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Introduction
This user guide describes the datasets released from the Arctic Regional Reanalysis service, which is part of the Copernicus Climate Change Service (C3S). The datasets will include the actual grid point reanalysis information on different levels (atmospheric vertical levels, surface including soil). This version also provides details on the uncertainty information provided. We will refer to the dataset as the CARRA (Copernicus Arctic Regional ReAnalysis) dataset.
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Table 1: Overview of single level variables. Some variables have not yet been uploaded to CDS, these are marked with * and unfortunately are not included amongst the released reanalysis data. Most static fields (except land-sea mask and orography) marked with * * are available only as NetCDF-files below. Anchor table1 table1
Precipitation, cloud water and humidity | ||||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… | Height |
2r | % | 260242 | yes | yes | 2m | |
2sh | kg/kg | 174096 | yes | yes | 2m | |
tciwv | kg/m2 | 260057 | yes | yes | vertically integrated above the surface | |
tclw | kg/m2 | 78 | no | yes | vertically integrated above the surface | |
tciw | kg/m2 | 79 | no | yes | vertically integrated above the surface | |
tcolg | kg/m2 | 260001 | yes | yes | vertically integrated above the surface | |
tp | kg/m2 | 228228 | no | yes | surface | |
tirf | kg/m2 | 235015 | no | yes | surface | |
titspf | kg/m2 | 260645 | no | yes | surface | |
ptype | integer code | 260015 | no | yes | surface | |
sro | kg/m2 | 174008 | no | yes | surface | |
Percolation (drainage) | perc | kg/m2 | 260430 | no | yes | sub-surface |
Temperature and wind speed | ||||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… | Height |
10si | m/s | 207 | yes | yes | 10m | |
10wdir | degrees | 260260 | yes | yes | 10m | |
10m u-component of wind (defined relative to the rotated model grid) | 10u | m/s | 165 | yes | yes | 10m |
10m v component of wind | 10v | m/s | 166 | yes | yes | 10m |
10m eastward wind gust since previous post-processing | 10efg | m/s | 260646 | no | yes | 10m |
10m northward wind gust since previous post-processing | 10nfg | m/s | 260647 | no | yes | 10m |
10fg | m/s | 49 | no | yes | 10m | |
mx2t | K | 201 | no | yes | 2m | |
mn2t | K | 202 | no | yes | 2m | |
2t | K | 167 | yes | yes | 2m | |
skt | K | 235 | yes | yes | Surface |
Accumulated fluxes | ||||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… | Height |
al | % | 260509 | no | yes | surface | |
eva | kg/m2 | 260259 | no | yes | surface | |
tisef | kg/m2 | 235072 | no | yes | surface | |
sshf | J/m2 | 146 | no | yes | surface | |
slhf | J/m2 | 147 | no | yes | surface | |
tislhef | J/m2 | 235019 | no | yes | surface | |
tislhsf | J/m2 | 235071 | no | yes | surface | |
dsrp | J/m2 | 47 | no | yes | surface | |
tidirswrf | J/m2 | 260264 | no | yes | surface | |
ssr | J/m2 | 176 | no | yes | surface | |
ssrd | J/m2 | 169 | no | yes | surface | |
ssrc | J/m2 | 210 | no | yes | surface | |
str | J/m2 | 177 | no | yes | surface | |
strd | J/m2 | 175 | no | yes | surface | |
strc | J/m2 | 211 | no | yes | surface | |
Top net solar radiation | tsr | J/m2 | 178 | no | yes | surface |
ttr | J/m2 | 179 | no | yes | surface | |
tisemf | kg⋅m/s | 235017 | no | yes | surface | |
tisnmf | kg⋅m/s | 235018 | no | yes | surface | |
Pressure | ||||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… | Height |
msl | Pa | 151 | yes | yes | surface (scaled to sea level) | |
sp | Pa | 134 | yes | yes | surface | |
Geometric cloud properties | ||||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… | Height |
hcc | % | 3075 | yes | yes | above 5000m | |
mcc | % | 3074 | yes | yes | 2500m - 5000m | |
lcc | % | 3073 | yes | yes | surface - 2500m | |
tcc | % | 228164 | yes | yes | above ground | |
fog | % | 260648 | no | yes | lowest model level | |
vis | m | 3020 | yes | yes | lowest model level | |
cdcb | m | 260107 | yes | yes | - | |
cdct | m | 260108 | yes | yes | - | |
Snow | ||||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… | Height |
rsn | kg/m3 | 33 | yes | yes | surface | |
sd | kg/m2 | 228141 | yes | yes | surface | |
fscov | 0-1 | 260289 | yes | no | surface | |
asn | % | 228032 | yes | no | surface | |
Surface roughness lengths | ||||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… | Height |
sr | m | 173 | yes | no | surface | |
srlh | m | 260651 | yes | no | surface | |
Sea states | ||||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… | Height |
sst | K | 34 | yes | no | surface | |
ci | 0-1 | 31 | yes | no | surface | |
sist | K | 260649 | yes | yes | surface | |
sithick | m | 174098 | yes | no | surface | |
sitd | m | 260650 | yes | yes | surface | |
Static fields | ||||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… | Height |
lsm | % | 172 | no | no | surface | |
Sea tile fraction |
* | NA | 0-1 | NA | no | no | surface |
Inland water tile fraction |
* | NA | 0-1 | NA | no | no | surface |
Urban tile fraction* |
NA | 0-1 | NA | no | no | surface | |
Nature tile fraction* |
NA | 0-1 | NA | no | no | surface | |
Glacier fraction* | NA | 0-1 | NA | no | no | surface |
Subgrid orography average slope* | NA | 0-1 | NA | no | no | surface |
Subgrid orography average direction* | NA | degrees | NA | no | no | surface |
Subgrid orography standard deviation* | NA | m | NA | no | no | surface |
orog | m | 228002 | no | no | surface |
The static fields marked as * * above are available as NetCDF files for the West and East domain respectively here: fractions.west.nc and fractions.east.nc
Soil level variables
Soil level variables are given for two model depths, where the first depth is the soil surface and the second depth is the so-called root depth. The root depth varies with the cover type climatology. Please note that the soil level variables are accommodated in the Arctic Regional Reanalysis single level variables catalogue entry.
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Soil level variables | |||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… |
vsi | m³/m³ | 260644 | yes | yes | |
vsw | m³/m³ | 260199 | yes | yes |
Model level variables
Model level variables are output at 65 hybrid model levels of the HARMONIE-AROME model. These follow the surface at the lowest levels and are gradually evolved into pure pressure levels at the highest levels. These are the levels at which the model computations are done. The height level and pressure level variables are interpolated from these data.
Diagnostic model level output (analysis), i.e. 0 hour forecasts, are available every 3 hours with 1 and 2 hour forecasts in between.
Table 3: Overview of model level variables Anchor table3 table3
Model level variables | |||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2 |
q | kg/kg | 133 | yes | yes | |
t | K | 130 | yes | yes | |
u-component of wind (defined relative to the rotated model grid) | u | m/s | 131 | yes | yes |
v-component of wind (defined relative to the rotated model grid) | v | m/s | 132 | yes | yes |
ccl | % | 260257 | yes | yes | |
clwc | kg/kg | 246 | yes | yes | |
ciwc | kg/kg | 247 | yes | yes | |
crwc | kg/kg | 75 | yes | yes | |
cswc | kg/kg | 76 | yes | yes | |
grle | kg/kg | 260028 | yes | yes | |
tke | J/kg | 260155 | yes | yes |
Pressure level variables
Pressure level variables are interpolated to 23 specific pressure levels: 1000, 950, 925, 875, 850, 800, 750, 700, 600, 500, 400, 300, 200, 100, 70, 50, 30, 20 and 10 hPa. Thus, they are on isobaric surfaces.
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Pressure level variables | ||||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… | |
r | % | 157 | yes | yes | ||
t | K | 130 | yes | yes | ||
u-component of wind (defined relative to the rotated model grid) | u | m/s | 131 | yes | yes | |
v-component of wind (Component defined relative to the rotated model grid) | v | m/s | 132 | yes | yes | |
wz | m/s | 260238 | yes | yes | ||
ccl | % | 260257 | yes | yes | ||
clwc | kg/kg | 246 | yes | yes | ||
ciwc | kg/kg | 247 | yes | yes | ||
crwc | kg/kg | 75 | yes | yes | ||
cswc | kg/kg | 76 | yes | yes | ||
grle | kg/kg | 260028 | yes | yes | ||
papt | K | 3014 | yes | yes | ||
z | m²/s² | 129 | yes | yes | ||
pv | K·m²/ (kg·s) | 60 | yes | yes |
Height level variables
Height level variables are interpolated to 11 specific height levels: 15, 30, 50, 75, 100, 150, 200, 250, 300, 400 and 500 metres above the surface.
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Height level variables | |||||
Name | Short Name | Unit | Param ID | Analysis: 0,3,...,21 | Forecast: 1,2,3,… |
r | % | 157 | yes | yes | |
t | K | 130 | yes | yes | |
ws | m/s | 10 | yes | yes | |
wdir | deg | 3031 | yes | yes | |
clwc | kg/kg | 246 | yes | yes | |
ciwc | kg/kg | 247 | yes | yes | |
Pressure | pres | Pa | 54 | yes | yes |
Details about the data fields
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The snow variables are given as instantaneous values from the most recent model time step relative to the output time. The snow density output unit is kg/m3, the snow water equivalent (SWE) output is in units of kg/m2, and the snow fraction output has fractional units in the range 0-1. The snow depth can be derived from these variables.
Sea and sea
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ice variables
For the sea the sea surface temperature is is output in units of K. For areas partially or completely covered with sea - ice, the following variables are output: Sea - ice area fraction [-], upper layer sea ice temperature [K], sea - ice thickness [m], and sea - ice snow thickness [m]. Here the sea-For sea ice thickness please note that the routine that computes this variable does not reproduce the evolution of ice thickness with all its complexity. Rather this variable should be treated as a rough estimate in order to get reasonable estimations for the energy fluxes. The sea ice fraction and sea surface temperatures are in fact interpolated input data and are only updated once every day. During the course of a forecast they are kept constant. All other sea and sea - ice variables are given as instantaneous values from the most recent model time step relative to the output time.
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Static fields are output variables that do not change depending on the model initial time or the forecast length (in other words they are time-independent). These include the land-sea mask, that is the fraction of land in a given model grid box of 2.5 x 2.5 km2 in units of %, and the orography in units of m. There are three more orography-related static parameters: subgrid orography average slope, subgrid orography average direction and subgrid orography standard deviation. For each model grid box in HARMONIE-AROME 4 tile fractions are defined in units of fraction. These are: The fraction of sea, the fraction of inland water (lakes and rivers), the fraction of urban areas, and the fraction of nature, i.e. land areas that are not inland water or urban. The fraction of glaciers is also output. This is assumed to be a constant field with glacier extents representative of the middle of the full reanalysis period (19971991-2021). Glacier extent in remote Arctic locations is not available as accurately mapped yearly datasets. The official maps are outdated due to major calving events in the recent decades. HARMONIE-AROME has not yet been designed to deal with changing land-sea masks or other surface classifications. Thus, these are static fields.
What are the uncertainties of the data fields?
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It should be noted that some reanalysis systems aim at describing how reanalysis uncertainties depend on the weather situation, and for instance in ERA5 this has been done by using a so-called ensemble data assimilation system. (For a description of ensemble data assimilation, see for instance the report on the system developed by ECMWF, https://www.ecmwf.int/en/elibrary/7496910125-ensemble-data-assimilations-ecmwf .) Unlike ERA5, the CARRA dataset has not been produced with such a system, so we will provide overall "static", not "weather dependent", uncertainties.
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Name | Levels |
Pressure | Surface as well as mean sea level |
U-component of wind | Pressure levels (50 - 1000 hPa) |
V-component of windy | Pressure levels (50 - 1000 hPa) |
Temperature | Pressure levels (50 - 1000 hPa) |
Geopotential (East domain only) | Pressure levels (50 - 1000 hPa) |
Relative humidity (East domain)/Specific humidity (West domain) | Pressure levels (50 - 1000 hPa) |
In section 6.5 we present uncertainties measured as statistics of actual deviations from observations (also known as verification statistics). Note that observations are a reference not identical to the actual truth, as they also will have uncertainties as well as representativeness issues. This verification statistics is provided for a set of near-surface quantities which are covered by the meteorological observation network, including 2m temperature, 10m winds and precipitation.
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Name | Short name | Unit | Level | Summer statistics | Winter statistics | ||
Upper Bound STDV | Refined STDV | Upper Bound STDV | Refined STDV | ||||
Surface pressure | sp | Pa | 0m above ground | 37.20 | 26.78 | 41.14 | 38.67 |
Mean sea level pressure | msl | Pa | 0m above sea level | 38.18 | 27.49 | 42.15 | 39.62 |
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Figure 2: Climatological analysis error standard deviation for u-component of wind: summer statistics (left), winter statistics (right) as function of standard vertical pressure levels for the CARRA-East domain.
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Name | Short name | Unit | Level | Summer statistics | Winter statistics | ||
Upper Bound STDV | Refined STDV | Upper Bound STDV | Refined STDV | ||||
u-component of wind | u | m/s | 50hPa | 0.545 | 0.223 | 0.556 | 0.228 |
u-component of wind | u | m/s | 100hPa | 0.372 | 0.153 | 0.397 | 0.169 |
u-component of wind | u | m/s | 150hPa | 0.584 | 0.239 | 0.619 | 0.254 |
u-component of wind | u | m/s | 200hPa | 0.865 | 0.355 | 0.923 | 0.378 |
u-component of wind | u | m/s | 250hPa | 1.077 | 0.442 | 1.089 | 0.447 |
u-component of wind | u | m/s | 300hPa | 1.290 | 0.530 | 1.240 | 0.508 |
u-component of wind | u | m/s | 400hPa | 1.282 | 0.526 | 1.292 | 0.530 |
u-component of wind | u | m/s | 500hPa | 1.284 | 0.526 | 1.364 | 0.559 |
u-component of wind | u | m/s | 600hPa | 1.322 | 0.648 | 1.392 | 0.738 |
u-component of wind | u | m/s | 700hPa | 1.346 | 0.740 | 1.404 | 0.927 |
u-component of wind | u | m/s | 800hPa | 1.344 | 0.833 | 1.324 | 1.006 |
u-component of wind | u | m/s | 850hPa | 1.331 | 0.865 | 1.274 | 1.045 |
u-component of wind | u | m/s | 900hPa | 1.311 | 0.905 | 1.275 | 1.122 |
u-component of wind | u | m/s | 925hPa | 1.315 | 0.921 | 1.295 | 1.178 |
u-component of wind | u | m/s | 950hPa | 1.330 | 0.958 | 1.305 | 1.227 |
u-component of wind | u | m/s | 1000hPa | 1.302 | 0.937 | 1.172 | 1.102 |
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Name | Short name | Unit | Level | Summer statistics | Winter statistics | ||
Upper Bound STDV | Refined STDV | Upper Bound STDV | Refined STDV | ||||
v-component of wind | v | m/s | 50hPa | 0.541 | 0.222 | 0.541 | 0.222 |
v-component of wind | v | m/s | 100hPa | 0.376 | 0.154 | 0.384 | 0.157 |
v-component of wind | v | m/s | 150hPa | 0.597 | 0.245 | 0.599 | 0.246 |
v-component of wind | v | m/s | 200hPa | 0.884 | 0.362 | 0.898 | 0.368 |
v-component of wind | v | m/s | 250hPa | 1.105 | 0.453 | 1.061 | 0.435 |
v-component of wind | v | m/s | 300hPa | 1.337 | 0.548 | 1.209 | 0.496 |
v-component of wind | v | m/s | 400hPa | 1.313 | 0.538 | 1.270 | 0.521 |
v-component of wind | v | m/s | 500hPa | 1.328 | 0.544 | 1.351 | 0.554 |
v-component of wind | v | m/s | 600hPa | 1.363 | 0.668 | 1.391 | 0.737 |
v-component of wind | v | m/s | 700hPa | 1.383 | 0.761 | 1.402 | 0.925 |
v-component of wind | v | m/s | 800hPa | 1.382 | 0.857 | 1.332 | 1.012 |
v-component of wind | v | m/s | 850hPa | 1.363 | 0.886 | 1.282 | 1.051 |
v-component of wind | v | m/s | 900hPa | 1.342 | 0.926 | 1.277 | 1.124 |
v-component of wind | v | m/s | 925hPa | 1.344 | 0.941 | 1.293 | 1.177 |
v-component of wind | v | m/s | 950hPa | 1.361 | 0.980 | 1.299 | 1.221 |
v-component of wind | v | m/s | 1000hPa | 1.318 | 0.949 | 1.167 | 1.097 |
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Name | Short name | Unit | Level | Summer statistics | Winter statistics | ||
Upper Bound STDV | Refined STDV | Upper Bound STDV | Refined STDV | ||||
temperature | t | K | 50hPa | 0.141 | 0.058 | 0.142 | 0.058 |
temperature | t | K | 100hPa | 0.122 | 0.050 | 0.122 | 0.050 |
temperature | t | K | 150hPa | 0.230 | 0.094 | 0.224 | 0.092 |
temperature | t | K | 200hPa | 0.466 | 0.191 | 0.441 | 0.181 |
temperature | t | K | 250hPa | 0.490 | 0.201 | 0.438 | 0.180 |
temperature | t | K | 300hPa | 0.392 | 0.161 | 0.406 | 0.167 |
temperature | t | K | 400hPa | 0.314 | 0.129 | 0.341 | 0.140 |
temperature | t | K | 500hPa | 0.346 | 0.142 | 0.359 | 0.147 |
temperature | t | K | 600hPa | 0.399 | 0.196 | 0.399 | 0.211 |
temperature | t | K | 700hPa | 0.465 | 0.256 | 0.465 | 0.307 |
temperature | t | K | 800hPa | 0.537 | 0.333 | 0.485 | 0.369 |
temperature | t | K | 850hPa | 0.586 | 0.381 | 0.508 | 0.417 |
temperature | t | K | 900hPa | 0.614 | 0.424 | 0.520 | 0.458 |
temperature | t | K | 925hPa | 0.604 | 0.423 | 0.531 | 0.483 |
temperature | t | K | 950hPa | 0.612 | 0.441 | 0.546 | 0.513 |
temperature | t | K | 1000hPa | 0.582 | 0.419 | 0.576 | 0.504 |
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Name | Short name | Unit | Level | Summer statistics | Winter statistics | ||
Upper Bound STDV | Refined STDV | Upper Bound STDV | Refined STDV | ||||
geopotential | z | m²/s² | 50hPa | 42.17 | 17.29 | 41.54 | 17.03 |
geopotential | z | m²/s² | 100hPa | 41.29 | 16.93 | 40.39 | 16.56 |
geopotential | z | m²/s² | 150hPa | 39.06 | 16.01 | 38.22 | 15.67 |
geopotential | z | m²/s² | 200hPa | 30.34 | 12.44 | 30.41 | 12.47 |
geopotential | z | m²/s² | 250hPa | 29.65 | 12.16 | 29.87 | 12.25 |
geopotential | z | m²/s² | 300hPa | 31.28 | 12.82 | 30.92 | 12.68 |
geopotential | z | m²/s² | 400hPa | 29.68 | 12.17 | 29.56 | 12.12 |
geopotential | z | m²/s² | 500hPa | 27.60 | 11.32 | 27.56 | 11.30 |
geopotential | z | m²/s² | 600hPa | 26.57 | 13.02 | 26.47 | 14.03 |
geopotential | z | m²/s² | 700hPa | 25.99 | 14.29 | 25.93 | 17.11 |
geopotential | z | m²/s² | 800hPa | 25.40 | 15.75 | 25.48 | 19.36 |
geopotential | z | m²/s² | 850hPa | 25.13 | 16.33 | 25.68 | 21.06 |
geopotential | z | m²/s² | 900hPa | 25.40 | 17.53 | 26.80 | 23.58 |
geopotential | z | m²/s² | 925hPa | 25.89 | 18.12 | 27.77 | 25.27 |
geopotential | z | m²/s² | 950hPa | 26.74 | 19.25 | 29.02 | 27.28 |
geopotential | z | m²/s² | 1000hPa | 29.47 | 21.22 | 32.43 | 30.48 |
Table 12: Climatological analysis error standard deviation relative humidity for the CARRA-East domain. Anchor table12 table12
Name | Short name | Unit | Level | Summer statistics | Winter statistics | ||
Upper Bound STDV | Refined STDV | Upper Bound STDV | Refined STDV | ||||
relative humidity | r | % | 50hPa | 0.024 | 0.010 | 1.256 | 0.515 |
relative humidity | r | % | 100hPa | 0.010 | 0.004 | 0.194 | 0.080 |
relative humidity | r | % | 150hPa | 0.040 | 0.016 | 0.425 | 0.174 |
relative humidity | r | % | 200hPa | 0.534 | 0.219 | 1.913 | 0.784 |
relative humidity | r | % | 250hPa | 3.223 | 1.321 | 4.900 | 2.009 |
relative humidity | r | % | 300hPa | 6.153 | 2.523 | 8.861 | 3.633 |
relative humidity | r | % | 400hPa | 8.236 | 3.377 | 12.634 | 5.180 |
relative humidity | r | % | 500hPa | 7.181 | 2.944 | 12.562 | 5.150 |
relative humidity | r | % | 600hPa | 6.819 | 3.341 | 11.824 | 6.267 |
relative humidity | r | % | 700hPa | 6.740 | 3.707 | 11.522 | 7.605 |
relative humidity | r | % | 800hPa | 6.544 | 4.057 | 9.638 | 7.325 |
relative humidity | r | % | 850hPa | 6.118 | 3.977 | 8.194 | 6.719 |
relative humidity | r | % | 900hPa | 5.215 | 3.598 | 6.820 | 6.002 |
relative humidity | r | % | 925hPa | 4.674 | 3.272 | 6.303 | 5.736 |
relative humidity | r | % | 950hPa | 4.285 | 3.085 | 5.767 | 5.421 |
relative humidity | r | % | 1000hPa | 3.477 | 2.503 | 4.277 | 4.020 |
Uncertainties for the CARRA-West model domain
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Name | Short name | Unit | Level | Upper Bound STDV | Refined STDV |
Surface pressure | sp | Pa | 0m above ground | 26.11 | 7.04 |
Mean sea level pressure | msl | Pa | 0m above sea level | 39.44 | 10.64 |
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Figure 7: Climatological analysis error standard deviation for u-component of wind (left plot) and for v-component of wind (right plot) as function of standard vertical pressure levels for the CARRA-West domain.
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Name | Short name | Unit | Level | Upper Bound STDV | Refined STDV |
u-component of wind | u | m/s | 50hPa | 0.540 | 0.146 |
u-component of wind | u | m/s | 100hPa | 0.370 | 0.100 |
u-component of wind | u | m/s | 150hPa | 0.447 | 0.121 |
u-component of wind | u | m/s | 200hPa | 0.611 | 0.165 |
u-component of wind | u | m/s | 250hPa | 0.732 | 0.198 |
u-component of wind | u | m/s | 300hPa | 0.871 | 0.235 |
u-component of wind | u | m/s | 400hPa | 0.869 | 0.235 |
u-component of wind | u | m/s | 500hPa | 0.862 | 0.233 |
u-component of wind | u | m/s | 600hPa | 0.887 | 0.240 |
u-component of wind | u | m/s | 700hPa | 0.893 | 0.241 |
u-component of wind | u | m/s | 800hPa | 0.856 | 0.231 |
u-component of wind | u | m/s | 850hPa | 0.831 | 0.224 |
u-component of wind | u | m/s | 900hPa | 0.810 | 0.219 |
u-component of wind | u | m/s | 925hPa | 0.803 | 0.217 |
u-component of wind | u | m/s | 950hPa | 0.799 | 0.216 |
u-component of wind | u | m/s | 1000hPa | 0.773 | 0.209 |
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Name | Short name | Unit | Level | Upper Bound STDV | Refined STDV |
v-component of wind | v | m/s | 50hPa | 0.535 | 0.144 |
v-component of wind | v | m/s | 100hPa | 0.360 | 0.097 |
v-component of wind | v | m/s | 150hPa | 0.449 | 0.135 |
v-component of wind | v | m/s | 200hPa | 0.603 | 0.162 |
v-component of wind | v | m/s | 250hPa | 0.714 | 0.193 |
v-component of wind | v | m/s | 300hPa | 0.851 | 0.230 |
v-component of wind | v | m/s | 400hPa | 0.853 | 0.230 |
v-component of wind | v | m/s | 500hPa | 0.852 | 0.230 |
v-component of wind | v | m/s | 600hPa | 0.877 | 0.237 |
v-component of wind | v | m/s | 700hPa | 0.884 | 0.239 |
v-component of wind | v | m/s | 800hPa | 0.852 | 0.230 |
v-component of wind | v | m/s | 850hPa | 0.826 | 0.223 |
v-component of wind | v | m/s | 900hPa | 0.801 | 0.216 |
v-component of wind | v | m/s | 925hPa | 0.794 | 0.214 |
v-component of wind | v | m/s | 950hPa | 0.792 | 0.214 |
v-component of wind | v | m/s | 1000hPa | 0.763 | 0.206 |
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Figure 8: Climatological analysis error standard deviation for temperature (left plot) and specific humidity (right plot) as a function of standard pressure levels for the CARRA-West domain.
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Name | Short name | Unit | Level | Upper Bound STDV | Refined STDV |
temperature | t | K | 50hPa | 0.130 | 0.035 |
temperature | t | K | 100hPa | 0.112 | 0.030 |
temperature | t | K | 150hPa | 0.169 | 0.045 |
temperature | t | K | 200hPa | 0.276 | 0.075 |
temperature | t | K | 250hPa | 0.285 | 0.077 |
temperature | t | K | 300hPa | 0.263 | 0.071 |
temperature | t | K | 400hPa | 0.227 | 0.061 |
temperature | t | K | 500hPa | 0.235 | 0.063 |
temperature | t | K | 600hPa | 0.259 | 0.070 |
temperature | t | K | 700hPa | 0.350 | 0.095 |
temperature | t | K | 800hPa | 0.473 | 0.128 |
temperature | t | K | 850hPa | 0.500 | 0.135 |
temperature | t | K | 900hPa | 0.508 | 0.137 |
temperature | t | K | 925hPa | 0.509 | 0.137 |
temperature | t | K | 950hPa | 0.520 | 0.140 |
temperature | t | K | 1000hPa | 0.542 | 0.146 |
Table 17: Climatological analysis error standard deviation for specific humidity for the CARRA-West domain. Anchor table17 table17
Name | Short name | Unit | Level | Upper Bound STDV | Refined STDV |
specific humidity | r | g/kg | 50hPa | 0. | 0. |
specific humidity | r | g/kg | 100hPa | 0. | 0. |
specific humidity | r | g/kg | 150hPa | 0. | 0. |
specific humidity | r | g/kg | 200hPa | 0.001 | 0.0002 |
specific humidity | r | g/kg | 250hPa | 0.002 | 0.0004 |
specific humidity | r | g/kg | 300hPa | 0.006 | 0.001 |
specific humidity | r | g/kg | 400hPa | 0.020 | 0.005 |
specific humidity | r | g/kg | 500hPa | 0.048 | 0.013 |
specific humidity | r | g/kg | 600hPa | 0.082 | 0.022 |
specific humidity | r | g/kg | 700hPa | 0.113 | 0.031 |
specific humidity | r | g/kg | 800hPa | 0.127 | 0.034 |
specific humidity | r | g/kg | 850hPa | 0.126 | 0.034 |
specific humidity | r | g/kg | 900hPa | 0.119 | 0.032 |
specific humidity | r | g/kg | 925hPa | 0.115 | 0.031 |
specific humidity | r | g/kg | 950hPa | 0.112 | 0.030 |
specific humidity | r | g/kg | 1000hPa | 0.099 | 0.027 |
Questions & Answers on field uncertainty estimates
For information and "questions and answers" (Q&A) on the uncertainty estimates for the ERA5 host reanalysis used on the lateral boundaries of this Arctic Regional Reanalysis, see this link:
ERA5: uncertainty estimation
The field uncertainty estimates provided here apply a different approach. The below Q&A is similar to the Q&A for the global reanalysis, adapted to apply for the uncertainty estimates provided here (for the Arctic reanalysis).
...
Since the regional reanalysis is run nested into the ERA5 global reanalysis, it is affected by the known issues of ERA5. In addition to those issues, we have found that ERA5 uses incorrect glacier masks for most of the glaciers in the regional Arctic reanalysis domain, and the glaciers in ERA5 always have an analysis albedo of 0.85. This is wrong, since for instance exposed glacier ice albedos during summer are unaccounted for. These areas affect the general circulation and thermodynamic state in ERA5 and can affect the quality of the Arctic regional reanalysis.
Additionally, the Arctic reanalysis has the following known issues:
...
The Arctic reanalysis system applies the so-called 3D variational data assimilation (3D-VAR) reanalysis method. The 3D-VAR method is depicted schematically in Figure 19. At fixed points in time the model state is adjusted based on the observed state, taking into account the statistics of model and observation errors. The Arctic reanalysis system is run with eight cycles per day performing analyses at 00 UTC, 03 UTC, 06 UTC, 09 UTC, 12 UTC, 15 UTC, 18 UTC and 21 UTC. The forecast lengths vary between 3 and 30 hours.
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This document has been produced in the context of the Copernicus Climate Change Service (C3S).The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of C3S on behalf of the European Union (DelegationAgreementagreement signed on 11/11/2014and Contribution Agreement signed on 22/07/2021). All information in this document is provided "as is" and no guarantee or warranty is given that the information is fit for any particular purpose.The users thereof use the information at their sole risk and liability. For the avoidance of all doubt , the European Commission and the European Centre for Medium - Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view. |
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