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Federal Department of Home Affairs FDHA Federal Office of Meteorology and Climatology Meteo. Swiss

Federal Department of Home Affairs FDHA Federal Office of Meteorology and Climatology Meteo. Swiss Evaluating modifications of the soil module TERRA Felix Ament, Meteo. Swiss COSMO General Meeting, September 2007

Dry soil moisture bias OPRerational COSMO, two-layer version Testsuite, multi-layer version Soil moisture T

Dry soil moisture bias OPRerational COSMO, two-layer version Testsuite, multi-layer version Soil moisture T 2 m • Strong dry out bias! • Negative effect on T 2 m forecast. COSMO GM, Athens Felix. Ament@meteoswiss. ch 2

Handling the dry out problem Long term Model improvement: • Model formulations • Parameters

Handling the dry out problem Long term Model improvement: • Model formulations • Parameters Short range Soil moisture nudging: Insertion ECWMF soil moisture at layers below 9 cm Negative effect on T 2 m forecasts vanishes COSMO GM, Athens Felix. Ament@meteoswiss. ch . F MW EC 3

Design of TERRA standalone experiments • • Atmospheric Forcing: COSMO analysis data Domain: see

Design of TERRA standalone experiments • • Atmospheric Forcing: COSMO analysis data Domain: see left; 64 x 61 gridpoints at 7 km resolution Period: year 2006 plus December 2005 for spin up Initialization: Operational COSMO analysis Meteorological Forcing: T, p, u, q, Qdown Precipitation RR SVAT „TERRA“ Simulation of • Energy balance • Soil processes • Annual cycle of vegetation time COSMO GM, Athens Felix. Ament@meteoswiss. ch Working in the dark – nearly no or insufficient observations! 4

Nudged mulitlayer versus two layer Analysis of the water budget Rain Evaporation Snow SM

Nudged mulitlayer versus two layer Analysis of the water budget Rain Evaporation Snow SM Surface Runfoff Intermediate Runfoff Ground Runfoff Features of “Nudged Multilayer”: • Despite Nudging, LE is reduced in July/August and Tmax is higher. • Most of the nudged water (=residuum) is converted into runoff. • Remarkable: Less precipitation. COSMO GM, Athens Felix. Ament@meteoswiss. ch Nudged multilayer Operational 2 -layer 5

CTL standalone versus OPR 2 -layer Features of “CTL standalone”: • Again, reduced LE

CTL standalone versus OPR 2 -layer Features of “CTL standalone”: • Again, reduced LE in July / August (no response in T_2 m due to external forcing) • Dry out in summer, but recovers until the end of the year. • Higher runoff. RR Runoff_s Runoff_g Evapo. DSM DSNOW Residuum Runoff_m l. E (JA) OPR 2 -layer 1389 334 291 699 -11 -37 -113 ? 111 W/m 2 Nudged ML 1148 503 678 727 6 -32 734 ? 95 W/m 2 CTL standalone 1397 440 359 621 4 -27 0 196 93 W/m 2 (mm) Doubts COSMO GM, Athens Felix. Ament@meteoswiss. ch • • Do we really have a dry-out problem? Probably, the T_2 m diagnosis is misleading? 6

Sensitivity experiments Lower boundary RIGID Rigid lit boundary condition = Impermeable rock below lowest

Sensitivity experiments Lower boundary RIGID Rigid lit boundary condition = Impermeable rock below lowest layer GWATER Ground water boundary condition = Water below lowest layer 6 type DWD classification; lookup table adopted from R. Grasselt (UBonn) BROOKS 1 Drainage & diffusion BROOKS 2 BROOKS 3 Drainage and capilary rise acording to Brooks and Corey formulation Exchange 11 type USDA soil classification; Shao et al lookup table Brooks and Corey parameters derived form Rawls and Brakensiek pedotransfer function PEDO Vegetation 6 type DWD classification; lookup table from J. Helmert (DWD) adopted from Shao and Irannejad (1999) MACROPOR Enhanced drainage by Macropores VEGPARA Spatially varying stomatal resistance limits and plant albedo ROOTDIST Implementation of a non-homogenous root density distribution ECOVEG All vegetation parameters adopted from ECOCLIMAP NP 89 Alternative bare soil evaporation Z 0 LOC Usage of local roughness length without gravity wave drag component COSMO GM, Athens Felix. Ament@meteoswiss. ch Formulation adopted from VEG 3 D (Braun, 2002 ) Noilhan and Platon (1989) 7

Lower Boundary Condition I - concepts RIGID GWATER wet dry medium rigid lid Free

Lower Boundary Condition I - concepts RIGID GWATER wet dry medium rigid lid Free drainage ground water COSMO GM, Athens Felix. Ament@meteoswiss. ch 8

Lower Boundary Condition II Ground water condition GWATER Problem: Definition of soil moisture gradient

Lower Boundary Condition II Ground water condition GWATER Problem: Definition of soil moisture gradient at top of water Solution: Solve Darcy equation with these simplifications: • F is constant below centre of lowest layer • D is constant there, too • K varies only linearly with Q : COSMO GM, Athens Felix. Ament@meteoswiss. ch 9

Drainage and capillary rise I • CTL: Rijtema (1969), e. g. for drainage K:

Drainage and capillary rise I • CTL: Rijtema (1969), e. g. for drainage K: • Brooks and Corey (1964) – much more popular • However, Brooks and Corey formulation requires three parameters to derive drainage and capillary rise (depending on soil moisture) – they are not well defined. BROOKS 1 BROOKS 2 BROOKS 1: 6 type DWD soil classification; lookup table adopted from R. Grasselt (UBonn) BROOKS 2: 6 type DWD soil classification; lookup table from J. Helmert (DWD) adopted from Shao and Irannejad (1999) COSMO GM, Athens Felix. Ament@meteoswiss. ch 10

Drainage and capillary rise II Ecoclimap Rawls and Brakensiek, 1989 DWD classification PEDO •

Drainage and capillary rise II Ecoclimap Rawls and Brakensiek, 1989 DWD classification PEDO • fields of soil properties (e. g. pore volume) USDA classification ECOSOIL • 6 classes • Lookup table by DWD COSMO GM, Athens Felix. Ament@meteoswiss. ch BROOKS 3 • 11 classes • Lookup by Shao • not fully done! 11

Drainage and capillary rise III MACROPOR Marcopores • help to infiltrate water rapidly during

Drainage and capillary rise III MACROPOR Marcopores • help to infiltrate water rapidly during rainfall • might avoid runoff generation of saturated top layer Runoff_g Parameterization (adopted from VEG 3 d, e. g. Braun 2002) mit Fmax=10 und Qmin=0. 5. COSMO GM, Athens Felix. Ament@meteoswiss. ch 12

Vegetation I VEGPARA • Minimal / maximal stomatal resistance as well as plant albedo

Vegetation I VEGPARA • Minimal / maximal stomatal resistance as well as plant albedo have constant value in TERRA CTL • VEGPARA uses spatially varying values depending on land-use CTL COSMO GM, Athens Felix. Ament@meteoswiss. ch CTL 13

Vegetation II ECOVEG External vegetation parameters prescribed by ECOCLIMAP dataset (Mason et al. ,

Vegetation II ECOVEG External vegetation parameters prescribed by ECOCLIMAP dataset (Mason et al. , 2002): • Exhibits more variabilty • Systematic higher root depth • More detailed seasonal cycle (not shown) (all maps are valid for July) COSMO GM, Athens Felix. Ament@meteoswiss. ch 14

Vegetation III CTL ROOTDIST • Uniform root depth • Linear root depth distribution COSMO

Vegetation III CTL ROOTDIST • Uniform root depth • Linear root depth distribution COSMO GM, Athens Felix. Ament@meteoswiss. ch ROOTDIST Recipe • Diagnose soil moisture stress function f. SM, loc for each layer separately • Determine mean SM stress by average weighted by layer thickness Dz and root density rroot • Extract transpired water proportional to f. SM, loc Dz rroot 15

Atmospheric exchange I ZOLOC Local roughness length z 0, local • CTL roughness depends

Atmospheric exchange I ZOLOC Local roughness length z 0, local • CTL roughness depends not only on local conditions, but also on variance of orography to account for gravity wave drag. Very high roughness length over mountainous areas. COSMO GM, Athens Felix. Ament@meteoswiss. ch 16

Atmospheric exchange II NP 89 Top Layer SM at Lindenberg Dickinson, 1984: BATS scheme

Atmospheric exchange II NP 89 Top Layer SM at Lindenberg Dickinson, 1984: BATS scheme Designed for a two layer soil module! COSMO GM, Athens Felix. Ament@meteoswiss. ch Noilhan and Platon, 1989 (NP 89): ISBA scheme, Meso-NH 17

Rain Result I - bare soil evaporation NP 89 Evaporation Snow SM Surface Runfoff

Rain Result I - bare soil evaporation NP 89 Evaporation Snow SM Surface Runfoff Intermediate Runfoff Ground Runfoff • Significant reduction of Evaporation during spring and fall, … • … but no effect during summer! COSMO GM, Athens Felix. Ament@meteoswiss. ch 18

Rain Result II Snow – Budget Summary CTL Evaporation SM Runoff_s mm Runoff_g mm

Rain Result II Snow – Budget Summary CTL Evaporation SM Runoff_s mm Runoff_g mm Runoff_m mm Evapo. mm DSM mm l. E (JA) W/m 2 440 359 196 621 4 93 Deviations in mm Surface Runfoff Intermediate Runfoff Ground Runfoff Reduced Runoff RIGID -1 -97 7 22 75 5 GWATER 0 -29 3 7 22 1 BROOKS 1 -21 20 -116 -6 7 -2 Reduced interm. Runoff BROOKS 2 -20 61 -128 -30 -11 -4 BROOKS 1, BROOKS 2 BROOKS 3 - - - ECOSOIL 29 -22 -2 -14 10 -2 Reduced Evapo. (sustainable) MACROPOR -12 2 -18 4 6 1 NP 89, VEGPARA, Z 0 LOC PEDO -9 54 -65 -34 -10 -4 VEGPARA 1 32 13 -44 12 -6 Little impact ROOTDIST 0 -2 -1 1 2 -2 ROOTDIST, MACROPOR ECOVEG 29 -11 45 101 -118 17 NP 89 1 66 22 -84 18 -2 Problematic Z 0 LOC 25 9 2 -37 4 -3 ECOVEG (dry out!) COSMO GM, Athens Felix. Ament@meteoswiss. ch RIGID, GWATER 19

Conclusions • • • COSMO TERRA-ML is very robust; modifications have in general surprisingly

Conclusions • • • COSMO TERRA-ML is very robust; modifications have in general surprisingly small impact TERRA-ML standalone has proven to be useful tool to asses the midterm effect of model modification. However, objective decisions about implementation of modification is difficult, due to lack of observational data. Scientifically the following modification can reasonably be recommended: • NP 89 (removes high evaporation in spring & fall) • VEGPARA (better representation of forest) • (GWATER (counteracting dry-out)) • (BROOKSX (being state-of-the-art)) Outlook: • Cross studies (e. g. BROOKS and GWATER) • Long term integration to reach model balance. • Combination with improved T_2 m diagnosis. COSMO GM, Athens Felix. Ament@meteoswiss. ch 20