Difference between revisions of "User:E Muller"

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__NOTOC__
 
{{Scientific}}
 
==Data acquisition from ECMWF==
 
The data for surface and pressure levels is delivered by ECMWF in FM-92 {{Gloshint|GRIB|GRIdded Binary. |GRIB}} format which is specified in WMO Publication 306 Manual on Codes.
 
  
6 products of the ECMWF model set are ingested into the MCYFS:
 
{|class="wikitable"
 
!Model set with ECMWF's abbrevation !! Abbreviation within Marsop-3 !!Number of forecast days !! Members !! Gaussian/Spectral grid* !! Horizontal model resolution* !! Acquired resolution** !! Emission of data files and maps
 
|-
 
|ERA-Interim**** || ERA || 1 || 1 || N128/T255 ||~80km || 0.75° x 0.75° || Once
 
|-
 
|Analysis HRES || OPE || 1 || 1 || N640/T1279 || ~16km || 0.25° x 0.25° || Daily (10.30 hr)
 
|-
 
|Deterministic forecast HRES || OPE ||10 || 1 || N640/T1279 || ~16km || 0.25° x 0.25° || Daily (12.00 hr)
 
|-
 
|Ensemble Prediction System ENS || ENS ||15 || 50+1 || N320 - N160 / T639 - T319 *** || ~30km / ~60km*** || 0.5° x 0.5° || Daily (14.00 hr)
 
|-
 
|Monthly forecast model ENS extended || MON ||32 || 50+1 || N320 - N160 / T639 - T319 *** || ~30km / ~60km*** || 0.5° x 0.5° || Every Friday (03.00 hr)
 
|-
 
|Seasonal forecast model SEAS || SEA ||183 || 50+1 || N128/T255 || ~80km || 0.75° x 0.75° || Every 8th of the month (14.00 hr)
 
|}
 
<nowiki>*</nowiki> resolution in which the model simulates the weather indicators (state: March 2014). Depending on the variable ECMWF uses either a {{Gloshint|Reduced Gaussian grid||Reduced Gaussian grid}} or a spectral model. The Gaussian grid names start with 'N' followed by number of lines by which latitude is divided. The spectral grids are named for the particular wave number where the spherical harmonic expansion is truncated, eg T1279 identifies truncation at wave number 1279. The results are made available by ECWMF on Gaussian or on corresponding regular lat-lon-grids.<br>
 
<nowiki>**</nowiki> resolution in which the simulated indicators are acquired and loaded into the MCYFS. The simulated indicators are distributed over the earth using a {{Gloshint|WGS84|World Geodetic System, revision 1984|WGS84}} coordinate system.<br>
 
<nowiki>***</nowiki> The first 10 days are simulated on a N320 grid (~30km horizontal resolution). The remaining days on a N160 grid (~60km horizontal resolution).<br>
 
<nowiki>****</nowiki> In more detail: ECWMF runs ERA-Interim on IFS Version Cy31r1
 
 
ERA-Interim is only used as archive containing daily data covering the period January 1989 - March 2013. From the OPE model the forecast for the current day (analysis) is processed and added to the archive assuming this is the best estimator for weather indicators of that day. Sometimes the term HIS is used to refer to the archive composed by: 1) ERA-interim and 2) the first day of each daily issue of the OPE model.
 
 
The data of other models are replaced when a more recent data set comes available (OPE, EPS, MON and SEA). Therefore only the ERA-Interim, extended with HIS data is used to calculate [[#Climatology (long term average weather)|climatology]].
 
 
For the OPE and EPS models the ECMWF model is run twice per day based on 00 and 12 UTC observations. As the delivery needs to take place until 15.00 hours of each day in standard situation the 00 UTC model run can be used. Sometimes, the model emission is delayed so that as fallback the 12 UTC model data of the previous day is taken into account.
 
 
==Spatial representation==
 
The ECMWF models run on Gaussian grids, for certain parameters and model levels on spectral grids, with different resolutions. The central MCYFS database however requires the initial data in a specific grid resolution with regular latitudes and longitudes. Therefore conversions are needed.
 
 
====OPE====
 
The Deterministic forecast model and Analysis model (OPE) produce forecast weather for grid cells on a Gaussian N640 reduced grid (~16x~16km). The resolution is converted to a Gaussian N400 reduced grid (~25x~25km) and after this to a regular 0.25 x 0.25 degrees latitude longitude grid (OPE grid). For the OPE grid two height models are kept. First a height model calculated in the same way as the data sets: first aggregation on the Gaussian grid from a Gaussian N640 reduced grid (~16x~16km) to a Gaussian N400 reduced grid (~25x~25km) and next a conversion from the Gaussian grid to the OPE grid. In addition the height model of a previous version of OPE model (prior to January 2010) is available. The previous OPE version was run on a Gaussian N400 reduced grid (~25x~25km) and the related height model was directly converted into the OPE grid. The grid description is stored in table {{Object|GRID_<MODEL>}}. 
 
[[File:gaussian_grid_n640_reduced.jpg|thumb|300px|none|Black dots: Gaussian N640 reduced grid (~16x~16km) to regular 0.25 x 0.25 degrees latitude longitude. Gray lines: 25x25km climate grid.|link=]]
 
 
====EPS & MON====
 
The first 10 forecast days (Leg A) of the Ensemble Prediction System and Monthly forecast are modelled for grid cells on a Gaussian N320 reduced grid (~30x~30km). Because the modelling of the remaining days (Leg B and C) is on the Gaussian N160 reduced grid (~60x~60km) it is not possible to switch for the whole forecast depth (EPS: 15 days and MON: 32 days) to a finer resolution. It means that the data of first 10 days must be aggregated. First the resolution is reduced to a Gaussian N200 reduced grid (~50x~50km) and finally converted to a regular 0.5 x 0.5 degrees latitude longitude grid. The height model of the latter grid is calculated in the same way as the data sets: first aggregation on the Gaussian grid from N320 (~30x~30km) to N200 (~50x~50km) and next a conversion from the Gaussian grid N200 to the regular 0.5 x 0.5 degrees latitude longitude grid.
 
[[File:gaussian_grid_n320_reduced.jpg|thumb|300px|none|Black dots: Gaussian N320 reduced grid (~30x~30km) to regular 0.5 x 0.5 degrees latitude longitude. Gray lines: 25x25km climate grid.|link=]]
 
 
After the first 10 day, the resolution of the models for the remaining forecast days (Leg B and C) is at a Gaussian N160 reduced grid (~60x~60km). The results are directly converted into a regular 0.5 x 0.5 degrees latitude longitude grid.
 
[[File:gaussian_grid_n160_reduced.jpg|thumb|300px|none|Black dots: Gaussian N160 reduced grid (~60x~60km) to regular 0.5 x 0.5 degrees latitude longitude. Gray lines: 25x25km climate grid.|link=]]
 
The grid description is stored in table {{Object|GRID_<MODEL>}}.
 
 
====SEA====
 
All forecast days of the Seasonal forecast are calculated for a Gaussian N128 reduced grid (~80x~80km). The results are directly converted into a regular 0.75 x 0.75 degrees latitude longitude grid. The grid description is stored in table {{Object|GRID_<MODEL>}}.[[File:gaussian_grid_n128_reduced.jpg|thumb|300px|none|Black dots: Gaussian N128 reduced grid (~80x~80km) to regular 0.75 x 0.75 degrees latitude longitude. Gray lines: 25x25km climate grid.|link=]]
 
 
====ERA====
 
The ERA data are calculated for a Gaussian N128 reduced grid (~80x~80km). The results are directly converted into a regular 0.75 x 0.75 degrees latitude longitude grid. The grid description is stored in table ECMWF_ERA_GRID_GLD (linked to view ECMWF_ERA_GRID).[[File:gaussian_grid_n128_reduced.jpg|thumb|300px|none|Black dots: Gaussian N128 reduced grid (~80x~80km) to regular 0.75 x 0.75 degrees latitude longitude. Gray lines: 25x25km climate grid.|link=]]
 
 
==Decoding and extraction of GRIB data==
 
Data is delivered in GRIB format and hence data is first decoded. In previous years the program ‘wgrib’ has been used which is capable of extracting GRIB content into ASCII files for further processing. Recently ECMWF has released version 1.2.0 of their GRIB {{Gloshint|API|Application Programming Interface. |API}} which is the successor of GRIBEX. While GRIBEX was used within FORTRAN programs the new GRIB API is designed for programs written in the C programming language.
 
 
{|class="collapsing_table collapsible collapsed"
 
!Abbreviations used in relation with ECMWF indicators
 
|-
 
|
 
{|class="wikitable"
 
!ECMWF indicator name!! MCYFS indicator name!! MCYFS abbriviation!! Description
 
|-
 
|10U|| || || 10 metre U-velocity (eastward component of wind vector)
 
|-
 
|10V|| || || 10 metre V-velocity (northward component of wind vector)
 
|-
 
| || Wind speed || Wind || 10 metre wind speed
 
|-
 
|2D || Dewpoint temperature || TD || 2 metre dewpoint temperature
 
|-
 
|2T || || || 2 metre temperature
 
|-
 
|MSL || Sea level pressure || SLP || Sea level pressure
 
|-
 
|SD || Snow depth || SD || Snow depth water equivalent
 
|-
 
|RSN || Snow density || || Snow density
 
|-
 
| || Snow height || SH || Snow height (thickness of snow layer)
 
|-
 
|TCC || Cloud cover || Cloud || Total cloud cover
 
|-
 
|MX2T6|| Maximum temperature || Tmax || Maximum temperature at 2m (in the past 6 hours)
 
|-
 
|MN2T6|| Minimum temperature || Tmin || Minimum temperature at 2m (in the past 6 hours)
 
|-
 
|MX2T24|| Maximum temperature || Tmax || Maximum temperature at 2m (in the past 24 hours)
 
|-
 
|MN2T24|| Minimum temperature || Tmin || Minimum temperature at 2m (in the past 24 hours)
 
|-
 
|SSRD|| Global radiation || Rg || Surface solar radiation downwards (accumulated during forecast period)
 
|-
 
|SunD|| || || Sunshine duration
 
|-
 
|TP|| Precipitation || Rain || Total precipitation (accumulated during forecast period)
 
|-
 
|GH|| Height || H500/H850 || Geopotential height
 
|-
 
|SF|| || || Snowfall
 
|-
 
|TGP20|| || || Probabiblity of total precipitation of at least 20mm
 
|-
 
|TAG4|| || || Probability of temperature anomaly greater than +4K
 
|-
 
|TAG8|| || || Probability of temperature anomaly greater than +8K
 
|-
 
|TALM4|| || || Probability of temperature anomaly less than -4K
 
|-
 
|TALM8|| || || Probability of temperature anomaly less than -8K
 
|-
 
|2TAG2|| || || Probability of 2m temperature anomaly greater than +2K
 
|-
 
|2TALM2|| || || Probability of 2m temperature anomaly less than -2K
 
|}
 
|}
 
 
During decoding additional indicators required by JRC and partners are calculated. This include aggregation to daily data, calculation of derived indicators and calculation of extreme weather events.
 
 
==Aggregation to daily data==
 
First of all an aggregation of 3-, 6- and 12-hourly data to daily data is calculated. Algorithms were developed in the ASEMARS project and differ per ECMWF model. The algorithms are presented in the box below.
 
 
{|class="collapsing_table collapsible collapsed"
 
!Algorithms for aggregation to daily data
 
|-
 
|Abbreviations are specified in section [[#Decoding and extraction of GRIB data|Decoding and extraction of GRIB data]]. Subscript numbers behind the indicator abbreviations indicate the time of the day.
 
 
====Aggregation areas====
 
[[File:map_world_zones.jpg||none|250px|Aggregation areas West, Central and East on world map.]]<br>
 
To consider the earth's different times zones aggregation rules for 3 different areas (East, Central, West) have been defined. The aggregation rules for the model data refer to the report schedule of synoptical weather stations (e.g. maximum air temperature in Europe and Africa refers to the period between 06 and 18 UTC of the corresponding day).
 
 
The following table summarized the deviation rules for the different aggregation zones and data sets.<br>
 
p = previous day, f = following day<br>
 
Temporal resolution of HIS is 3-hourly. Temporal resolution of OPE is 3-hourly for the first 72 hours and 6-hourly afterwards. Thus algorithms for air temperature, dew point and wind speed of the OPE data set change when the aggregation includes forecast time step +72h. Temporal resolution of MON and SEA is 6-hourly.
 
 
{|class="wikitable"
 
!Region !! West (only HIS, OPE)!!Centre!!East (only HIS, OPE)
 
|-
 
|Longitude||180W - 30W ||30W - 60E||60E - 180E
 
|-
 
|Precipitation HIS, OPE, ENS, MON, SEA, ERA||TP<sub>12</sub> – TP<sub>12f</sub>||TP<sub>06</sub> – TP<sub>06f</sub>||TP<sub>00</sub> – TP<sub>24</sub>
 
|-
 
|Average temperature HIS, OPE until +72h, ENS until +72h, ERA|| (2T<sub>09</sub> + 2T<sub>12</sub> + 2T<sub>15</sub> + 2T<sub>18</sub> + 2T<sub>21</sub> + 2T<sub>24</sub> + 2T<sub>03f</sub> + 2T<sub>06f</sub>) / 8 || (2T<sub>03</sub> + 2T<sub>06</sub> + 2T<sub>09</sub> + 2T<sub>12</sub> + 2T<sub>15</sub> + 2T<sub>18</sub> + 2T<sub>21</sub> + 2T<sub>24</sub>) / 8 || (2T<sub>21p</sub> + 2T<sub>00</sub> + 2T<sub>03</sub> + 2T<sub>06</sub> + 2T<sub>09</sub> + 2T<sub>12</sub> + 2T<sub>15</sub> + 2T<sub>18</sub>) / 8
 
|-
 
|Average temperature OPE after +72h, ENS after +72h, MON, SEA|| (2T<sub>12</sub> + 2T<sub>18</sub> + 2T<sub>24</sub> + 2T<sub>06f</sub>) / 4 || (2T<sub>06</sub> + 2T<sub>12</sub> + 2T<sub>18</sub> + 2T<sub>24</sub>) / 4 || (2T<sub>00</sub> + 2T<sub>06</sub> + 2T<sub>12</sub> + 2T<sub>18</sub>) / 4
 
|-
 
|Dew point HIS, OPE until +72h, ENS until +72h, ERA|| (2D<sub>09</sub> + 2D<sub>12</sub> + 2D<sub>15</sub> + 2D<sub>18</sub> + 2D<sub>21</sub> + 2D<sub>24</sub> + 2D<sub>03f</sub> + 2D<sub>06f</sub>) / 8 || (2D<sub>03</sub> + 2D<sub>06</sub> + 2D<sub>09</sub> + 2D<sub>12</sub> + 2D<sub>15</sub> + 2D<sub>18</sub> + 2D<sub>21</sub> + 2D<sub>24</sub>) / 8 || (2D<sub>21p</sub> + 2D<sub>00</sub> + 2D<sub>03</sub> + 2D<sub>06</sub> + 2D<sub>09</sub> + 2D<sub>12</sub> + 2D<sub>15</sub> + 2D<sub>18</sub>) / 8
 
|-
 
|Dew point OPE after +72h, ENS after +72h, MON, SEA|| (2D<sub>12</sub> + 2D<sub>18</sub> + 2D<sub>24</sub> + 2D<sub>06f</sub>) / 4 || (2D<sub>06</sub> + 2D<sub>12</sub> + 2D<sub>18</sub> + 2D<sub>24</sub>) / 4 || (2D<sub>00</sub> + 2D<sub>06</sub> + 2D<sub>12</sub> + 2D<sub>18</sub>) / 4
 
|-
 
|Maximum temperature HIS, OPE, ENS, MON, ERA||Maximum(MX2T6<sub>18</sub>, MX2T6<sub>24</sub>)||Maximum(MX2T6<sub>12</sub>, MX2T6<sub>18</sub>)||Maximum(MX2T6<sub>06</sub>, MX2T6<sub>12</sub>)
 
|-
 
|Maximum temperature SEA||-||MX2T24<sub>24</sub>||-
 
|-
 
|Minimum temperature HIS, OPE, ENS, MON, ERA||Minimum(MN2T6<sub>06</sub>, MN2T6<sub>12</sub>||Minimum(MN2T6<sub>00</sub>, MN2T6<sub>06</sub>||Minimum(MN2T6<sub>18p</sub>, MN2T6<sub>00</sub>)
 
|-
 
|Minimum temperature SEA||-||MN2T24<sub>24</sub>||-
 
|-
 
|Wind speed HIS, OPE until +72h, ENS until +72h, ERA||(√(10U<sub>09</sub><sup>2</sup> + 10V<sub>09</sub><sup>2</sup>) + √(10U<sub>12</sub><sup>2</sup> + 10V<sub>12</sub><sup>2</sup>) + √(10U<sub>15</sub><sup>2</sup> + 10V<sub>15</sub><sup>2</sup>) + √(10U<sub>18</sub><sup>2</sup> + 10V<sub>18</sub><sup>2</sup>) + √(10U<sub>21</sub><sup>2</sup> + 10V<sub>21</sub><sup>2</sup>) + √(10U<sub>24</sub><sup>2</sup> + 10V<sub>24</sub><sup>2</sup>) + √(10U<sub>03f</sub><sup>2</sup> + 10V<sub>03f</sub><sup>2</sup>) + √(10U<sub>06f</sub><sup>2</sup> + 10V<sub>06f</sub><sup>2</sup>)) / 8||(√(10U<sub>03</sub><sup>2</sup> + 10V<sub>03</sub><sup>2</sup>) + √(10U<sub>06</sub><sup>2</sup> + 10V<sub>06</sub><sup>2</sup>) + √(10U<sub>09</sub><sup>2</sup> + 10V<sub>09</sub><sup>2</sup>) + √(10U<sub>12</sub><sup>2</sup> + 10V<sub>12</sub><sup>2</sup>) + √(10U<sub>15</sub><sup>2</sup> + 10V<sub>15</sub><sup>2</sup>) + √(10U<sub>18</sub><sup>2</sup> + 10V<sub>18</sub><sup>2</sup>) + √(10U<sub>21</sub><sup>2</sup> + 10V<sub>21</sub><sup>2</sup>) + √(10U<sub>24</sub><sup>2</sup> + 10V<sub>24</sub><sup>2</sup>)) / 8||(√(10U<sub>21f</sub><sup>2</sup> + 10V<sub>21f</sub><sup>2</sup>) + √(10U<sub>00</sub><sup>2</sup> + 10V<sub>00</sub><sup>2</sup>) + √(10U<sub>03</sub><sup>2</sup> + 10V<sub>03</sub><sup>2</sup>) + √(10U<sub>06</sub><sup>2</sup> + 10V<sub>06</sub><sup>2</sup>) + √(10U<sub>09</sub><sup>2</sup> + 10V<sub>09</sub><sup>2</sup>) + √(10U<sub>12</sub><sup>2</sup> + 10V<sub>12</sub><sup>2</sup>) + √(10U<sub>15</sub><sup>2</sup> + 10V<sub>15</sub><sup>2</sup>) + √(10U<sub>18</sub><sup>2</sup> + 10V<sub>18</sub><sup>2</sup>)) / 8
 
|-
 
|Wind speed OPE after +72h, ENS after +72h, MON, SEA||(√(10U<sub>12</sub><sup>2</sup> + 10V<sub>12</sub><sup>2</sup>) + √(10U<sub>18</sub><sup>2</sup> + 10V<sub>18</sub><sup>2</sup>) + √(10U<sub>24</sub><sup>2</sup> + 10V<sub>24</sub><sup>2</sup>) + √(10U<sub>06f</sub><sup>2</sup> + 10V<sub>06f</sub><sup>2</sup>)) / 4||(√(10U<sub>06</sub><sup>2</sup> + 10V<sub>06</sub><sup>2</sup>) + √(10U<sub>12</sub><sup>2</sup> + 10V<sub>12</sub><sup>2</sup>) + √(10U<sub>18</sub><sup>2</sup> + 10V<sub>18</sub><sup>2</sup>) + √(10U<sub>24</sub><sup>2</sup> + 10V<sub>24</sub><sup>2</sup>)) / 4||(√(10U<sub>00</sub><sup>2</sup> + 10V<sub>00</sub><sup>2</sup>) + √(10U<sub>06</sub><sup>2</sup> + 10V<sub>06</sub><sup>2</sup>) + √(10U<sub>12</sub><sup>2</sup> + 10V<sub>12</sub><sup>2</sup>) + √(10U<sub>18</sub><sup>2</sup> + 10V<sub>18</sub><sup>2</sup>)) / 4
 
|-
 
|Global radiation HIS, OPE, ENS, MON, SEA, ERA||SSRD<sub>06f</sub> – SSRD<sub>06</sub>||SSRD<sub>24</sub> – SSRD<sub>00</sub>||SSRD<sub>18</sub> – SSRD<sub>18p</sub>
 
|-
 
|Snow depth HIS, OPE, ENS, MON, SEA, ERA||SD<sub>12</sub>||SD<sub>06</sub>||SD<sub>00</sub>
 
|}
 
|}
 
 
==Calculation of advanced parameters==
 
Not all indicators can be retrieved directly from the models. These include:
 
* Evapotranspiration
 
* Transpiration of water surface
 
* Transpiration of wet bare soil
 
* Climate water balance
 
* Vapour pressure
 
* Snow height
 
 
===Evapotranspiration===
 
In general, the evapotranspiration from a reference surface, the so-called reference crop evapotranspiration or reference evapotranspiration can be described by the FAO‑Penman-Monteith ([[References|Allen et all., 1998]]).
 
 
{{Hidden
 
|[[File:ET0.jpg|FAO‑Penman-Monteith equation]]
 
|where:
 
* ''ETo  : reference evapotranspiration [mm*day-1]''
 
* ''Rn    : net radiation at the crop surface [MJ*m-2* day-1]''
 
* ''G    : soil heat flux density [MJ* m-2*day-1]''
 
* ''T    : mean daily air temperature at 2 m height [°C]''
 
* ''u2    : wind speed at 2 m height [m*s-1]''
 
* ''es    : saturation vapor pressure [kPa]''
 
* ''ea    : actual vapor pressure [kPa]''
 
* ''es-ea : saturation vapor pressure deficit [kPa]''
 
* ''Δ : slope vapor pressure curve [kPa* °C-1]''
 
* ''γ    : psychrometric constant [kPa*°C-1]''
 
 
 
Derived by the original Penman-Monteith equation:
 
 
[[File:ET0_original.jpg|Original Penman-Monteith equation]]
 
 
but where the aerodynamic resistance ra and surface resistance rs were defined as:
 
 
[[File:aerodynamic_resistance.jpg|Aerodynamic resistance]]
 
 
where:
 
* ''ra : aerodynamic resistance [s*m-1]''
 
* ''zm : height of wind measurements [m]''
 
* ''zh : height of humidity measurements [m]''
 
* ''d : zero plane displacement height [m]''
 
* ''zom : roughness length governing momentum transfer [m]''
 
* ''zoh : roughness length governing transfer of heat and vapor [m]''
 
* ''k : von Karman's constant, 0.41 [-]''
 
 
 
and
 
 
[[File:surface_resistance.jpg|Surface resistance]]
 
 
Where:
 
* ''rs : (bulk) surface resistance [s*m-1]''
 
* ''rl : bulk stomatal resistance of the well-illuminated leaf [s*m-1]''
 
* ''LAIactive : active (sunlit) leaf area index [m2 (leaf area) m-2 (soil surface)]''
 
}}
 
Evapotranspiration from a wet bare soil surface (ES0) and from a crop canopy (ET0) is calculated with the well-known Penman formula ([[References|Penman, 1948]]). In general, the evapotranspiration from a water surface can be described by the Penman formula. Only the albedo and surface roughness differs for these two types of evapotranspiration as explained below.
 
 
{{Hidden
 
|[[File:E0.jpg|Penman equation]]
 
|where:
 
* ''E0 : evapotranspiration from a water surface [mm*d-1]''
 
* ''Rna : net absorbed radiation [mm*d-1]''
 
* ''EA : Evaporative demand [mm*d-1]''
 
* ''Δ : Slope of the saturation vapor pressure curve [mbar*C-1]''
 
* ''γ : Psychometric constant (0.67) [mbar*C-1]''
 
}}
 
The net absorbed radiation depends on incoming global radiation, net outgoing long-wave radiation, the latent heat and the reflection coefficient of the considered surface (albedo). For ET0, ES0, and ET0 albedo values of 0.05, 0.15 and 0.20 are used respectively. The evaporative demand is determined by humidity, wind speed and surface roughness. For a free water surface and for the wet bare soil (E0, ES0) a surface roughness value of 0.5 is used. For a more detailed description of the underlying formulae we refer to [[References|Supit et al. (1994)]] and [[References|van der Goot (1997)]].
 
 
===Climatic water balance===
 
Climatic water balance is calculated based on evapotranspiration calculated through the equation of Penman-Monteith and the total precipitation of a day.
 
 
{{Hidden
 
|CWB equals Rain – ET0
 
|where:
 
*''Rain : 24-hour amount of precipitation[mm*day-1]''
 
*''ET0  : reference evapotranspiration [mm*day-1]''
 
}}
 
 
===Snow height===
 
The snow height (thickness of the snow layer) is derived from snow depth (water equivalent) and snow density.
 
 
{{Hidden
 
|Dsn equals r_water/r_water * S/c_snow
 
|The ECMWF catalogue lists snow depth SD (water equivalent) for all sets and snow density RSN (kg/m-3) which is available for OPE, ENS, MON but not for SEA. According to ECMWF documentation snow height Dsn can be derived with the approach:
 
 
Dsn equals r_water/r_snow*S/c_snow
 
 
with
 
*'' r_water density of water in kg/m**3''
 
*'' r_snow density of snow in kg/m**3''
 
*'' S snow mass in m''
 
*'' c_snow snow fraction, dimensionless''
 
 
In ECMWF's model documentation snow mass is (sometimes) referred as “snow water equivalent”, and leads to parameter SD, snow depth. Snow fraction is not in the catalogue. ECMWF assumes c_snow to be 1 for snow height > 15 cm (average of the grid box) and <1 for a thinner snow cover.
 
 
}}
 
 
==Calculation of extreme weather events==
 
For the static map production over Europe it is necessary to derive additional parameters out of the raw data set. This especially concerns probabilities and aggregated counts of number of days where a special condition is met. Some of the probabilities to be mapped are available directly from ECMWF. Other probabilities need to be derived from individual ensemble runs. In this case it is checked for how many of the ensemble members a certain condition applies (e.g. TempMin < 0°C). The probability of the event is the fraction of ensemble members forecasting it against the total number of ensemble members. The operational run and the ensemble control run are treated like any other ensemble member.
 
 
{|class="collapsing_table collapsible collapsed"
 
!Derived probability and other threshold-dependent indicators
 
|-
 
|
 
{|class="wikitable"
 
!Type of map!! Indicator
 
|-
 
|Daily||1-day base Probability TempMin < 0°C
 
|-
 
|Daily||1-day base Probability TempMax > 30°C
 
|-
 
|Daily||10-day base Number of rainy days with Rain > 1mm
 
|-
 
|Daily||10-day base Number of hot days with TempMax > 30°C
 
|-
 
|Daily||10-day base Number of freezing days with TempMin < 0°C
 
|-
 
|Weekly||Probability of rain > 10mm
 
|-
 
|Weekly||Probability of rain > 20mm
 
|-
 
|Weekly||Probability TempMin < 0°C
 
|-
 
|Weekly||Probability TempMax > 30°C
 
|-
 
|Weekly||Number of rainy days with Rain > 1mm
 
|-
 
|Weekly||Number of hot days with TempMax > 30°C
 
|-
 
|Weekly||Number of freezing days with TempMin < 0°C
 
|-
 
|Monthly||Probability of warm anomaly (+2°C)
 
|-
 
|Monthly||Probability of cold anomaly (-2°C)
 
|-
 
|Monthly||Probability of rain > 10mm
 
|-
 
|Monthly||Probability of rain > 20mm
 
|-
 
|Monthly||Probability TempMin < 0°C
 
|-
 
|Monthly||Probability TempMax > 30°C
 
|-
 
|Monthly||Number of rainy days with Rain > 1mm
 
|-
 
|Monthly||Number of hot days with TempMax > 30°C
 
|}
 
|}
 
 
==Aggregation to 10-daily and monthly data==
 
After each 10-day period and at the end of each month aggregation for this 10-day/month period takes place. Additionally a forecast of the next dekad, basing on aggregated forecasts for the next 10 days (resp. 8/9/11 days for the last dekad) is delivered. The daily data are aggregated from days to dekads by taking the '''average''' of mean temperature, maximum temperature, minimum temperature, snow depth and the '''sum''' of precipitation, ET0 and global radiation.
 
 
Additionally for the map production the number of occurrences of certain events (such as frost, hot or rainy days) is counted.
 
 
 
==Extraction of data into files==
 
After processing data are exported as data files and static maps that can be distributed to users and other MCYFS processes.
 
 
A simple file naming scheme was adopted with the general format:
 
<nowiki><ROI>_<model_code>_<timestep>_<yyyy><mm><dd>_<member>.dat</nowiki><br>
 
 
In which:
 
* ROI = region (GLD, EUR, ASI)
 
* model_code = ECMWF model (ERA, OPE, EPS, MON or SEA)
 
* timestep = temporal resolution of data: day, dekad, month
 
* yyyy = the year (four digits),
 
* mm = the month number (two digits),
 
* dd = the day in the month (two digits)
 
* member = the member number (two digits)
 
 
Note the OPE and EPS start with member number 0 while the MON and SEA start with member number 1. The date in the filename links to the forecast day = 0 (FORECAST_OFFSET = 0).
 
 
 
An example of a file name for each of the 4 models is:
 
* EUR_OPE_day_20100715_00.dat OPE data for July 15, 2010 (only member 00 allowed)
 
* EUR_EPS_day_20100704_35.dat EPS data for July 4, 2010, member 35
 
* EUR_MON_day_20100702_32.dat MON data for  Friday July 2, 2010, member 32
 
* EUR_SEA_day_20100601_34.dat SEA data for June 1*, 2007, member 34
 
<nowiki>* Model runs the 8th but has a hindcast of 8 days</nowiki><br>
 
 
 
Note the OPE and EPS start with member number 0 while the MON and SEA start with member number 1. The date in the filename links to the forecast day = 0 (FORECAST_OFFSET = 0).
 
 
 
 
An input file basically contains the following structure:
 
* A header providing geo referencing information
 
* Blocks of data for the first forecast date (for each variable)
 
* Blocks of data for the second forecast date (for each variable)
 
* etc.
 
 
For simplification purposes, below a simple example is given with a detailed explanation.
 
 
 
 
{|class="collapsing_table collapsible collapsed"
 
!Explanation of file format
 
|-
 
| The example contains just rainfall and daily mean temperature for two forecast dates for a grid ranging from 20 to 40 degrees longitude and from 50 to 60 degrees latitude, with a grid size of 5 degrees. The forecast is issued on 23 January 2009 and first day in the forecast (FORECAST_OFFSET=0) is linked to this date.
 
 
[[File:FormatECMWF.JPG|full|500px]]
 
 
The meaning of each of the lines is given in the following table:
 
 
{|class="wikitable"
 
!Line number!! Meaning
 
|-
 
|1|| ignored
 
|-
 
|2|| nr of columns
 
|-
 
|2|| nr of rows
 
|-
 
|2|| latitude max
 
|-
 
|2|| longitude min
 
|-
 
|2|| latitude min
 
|-
 
|2|| longitude max
 
|-
 
|2|| cell size longitude direction
 
|-
 
|2|| cell size latitude direction (cell sizes should be equal)
 
|-
 
|3|| announce variable rainfall (see below for a list of variable abbreviations)
 
|-
 
|4|| announce first forecast date (start with 0)
 
|-
 
|5,6,7|| rainfall data starting with upper left most cell, as it would be laid out on a map (5 columns, 3 rows)
 
|-
 
|9|| announce daily mean temperature (see below for a list of variable abbreviations)
 
|-
 
|10|| announce first forecast date
 
|-
 
|11,12,13|| daily mean temperature data
 
|-
 
|15|| new block of data, but now for the second forecast date
 
|}
 
 
The variable abbreviations and their explanation are given in the following table:
 
 
{|class="wikitable"
 
!Code!! Meaning !! Unit
 
|-
 
|T2M|| Mean temperature || degrees Kelvin
 
|-
 
|TX|| Maximum temperature || degrees Kelvin
 
|-
 
|TN|| Minimum temperature || degrees Kelvin
 
|-
 
|TD|| Dew point temperature || degrees Kelvin
 
|-
 
|RR|| Precipitation || m
 
|-
 
|SSRD|| Global radiation || J.m-2.d-1
 
|-
 
|SN|| Snow water equivalent || m
 
|-
 
|FFM|| Wind speed at 10 m altitude || m.s-1
 
|-
 
|SH|| Snow depth || m
 
|}
 
|}
 
 
 
The data files are loaded in the tables {{Object|WEATHER_<MODEL>_GRID_RAW}} where <MODEL> is to be replaced by the abbreviation of one of the five ECMWF products (HIS, OPE, EPS, MON or SEA). In case of ERA data are stored in table ECMWF_ERA_DATA. During loading two actions are executed:
 
* unit conversion
 
* plausible range checks
 
 
 
{|class="collapsing_table collapsible collapsed"
 
!Unit conversion and range checking
 
|-
 
|
 
{|class="wikitable"
 
!Variable!! Unit before !! Unit after
 
|-
 
|T2M (Mean temperature)|| degrees Kelvin || degrees Celsius
 
|-
 
|TX (Maximum temperature)|| degrees Kelvin || degrees Celsius
 
|-
 
|TN (Minimum temperature)|| degrees Kelvin || degrees Celsius
 
|-
 
|TD (Dew point temperature)|| degrees Kelvin || degrees Celsius
 
|-
 
|RR (Precipitation)|| m.d-1 || mm.d-1
 
|-
 
|SSRD (Global radiation)|| J.m-2.d-1 || kJ.m-2.d-1
 
|-
 
|SN (Snow water equivalent)|| m || cm
 
|-
 
|FFM (Wind speed at 10 m)|| m.s-1 || m.s-1
 
|-
 
|SH (Snow depth)|| m || cm
 
|}
 
 
{|class="wikitable"
 
!Variable!! Correction
 
|-
 
|RR (Precipitation)|| 0, when < 0
 
|-
 
|SN (Snow water equivalent)|| 0, when < 0
 
|-
 
|FFM (Wind speed at 10 m)|| 0, when < 0
 
|-
 
|SH (Snow depth)|| 0, when < 0
 
|-
 
|SSRD (Global radiation)|| 0, when < 0
 
|}
 
|}
 
 
 
 
In parallel daily, decadal and monthly aggregates of the analysis and deterministic forecast (HIS, OPE) is provided as csv to JRC and Vito.
 
{|class="collapsing_table collapsible collapsed"
 
!csv format description and deliverables
 
|-
 
|
 
{|class="wikitable"
 
!column!! Daily HIS, OPE, ERA !! Decadal HIS, OPE, ERA !! Monthly HIS, OPE, ERA
 
|-
 
|1||lat||lat||lat
 
|-
 
|2||long||long||long
 
|-
 
|3||YYYYMMDD||YYYY||YYYY
 
|-
 
|4||tav||MM||MM
 
|-
 
|5||tmax||dekad (1 or 2 or 3)||dekad (0)
 
|-
 
|6||tmin||tav||tav
 
|-
 
|7||rrr||tmax||tmax
 
|-
 
|8||E0||tmin||tmin
 
|-
 
|9||ES0||rrr||rrr
 
|-
 
|10||ET0||E0||E0
 
|-
 
|11||rad||ES0||ES0
 
|-
 
|12||sdav||ET0||ET0
 
|-
 
|13||cwb||rad||rad
 
|-
 
|14||tav_sum||sdav||sdav
 
|-
 
|15||ffav||cwb||cwb
 
|-
 
|16||vapav||tav_sum||tav_sum
 
|-
 
|17||||ffav||ffav
 
|-
 
|18||||vapav||vapav
 
|-
 
|19||||sdmax||sdmax
 
|-
 
|20||||sdmin||sdmin
 
|}
 
 
{|class="wikitable"
 
!abbreviation!! unit !! meaning
 
|-
 
|lat||Deg.decDeg||latitude
 
|-
 
|long||Deg.decDeg||longitude
 
|-
 
|tav||°C||average temperature
 
|-
 
|tmin||°C||minimum temperature
 
|-
 
|tmax||°C||maximum temperature<br>
 
|-
 
|rrr||mm = liters/m2||precipitation; sum over day, dekad or month
 
|-
 
|E0||mm = liters/m2||evapotranspiration open water; sum over day, dekad or month
 
|-
 
|ES0||mm = liters/m2||evapotranspiration bare soil; sum over day, dekad or month
 
|-
 
|ET0||mm = liters/m2||evapotranspiration Penman-Monteith; sum over day, dekad or month
 
|-
 
|rad||kJ/m2||global radiation; sum over day, dekad or month
 
|-
 
|sdav||cm||average snow depth (water equivalent)
 
|-
 
|sdmax||cm||maximum snow depth (water equivalent)
 
|-
 
|cwb||mm = liters/m2||climatic water balance (rrr - ET0); sum over day, dekad or month
 
|-
 
|tav_sum||°C||mean temperature; sum over day, dekad ormonth
 
|-
 
|ffav||m/s||average wind speed
 
|-
 
|vapav||hPa||average water vapour pressure
 
|-
 
|YYYY||||year
 
|-
 
|MM||||month
 
|-
 
|DD||||day
 
|}
 
 
{|class="wikitable"
 
!model set!! destination !! naming
 
|-
 
|Daily analysis||JRC (ECMWF/fine_global/daily/analysis/YYYY)||Meteodata_world_[day as YYYYmmdd].csv.gz
 
|-
 
|Daily analysis||Alterra (marsop/meteodata/global)||Meteodata_world_[day as YYYYmmdd].csv.gz
 
|-
 
|Daily analysis||Vito (MARSOP3/Global)||YYYYmmdd.csv
 
|-
 
|Daily forecast||JRC FOOD-SEC (ECMWF/file_global/daily/forecast/YYYY)||Meteodata_world_[day as YYYYmmdd].csv.gz
 
|-
 
|10-daily analysis||JRC FOOD-SEC (ECMWF/fine_global/ten-daily/analysis/YYYY)||Meteodata_world_[YYYYmm_dec[1 or 2 or 3].csv.gz
 
|-
 
|10-daily analysis||Alterra (GWSI_MARSOP3)||GLD_OPE_dekad_[end of decad as YYYYmmdd]_00.csv.gz
 
|-
 
|10-daily forecast||JRC FOOD-SEC (ECMWF/fine_global/ten-daily/forecast/YYYY)||Meteodata_world_[YYYYmm_dec[1 or 2 or 3].csv.gz
 
|-
 
|monthly analysis||JRC FOOD-SEC (ECMWF/fine_global/ten-daily/analysis/YYYY)||Meteodata_world_[YYYYmm]_month.csv.gz
 
|}
 
 
|}
 
 
==Extraction of data into maps==
 
The static maps are exported as flat images or animated images with full layout and directly made available to analysts that use them during [[Analysis of weather indicators|analysis of weather indicators]]. The geographic extent of the static maps is defined by the upper-left corner at 75° North/25° West and the lower-right corner 20° North/70° East. This production line includes GrADS mapping software which is able to create maps directly from GRIB files. For the weekly and monthly maps the absolute difference to long-term average values are calculated.
 
 
[[File:Quick_look_tmax_20110207_024.jpg|thumb|left|250px|Static map of maximum temperature on 7-feb-2011 with a spring breeze in Central and Western Europe.]]
 
[[File:Quick_look_anim_rain_20101220_small.gif|frame|centre|Animated Rainfall, emitted 20-dec-2010 with the forecasted precipitation of low "Petra". Petra's snow masses retarded travel in many regions of Europe before Christmas 2010. [http://marswiki.jrc.ec.europa.eu/agri4castwiki/images/4/41/Quick_look_anim_rain_20101220.gif Large animation]]]
 
 
{|class="collapsing_table collapsible collapsed"
 
!Overview: Produced maps
 
|-
 
|
 
{|class="wikitable"
 
!DAILY!! !!*anim = animation !! !! !! !! namepattern at jrc-ftp-server !! !! !!
 
|-
 
|Parameter||Operational ECMWF||EPS ECMWF||calculated Operational||calculated EPS||Number of Maps||||||||
 
|-
 
|Sea-level pressure||10+anim.||15+anim.||||||22||SLP||ENS-SLP||||
 
|-
 
|GPH 500hPa||10+anim.||15+anim.||||||22||GPH500||ENS-GPH500||||
 
|-
 
|GPH 850 hPa||10+anim.||15+anim.||||||22||GPH850||ENS-GPH850||||
 
|-
 
|Tmin-24h||||||10+anim.||15+anim.||27||||||TMIN||ENS-TMIN
 
|-
 
|Tmax-24h||||||10+anim.||15+anim.||27||||||TMAX||ENS-TMAX
 
|-
 
|Tmean-24h||||||10+anim.||15+anim.||27||||||TAVG||ENS-TAVG
 
|-
 
|SRain-24h||||||10+anim.||15+anim.||27||||||RAIN||ENS-RAIN
 
|-
 
|SSnow-24h||||||10||15||25||||||SNOW||ENS-SNOW
 
|-
 
|SET0-24h||||||10||15||25||||||ET0||ENS-ET0
 
|-
 
|SCWB-24h||||||10||15||25||||||CWB||ENS-CWB
 
|-
 
|SRg-24h||||||10||15||25||||||SOL.RAD||ENS-SOL.RAD
 
|-
 
|Total Cloud Cover-24h||||||10||15||25||||||CLOUD||ENS-CLOUD
 
|-
 
|Prob Warm Anomaly +4 (850 hPa)||||15||||||15||||T850ANOM+4||||
 
|-
 
|Prob Warm Anomaly +8 (850 hPa)||||15||||||15||||T850ANOM+8||||
 
|-
 
|Prob Cold Anomaly -4 (850 hPa)||||15||||||15||||T850ANOM-4||||
 
|-
 
|Prob Cold Anomaly -8 (850 hPa)||||15||||||15||||T850ANOM-8||||
 
|-
 
|Prob Rain > 20mm||||||||15||15||||||||PROB-RAIN20
 
|-
 
|Prob TempMin < 0 C||||||||15||15||||||||PROB-NR.TN0
 
|-
 
|Prob TempMax > 30 C||||||||15||15||||||||PROB-NR.TX30
 
|-
 
|||||||||||||||||||
 
|-
 
|Rain-10D||1||1||||||2||RAIN-10D||ENS-RAIN-10D||||
 
|-
 
|Snow-10D||1||1||||||2||SNOW-10D||ENS-SNOW-10D||||
 
|-
 
|ET0-10D||||||1||1||2||||||ET0-10D||
 
|-
 
|CWB -10D||||||1||1||2||||||CWB-10D||
 
|-
 
|Nr Rainy days (Rain > 1mm)||||||1||1||||||||NR.RAINY||
 
|-
 
|Nr Hot days (Tx > 30 C) ||||||1||1||2||||||NR.TX30||
 
|-
 
|Nr Freezing days (Tn < 0 C)||||||1||1||2||||||NR.TN0||
 
|-
 
|||||||||||||||||||
 
|-
 
|WEEKLY (Set VI)||||||||||||||||||
 
|-
 
|Parameter (each to be produced for every 4 forecast weeks)||Direct ECMWF||Calculated ECMWF||||||Number of Maps||||||||
 
|-
 
|Tmin||4||||||||4||MON-TMAX||||||
 
|-
 
|Tmax||4||||||||4||MON-TMIN||||||
 
|-
 
|Sum Rain||4||||||||4||MON-RAIN||||||
 
|-
 
|Sum snow||||4||||||4||||MON-SNOW||||
 
|-
 
|Sum ET0||||4||||||4||||MON-ET0||||
 
|-
 
|sum CWB||||4||||||4||||MON-CWB||||
 
|-
 
|Sum Rg||4||||||||4||||MON-SOL.RAD||||
 
|-
 
|Probab. Of Rain > 10mm||4||||||||4||MON-PROB-RAIN10||||||
 
|-
 
|Probab. of Rain > 20mm||4||||||||4||MON-PROB-RAIN20||||||
 
|-
 
|Probab.  Temp <0°C||||4||||||4||||MON-PROB-NR.TN0||||
 
|-
 
|Probab. Temp > 30°C||||4||||||4||||MON-PROB-NR.TX30||||
 
|-
 
|Nr. rainy days (Rain > 1mm)||||4||||||4||||MON-NR.RAINY||||
 
|-
 
|Nr. hot days (TempMax > 30°C)||||4||||||4||||MON-NR.TX30||||
 
|-
 
|Nr freezing days (TempMin < 0°C)||||4||||||4||||MON-NR.TN0||||
 
|-
 
|||||||||||||||||||
 
|-
 
|MONTHLY (Set V)||||||||||||||||||
 
|-
 
|Parameter (each to be produced for every 4 forecast weeks)||Direct ECMWF||Calculated ECMWF||||||Number of Maps||||||||
 
|-
 
|Tmin||4||||||||4||SEA-TMIN||||||
 
|-
 
|Tmax||4||||||||4||SEA-TMAX||||||
 
|-
 
|Sum Rain||4||||||||4||SEA-RAIN||||||
 
|-
 
|Sum snow||||4||||||4||||SEA-SNOW||||
 
|-
 
|Sum ET0||||4||||||4||||SEA-ET0||||
 
|-
 
|sum CWB||||4||||||4||||SEA-CWB||||
 
|-
 
|Sum Rg||||4||||||4||||SEA-SOL.RAD||||
 
|-
 
|Probab. Of Rain > 10mm||||4||||||4||||SEA-PROB-RAIN10||||
 
|-
 
|Probab. of Rain > 20mm||||4||||||4||||SEA-PROB-RAIN20||||
 
|-
 
|Probab.  Temp <0°C||||4||||||4||||SEA-PROB-NR.TN0||||
 
|-
 
|Probab. Temp > 30°C||||4||||||4||||SEA-PROB-NR.TX30||||
 
|-
 
|Nr. rainy days (Rain > 1mm)||||4||||||4||||SEA-NR.RAINY||||
 
|-
 
|Nr. hot days (TempMax > 30°C)||||4||||||4||||SEA-NR.TX30||||
 
|-
 
|Nr freezing days (TempMin < 0°C)||||4||||||4||||SEA-NR.TN0||||
 
|}
 
|}
 
 
 
 
 
[[Category:Weather Monitoring]]
 

Latest revision as of 16:12, 15 June 2016