Assimilation of radiance data at JMA:
recent developments and prospective plans
Kozo Okamoto, Hiromi Owada, Toshinobu Ishibashi and Takumu Egawa
Japan Meteorological Agency (JMA)
okamoto@naps.kishou.go.jp
1.
1. Outline
Outline of
of NWP
NWP systems
systems at
at JMA
JMA
Satellites operationally assimilated
Data introduced after ITSC15 are shown in red, and those under development or suspended are in parentheses
Deterministic models and analysis schemes
* TCWV : total column water vapor, RR : rain rate, AMV : atmospheric motion vector
Satellite/Instrument
Global Anal (GDAS)
Meso Anal (MDAS)
NOAA15-17
AMSU-A/-B Radiance
Temperature retrieval
NOAA18
AMSU-A/MHS Radiance (2007.4)
Temperature retrieval
Aqua/AMSU-A
Radiance
X
Metop
AMSU-A/MHS radiance (2007.11)
Temperature retrieval (2008.1)
Aqua/AIRS
(Radiance)
Model
Global Model (GSM)
Meso-scale Model (MSM)
Horizontal res.
TL959 (20km)
5km
Vertical res. (model top)
60 (0.1hPa)
50 (21.8km)
Forecast range
(Initial time)
84h (00,06,18UTC)
216h (12UTC)
15h (00,06,12,18UTC)
33h (03,09,15,21UTC
frequency
4/day
8/day
Target
One-week forecast
Short-range forecast
Aeronautical forecast
Disaster prevention information
4D-Var
(TL959/T159 or 20km/80km)
4D-Var
(10/20km)
Aqua/AMSR-E
Radiance
TCWV,RR
(DMSP16/SSMIS)
(Radiance)
(TCWV,RR)
AMV
Data Assimilation
(outer/inner loop)
X
Metop/IASI
(Radiance)
X
DMSP13,14/SSMI
Radiance
TCWV,RR
TRMM/TMI
Radiance
TCWV,RR
Assimilation window
6h
6h
MTSAT-1R, Meteosat-7,9, GOES-11,12
AMV, (CSR 2007.6)
Radiance assimilation
RTTOV7, VarBC
X
Aqua,Terra/MODIS
AMV
X
Cut off time
Early Analysis (EA) : 2h25m
Cycle Analysis (CA): 11h15m(00,12), 5h15m(06,18)
50m
QuikSCAT/SeaWinds
Sea surface wind
Sea surface wind
Assimilate
Assimilate radiances
radiances that
that are
are less
lesscloud-affected
cloud-affectedand
and less
lesssurface-dependent
surface-dependent as
as other
other ATOVS
ATOVS on
onNOAA.
NOAA.
Static
Static scan-dependent
scan-dependent Bias
Bias Correction
Correction (BC)
(BC) and
and adaptive
adaptive air-mass
air-mass dependent
dependent BC
BC using
using aa Variational
Variational
Bias
Bias Correction
Correction (VarBC)
(VarBC) method
method
Significantly
Significantlypositive
positive impact
impact on
onforecast,
forecast, especially,
especially, of
of the
the geopotential
geopotentialheight
height even
even when
when NOAA15-18
NOAA15-18
and
and Aqua
Aqua ATOVS
ATOVS were
were already
alreadyassimilated.
assimilated.
Moreover,
Moreover, great
great benefits
benefitsof
of early
earlyand
and stable
stable data
datadissemination
dissemination
T850
Z500
X
X
Channel
Channelselection
selectionisisbased
basedon
onEntropy
EntropyReduction
Reduction(Rodgers
(Rodgers2000)
2000)
Detection
Detection of
of cloud-affected
cloud-affected radiances
radiances using
usingaa 2-step
2-step schemes
schemes
[1]
[1]Clear
Clearpixel
pixeldetection
detectionusing
using
At
Atdaytime,
daytime,cloud
cloudcover
coverfrom
fromVIS~NIR
VIS~NIRch
ch
AT
night,
TB
difference
AT night, TB differencebetween
betweenshortwave
shortwavech
chand
andlongwave
longwavech
chand
and
between
betweenSST
SSTpredicted
predictedand
andSST
SSTanalyzed
analyzedat
atnighttime
nighttime
[2]
Cloud-affected
channel
detection
based
on
McNally
and
Watts
(2003)
[2] Cloud-affected channel detection based on McNally and Watts (2003)
AIRS
CloudSat
5
4
3
2
1
0
0
1
2
3
4
5
6
7 8 9 10 11 12 13 14 15 16 17 18
cloud top height [km]
Frequency of cloud top height from AIRS
Better
Worse
AIRS
AIRSclouds
cloudstend
tendto
tobe
behigher
higherthan
thanCloudSat
CloudSatclouds.
clouds.
AIRS,
AIRS,generally,
generally,more
morefrequently
frequentlyfinds
findsclouds
cloudsthan
thanCloudSat
CloudSat
but
often
misses
low
clouds.
but often misses low clouds.
These
Thesecharacteristics
characteristicsof
ofthe
thescheme
schememay
maynot
notbe
beaccurate
accurateenough
enough
to
toestimate
estimatethe
thecloud
cloudtop
topheight
heightbut
butsafe
safefrom
fromthe
theview
viewpoint
pointof
of
avoiding
avoidingthe
theinclusion
inclusionof
ofcloud
cloudcontaminated
contaminatedchannels
channelsininthe
theassimilation.
assimilation.
to 7 2007. The frequency is normalized by
their total numbers.
Bias
Bias correction
correctionscheme
schemeisis the
the same
same as
as ATOVS
ATOVS except
except VarBC
VarBC predictors
predictors
VarBC
VarBCpredictors:
predictors:background
backgroundTB,
TB,1/cosθ,
1/cosθ,constant
constant
Positive
Positive impact
impact on
on analysis
analysis but
but neutral
neutral or
or negative
negative on
onforecast
forecast
Reduce
Reducemodel
modelbiases
biasesof
oftemperature
temperatureand
andhumidity
humidityininthe
theanalysis
analysisand
andfirst-guess
first-guess
Degrade
Degradeforecast
forecastskills
skillsof
ofthe
thelower
lowertropospheric
tropospherictemperature
temperature
Assimilates
Assimilates12
12 AP-RARS
AP-RARS stations
stationsin
in Japan(2),
Japan(2), China(4),
China(4), Australia(5)
Australia(5) and
andKorea(1),
Korea(1), and
and EARS
EARS
AP-RARS
AP-RARS ATOVS
ATOVS data
data improve
improveEarly
EarlyAnalysis
Analysis (EA)
(EA)
(a)
(b)
reduce
reducethe
thedifference
differencefrom
fromdata-richer,
data-richer,more
moreaccurate
accuratecycle
cycleanalysis
analysis(CA)
(CA)
but
butindiscernible
indiscernibleimpact
impacton
onforecast
forecast
EARS
EARS ATOVS
ATOVS data
data have
have aamore
more positive
positive impact
impacton
on EA
EA and
andforecast
forecast
AIRS
Comparison of cloud top height from AIRS
and CloudSat/CPR closest to the center of
AIRS FOV from 1 to 7 2007.
(a)
(c)
(b)
(d)
NOAA18
Difference between EA and CA for geopotential
height at 500 hPa (Z500) when AP-RARS
ATOVS not assimilated (left) and when
assimilated (right) at 18UTC on 26 June 2007.
Blue (red) shades depict positive (negative)
value of the difference and contours indicate
Z500. The area of ATOVS used in this analysis
are surrounded by dashed lines.
NOAA15
6
Assimilate
Assimilateclear
clear radiances
radiances of
of 54ch/324ch
54ch/324ch oover
verthe
theseaice-free
seaice-freesea
sea
2.2
2.2 RARS
RARS ATOVS
ATOVS impact
impact (( AP-RARS
AP-RARS 2007.2,
2007.2, EARS
EARS 2007.8)
2007.8)
NOAA15
7
Verification
Verification of
of the
the cloud
cloudtop
top height
height derived
derivedfrom
from AIRS
AIRS against
against CloudSat
CloudSat and CloudSat/CPR (2B-GEOPROF) from 1
Forecast hours
Forecast Improvement rate when Metop/AMSU-A and MHS are assimilated in GDAS. The rate is calculated with
(Cntl-Test)/Cntl with respect to RMSE for 1-9 day forecasts. Cntl uses NOAA15-18 and Aqua, and Test adds Metop to
Cntl. Dots on lines indicate that the rate is statistically significant. The assimilation period is 23 May to 13 July 2007.
more
moreavailable
availabledata
dataused
used
Frequency of cloud top height from AIRS and CloudSat
3.1
3.1 AIRS
AIRS radiance
radiance assimilation
assimilation
Wsp250
Wsp850
(Sea surface wind)
(Refractivity)
CloudSat
Psea
(Sea surface wind)
(Refractivity, 2007.2)
(Metop/GRAS)
frequency [%]
2.1
2.1 Metop/AMSU-A
Metop/AMSU-A &
& MHS
MHS (2007.11)
(2007.11)
Metop/ASCAT
(CHAMP, GRACE)
Anal (use AIRS)
Guess (use AIRS)
Anal (no AIRS)
Guess (no AIRS)
Fits of analysis and first-guess to RAOBs with and
without AIRS radiance assimilation. (a) Biases of
temperature in the Southern Hemisphere and (b)
biases of relative humidity in the tropics are calculated
from a one-month cycle experiment in August 2007.
Time sequence of the forecast at day-1and -5 for Z500 (a, b) and T850
(c, d) from 1 to 31 August, 2007. Test run assimilates AIRS radiances
and Control run does not.
NOAA16 NOAA18
Same as above , but for EARS ATOVS
assimilation at 12UTC on 17 June 2007.
3.2
3.2 MW
MW window
window channel
channel assimilation
assimilation
Operational
Operational use
use of
of SSM/I,
SSM/I, TMI
TMI and
and AMSR-E
AMSR-E since
since May
May2007
2007
TCWV
TCWVin
in clear
clear areas
areas and
and precipitation
precipitation in
inother
other areas
areas in
in MDAS
MDAS (2003.10)
(2003.10)
Less
cloud-affected
radiances
in
GDAS
(2006.5)
Less cloud-affected radiances in GDAS (2006.5)
Only
Onlyvertical
verticalpolarized
polarizedchannels
channelsassimilated
assimilated
Biases
Biasesare
areremoved
removedwith
withVarBC
VarBC
2.3
2.3 Clear
Clear Sky
Sky Radiances
Radiances (CSRs)
(CSRs) of
of WV-ch
WV-ch from
from geostationary
geostationary satellite
satellite imagers
imagers
(2007.6)
(2007.6)
Increase
Increase humidity
humidityin
in the
the midmid-to
to upper-troposphere
upper-troposphere in
in wet
wet areas,
areas,
and
and even
even in
in the
thelower-troposphere
lower-troposphere in
in dry
dryareas
areas
Frequent
Frequentmeasurements
measurementsover
overthe
theland
landcompliment
complimentmicrowave
microwaveradiometer
radiometer
Bring
Bring analysis/guess
analysis/guess humidity
humiditycloser
closer to
to RAOB
RAOB around
around 500hPa
500hPa
and
and MHS/AMSU-B
MHS/AMSU-B ch3
ch3
Positive
Positive impact
impact on
onforecast,
forecast, especially
especiallyat
at day
day11 to
to 33
Impact
Impactfrom
from55satellites
satellitesare
aremuch
muchgreater
greaterthan
thanthat
thatfrom
from11satellite
satellite(MTSAT-1R)
(MTSAT-1R)
Cycle
Cycle assimilation
assimilation experiment
experiment in
in August
August2007
2007 and
and January
January2008:
2008:
test2 cntl
cntl:
cntl:no
noCSRs
CSRsfrom
fromgeostationary
geostationarysatellites
satellites
test1:
test1:add
addCSRs
CSRsfrom
fromMTSAT-1R
MTSAT-1Ronly
only
test2:
add
CSRs
from
MTSAT-1R,
test2: add CSRs from MTSAT-1R,GOES11,12
GOES11,12and
andMeteosat7,9
Meteosat7,9
Psea
Psea
T850
T850
Z500
Z500
Wsp850
Wsp850
Monthly averaged TCWV between
test2 and cntl in August 2007
Time sequence
of TB O-B STD
of test2 and cntl
2
TCWV,
TCWV,Ts,
Ts,Ts
Ts2, ,ocean
oceansurface
surfacewind
windspeed,
speed,1/cosθ,
1/cosθ,constant
constant
Test1:
Test1: Improve
Improve QC
QC and
and BC
BC
Stricter
Strictercloud
cloudscreening
screening&&addition
additionof
ofTotal
TotalColumn
ColumnCloud
Cloud
Liquid
LiquidWater
Water(TCCLW)
(TCCLW)predictor
predictorininVarBC
VarBC
Reject
Rejectpixels
pixelswith
withretrieved
retrievedTCCLW
TCCLWover
over0.18
0.18kg/m2
kg/m2
More
Moresymmetric
symmetricdistribution
distributionof
ofO-B
O-Bininradiance
radiancespace
space
Small
Smallbut
butconsistent
consistentpositive
positiveimpact
impacton
onthe
theforecast
forecastof
ofT850
T850
Test2:
Test2: Add
Add SSMIS
SSMIS window
window channels
channels to
to Test1
Test1
19V,
19V,22V,
22V,37V
37Vand
and 92V
92Vradiances
radiancesare
areassimilated
assimilated
Neutral
Neutralimpact
impact
O-B of AMSR-E 37V on 1st August
2007 before (upper panel) and after
(lower panel) improved QC and BC
Time sequence of the forecast at
day-1, -3 and -5 for T850 from 131 Aug, 2007. Test run adds
improved QC and BC to Control
run (“Test1 in the main text )
4.
4. Plans
Plans on
on radiance
radiance assimilation
assimilation
Improve
Improve AIRS
AIRS assimilation
assimilation processing
processing and
andintroduce
introduce IASI
IASI
Wsp250
Wsp250
test1
vs
cntl
Forecast Improvement rate when
MTSAT CSRs are added in GDAS.
The rate are calculated from one
month forecast of August 2007.
test2
vs
cntl
The same as above but for CSRs of
five geostationary satellites added.
Implement
ImplementRochon’s
Rochon’sJacobian
Jacobianmapping
mappinginstead
insteadof
ofnearest
nearestneighbor
neighbormapping
mappingininthe
thevertical
verticalinterpolation
interpolationscheme
scheme
Review
Reviewbias
biascorrection
correctionpredictors
predictorsand
andtune
tuneobservation
observationerrors
errorsespecially
especiallyof
ofshort
shortwave
wavechannels
channels
How
to
address
the
conflict
with
model
biases?
How to address the conflict with model biases?
Introduce
Introduce SSMIS
SSMIS window
window channels
channels and
and evaluate
evaluate sounding
sounding channel
channel impact
impact
Improve
Improve AMSU-A/-B/MHS
AMSU-A/-B/MHS assimilation
assimilation
Switch
Switchthe
thecurrent
currentretrieval
retrievalassimilation
assimilationto
tothe
theradiance
radianceassimilation
assimilationininMDAS
MDAS
IsIsVarBC
VarBCgoing
goingtotobe
beintroduced
introducedas
asGDAS
GDASdoes?
does? =>
=>Need
Needtotoexamine
examineeffect
effectofofsampling
samplingerrors
errors
Land/snow
Land/snowemissivity
emissivitymodel
modelor
orretrieved
retrievedvalues
valuesare
arebeing
beingtested
tested
Optimize
Optimizestatic
staticobservation
observationerrors
errorsininaavariational
variationalscheme
scheme
Assimilate
Assimilatecloud
cloud affected
affected radiances
radiances of
of IR/MW
IR/MW sounders
sounders and
and imagers
imagers