Pp coloboc 9 2008 9 2011 different aspects of snow parameterization
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General Meeting 2011, COLOBOC Workshop. PP COLOBOC 9.2008-9.2011 : Different aspects of snow parameterization. Developments at Roshydromet, with an emphasis on snow density, partial snow cover and T2m forecasting errors. 2010-2011: task 5 “Revision of snow analysis and snow model”.

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PP COLOBOC 9.2008-9.2011 : Different aspects of snow parameterization

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Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

General Meeting 2011, COLOBOC Workshop

PP COLOBOC 9.2008-9.2011: Different aspects of snow parameterization

Developments at Roshydromet, with an emphasis on snow density, partial snow cover and T2m forecasting errors

2010-2011: task 5 “Revision of snow analysis and snow model”

Inna Rozinkina, [email protected],

Ekaterina Kazakova, [email protected],


Why roshydromet

Why Roshydromet?

Near 95% of territory of Russia (incl 85 % of modeling domain of COSMO-RU07 and 100% of COSMO-RU02c) is covered by snow during winter period

The data of hydrological monitoring (from Roshydrometnetwork) permits to realize the verification of snow modeling results (from polar to subtropical zones)

During 3-5 cold months the quality of COSMO-Ru weather forecasts depends on success of snow-cover parameterization


Review of results 2008 2009

Review of results 2008-2009:

The new multi-layer snow parameterization scheme was developed (Lykosov, Machulkaya)with description of metamorphism and snow compression, cooling/melting of snow layers, penetration of solar radiation, water dynamic with phase perturbation (melting & freezing) and heat release.

Ekaterina Machulskaya (Roshydromet) realized this scheme, made the validation (based on the data of Valday observatory, 1-d stand-alone experiments), adapted the codes of new multi-layer snow scheme to TERRA soft.

In development of this activities the new multi-layer scheme was included into MeteoSwiss forecast system (data assimilation system) and also into operational COSMO versions since 4.11 . Tests for some points in Swiss mountains were carried out.


Review of results 2009 2010

General Meeting 2011, COLOBOC Workshop

Review of results 2009-2010:

Analysis of effects of new multi-layer snow parameterization scheme coupled to TERRA into COSMO-model is made for European part of Russia:

The measurements more than 30 hydrological stations with special snow measurements in northern, central, south parts of European Russia were used during 2-6 months

The different criteria of scores were analyzed.

North

Centre

South


Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

Snow layer appeared warmer

Freezing after melting

General Meeting 2011, COLOBOC Workshop

Review or results 2009-2010

  • It was established:

  • TERRA with multi-layer snowscheme simulates more accurately the process of snow melting;

  • TERRA with multi-layer now schemeproduces more accurately T2m for the night – timeduring the period of snow melting;

  • There is some underestimation of fresh snow density (immediately after snow-fall events) by multi-layer snow scheme


Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

General Meeting 2011, COLOBOC Workshop

Review or results 2009-2010

  • It was established, that in independemce of use snow parameterisation:

  • There arelarge errors (150-300%)of COSMO-model simulations of snow water equivalent (SWE). They are due to large errors in the prescribed SWE as initial data. On the other hand, the initial data of values of snow height (SH) are convenient. Also SH is well simulated by the COSMO-model

  • There arelarge errors (2-15°C) of COSMO-model simulations of T2m during the melting period. They are originated from the fact that TS within the cell, covered by snow, can not be more thanmelting-point


Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

General Meeting 2011, COLOBOC Workshop

Review or results 2009-2010

Next recommendations were obtained:

  • - To refresh TERRA code usingSH instead of SWE;

  • - To change the algorithms of TERRA to improve the calculationsof Ts and TGof fractional snow covered cells with possible valuesabove the melting point;

  • - To propose and to validate the new algorithms for determinationthe initial values of snow density(to include into codes preparation of the start information);

  • - Toinclude the multi-layer snow scheme into operational codes of COSMO-Model. The more important effects should appear in systems of long-term integrations (f.ex, DAS, CLM)


Review of results 2010 2011

General Meeting 2011, COLOBOC Workshop

Review of results 2010-2011:

1. T2m forecasting:

Some changes in TERRA were made to improve T2m forecasts during snow-melt period.

T2m forecast errors were significantly reduced for test forecasts for winters of 2009-2010 and 2010-1011 in COSMO-Ru07 and COSMO-Ru14

Since 4th Apr 2011 the modifications were included in operational codesfor COSMO-Ru07 and COSMO-RUSib. The results of mechanisms of such changes were analyzed.

Date of changing operational codes COSMO-RU


T2m experiment t2m ctrl

General Meeting 2011, COLOBOC Workshop

T2m(experiment)-T2m(ctrl)

Review or results 2010-2011

36h forecast

48h forecast

T2m temperature raised up to 10ºC on the territory where according to model data snow cover was below 40 cm


Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

General Meeting 2011, COLOBOC Workshop

Review or results 2010-2011

  • Snow-density

  • Some parameterizations for the start values of snow-density are proposed and tested. The more realistic variant was selected. The data of the tests for 33 stations in different climatic zones were used.

  • motivation: large errors in initial SWE. No regular observation data

Example of start field of snow density in COSMO- model. 25 March 2010


Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

General Meeting 2011, COLOBOC Workshop

Review or results 2010-2011

It was etablished:

  • The values ofsnow density are in dependenceof weather during the full winterperiod, using of constant values of snow density led to large errors in most part of snow-covered regions

  • Connection between typical (climatic) snow density values andtypes of vegetation cover may be showed

  • - The algorithm of calculations of snow density as function of sum of positives values of T2m duringfull snow period andclimatic values of snow density (Vg, LAI and Zo) was proposed and tested for stations in different zones. The algorithm can be recommended to be included into COSMO- forecasting technologies


The distribution snow density before melting like the allocation of plants cover

General Meeting 2011, COLOBOC Workshop

The distribution snow density before melting like the allocation of plants cover

Average snow density (g/cm3)

at maximum ten-day snow height

Types of vegetation

0,28-0,30 tundra, forest-tundra; south - steppe

0,20-0,22 swamp vegetation, taiga (spruce); west - broadleaf forests (with predominance of oak and hornbeam)

0,26-0,28 north - forest-tundra;steppe and

broadleaf forests (with predominance of birch)

<0.20 taiga (with predominance of larch)

0,22-0,26 taiga (spruce; spruce with a touch

of oak); south - steppe


Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

General Meeting 2011, COLOBOC Workshop

Review or results 2010-2011

Taiga (spruce predominance):

- Sum of positive average daily temperatures

Broad-leaved forest (oak predominance):

With spruce/pine

With birch

The errors of initial values of SWE were decreased from 200-300% to 25-50% on the must part of stations

Steppe

Forest-steppe


Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

General Meeting 2011, COLOBOC Workshop

Review or results 2010-2011

The errors of initial values of WE were decreased from 200-300% to 25-50% on the must part of stations


Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

General Meeting 2011, COLOBOC Workshop

Review or results 2010-2011

Summary for 2010-2011

  • It is not enough to change the fractional snow cover parameter in TERRA to take into account the thermal effects of thawed patches.

    (It is needed to made the changes into codes of calculations of T of soil layers, radiation fluxes, effective TG)

  • The success for T2m prediction can be achieved with the introduction in scheme  of artificial heating surface ( looks like the effects of routes, buildings, tree branches without snow) or with modeling of more rapid melting of snow. As alternative, the mosaic approach can be developed, with mosaic calculations for some soil layers

  • The values of snow density are in dependence of weather during the full winter period, the using of constants led to large errors

  • It is existed the connection between typical (climatic) snow density values and types of vegetation.


Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

General Meeting 2011, COLOBOC Workshop

2011 – start of participation of Roshydromet in the SRNWP  Data Exchange Programme EUMETNET.The necessary preliminary jobs for organization of activities on Valday observatory were carried out

Review or results 2010-2011


Observatory valday

General Meeting 2011, COLOBOC Workshop

Observatory Valday

Valdaywater-balanceresearchstationinRussia (57º58'N, 33º 14'E)locatedinaborealforestarea.

- Seasonalvariationswithanannualtemperature: rangeof 35ºC

- Annualaverageprecipitationof 730 mm(themaximuminthesummerand autumn).

- Persistentsnowcover period: fromNovemberuntilApril.

Smirnova T.Parameterization of cold-season processes in the MAPS land-surface scheme // Journalof Geophysical Research, Vol. 105, NO. D3, 2000.


Valday principal observations precipitation polygon

General Meeting 2011, COLOBOC Workshop

Valday principal observations: Precipitation polygon:

Valday observations

Measured parameters: precipitation,

precipitation intensity, evaporation, wind

Gagingstation:

Measured parameters: daily runoff on 9 stations of river Polomet’ and its tributaries, maximal snow survey


Meteorological station

General Meeting 2011, COLOBOC Workshop

Meteorological station

Valday observations

Measured parameters: solarradiometry,

standart meteorological measurements,

frostpenetration

Weir

Measured parameters: runoff, frostpenetration, precipitation, snowreserves, evaporation from soil


Gradient measurements

General Meeting 2011, COLOBOC Workshop

Gradientmeasurements

Valday observations

Measurements: Turbulent fluxes

Meteorological radar


Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

General Meeting 2011, COLOBOC Workshop

Plans

Plans for 2011-2012:

 1. A new parameterization of the snow pack density should be tested  and adapted to operational snow analysis step

2. The geographical maps of values of climatic density will be prepared (or algorithms for its calculating as function of vegetation parameters)

3. Proposals for modification of TERRA codes for fractional covering (heating effects of near- surface air) should be formalized


Pp coloboc 9 2008 9 2011 different aspects of snow parameterization

General Meeting 2011, COLOBOC Workshop

THANK YOU!


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