interpretation of the new high-resolution model lmk heike hoffmann [email protected]

Sept. 22-24 Milano Interpretation of the new high resolution model LMK

COSMO 2004

Interpretation of the new high-resolution model LMK

Heike Hoffmann [email protected]

Volker Renner [email protected]


COSMO 2004

Aims

- high-resolution numerical weather forecasts include stochastic elements even in the short range

- direct model output should therefore be transformed for point forecasts

- probability information of the exceedance for given thresholds and/or warning events should be derived by statistical means


COSMO 2004

Method

We plan a two step approach

1. Using information of a single model forecast by applying the Neighbourhood Method (NM)

2. Using information resulting from LMK-forecasts that are started every 3 h (LAF-Ensemble)


COSMO 2004

Products

Probabilistic information for hazardous weather warnings

- exceedance probabilities for certain threshold values andwarning events for different parameters, (e.g. strong gales, heavyrain; long list with warning criteria from our forecast department)

„Statistically smoothed” fields for point forecasts

- Expectation Values from spatiotemporal neighbourhood- simple averaging over quadratic grid boxes


COSMO 2004

LMK Total Precipitation [mm/h] 04/01/13, 00 UTC, vv=17-18


COSMO 2004

Exceedance Probability of 1 mm/h, 04/01/13, 17-18 UTC

[%]

calculated with the NM with 10 grid increments, 3 time levels (t-1, t, t+1)


COSMO 2004

Verification results

deterministic verification

probabilistic verification


COSMO 2004

Verification

DataLMK forecasts; 2004, Jan 3-17; July 13-27, 1 h values, 00 UTC and12 UTC starting time; 7-18 h forecast timeall SYNOPs available from German stationscomparison with nearest land grid point

Neighbourhood-Method-Parameterstemporal: 3 time levels (3 h); spatial: radius: 10s ( 28 km)

Simple Averagingsquare areas of different size (3*3, 5*5, 7*7, 9*9, 11*11, 15*15, 25*25)temperatures adjusted with -0.65 K/(100 m)


COSMO 2004

LMK und LM, 3-17. Jan., vv=7-18, 00 UTC, ETS

-5

0

5

10

15

20

25

30

35

40

0,1 0,2 0,5 1,0 2,0 5,0

original

Mittel

quantil_3

original_v

mittel

quantil_3

LMK and LM, Jan 3-17, vv = 7-18, 00 UTC, ETSLMK DMOLMK expectation valueLMK medianLM DMOLM expectation valueLM median

threshold [mm/h]


COSMO 2004

LMK, Jan 3-17, vv = 7-18, 00 UTC, FBI

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

0,1 0,2 0,5 1,0 2,0 5,0

threshold [mm/h]

LMK DMO

3*3

11*11

NM expectation value

25*25

NM median


COSMO 2004

LMK, Jan 3-17, vv = 7-18, 00 UTC, ETS

0

5

10

15

20

25

30

35

40

0,1 0,2 0,5 1,0 2,0 5,0

threshold [mm/h]

LMK DMO

3*3

11*11

NM expectation value

25*25

NM median


COSMO 2004

LMK, July 13-27, vv = 7-18, 00 UTC, ETS

0

2

4

6

8

10

12

14

16

18

20

0,1 0,2 0,5 1 2 5

threshold [mm/h]

LMK DMO

3*3

5*5

7*7

9*9

11*11

15*15


COSMO 2004

reliability diagram precipitation Jan 2004

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

0,1 mm

1 mm

perfect

0,5

Frequency of forecast

Fre

quen

cy o

f obs

erva

tion

Reliability diagram precipitation Jan 2004


COSMO 2004

LMK, Jan 3-17, July 13-27 vv = 7-18, 00 UTC, BSS

-20

-10

0

10

20

30

40

50

60

70

0,1 0,2 0,5 1 2 5

threshold [mm/h]

BSS Jan climate

BSS July climate

BSS Jan LMK

BSS July LMK


COSMO 2004

Summary

– NM seems to work similarly for the LMK fields like for the LM

– results for original and postprocessed LMK-fields are slightly better than for LM fields

– 00 UTC runs show slightly better scores than 12 UTC runs

– scores in winter are much better than in summer, in summer there is more effect in postprocessing

– expectation values do not integrate into simple averaging, show advantages especially for intermediate thresholds

– BSS vs. climate also show better quality in winter, BSS vs. LMK indicate stronger influence of postprocessing in summer


COSMO 2004

Outlook

- further work on the NM- investigations on the influence of neighbourhood size

and shape- investigations on spatiotemporal autocorrelations of the

forecast fields- conceptual and technical optimization of the NM- work on Probabilistic Products for different parameters

- development of a new weather-interpretation for the LMK-------------------------------------------------------------------------------- development of products from the LMK-LAF-Ensemble


COSMO 2004

Acknowledgements

Many thanks to ...

- Andreas Hense and Susanne Theis for the idea and the imple-mentation of the NM for the LM

- Ulrich Damrath for his help with the verification

- Elke Wolff for introducing me into the NM program package

- the DWD for enabling the “Aktionsprogramm 2003” and providing a great working environment

- you for your attention and your contribution to the discussion

interpretation of the new high-resolution model lmk heike hoffmann [email protected]

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