic temporary sub-division of tracer advection time step. This feature is needed in severe storm events The tidal potential is included additional to the prescribed tidal constituents at the open boundaries. At the rivers, the temperature of the inflow is updated more EU Copernicus Marine Service Public Page 7/ 19

8 II DESCRIPTION OF THE PRODUCT SPECIFICATION II.1 General Information Product Specification BALTIC_ANALYSIS_FORECAST_PHY_003_006 Geographical coverage 9 E 30 E ; 53 N 66 N Variables Analysis Forecast Available time series Temporal resolution Target delivery time Delivery mechanism Horizontal resolution Number of vertical levels Format Sea surface variations Ice concentration and thickness Temperature Salinity Horizontal velocities (eastward and northward) Mixed Layer Depth (MLD) Bottom Temperature Bottom Salinity Yes Yes: 120 hours forecasts The latest 2 years of model forecasts are available on-line via the CMEMS webportal. Model data older than 2 years are available on request to the CMEMS Service Desk: servicedesk.cmems@mercator-ocean.eu Hourly instantaneous values. Daily mean values Monthly mean values New Forecast: twice daily at 10 am and 10 pm UTC. CMEMS Information System (Subsetter and FTP) App. 1 nautical miles: Delta Longitude: 1 40 or degrees Delta Latitude: 1 or degrees Up to 25 levels. Levels [m]: 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 150, 200, 300, 400 Netcdf & CF1.0 Table 1: Product EU Copernicus Marine Service Public Page 8/ 19

9 II.2 Details of datasets BALTIC_ANALYSIS_FORECAST_PHY_003_006 dataset-bal-analysis-forecast-phy-hourly contains: hourly instantaneous values dataset-bal-analysis-forecast-phy-dailymeans contains: daily mean values (24 hours average) dataset-bal-analysis-forecast-phy-moonthlymeans contains: monthly mean values dataset-bal-analysis-forecast-phy-hourly dataset-bal-analysis-forecast-phy-dailymeans dataset-bal-analysis-forecast-phy-monthlymeans Variables name in the NetCDF file and Unit Long_name Standard_name sla [m] Sea level anomalies sea_surface_height_above_sea_level U0 [m/s] Eastward current eastward_sea_water_velocity v0 [m/s] Northward current northward_sea_water_velocity so [1e-3] Salinity sea_water_salinity thetao [degree_c] Potential temperature sea_water_potential_temperature sithick [m] Sea ice thickness sea_ice_thickness siconc [0, 1] Sea ice cover sea_ice_area_fraction mlotst [m] Ocean mixed layer thickness defined by density (as in de Boyer Montegut, 2004) ocean_mixed_layer_thickness_defined_by_sigma_theta bottomt [degree_c] Sea floor potential temperature (given for depth comprise between 0 and 500m) sea_water_potential_temperature_at_sea_floor sob [1e-3] Sea water salinity at sea floor sea_water_salinity Table 2 list of the datasets (column 1) and variable names and unit (column2) for the BALTIC_ANALYSIS_FORECAST_PHY_003_006 EU Copernicus Marine Service Public Page 9/ 19

10 II.3 Production System Description The product is based on simulations with the HBM ocean model code (HIROMB-BOOS-Model). For details on the HBM ocean code please see (Berg, 2012; Berg and Poulsen, 2012; Poulsen and Berg, 2012; Poulsen and Berg, 2013). For information on the quality of the HBM results see CMEMS-BAL-QUID available via the CMEMS on-line Catalogue. The production of the forecast product for the physical conditions in the Baltic Sea is performed at DMI (the Danish Meteorological Institute), EU Copernicus Marine Service Public Page 10/ 19

11 II.3.1 Summary of the operational model EU Copernicus Marine Service Public Page 11/ 19

12 Summary of the operational model setups:domain North Sea Baltic Sea : 53 N - 66 N, 9 E - 30 E Resolution and grid Geographic coverage The horizontal grid step is regular in latitude and longitude and is of approximately 1 nautical miles (lat: degrees; lon: degrees) for. The grid is a staggered Arakawa C-grid (see figure 1). The dataset of the scalar variables (temperature, salinity, sea Level, ice, and biogeochemical variables) are centred in the T point of the grid; at the grid cell node. The velocity components are located half-way between adjacent grid cell nodes on the face of the grid cell in the respective direction. That is, the components of the velocity vector (u, v) have spatially staggered locations. Figure 1: The staggered Arakawa C-grid used by BAL-MFC numerical models. VARIABLE GRID LON MIN LON MAX LAT MIN LAT MAX XPOINT All scalar variables (see text) Eastward velocity Northward velocity T E E N N 767 u As above As above As above As above As above v As above As above As above As above As above Table 3: Description of the staggered grid and spatial coverage for each EU Copernicus Marine Service Public Page 12/ 19

13 Bathymetry GEBCO at 1-minute resolution Vertical grid 25 levels [m]: 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 150, 200, 300, 400. Model Version Production units Period of validation Assimilation scheme Assimilated observations Initial conditions (spin-up process) The model native computational grid has a higher resolution (Maximum number of model depth levels: 122) N/A N/A HIROMB-BOOS-Model V4 DMI The model started at July 1 st 2013 Surface forcing and boundary forcing The DMI calibration set up uses meteorological data from the DMI- HIRLAM SKA with a horizontal resolution of 3 km. The forecast production is produced with forcing from the DMI- HARMONIE 2.5 km system for the first 2.5 days, and the available ECMWF forcing for the next 2.5 days. At the models open boundaries surge data are used from a separate 2D surge model. Further climatological values for temperature and salinity are used at the open boundaries in the North Sea. Furthermore model derived climatology is used for a baroclinic correction at the open northern boundary in the North Sea. River run-off Data from the operational hydrological model HBV of SMHI (Bergström, 1976 and Bergström, 1992). Furthermore observations from BSH are included when available For more details see section EU Copernicus Marine Service Public Page 13/ 19

14 II.4 Processing Information II.4.1 Update Time The product is updated twice daily at 10 am and 10 pm. The production and update is like this: The ocean model is run twice per day for the 00Z and 12Z analyses following this schedule: The ocean model run starts when the weather model forecast for the 00Z analysis or 12Z analysis has finalized. First a 12 hours hindcast for the ocean is re-calculated with the best available weather analysis fields covering the 12 hours before the analysis time. This is followed by a 120 hours forecast calculation for the ocean with the new calculated weather forecast as forcing fields. These ocean model data are after calculation processed onto the BAL MFC product grid and the products are updated as indicated in the figure above: 1 file containing the 12 hours best estimate for the hindcast period: these data substitutes the first 12 hours of the previous analysis forecast. 10 files containing the latest available 120 hours forecast, i.e. each file contains 12 hours of data. The Baltic ocean data are updated at the CMEMS server at 10 UTC and 22 UTC at the latest for the 00 UTC and 12 UTC analysis, respectively. Example of a product update: for the analysis valid at 00Z April 15 th 2017 the ocean model run will start at 03 AM UTC and the results will be updated into the CMEMS Catalogue at 10 AM UTC with these 6 new netcdf files: - The 12 hours hindcast (best estimate) BAL-HBMV2_PHY nc This is a re-calculation of the previous forecast; and by that replaces the results in the file with the same name produced at the previous analysis from April 14 th 12Z. - The new 60 hours forecast covering the period April 15 th 0Z April 17 th 12Z in these 10 files: BAL-HBM_PHY nc BAL-HBM_PHY nc EU Copernicus Marine Service Public Page 14/ 19

15 BAL-HBM_PHY nc BAL-HBM_PHY nc BAL-HBM_PHY nc BAL-HBM_PHY nc BAL-HBM_PHY nc BAL-HBM_PHY nc BAL-HBM_PHY nc II.4.2 Temporal extend of analysis and forecast stored on delivery mechanism product s temporal coverage: In the CMEMS online system data from the latest 2 years (running window) are available via these 3 download interfaces: via Subsetter, FTP download, and DirectGetFile Older data are archived in the Production Unit, and will be made accessible on request. Please contact the CMEMS Service Desk EU Copernicus Marine Service Public Page 15/ 19

16 III HOW TO DOWNLOAD A PRODUCT Before download of a product you first need to register. Please register through CMEMS web page by following link 'Register now' ( or see the online tutorial at III.1 Download a product through the CMEMS Web Portal Once registered, the tutorial: will guide you on How to download a EU Copernicus Marine Service Public Page 16/ 19

17 IV NOMENCLATURE OF FILES IV.1 Nomenclature of files when downloaded through the CMEMS Web Portal Subsetter Service file nomenclature when downloaded through the CMEMS Web Portal Subsetter is based on product dataset name and a numerical reference related to the request date. The scheme is: datasetname_nnnnnnnnnnnnn.nc where : datasetname is the character string : dataset-bal-analysis-forecast-phy-hourly dataset-bal-analysis-forecast-phy-dailymeans dataset-bal-analysis-forecast-phy-monthlymeans nnnnnnnnnnnnn: 13 digit integer corresponding to the current time (download time) in milliseconds since January 1, 1970 midnight UTC..nc: standard NetCDF filename extension. IV.2 Nomenclature of files when downloaded through the CMEMS Web Portal FTP Service file nomenclature when downloaded through the CMEMS FTP service is based on the original file names behind the products. The files are in NetCDF and are named: For the hourly instantaneous values: BAL-HBM_PHY- analysistime.nc Each file contains 12 hours of data. Analysistime indicate the first timestamp in the file. For the daily mean EU Copernicus Marine Service Public Page 17/ 19

18 BAL-HBM_PHY-DailyMeans- ccyymmdd.nc Each file contains 1 timestamp for the calendar day. For the monthly mean values: BAL-HBM_PHY-MonthlyMeans- ccyymm.nc Each file contains 1 timestamp for the calendar EU Copernicus Marine Service Public Page 18/ 19

19 V FILE FORMAT V.1 Netcdf The products are stored using the NetCDF format. NetCDF (network Common Data Form) is an interface for array-oriented data access and a library that provides an implementation of the interface. The netcdf library also defines a machineindependent format for representing scientific data. Together, the interface, library, and format support the creation, access, and sharing of scientific data. The netcdf software was developed at the Unidata Program Center in Boulder, Colorado. The netcdf libraries define a machineindependent format for representing scientific data. Please see Unidata netcdf pages for more information, and to retrieve netcdf software package. NetCDF data is: * Self-Describing. A netcdf file includes information about the data it contains. * Architecture-independent. A netcdf file is represented in a form that can be accessed by computers with different ways of storing integers, characters, and floating-point numbers. * Direct-access. A small subset of a large dataset may be accessed efficiently, without first reading through all the preceding data. * Appendable. Data can be appended to a netcdf dataset along one dimension without copying the dataset or redefining its structure. The structure of a netcdf dataset can be changed, though this sometimes causes the dataset to be copied. * Sharable. One writer and multiple readers may simultaneously access the same netcdf file. V.2 Reading software NetCDF data can be browsed and used through a number of software, like: ncbrowse: NetCDF Operator (NCO): IDL, Matlab, EU Copernicus Marine Service Public Page 19/ 19