COMPARISON OF AREAL PRECIPITATION ESTIMATES: A CASE STUDY FOR A CENTRAL SWEDISH CATCHMENT

Swedish Meteorological and Hydrological InstituteSE-601 76 Norrköping, SWEDEN

COMPARISON OF AREAL PRECIPITATION ESTIMATES: A CASE STUDY FOR A

CENTRAL SWEDISH CATCHMENT

Jonas Olsson, Barbro Johansson(presented by Günther Haase)



Study region - Gimån catchment

• Catchment area: 4 300 km²• Mean annual precipitation: 700 mm• Mean altitude: 340 m.a.s.l. (range: 20-540 m.a.s.l.)


Data sources and analyses

Sources:• PTHBV: interpolated gauge data• HIRLAM: NWP model (+30h - +6h forecasts)• RADAR: gauge-adjusted radar data• MA22, MA11: mesoscale analysis, real-time (22) and climate-

corrected(11)

Resolution, extension:• Temporal: daily accumulations during 2002• Spatial: ~22 km resolution in 72120 km2 grid (20 grid nodes)

Analyses:• Temporal: descriptive statistics and autocorrelation of daily spatial

mean precipitation• Spatial: standard deviation and correlation


Temporal analysis - descriptive statistics

Annual total

300

400

500

600

HIRLAM MA22 MA11 PTHBV RADAR

(mm

)

Mean daily standard deviation

1,5

2

2,5

3


(mm

)

Daily maximum

0

5

10

15

20

25


(mm

)

Dry days (prec.<0.1 mm)

0

10

20

30

40

50


(%)


Temporal analysis - seasonal & autocorrelation

0

20

40

60

80

100

120

J F M A M J J A S O N D

Pre

cip

ita

tio

n (

mm

)

HIRLAM

MA22

MA11

PTHBV

RADAR

-0,1

0

0,1

0,2

0,3

0,4

0,5

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Lag (days)

Co

rre

lati

on

co

eff

icie

nt

HIRLAM

MA22

MA11

PTHBV

RADAR


Spatial analysis2002 totals

1440000 1460000 1480000 1500000 1520000 1540000

6940000

6960000

6980000

7000000

400m m

450m m

500m m

550m m

600m m

650m m

700m m

750m m

1440000 1460000 1480000 1500000 1520000 1540000

6940000

6960000

6980000

7000000

400m m

450m m

500m m

550m m

600m m

650m m

700m m

750m m

1440000 1460000 1480000 1500000 1520000 1540000

6940000

6960000

6980000

7000000

400m m

450m m

500m m

550m m

600m m

650m m

700m m

750m m

1440000 1460000 1480000 1500000 1520000 1540000

6940000

6960000

6980000

7000000

400m m

450m m

500m m

550m m

600m m

650m m

700m m

750m m

1440000 1460000 1480000 1500000 1520000 1540000

6940000

6960000

6980000

7000000

400m m

450m m

500m m

550m m

600m m

650m m

700m m

750m m

PTHBV

HIRLAM

RADAR (maximum=1390 mm)

MA22

MA11


Spatial analysis - standard deviation & correlation

Standard deviation: mean daily

0,5

1

1,5


(mm

)

Standard deviation: 2002 total

0

50

100


(mm

)

206

0,4

0,5

0,6

0,7

0,8

0,9

1

25 50 75 100 125

Distance (km)

Co

rre

lati

on

co

eff

icie

nt

HIRLAM

MA22

MA11

PTHBV

RADAR


Summary

- PTHBV vs. MA: The mesoscale analysis consistently generated the lowest amount of precipitation, possibly due to (i) no correction for observation losses and (ii) an underestimation in synoptical observations.

- HIRLAM: Somewat different seasonal cycle than the other sources. Low daily areal variability, possibly due to areal smoothing in the model. High areal variability of 2002 totals, possibly due to orographically induced small but systematic areal variations.

- RADAR: A distinct inhomogeneity was found, with precipitation amounts being consistently overestimated by ~8 mm/day over a region of 500-1000 km² during October-December. Possible cause: temporary improper functionality of the Östersund radar, north-west of the study catchment.


Runoff simulation (HBV model) 2000-2002Input: PTHBV

0

200

400

600

00-01-01 00-07-01 01-01-01 01-07-01 02-01-01 02-07-01

Dis

char

ge

(mm

)

HBV OBSERVED

Input: RADAR

0

200

400

600

00-01-01 00-07-01 01-01-01 01-07-01 02-01-01 02-07-01

Dis

char

ge

(mm

)

HBV OBSERVED

COMPARISON OF AREAL PRECIPITATION ESTIMATES: A CASE STUDY FOR A CENTRAL SWEDISH CATCHMENT

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