Workshop on snow data assimilation

Roland Koch and Marc Olefs

Zentralanstalt für Meteorologie und Geodynamik (ZAMG), Vienna,

Impact of MODIS snow cover fraction on modeled SNOWGRID quantities Outline

SNOWGRID Snow model

Assimilation of MODIS fractional snow cover

Impact of MODIS observation

Validation

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Snow depth variability (daily base)

Seasonal (Nov–Apr) snow depth time series of stations elevated between 800 m and 1600 m

110 AT 90

70

50

30 NDJFMA snow depth [cm]

10 11–year low–pass (Gaussian) filtered

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 year

110 CH 90

70

50 Marty, C. (2008). Regime shift of snow days 30 NDJFMA snow depth [cm] in Switzerland, Geophys. Res. Lett., 35, 10 11–year low–pass (Gaussian) filtered L12501, doi:10.1029/2008GL033998. 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 year

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany SNOWGRID Snow model

I Operational spatially distributed snow cover model with high spatial (100 m) and temporal (15 minutes time step) resolution for INCA-L grid (Zürich-Bratislava, Nürnberg-Triest)

I Upper BC: Meteorological input from INCA (air temperature, rel. humidity, snowline (wet–bulb temp.), precipitation). Lower BC: INCA ground temperatures

I Simple degree–day scheme

I Simple 1–2 layer model

I Snow settling (rapid setting after snowfall - destructive metamorphism, density-dependant slower settling thereafter (overburden pressure, metamorphism)

I State variables are: snow depth (SD), snow water equivalent (SWE), average snow temperature (ST)

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany SNOWGRID model domain and topography

Topography: 100 m DEM (corrected NASA SRTM3 + add. Data)

5°W 0° 5°E 10°E 15°E 20°E 25°E 30°E

55°N

50°N

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E

3250

45°N 49°N 3000

2750

40°N 2500

2250 5°W 0° 5°E 10°E 15°E 20°E 25°E 30°E

48°N 2000

1750

1500

1250 topography [m]

47°N 1000

750

500

250

46°N 0

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany SNOWGRID products

I Internal use (weather forecasts)

I road weather products

I Avalanche warning service

I Wintertourism (websites)

I snow melt runoff calculations

I ...

Olefs, M., Schöner, W., Suklitsch, M., Wittmann, C., Niedermoser, B., Neururer, A., Wurzer, A. (2013). SNOWGRID – A new operational snow cover model in Austria. International Snow Science Workshop Gre- noble, 2013.

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany Assimilation of MODIS fractional snow cover (FSC)

initialize SNOWGRID I Experiment duration: model 01 Oct 2015 to 01 May 2016

I MODIS fields are interpolated onto SNOWGRID grid (nearest neighbour) model run I Nmax(MODIS) = 214

I 160 MODIS fields available

10UTC MODIS MODIS binary mask yes 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E modis

49°N

model FSC yes model

SD > 0 no 50 %≥ SD = 0 fsc>=50% 48°N

update model update model fsc<50% 47°N SD = 0 m SD = 0.1 m ST = nan ST = -3 ◦C 2 2 SWE = 0 kgm− SWE = 150 kgm− 46°N masked

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 50 49°N Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany 25

48°N

5

47°N difference [cm] 5

46°N

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 25 Analysis departures (MODIS: passively assimilated)

analysis departures: d = M(MODIS)pas − M

01 Okt 2015 10UTC 21 Okt 2015 10UTC 08 Jan 2016 10UTC 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 25 25 25 49°N 49°N 49°N

10 10 10

48°N 48°N 48°N 1 1 1

1 1 1 47°N 47°N 47°N

10 SH departures [cm] 10 SH departures [cm] 10 SH departures [cm]

46°N 46°N 25 46°N 25 25

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E

22 Jan 2016 10UTC 13 Feb 2016 10UTC 17 Mar 2016 10UTC 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 25 25 25 49°N 49°N 49°N

10 10 10

48°N 48°N 48°N 1 1 1

1 1 1 47°N 47°N 47°N

10 SH departures [cm] 10 SH departures [cm] 10 SH departures [cm]

46°N 46°N 25 46°N 25 25

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany Analysis differences (MODIS: actively assimilated)

analysis differences: a = M(MODIS)act − M

01 Nov 2015 00UTC 01 Dec 2015 00UTC 01 Jan 2016 00UTC 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 20 20 20 49°N 49°N 49°N 10 10 10 5 5 5 3 3 3 48°N 48°N 48°N 1 1 1 1 1 1

47°N 47°N 3 47°N 3 3 difference [cm] difference [cm] difference [cm] 5 5 5 10 10 10 46°N 46°N 20 46°N 20 20

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E

01 Feb 2016 00UTC 01 Mar 2016 00UTC 01 Apr 2016 00UTC 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 20 20 20 49°N 49°N 49°N 10 10 10 5 5 5 3 3 3 48°N 48°N 48°N 1 1 1 1 1 1

47°N 47°N 3 47°N 3 3 difference [cm] difference [cm] difference [cm] 5 5 5 10 10 10 46°N 46°N 20 46°N 20 20

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany Available valid MODIS data at station location I

Selection of 63 TAWES stations Station snow depth sensor: Laser distance sensor (Jenoptik SHM 30)

01 Oct 2015 to 01 May 2016

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 70 49°N 60

50

48°N 40

30

47°N 20

10 MODIS availability [days]

46°N 0

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany Available valid MODIS data at station location II

available valid MODIS OBS [days]

Sonnblick Pitztaler Gletscher Galzig Schmittenhoehe Obergurgl Hahnenkamm/Ehrenbachhoehe Katschberg Loferer Alm Laterns Gapfohl Kanzelhoehe Hintertux im Zillertal Warth Schmirn am St.Jakob im Defereggen Brenner Kals St.Anton am Arlberg Stolzalpe Schroecken Langen am Arlberg Ramsau am Dachstein Mittelberg Seefeld Loibl Tunnel Holzgau Doellach St.Michael im Lungau Preitenegg Brand Krimml Neustift/Milders Saalbach Hochfilzen Bad Bleiberg Arriach Seckau Neumarkt Mariazell/St.Sebastian Koetschach-Mauthen Abtenau Obervellach Lienz Friesach Kirchdorf in Tirol Dellach im Drautal Allentsteig Rohrbach Koessen Hermagor Bischofshofen Krumbach in der Buckligen Welt Spittal an der Drau Mooslandl Bad Ischl Kufstein Bruck an der Mur St.Veit an der Glan Ferlach Graz Strassgang Deutschlandsberg Wien Hohe Warte 11033/11035

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 500 1500 2500 available MODIS obs [days] elev [m]

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany Observations vs Control run vs. Experiment

black: observation, red: control run, blue: assimilation experiment

Seefeld (1182 m) Obergurgl (1942 m) 11119 Seefeld (1182 m) 11127 Obergurgl (1942 m) 70 100 observation observation 60 control run control run experiment 80 experiment 50

60 40

30 40

snow depth [cm] 20 snow depth [cm] 20 10

0 0

Oct 2015 Nov 2015 Dec 2015 Jan 2016 Feb 2016 Mar 2016 Apr 2016 May 2016 Oct 2015 Nov 2015 Dec 2015 Jan 2016 Feb 2016 Mar 2016 Apr 2016 May 2016 date date Lienz (661 m) Warth (1478 m) 11204 Lienz (661 m) 11308 Warth (1478 m) 16 140 observation observation 14 control run 120 control run experiment experiment 12 100 10 80 8 60 6 snow depth [cm] snow depth [cm] 40 4

2 20

0 0

Oct 2015 Nov 2015 Dec 2015 Jan 2016 Feb 2016 Mar 2016 Apr 2016 May 2016 Oct 2015 Nov 2015 Dec 2015 Jan 2016 Feb 2016 Mar 2016 Apr 2016 May 2016 date date

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany Impact of MODIS data I

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 50 49°N 30

20 ] % [ 2 10 x R 48°N control e (1 ) 100 > 0 d

2 1 n R i − exper × t

1 c a p 47°N

positive impact 10 m i

→ 2

20 R 30 46°N 50 blue: positive impact 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E

red: negative impact 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 50 49°N 30 20 10 RMSEexper 48°N (1 ) 100 > 0 1 − RMSEcontrol × 1

positive impact 47°N 10 → 20 RMSE impact index [%] 30 46°N 50

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany Impact of MODIS data II

R2 impact index [%] 50 30 20 10 1 1 10 20 30 50 RMSE impact index [%] − − − − − 50 30 20 10 1 1 10 20 30 50 − − − − −

Sonnblick Sonnblick Pitztaler Gletscher Pitztaler Gletscher Galzig Schmittenhoehe Galzig Obergurgl Schmittenhoehe Hahnenkamm/Ehrenbachhoehe Obergurgl Katschberg Loferer Alm Hahnenkamm/Ehrenbachhoehe Laterns Gapfohl Katschberg Kanzelhoehe Loferer Alm Hintertux im Zillertal Warth Laterns Gapfohl Schmirn Kanzelhoehe Lech am Arlberg Hintertux im Zillertal St.Jakob im Defereggen Brenner Warth Kals Schmirn Nauders Lech am Arlberg St.Anton am Arlberg Stolzalpe St.Jakob im Defereggen Schroecken Brenner Langen am Arlberg Kals Ramsau am Dachstein Mittelberg Nauders Seefeld St.Anton am Arlberg Loibl Tunnel Stolzalpe Holzgau Doellach Schroecken St.Michael im Lungau Langen am Arlberg Preitenegg Ramsau am Dachstein Brand Krimml Mittelberg Neustift/Milders Seefeld Saalbach Loibl Tunnel Hochfilzen Bad Bleiberg Holzgau Arriach Doellach Seckau St.Michael im Lungau Neumarkt Mariazell/St.Sebastian Preitenegg Koetschach-Mauthen Brand Abtenau Krimml Obervellach Lienz Neustift/Milders Friesach Saalbach Kirchdorf in Tirol Hochfilzen Dellach im Drautal Allentsteig Bad Bleiberg Rohrbach Arriach Koessen Seckau Hermagor Bischofshofen Neumarkt Krumbach in der Buckligen Welt Mariazell/St.Sebastian Spittal an der Drau Koetschach-Mauthen Mooslandl Bad Ischl Abtenau Kufstein Obervellach Bruck an der Mur Lienz St.Veit an der Glan Ferlach Friesach Graz Strassgang Kirchdorf in Tirol Deutschlandsberg Dellach im Drautal Wien Hohe Warte 11033/11035 Allentsteig Rohrbach Koessen 0 5 10 15 20 25 Hermagor 500 1500 2500 Bischofshofen number of nonzero analysis departures [days] elev [m] Krumbach in der Buckligen Welt Spittal an der Drau Mooslandl Bad Ischl Kufstein Bruck an der Mur St.Veit an der Glan Ferlach Graz Strassgang Deutschlandsberg Wien Hohe Warte 11033/11035

0 5 10 15 20 25 500 1500 2500 number of nonzero analysis departures [days] elev [m]

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany Results and summary

Average statistics control run experiment Ndates = 149 R2 0.69 0.64 = Nstations 63 RMSE [cm] 15.17 15.57 MBE [cm] -6.01 -8.81 MAE [cm] 11.31 11.65

I No improvement on average

I Improper use of MODIS information?

I MODIS misclassification?

I Initial thresholds? FSC, snow depth, snow temperature, snow density (SWE)

I More experiments are strongly needed...

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany FSC threshold

Experiments with different FSC thresholds (01 Jan to 01 Apr 2016)

Average statistics experiment Ndates = 91 control run FSC 50 % FSC 25 % FSC 10 % Nstations = 63 R2 0.62 0.58 0.60 ? RMSE [cm] 17.54 18.26 17.63 ? MBE [cm] -5.88 -11.15 -7.94 ? MAE [cm] 14.71 15.43 14.79 ?

FSC 50% FSC 25% 01 Mar 2016 00UTC 01 Mar 2016 00UTC 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 20 20 49°N 49°N 10 10 5 5 3 3 48°N 48°N 1 1 1 1

47°N 3 47°N 3 difference [cm] difference [cm] 5 5 10 10 46°N 20 46°N 20

9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E 9°E 10°E 11°E 12°E 13°E 14°E 15°E 16°E 17°E

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany Thank you for your attention!

Workshop on snow data assimilation March, 8/9, 2017, Offenbach, Germany