SURFEX Meso-NH training course February 2008 Patrick Le Moigne.
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Transcript of SURFEX Meso-NH training course February 2008 Patrick Le Moigne.
![Page 1: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/1.jpg)
SURFEX
Meso-NH training courseFebruary 2008
Patrick Le Moigne
![Page 2: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/2.jpg)
Overview of the externalized surface: theoretical background
A. Introduction to SURFEX
A1. The objectives of SURFEXA2. How to reach these objectives?A3. Surface energy budgetA4. Water cycle
B. SURFEX package algorithms
B1. Initialization of physiographic fieldsB2. Initialization of prognostic variablesB3. Running surface physical parameterizations
![Page 3: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/3.jpg)
Overview of the externalized surface: theoretical background
C. Princip of SURFEX
C1. InitializationC2. I/OC3. Organization of physical computations
D. Computation of T2m, Q2m and U10m
D1. DiagnosticsD2. 1D Surface Boundary Layer
E. Namelists
E1. Main namelist optionsE2. DiagnosticsE3. Physical options
![Page 4: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/4.jpg)
Overview of the externalized surface: theoretical background
A. Introduction to SURFEX
B. SURFEX package algorithms
C. Princip of SURFEX
D. Computation of T2m, Q2m and U10m
E. Namelists
![Page 5: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/5.jpg)
A1. The objectives of SURFEX
► The role of surface in a NWP model is to simulate the exchanges of momentum, heat, water, carbon dioxyd concentration or chemical species with the atmosphere. These exchanges are performed by the mean of fluxes.
atmospheric model
forcingfluxes
surface
![Page 6: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/6.jpg)
A1. The objectives of SURFEX
► The role of surface in a NWP model is to simulate the exchanges of momentum, heat, water, carbon dioxyd concentration or chemical species with the atmosphere. These exchanges are performed by the mean of fluxes.
► An important feature is to separate the surface schemes from the atmospheric model:
♦ it allows the use of the same surface code in different atmospheric models: meso-NH, Arome, Arpege/Aladin, ...
♦ the switch between surface schemes and options is easy
► Combines different level of complexity in the proposed schemes
♦ ideal fluxes approach♦ 2 levels of tiling for surface areas
![Page 7: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/7.jpg)
A2. How to reach these objectives?
► Use dedicated physical parameterizations
Lake
Town
Sea and ocean
Soil and Vegetation
Prescribed temperature, Flake
TEB: Town Energy Balance(Masson 2000)
Prescribed temperature, 1D model
ISBA: Interface Soil Biosphere Atmosphere(Noilhan-Planton 1989, Noilhan-Mahfouf 1996)
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A2. How to reach these objectives?
► Use accurate databases for surface parameters
ECOCLIMAP
FAO
GTOPO30
1km land surface parameters
10km texture of soil
1km Orography
BATHY 2km bathymetry
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A3. Surface energy budget (source IPCC* 2001)
ATMOSPHERE
SURFACE
SPACE342 107
168
67
40
390
350
195
32478 24
0.2 – 3 microns 3 - 100 microns
UV solar radiation Infra-red radiation
Water vapour
aerosols,
ozone
Water vapour,
water, cloud ice,
CO2, CH4, ozone
Sensible
heat
Latent
heat
IPCC : Intergovernemental Panel on Climate Change
heating=emission
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A3. Surface energy budget
thermodynamics gives:
Rn
G
H LE
Radiative transfer
Conduction transfer
Convection transfer
RG RAT
αRG ε σTs4
Energy absorbed by surface: RG – αRG + εRAT
)(1 4STRRR
ATGtN
LEHGRN
z
qLE
zH
~
~
Turbulent Fluxes: Louis, 1979
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A4. Water cycle
precipitation
interceptiontranspiration
runoff
Drainage
evaporation
precipitation
evaporation
outlet
20
8086
14
underground streamflow
25%
15%
60%
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Overview of the externalized surface: theoretical background
A. Introduction to SURFEX
B. SURFEX package algorithms
C. Princip of SURFEX
D. Computation of T2m, Q2m and U10m
E. Namelists
![Page 13: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/13.jpg)
B1. Initialization of physiographic fields
► PGD facility (~e923) is used to prepare physiographic fields at any scale, including subgrid orography fields at 30'' resolution from GTOPO30 database
the user has to define (namelist):
♦ a geographic area of interest (at any place of the globe)♦ a projection (between latlon, cartesian, conformal, ...)♦ a grid (resolution, number of points in both directions, ...)
and to specify databases for (namelist):
♦ orography♦ soil texture♦ vegetation
♦ bathymetry
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B1. Initialization of physiographic fields
► GTOPO30 database
Orography (m) at 1km resolution
~10km mesh
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B1. Initialization of physiographic fields
► FAO database (http://www.fao.org)
Soil texture: proportion of sand and clay at 10km resolution
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B1. Initialization of physiographic fields
► ECOCLIMAP database
Global database at 1km resolution for surface parameters
☻ Depending on soil% sand % clay depth
☻ Depending on vegetationfraction of vegetation (veg)leaf area index (LAI)minimal stomatal resistance (Rsmin)roughness length (z0)
☻ Depending on soil and vegetationalbedoemissivity
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B1. Initialization of physiographic fields
► ECOCLIMAP database
DEFINING ECOSYSTEMS
CLIMATE MAP LAND COVER MAPS NDVI profiles: NOAA/AVHRR
Koeppe et de Lond 1958
1km: 16 classes
University of Maryland
1km: 15 classes
Corine land cover
« 250m »: 44 cl.
215 ecosystems
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B1. Initialization of physiographic fields
► ECOCLIMAP database
NDVI : Normalized Digital Vegetation Index
NDVI = ( PIR – VIS ) / ( PIR + VIS )
PIR : near infra-red reflectance [0.725 microns, 1.0 microns]
VIS : visible reflectance [0.58 microns, 0.68 microns]
NDVI = { 0.1 ; 0.6 }
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B1. Initialization of physiographic fields
► ECOCLIMAP database
CLIMATE MAP (Koeppe et de Lond, 1958)
![Page 20: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/20.jpg)
B1. Initialization of physiographic fields
► ECOCLIMAP database
LAND COVER MAPS (university of Maryland, 1km)
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B1. Initialization of physiographic fields
► ECOCLIMAP database
LAND COVER MAPS (Corine land cover, 1km)
![Page 22: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/22.jpg)
B1. Initialization of physiographic fields
► ECOCLIMAP algorithm
Each land cover is represented as a fraction of vegetation types (12 vegetation types):fraction of woody vegetation, herbaceous vegetation and bare soil for each land cover
landcover
% variation depends on climate
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B1. Initialization of physiographic fields
► ECOCLIMAP algorithm
1. Global repartition of
woodland
2. NDVI profiles of wooded grassland
Humid continental Extreme subpolar
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B1. Initialization of physiographic fields
► ECOCLIMAP algorithm: computation of surface parameters
LAI=LAImin + (LAImax-LAImin) * (NDVI-NDVImin)/(NDVImax-NDVImin)
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B1. Initialization of physiographic fields
► ECOCLIMAP algorithm: aggregation rules
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216
183
165
10%40%
50%
VGT %
No
Rock
Snow
Tree
Coni
Ever
C3
C4
Irr
Gras 1.
Trog
Park
VGT %
No
Rock
Snow
Tree
Coni
Ever
C3 0.9
C4 0.1
Irr
Gras
Trog
Park
VGT %
No
Rock
Snow
Tree 0.5
Coni 0.5
Ever
C3
C4
Irr
Gras
Trog
Park
165: Atlantic crops
183: Atlantic pastures
216: Atlantic mixed forest
ECOCLIMAP SURFEX SETUP
),(*)cov,(*)cov(12
11cov
tivegtypeFerjivegtypeferjfivegtype
N
erj
Moyenne arithmétique basée sur:
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B1. Initialization of physiographic fields
► ECOCLIMAP results: Leaf Area Index for July
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B1. Initialization of physiographic fields
► ECOCLIMAP results: particular covers
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B1. Initialization of physiographic fields
► BATHYMETRY (2km)
![Page 30: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/30.jpg)
B2. Initialization of prognostic fields
► PREP facility (~e927) is used to initialize prognostic variables from different atmospheric models like:
ECMWF, ARPEGE, ALADIN, MESO-NH, MOCAGE, MERCATOR
usually following variables need to be set up:
☺ vertical profiles for temperature, liquid water and ice (nature)☺ temperatures of road, wall and roof (urban areas)☺ sst and water temperature for respectively seas and lakes☺ interception water content☺ snow water equivalent and other snow prognostic variable
(depending on the snow scheme)
Fields computed with PGD will also be written in file generated by PREP application.
...t
)0( t
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B3. Running surface schemes
► Méso-NH AROME Arpège / Aladin
Atmospheric forcing Sun position Downward radiative fluxes
albedo emissivity radiative temperature
momentum flux sensible heat latent heat CO2 flux Chemical fluxes
Surfex output as surface boundary conditions for atmospheric radiation and turbulent scheme (additional output needed for the convection scheme)
![Page 32: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/32.jpg)
Overview of the externalized surface: theoretical background
A. Introduction to SURFEX
B. SURFEX package algorithms
C. Princip of SURFEX
D. Computation of T2m, Q2m and U10m
E. Namelists
![Page 33: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/33.jpg)
C1. SURFEX setup
► tiling is one important feature of the externalized surface: each grid cell is divided into 4 elementary units according to the fraction of covers in the grid cell:
nature
water
sea
town
![Page 34: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/34.jpg)
C1. SURFEX setup
► second level of tiling for vegetation: natural areas of each grid cell may be divided into several peaces called patches.
1: bare ground2: rocks3: permanent snow4: deciduous forest5: conifer forest6: evergreen broadleaf trees7: C3 crops8: C4 crops9: irrigated crops10: grassland11: tropical grassland12: garden and parks
Tile nature
![Page 35: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/35.jpg)
C1. SURFEX setup
► initialization of masks.
In order to optimize physical computations, a mask is associated to each tile (each patch as well if more than one patch has been defined) and the physical parameterizations are performed on physical points only (town-tile is treated only with the town scheme).
The size of the masks are computed by counting the number of grid cells which have a non-zero fraction of the tile in the domain of interest.
The definition of the masks are based on fortran routines PACK and UNPACK:
![Page 36: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/36.jpg)
C1. SURFEX setup
► initialization of masks: example
Particular case where each grid box is represented with only one tile (pure pixel, while in reality each tile may be present in the box)
The grid is composed of 12 grid cells organized as follows:
In this case the fraction of each tile is given by:
XNATURE = ( 1 1 0 0 0 1 0 0 1 0 0 1 ) XTOWN = ( 0 0 1 1 0 0 0 1 0 0 0 0 ) XSEA = ( 0 0 0 0 0 0 1 0 0 1 1 0 ) XWATER = ( 0 0 0 0 1 0 0 0 0 0 0 0 )
The dimensions of the masks are respectively 5, 3, 3 and 1
1 NATURE 2 NATURE 3 TOWN 4 TOWN 5 WATER 6 NATURE 7 SEA 8 TOWN 9 NATURE 10 SEA 11 SEA 12 NATURE
![Page 37: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/37.jpg)
C1. SURFEX setup
► initialization of masks: example
Once the fraction and the size of the mask of each tile is computed, it becomes possible to pack the variables over each tile to deduce effective mask (1D vector):
repartition of each tile over the grid
associated mask (1, 2, 6, 9, 12) (3, 4, 8) (7, 10, 11) (5)
XP_NATURE (3) = X(NATURE_MASK(3)) = X(6)
N N N N N
T T T
S S S
W
N N N N N1 2 6 9 12
W
5
T T T3 4 8
S S S7 10 11
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Sea schemeinit_sea_n
modd_surf_atm_n
Lake schemeinit_inland_water_nmodd_surf_atm_n
Town schemeinit_town_n
modd_surf_atm_n
Vegetation schemeinit_nature_n
modd_surf_atm_n
sea
inland_water
town
nature
1d field
C1. SURFEX setup
► initialization of tiles:
![Page 39: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/39.jpg)
C1. SURFEX setup
► initialization of data from cover fields
information from PGD file is read and then for each cover (1 to 255) some parameters are initialized like for example:
fractions of sea, nature, town and lakes temporal cycle of LAI fraction, root and ground depth of each vegetation type albedo, emissivity, heat capacities, ... of artificial areas
► prognostic variables are read from initial file (PREP)
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C2. I/O
► I/O belong to the model that calls SURFEX. Reading and writing orders are done using the same generic subroutine, called respectively read_surf and write_surf.
► According to the atmospheric model (AROME or Meso-NH), different subroutines are then called:
read_surfxx_mnh write_surf_mnh meso-nh read_surfxx_aro write_surfxx_aro arome read_surfxx_ol write_surfxx_ol off-line read_surfxx_asc write_surfxx_asc off-line xx is the type of the variable to be read or written
► reading and writing orders are distributed over processors
► necessary link with I/O library
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C3. Organization of physical computations
► Computation of fluxes: u*, q*, θ*: Monin Oboukov characteristic scale parameters
► Bulk formulation
CD, CH and CE are expressed as functions of 1st layer height, atmosphere stratification and roughness lengths
**''
**''
2*
''
quLqwLLE
ucwcH
uuw
vava
papa
aa
aa
)(
)(
2
asEva
asHpa
Da
qqUCLLE
UCcH
UC
a
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C3. Organization of physical computations
► Aggregation of fluxes :
f TOWN f NATURE f SEA f WATER
FTOWN FNATURE FSEA FWATER
Mean Flux
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C3. Organization of physical computations
► ISBA :
![Page 44: SURFEX Meso-NH training course February 2008 Patrick Le Moigne.](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec13c/html5/thumbnails/44.jpg)
C3. Organization of physical computations
► ISBA :
Interaction between Soil, Biosphere and Atmosphere
there are 2 main options to treat the transfer of water andheat in the soil:
- Force restore method (Noilhan-Planton 1989):
2 or 3 layers for temperature, liquid water and ice
- Diffusion method (Boone 1999):
n-layers for temperature, liquid water and ice
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C3. Organization of physical computations
► ISBA : Interaction Soil, Biosphere and Atmosphere
ATMOSPHERIC FORCING: rain, snow, T, q, v, Ps, Rg, Rat vegetatio
nbare groundsnow
Er Etr Es Eg
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C3. Organization of physical computations
► ISBA : basic equations
Temperature:
CT thermal capacity for soil-vegetation-snow τ day duration G ground heat flux
without ice :
(1)
(2)
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C3. Organization of physical computations
► ISBA : basic equations
Water content:
P total precipitation rate Eg bare ground evaporation wgeq balance water content (gravity/capillarity) Rr interception runoff Qr surface runoff
(3)
P
Rr Qr
Eg
surface runoff Qr occurs oversaturated area
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C3. Organization of physical computations
► ISBA : basic equations
Water content:
Etr evapotranspiration of plantDr1 root layer drainageDf1 diffusion between w2 and w3 layers
(4)
Pg Eg
Etr
Dr1 Df1
d1d2
d3
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C3. Organization of physical computations
► ISBA : basic equations
Water content:
Dr2: deep layer drainage
(5)Dr1 Df1
Dr2
d1d2
d3
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C3. Organization of physical computations
► ISBA : basic equations
Available water:
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C3. Organization of physical computations
► ISBA : basic equations
Interception reservoir:
(6)P
Er
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C3. Organization of physical computations
► ISBA : basic equations
summary:
(6)
(1)
(2)
(3)
(5)
(4)
fct of precipitation and runoff
fct of water contents, soil texture
terms of the energy balance:ground flux and evaporation
G = Rn-H-LE
=> parameterizations for sensible heat flux H and latent heat flux LE
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C3. Organization of physical computations
► ISBA : basic equations
sensible heat flux: following Louis 1979
Cp air specific heatCh turbulent exchange coefficientVa wind speedT potential temperature
Ta
Ts
r
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C3. Organization of physical computations
► ISBA : basic equations
latent heat flux:
S
Fraction of foliage covered by intercepted water
Minimum stomatal resistance of vegetation:
(i) Jarvis formulation (1976)(ii) Isba-A-gs: Rs depends on CO2 concentration and of the capability of plants to assimilate it
Relative humidity on surface
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C3. Organization of physical computations
► ISBA : basic equations
A-gs approach: the role of stomatal control
Photosynthesis/Transpiration
The stomatal aperture controls the ratio:
according to the environment conditions
Light, temperature , air humiditysoil moisture atmospheric [CO2]
qa Ta
qs Ts
H20
Ci
Cs
Ca CO
2
PAR
Glucides
qsat
stomatestomate
,
10
m
photosynthesisrespiration
transpiration
water extraction
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C3. Organization of physical computations
► ISBA : basic equations
A-gs approach:
ISBA-A-gs
Met. forcing LAI
LE, H, Rn, W, Ts…
Active Biomass
CO2 Flux[CO2]atm
ISBA
Met. forcing LAI
LE, H, Rn, W, Ts…
♦ The active biomass is a reservoir fed by the net CO2 uptake by leaves (ie An = photosynthesis – leaf respiration)
♦ LAI is computed by the model
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C3. Organization of physical computations
► ISBA : basic equations
Simulated CO2 concentrations (ppm) 14HUTC
FORESTAREA
AGRICUL.AREA
CO
2 co
ncen
trat
ions
Comparison of Simulated and obesrved CO2 concentrations (ppm) 14HUTC
Atmospheric CO2 modeling with MesoNH coupled with Isba-A-gs (Ceres, May-June 2005)
(Sarrat et al., JGR, 2006)
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C3. Organization of physical computations
► ISBA : basic equations
snow: 3 schemes available in SURFEX
- Douville 95: 1 layeralbedo, density and swe
- Boone and Etchevers 2000: 3 layersalbedo, density and heat flux at the interface soil-snow
- Bogatchev and Bazile 2005: 1 layeralbedo and swe
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C3. Organization of physical computations
► ISBA Explicit Snow
Prognostic variables:
thickness of each snow layer (D)snow density snowpack heat content (Hs)
Diagnostic variables:
snow water equivalent snowpack liquid water (Wl)snow layer temperature (T)
Ds is recomputed when snow cover is modified (fresh snowfall, compaction or melting)
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C3. Organization of physical computations
► TEB :
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C3. Organization of physical computations
► TEB :
Town Energy Balance
Urban Canyon concept:
building road
air volume
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C3. Organization of physical computations
► TEB : Town Energy Balance
♦ Radiative perturbations
- shading effect on walls and roads
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C3. Organization of physical computations
► TEB : Town Energy Balance
♦ Radiative perturbations:
- shading effect on walls and roads - radiative trapping inside the canyon
Incoming Incoming shortwave shortwave radiationradiation
Infrared emissionsInfrared emissions
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C3. Organization of physical computations
► TEB : Town Energy Balance
♦ Radiative perturbations
♦ Thermal perturbations
- specific properties of materials - lot of available surface
Strong heat storage
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C3. Organization of physical computations
► TEB : Town Energy Balance
♦ Radiative perturbations
♦ Thermal perturbations
♦ Anthopogenic emissions
- metabolism
- road traffic
- heating and cooling domestic systems
- industrial areas
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C3. Organization of physical computations
► TEB : Town Energy Balance
♦ Radiative perturbations
♦ Thermal perturbations
♦ Anthopogenic emissions
♦ Hydrological perturbations
- sewer network
- waterproof surfaces
Strong runoff and weak evaporation
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C3. Organization of physical computations
► TEB : Town Energy Balance
Urban canopy energy balance:
Q* : net radiationQF : anthropogenic fluxQH : sensible heat fluxQE : latent heat fluxΔQS : heat storage fluxΔQA : heat advection net flux
Mexico-city center
Oke et al., 1999
Q* + QF = QH + QE + ΔQS + ΔQA
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C3. Organization of physical computations
► TEB : Town Energy Balance
Urban canopy model : Parameterization of the exchanges of water and energy between canopy and the atmosphere
Exclusive treatment of built surfaces
Idealized geometry : Computations are made on a mean
urban canyon representative of all roads of the area of interest.
Use of 3 elementary surfaces : 1 roof, 2 identical walls and 1 road
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C3. Organization of physical computations
► TEB : Town Energy Balance
1. Computation of the energy budget of each surface:
- incoming shortwave and longwave radiation- fraction of absorbed radiation
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C3. Organization of physical computations
► TEB : Town Energy Balance
1. Computation of the energy budget of each surface:
- incoming shortwave and longwave radiation- fraction of absorbed radiation
2. Computation of the surface temperatures as well as the temperatures of each material layer
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C3. Organization of physical computations
► TEB : Town Energy Balance
1. Computation of the energy budget of each surface:
- incoming shortwave and longwave radiation- fraction of absorbed radiation
2. Computation of the surface temperatures as well as the temperatures of each material layer
3. Computation for each surface of the exchanges of energy with an aerodynamical resistance network
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C3. Organization of physical computations
► TEB : Town Energy Balance
1. Computation of the energy budget of each surface:
- incoming shortwave and longwave radiation- fraction of absorbed radiation
2. Computation of the surface temperatures as well as the temperatures of each material layer
3. Computation for each surface of the exchanges of energy with an aerodynamical resistance network
4. Computation of air temperature and humidity inside the canyon
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C3. Organization of physical computations
► TEB : Town Energy Balance Arome forecast valid for 18th of November 2005 midnight
Urban heat Island around Lyon and Toulouse cities
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C3. Organization of physical computations
► TEB :
Town Energy Balance
Urban Canyon concept:
building road
air volume
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C3. Organization of physical computations
► SEA :
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C3. Organization of physical computations
► SEA : simple parameterization
surface temperature is prescribed
use of Charnock formulation to compute Z0 over sea:
Z0 = 0.015 (u*)² / G in order to compute turbulent exchangecoefficients and then fluxes
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C3. Organization of physical computations
► SEA : 1D Ocean Boundary Layer
Gaspar, et al. 1990:
Prognostic SST, salinity, wind and tke
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C3. Organization of physical computations
► SEA : Fluxes
)(
)(
2
asEva
asHpa
Da
qqUCLLE
UCcH
UC
a
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C3. Organization of physical computations
► SEA :
SST SALINITY
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C3. Organization of physical computations
► FLAKE :
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C3. Organization of physical computations
► FLAKE :
(a) The evolving temperature profile is characterized by five time-dependent parameters, namely, the temperature θs(t) and the depth h(t) of the mixed layer, the bottom temperature θb(t), the depth H(t) within bottom sediments penetrated by the thermal wave and the temperature θH(t) at that depth.
s(t)
b(t)
(a)
L
H
(t)
h(t)
D
L
H(t)
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C3. Organization of physical computations
► FLAKE :
(b) In winter, four more variables are computed, namely, the temperature θS(t) at the air-snow interface, the temperature θI(t) at the the snow-ice interface, the snow thickness HS(t) and the ice thickness HI(t).
s(t)
b(t)
I(t)
S(t)
(b)
L
H
(t)
h(t)
D
L
H(t)
-HI(t)
-HI(t)-H
S(t)
Snow
Ice
Water
Sediment
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During run, at each timestep
Albedo, Emissivity,radiative temp.
Momentum fluxesHeat fluxWater vapor fluxCO2 fluxChemical fluxes
SurfaceInitialisation
Before first time step
Surfacerun
Surfacewriting
Output files
Type of input fileSun position
Albedo, Emissivity,radiative temp.
Radiative fluxesSun positionAtm. ForcingRain, snow fall
Type of output file
Atm
osph
eric mod
elsu
rface
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C3. Use of surfex in NWP
► AROME
► MESONH
► ALADIN
► ARPEGE - CLIMAT
RADIATION
TURBULENCE
CONVECTION
SURFACE
MICRO PHYSICS
AROME / MESONH
ADJUSTMENT
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C3. Use of surfex in NWP
► OFF-LINE mode
SURFACE
Ta, Qa, Ua, Rain, Snow, P, Sw, Lw
ATMOSPHERE
Surface fluxes and diagnostics computed for each tile and each grid box at each time step
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Overview of the externalized surface: theoretical background
A. Introduction to SURFEX
B. SURFEX package algorithms
C. Princip of SURFEX
D. Computation of T2m, Q2m and U10m
E. Namelists
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D1. Computation of T2M, Q2M, U10M
► Diagnostic
► Prognostic: 1d surface boundary layer scheme (canopy)
By using CLS laws between surface and 1st atmospheric layer:
N2M=2: Geleyn 88
N2M=1: Businger-Dyer
0.5
2
4
6.5
10
14
surface
1st atm. layerz (m)
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Overview of the externalized surface: theoretical background
A. Introduction to SURFEX
B. SURFEX package algorithms
C. Princip of SURFEX
D. Computation of T2m, Q2m and
E. Namelists
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E1. Main namelist options
► PGD
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E1. Main namelist options
► PREP
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E1. Main namelist options
► OFF-LINE
DIAG
PHYS
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E2. Diagnostics
► SURFEX produces several diagnostics:
N2M=1 or 2 temperature, humidity at 2m and wind 10m
LSURF_BUDGET=T net radiation, heat, water vapour and conduction fluxes
LSURF_EVAP_BUDGET=T all ISBA fluxes (evaporation of vegetation, bare ground, sublimation over snow and ice, ...)
LSURF_MISC_BUDGET=T possibility to diagnose specific quantities in ISBA or TEB (roughness length over urban area, halstead coefficient, ...)
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E3. Physical options
► CROUGH:
type of orographic roughness length:
Z01D: orographic roughness length does not depend on wind directionZ04D: orographic roughness length depends on wind direction
► CRUNOFF:
type of subgrid runoff:
WSAT: runoff occurs only when saturation is reachedDT92 : Dumenil and Todini (1992) subgrid runoff
► CSCOND:
type of thermal conductivity:
NP89: Noilhan and Planton (1989) formulaPL98: Peters-Lidar et al. (1998) formula
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E3. Physical options (isba only)
► CALBEDO:
type of bare soil albedo:
DRY : dry bare soil albedoWET : wet bare soil albedoMEAN: albedo of bare soil half dry, half wetEVOL : albedo of bare soil evolving with soil moisture
► CC1DRY:
type of C1 formulation for bar soils:
DEF : Giard and Bazile formulationGB93 : Giordani and Braud (1993) propose a gaussian formulation for C1 force restore coefficient
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E3. Physical options (isba only)
► CSOILFRZ:
type of soil freezing physics option:
DEF : Boone et al. (2000), Giard and Bazile (2000)LWT: phase changes as above, but relation between
unfrozenwater and temperature is considered
► CDIFSFCOND:
type of mulch effect:
DEF : no mulch effectMLCH: include the insulating effect of litter/mulch on the surface thermal conductivity (decreasing of thermal conductivity)
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E3. Physical options (isba only)
► CCPSURF:
type of specific heat at surface:
DRY : specific heat does not depend on surface specific humudity surfaceHUM: specific heat depends on surface specific humudity surface
► CSNOWRES:
type of turbulent exchange over snow:
DEF: Louis (1979)RIL : maximum Richardson number limit for stable conditions