Um 4d var regional reanalysis progress
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UM 4D-Var Regional Reanalysis Progress. Richard Renshaw, Stephen Oxley, Adam Maycock, Peter Jermey, Dale Barker, Tom Green, DingMin Li. Contents. Technical highlights First full reanalysis 2008/9 Validation Developments for 2013/14.

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UM 4D-Var Regional Reanalysis Progress

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UM 4D-Var Regional Reanalysis Progress

Richard Renshaw, Stephen Oxley, Adam Maycock, Peter Jermey,

Dale Barker, Tom Green, DingMin Li


Contents

Technical highlights

First full reanalysis 2008/9

Validation

Developments for 2013/14


WP2.1 Building capacity for advanced regional data assimilation

orography

12km grid

480 x 384

reanalysis period 2008/2009


Technical Highlights

Capability to generate ODBs


ODB – obs monitoring database

ODB stores observations + qc + O-B + O-A + ...

Established ECMWF database + utilities

Array of tools available “for free”

Metview macros (quick look)

Obstat (detailed stats / graphics)


Technical Highlights

Capability to generate ODBs

Able to archive reanalysis fields in ECMWF mars


First run 2008/9


4 Parallel Streams

2009

2008

A

B

C

D

with 1 month overlap for spin-up


How long to spin up ?

rms screen temperature


How long to spin up ?

rms surface pressure


Var Resolution

UM 12km

Var 24km


Var Resolution

4DVar run time:

36km1 node hour

24km3 node hours

12km20 node hours

UM T+241.5 node hours


Var Resolution: 24 vs 36 km


Observations

Surface (SYNOP, buoy, etc) incl visibility

Upper air (sonde, pilot, wind profiler)

Aircraft

AMV (‘satwinds’)

GPS-RO

Scatterometer winds

ATOVS

AIRS

IASI

GPSRO

MSG clear sky radiances


Bias correction ofsatellite radiances

Initial reanalysis:

Radiances processed, not assimilated

monthly bias statistics

Final reanalysis:

Radiances assimilated


ValidationPeter Jermey


Verification - Results

  • Verifying at T+6 – a good analysis should produce a good short range forecast

Jul/Aug 08

Jan 08

+6.6 wtd skill diff

+2.7 wtd skill diff

Sept/Oct 09

+3.2 wtd skill diff


Statistics and

EXTREME Statistics!


First run 2008-2009


Statistics

Extreme Statistics are defined as ‘core indices’ of climate change by The joint CCI/CLIVAR/JCOMM Expert Team on Climate Change Detection and Indices.

Standard Statistics

Extreme Statistics

  • We calculate these statistics for ERA and EURO4M and compare with observations statistics from European Climate Assessment & Dataset ECA&D http://eca.knmi.nl

  • Mean

  • Max of Daily Max

  • Std Dev

  • Max of Daily Min

  • Range

  • Min of Daily Max

  • Min of Daily Min

Summer Days Count of days for which daily max T>25 degrees

  • Icing days, Frost days, Summer days, Tropical Nights

Wet Days A day on which precip is greater than 1mm

  • Maximum count of consecutive dry/wet days

Percentiles For base period (ERA) 1961-1990

  • Count of wetdays, count of days with precip above 10mm, 20mm.

  • Average precip on wetdays, max precip on 5 consecutive days, maximum precip on a single day, total precip, precip above 95th and 99th percentiles.

  • Percentage of days where max temp > 90th percentile etc…


Validation of climate indicesPeter Jermey


Validation of climate indicesPeter Jermey


July 2008


July 2008 Floods

Max of 5 Daily Precip/mm

RMS

Mean

-37

73

ERA

ERA

69

-36

EURO4M

  • EURO4M more detail

  • EURO4M closer to Obs

  • Both models not as wet as Obs

EURO4M

mm


Developments for 2013


Cloud assimilation

NAE assimilates 3D cloud fields from nowcasting system

(combines satellite imagery + surface reports)

EURO4M will have to rely on using surface reports directly


Cloud from SYNOP reportsPeter Francis

Wattisham, 00Z 2012/03/13AAXX 13004 03590 11238 83504 10064 20060 30240 40352 53002 60001 71022 886// 92350 333 55/// 20411 84703 86706 88708


Cloud from SYNOP report

Wattisham, 00Z 2012/03/13AAXX 13004 03590 11238 83504 10064 20060 30240 40352 53002 60001 71022 886// 92350 333 55/// 20411 84703 86706 88708

847034 oktas Stratus, height 90m


Cloud from SYNOP report

Wattisham, 00Z 2012/03/13AAXX 13004 03590 11238 83504 10064 20060 30240 40352 53002 60001 71022 886// 92350 333 55/// 20411 84703 86706 88708

847034 oktas Stratus, height 90m

867066 oktas Stratus, height 180m

887088 oktas Stratus, height 240m


Precipitation assimilation

  • Operational UK models assimilate radar rainrate (latent heat nudging)

  • For EURO4M, aim to assimilate raingauge accumulations


Precipitation assimilation

Plan

Use E-Obs gridded daily precipitations

Keith Ngan, Andrew Lorenc, Richard


Precipitation assimilation

Plan

Use E-Obs gridded daily precipitations

System to disaggregate 24hr accumulations to 6hrs

Var outer loop with spin-up problems minimised

(analysis increments trigger rain in model).

Keith Ngan, Andrew Lorenc, Richard


Variational Bias Correction

Airmass-dependent bias correction of satellite radiances (based on Harris and Kelly, 2001)

Currently coeffs c are calculated off-line monthly

VarBC will give smooth and automatic updating

Code is in place – hope to trial in 2013

(DingMin Li, Andrew Lorenc , Dale Barker)


Collaboration – Cross-Validation

Compare our reanalysis against:

SMHI

ERA

Obs climatologies

Peter


Summary

  • Initial reanalysis is run (2008-9)

    • new validation tools

  • Production reanalysis will be better:

    • satellite radiances

    • surface cloud

    • ODBs and mars archive

  • A final reanalysis aims to include later developments

    • precipitation assimilation

    • variational bias correction


Questions ?


Extra slides...


model orography

ERA-Interim

Model T255 (80km)

Var T159 (125km)

Met Office

Model 12km

Var 24km


ERA-Interim vs EURO4M

  • T255 (80km), 60 levels

  • T159 (125km) 4D-Var

  • 12-hour analysis window

  • assimilate:

    • conventional obs

    • satellite radiances

  • 12km, 70 levels

  • 24km 4D-Var

  • 6-hour analysis window

  • assimilate:

    • conventional obs incl vis

    • satellite radiances

    • GPS (ground & RO)

    • Cloud

    • Precipitation

  • Initial state and boundary conditions from ERA-Interim analyses


Observation processing

Corrections to radiosonde temperature, surface pressure,

- use same as UKMO Global

Rejection lists

- use old UKMO Global and NAE lists


Observations from ECMWF

Surface (SYNOP, buoy, etc) incl visibility

Upper air (sonde, pilot, wind profiler)

Aircraft

AMV (‘satwinds’)

ATOVS

AIRS

IASI

GPSRO

MSG clear sky radiances


Observations from MetDB

Ground-based GPS

Scatterometer winds


(Per(Anal))2 – Fc2

Skill =

(Per(Anal))2

Verification

  • Description of Work:

Temperature,

Water Vapour,

Rel. Hum.

Surf. P.,

Surf. Radiation Budget,

Wind,

Earth Radiation Budget,

Cloud Properties,

Tot/Base

Snow Cover,

SST,

Precip,

and Visibility.

  • Skill Scores (as in NWP Index):

  • ETS as (in UK Index):

Total Cloud

3, 5, 7 octs.

Cloud Base

100m, 500m, 1500m

Precip

0.5mm, 1mm, 4mm

Vis (1.5m)

200m, 1000m, 4000m


February 2009


February 2009 Snow

Min of Daily Min Temp/degrees

Max of Daily Precip/mm

ERA

EURO4M


February 2009 Snow

Min of Daily Min Temp/degrees

RMS

Mean

0.3

2.8

ERA

ERA

2.3

0.9

EURO4M

  • EURO4M closer to Obs

  • EURO4M larger bias

EURO4M

  • EURO4M and ERA warmer than obs


February 2009 Snow

Max of Daily Precip/mm

RMS

Mean

-5.6

7.5

ERA

ERA

6.2

-0.45

EURO4M

  • EURO4M closer to Obs

  • EURO4M smaller bias

EURO4M

  • EURO4M and ERA dryer than obs


Reports of 24hr accum precip


12Z Reports of 6hr precip


00Z Reports of 6hr precip


15Z Reports of 6hr precip


Covariances

NAE

Old covariances from Global model

Horizontal length scales are ‘guesses’

EURO4M

Covariances calculated (NMC method) in CVT

Horizontal length scales also from CVT

Marek, Gordon, Jean-Francois


CVT covariances: psi horizontal length scales

350km

100km

vertical mode (1 to 70)


CVT covariances: psi horizontal length scales

350km

NAE 180km

100km

vertical mode (1 to 70)


Cov: CVT vs NAE


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