NMMB-DUST developments Carlos Pérez 29 July 2008 Includes preprocessing and first succesful model tests with: - Dust emission with viscous sublayer Dust horizontal advection Dust vertical advection Horizontal diffusion Vertical diffusion Also some notes, comments and future steps

Dust preprocessing in the NMMB-DUST

Dust calculations in preprocessing Surface concentration (instead of emission) is the basis of viscous sublayer emission scheme during model integration Surface concentration Tunning parameter Friction velocity Threshold Friction velocity Dry Threshold Friction velocity Soil moisture Soil water potential Parameter function of particle Reynolds number Particle radius Particle density (1-Veg) air density Landuse fraction (desert mask) Mass available for uptake (fraction ~source size distribution) Calculated in preprocessing fractions of clay (bins 1 to 4) or silt (bins 5 to 8) Calculated during model integration Veg Vegetation fraction (NEW) k Size bin number (total is 8)

MAPS produced in preprocessing Interpolation from initial database format to NMM B grid In this example NMM B grid global at ~50 km resolution

Land use dust producing categories 2 LOW SPARSE GRASSLAND 8 BARE DESERT 11 SEMIDESERT 50 SAND DESERT 51 SEMIDESERT SHRUBS 52 SEMIDESERT SAGE

Land use fraction (0-1) Set to 1 at this point (future tunning) if(landusedust(i,j).eq.2) landusefrac(i,j)=1.0 !LOW SPARSE GRASSLAND (DREAM 0.2) if(landusedust(i,j).eq.8) landusefrac(i,j)=1.0 !BARE DESERT if(landusedust(i,j).eq.11)landusefrac(i,j)=1.0 !SEMIDESERT (DREAM 0.8) if(landusedust(i,j).eq.50)landusefrac(i,j)=1.0 !SAND DESERT if(landusedust(i,j).eq.51)landusefrac(i,j)=1.0 !SEMIDESERT SHRUBS (DREAM 0.7) if(landusedust(i,j).eq.52)landusefrac(i,j)=1.0 !SEMIDESERT SAGE (DREAM 0.7)

Vegetation fraction (0-1) NEW Vegetation fraction (0-1) NEW!! Daily interpolated from monthly climatology. Not existing in DREAM

1-Vegetation fraction (0-1)

Top soil type (New STASGO database 30s… previous DREAM Class No. Soil texture class 1 Sand 2 Loamy Sand 3 Sandy Loam 4 Silt Loam 5 Silt 6 Loam 7 Sandy Clay Loam 8 Silty Clay Loam 9 Clay Loam 10 Sandy Clay 11 Silty Clay 12 Clay Top soil type (New STASGO database 30s… previous DREAM was a combination of FAO (2min) and ZOBLER (1º) )

Soil Texture triangle to determine the fractions of clay and silt Class No. Soil texture class % Sand % Silt % Clay 1 Sand 92 5 3 2 Loamy Sand 82 12 6 Sandy Loam 58 32 10 4 Silt Loam 17 70 13 Silt 85 Loam 43 39 18 7 Sandy Clay Loam 15 27 8 Silty Clay Loam 56 34 9 Clay Loam Sandy Clay 52 42 11 Silty Clay 47 Clay 22 20

Clay Fraction (0-1) Class No. % Clay 1 3 2 6 10 4 13 5 18 7 27 8 34 9 42 11 47 12 58 Clay Fraction (0-1)

Silt Fraction (0-1) Class No. % Silt 1 5 2 12 3 32 4 70 85 6 39 7 15 8 56 9 34 10 11 47 20 Silt Fraction (0-1)

w´ Soil water potential (volume fraction (%))

DELTA * Tunning parameter ( * ) Shown for k=4 (kg * s2 /m5)

1 2 3 4 5 6 7 8 Dry threshold friction velocity (m/s) Comes from old Bagnold’s theory which is valid for coarse particles (>30-40um radius) But in fact, the friction velocity for saltation of fine particles should increase due to cohesive forces Theory says that fine particles are uplifted by sandblasting (not saltation) which is not taken into account by DREAM parameterization with viscous sublayer. Instead, in DREAM the decreasing function of Balgnold uplifts the fine particles by saltation (which is strictly incorrect if we believe in Saltation/Sandblasting Theory). We need to conciliate viscous sublayer approach with saltation/sanblastingtheory. If not possible we will have to switch to a flux form emission scheme taking into account saltation and sandblasting.

BSC NMMB-DUST (V200712 with old ESMF) First successful test simulation including: - Dust emission with viscous sublayer (PHYSICS) - Dust vertical diffusion (PHYSICS) - Dust horizontal diffusion (DYNAMICS) - Dust horizontal advection (DYNAMICS) Dust vertical advection (DYNAMICS)

In this version, dust is included in the existing components of the ESMF/NMMB Experience has shown that switching to a new NMMB version would take 3-4 days. This is the best way to develop at this moment. Final version may include a separate module for dust emission, vertical diffusion and deposition although this is not strictly necessary: it can be included as a subroutine in the already existing physics component. Dust dynamics will be kept in the NMMB dynamics component. ATM Coupler DYN-PHYS Dynamics export T, U, V, Q, CW, Q2, OMGALF, DUST RUN DYN (Now includes dust hadv,vadv and hdiff) RUN PHYS (Now includes dust emission and vdiff) Coupler DYN-PHYS Physics Export T, U, V, Q, CW, Q2, DUST

PRELIMINARY ENCOURAGING RESULTS Simulation set-up: Global Cycle 20080124 12 UTC 60 hours forecast 160 CPU’s 8 dust bins 769x541 64 sigma layers

Cycle 20080124_12 54h forecast Dust conc bin 4 Sigma layer 52 Kg/m3 Sorry for such a rudimentary visualization

Cycle 20080124_12 60h forecast Dust conc bin 4 Sigma layer 52 Kg/m3

Next steps (I): Finish a crude version of the model in the NMMB V200712 version. This means: include dry deposition (sedimentation and turbulent mix out) and wet deposition as implemented in DREAM Turbulent mix out parameterization from Giorgi 1986 in DREAM is a good option. However I have checked the sedimentation scheme and compared to other models (Chimere, Gocart) and needs to be changed (we need to talk about it). We should remember also that wet deposition is very very simple and should be changed as well in future versions Once everything works in V200712: switch to the new V200807 (includes new ESMF Version). Also includes new tracer advection schemes (Old ones are lagrangian. New ones are Eulerian, positive definite, mass conservative and monotonic). This change will be straightforward. Once a full version of the system works, Karsten can go on with his thesis and improve/change emission, deposition schemes.

Next steps (I): Other things to be done in the near future (list is not exhaustive): - tests in regional mode - postprocessing of DUST (currently does not write through the ESMF write component), visualization of the NMMB in general scalability tests improvement of parallel behaviour with introduced dust component ….