CARPE DIEM FMI (Partner 5) progress report

04/20/23 FINNISH METEOROLOGICAL INSTITUTE

Jarmo Koistinen, Heikki PohjolaFinnish Meteorological Institute

CARPE DIEMFMI (Partner 5) progress report


Work Packages

· Area 1/WP3: Development of a variational assimilation scheme for Doppler winds (FMI+SMHI, responsible persons at FMI Heikki Järvinen, Kirsti Salonen).

· Area 2/WP7: Advanced surface radar-based precipitation estimate applying NWP data (FMI, Jarmo Koistinen, Heikki Pohjola).


1(2)

Objective: Improve the accuracy of operational precipitation

measurements


National End User Meeting in Feb. 2003

1. Finnish Road AuthorityApplies observed and nowcast distributions of rain,

sleet and snow for road operations (snow clearing and salting costs ~100 M euros/winter).

2. Kemijoki hydroelectric power companySee the presentation of Hannu Puranen.3. FMI Continuous need to improve radar products (we are

working in the Operative Services).


Better accuracy with integrated

data· Existing: Hydrometeor

phase analysis (rain, sleet, snow) based on surface data (T,RH). Resolution 5 min & 1 km.Time-space variable Z – R / Ze – S relations.

· New from CARPE DIEM: apply a NWP model (HIRLAM) to obtain 3D hydrometeors.


WP 7.1: Attenuation correction based on 3D water phase diagnosis from

NWP model quantities (single polarisation).

Deliverables:· Diagnosis of hydrometeor water phase in 3D radar

volumes based on NWP model fields.· Large attenuation statistics for rain only (assumed

in most existing radar systems) compared to variable hydrometeor phase statistics.

· Improvement in surface precipitation estimates.


An axample of severe C-band attenuation


WP 7.1: Attenuation correction based on 3D water phase diagnosis from

NWP model quantities (single polarisation).

Work started in spring 2003:· Software to read 3D HIRLAM real time fields

from the FMI database into the 3D radar composite grid partly ready (see the manual slides by Harri Hohti).

· Hail algorithm (POH) implemented (see separate manual slides by Harri and Markus Peura).


WP 7.2: Elimination of overhanging precipitation (OP) from surface estimates

Altostratus 19 % of all VPR in Finland


WP 7.2: Rejection of overhanging precipitation (OP) from surface

estimates

Deliverables:· 1D diagnosis of OP from polar volumes above

each radar (see WP 7.3).· 3D diagnosis of OP from NWP fields between

radar sites. · Integrated radar-NWP correction method to reject

OP from the network products.Work done:· 1D diagnosis ready, 3D HIRLAM fields can be

read.


WP 7.3: Vertical reflectivity profile (VPR) correction applying radars and NWP

Deliverables:

•Automatic classification of VPR above each radar based on radar, soundings and NWP.

•Automatic quality control of each measured VPR.

•Operational VPR correction in a network of 7 radars.


1(2)

Measured VPR

• 7 radars • every 15 minutes• layer thickness 200 m• range 2 - 40 km• max bin count 5000 / layer

3D polar

volume

Vertical Profile of Reflectivity

(VPR)


1(2)

Classification and QC of each VPR

• representativity • rain• bright band• snow• clutter• clear air echo• overhanging precipitation• unphysical gradient

Statistics

Reference dBZ at ground level (green dot in VPR)

Calculation of the correction

Freezing level (FL) from radio

soundings (soon: from HIRLAM also)

Climatological profile adjusted to freezing level


1(2)

Overhanging

precipitation

Examples of classified VPR´s

Main parameters in profile recognition:

• Height

• Intensity

• Gradients (dBZ/km)

• Freezing level


1(2)

Clear air echo and clutterEvaporation and clutter


Snow

1(2)

Rain and bright band


1(2)

Climatological profileBright band at ground,

sleet


1(2)

Profile representativity


1(2)

40 %

19 %

2 %

12 %

4 %

23 %

Snow

Rain (no bright band)

Rain (with bright band)

Sleet

Overhanging prec.

Clear air echo

Statistics of VPR from March 2001 to February 2002 (234 908 profiles)


1(2)

Precipitation top height Mar 2001 – Feb 2002

0

5

10

15

20

25

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Height (m)

%


1(2)

VPR correction ),(

)0(log10

rhZ

ZS

e

e


Snow

1(2)

Profile correction for 500

m PsCAPPI


1(2)

Rain Profile correction


1(2)

Bright band at ground Profile correction


1(2)

Climatological profile Profile correction


1(2)

Time averaging of the single radar VPR correction

t

httt

t

httcp

t

htttccpp

www

wwCwCC

66

6

)(

))((

h

twt 6

1


1(2)

VPR correction in the network


1(2)

24 h accumulated precipitation Nov 7, 2002, 14 UTC No VPR correction With VPR correction


1(2)

24 h accumulated precipitation Nov 8, 2002, 23 UTC No VPR correction No VPR correction


1(2)

24 h accumulated precipitation Dec 21, 2002, 21 UTC No VPR correction VPR correction


1(2)

Yearly average VPR correction


1(2)

Validation of the VPR correction 1. With rain gauges2. With overlapping radars


1(2)


Validation of VAN VPR correction with ANJ data (distances 130-150 km)

· Only precipitation cases included (dBZ>10 and ANJ profile classified as precipitation).

· Length of validation period 13 months (other radar pairs 2 months, not shown).

· Blue: non-corrected ANJ-VAN (dB)· Red: VPR correction performed for VAN data,

ANJ-(VAN+correction), (dB). Correction applies both measured and climatological VPR at VAN.

· Black: VPR correction performed for VAN data applying only climatological profiles.





Future development of the VPR correction

· Diagnosis and rejection of OP prior to the VPR correction WP 7.2).

· Improved climatological profile (now overcorrecting).

· Use of freezing level height from HIRLAM model and simulated VPR (at least comparison of measured and NWP profiles).

· More validation, also with gauges.· Fully operational in all FMI products in

2003 even without OP-correction (End User requirement).


Dissemination of the results

· Operational FMI products, feedback from End Users and other customers

· CARPE DIEM and related EU-projects· Textbook (eds. Meischner et al.)· Peer reviewed papers · AMS Radar Conference· 3rd GPM Workshop· ERAD 2004· BALTEX/CEOP, NORDRAD, OPERA


1(2)

Monthly classified VPR´s from Mar 2001 to Feb 2002


1(2)

0

5

10

15

20

25

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Height (m)

%Precipitation top height March 2001 (snow)


1(2)

0

5

10

15

20

25

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Height (m)

%

Precipitation top height July 2001 (rain)


1(2)

0

1

2

3

4

5

6

7

8

92

00

40

0

60

0

80

0

10

00

12

00

14

00

16

00

18

00

20

00

22

00

24

00

26

00

28

00

30

00

32

00

34

00

36

00

38

00

40

00

Height (m)

Fra

cti

on

(%

)

Bright band height Mar 2001 – Feb 2002


1(2)

0

2

4

6

8

10

12

14

16

18

20

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Amplitude (dBZ)

Fra

cti

on

(%

)

Bright band amplitude Mar 2001 – Feb 2002


1(2)

Snow and clutter Profile correction


1(2)



1(2)



1(2)

Rain Profile correction (no

cutter)


1(2)

Profile correction (no

extrapol.)

Bright band at ground


1(2)

Magnitude of the VPR correction at various rangesMarch 2001 – February 2002

0

10

20

30

40

50

60-3

0...

-25

-25

..-2

0

-20

..-1

5

-15

...-1

0

-10

...-5

-5...

-0

0...

5

5...

10

10

...1

5

15

...2

0

20

...2

5

25

...3

0

> 3

0

Correction (dB)

%

50 km100 km150 km250 km

Date post:	07-Jan-2016
Category:	Documents
Upload:	liseli
View:	31 times
Download:	0 times

CARPE DIEM FMI (Partner 5) progress report

Documents