ETA and GFS Validation (Southeastern Mexico) John M. Dickens RSIS/CPC.
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ETA and GFS ValidationETA and GFS Validation(Southeastern Mexico)(Southeastern Mexico)
John M. DickensJohn M. Dickens
RSIS/CPCRSIS/CPC
OutlineOutline
Models Models DataDataMethodsMethodsResultsResultsConclusionsConclusions
PurposePurpose
To determine whether it is appropriate to To determine whether it is appropriate to replace the 20 km ETA model with the 50 replace the 20 km ETA model with the 50 km GFS model for forecasting precipitation km GFS model for forecasting precipitation amounts in Central America and the amounts in Central America and the Caribbean. Caribbean.
ModelsModels
ETA 20ETA 20 20 km20 km CPC DomainCPC Domain
GFS 50GFS 50 GlobalGlobal 50 km50 km
Show model domain
DataData Central America GTS Stations (75):
The data from these stations are quality controlled downstairs and in the CPC, making them more reliable than their NOAA/USGS counterparts. Due to the sparse data these stations will not be used.
NOAA/USGS Stations (101):These stations were set up as part of the
Hurricane Mitch Program. No money was
set aside for maintenance of these stations
so their reliability is in question. Also, the
exact units of the measurements have never
been determined. Therefore, these stations
will not be used. Mexico Co-Op Stations (~500 out
of 1000):The Mexico stations will be used because
they are fairly dense in the southern half of
the country and therefore will be a decent
representation of the Central American
region.
DataData
Only used stations reporting precipitation Only used stations reporting precipitation amounts greater than zeroamounts greater than zero
Time period: May 1 to August 31, 2004Time period: May 1 to August 31, 2004
August 2 Mexico Data: The Mexico data runs from 12Z to 12Z.
August 1 Forecast
August 2 Forecast
* For the August 1st forecasts of 24 hrs and 48 hrs the Mexico data for August 1st and 2nd are required.
August 3 Forecast
August 1Forecast
Times
F00
F06
F12
F18
F24
F30
F36
F42
F48
F54
F60
F66
F72
F78
The forecasts represent the precipitation for the past 6 hours. • F06 represents rainfall from F00 to F06• F12 represents rainfall from F06 to F12 …….
August 1 Mexico Data: The Mexico data runs from 12Z to 12Z.
DataData
MethodsMethods
Match Co-op stations to model grid points Match Co-op stations to model grid points in a point-to-grid comparisonin a point-to-grid comparison
= model grid points
= Co-op stations
MethodsMethods
RegularRegular 24 hr / 48 hr24 hr / 48 hr forecastsforecasts
No CoastNo Coast 24 hr / 48 hr24 hr / 48 hr
forecastsforecasts
No MountainsNo Mountains 24 hr / 48 hr24 hr / 48 hr
forecastsforecasts
Data PointsData Points
15148
10543
7183
0
2000
4000
6000
8000
10000
12000
14000
16000
Po
ints
Regular No Coast No Mountains
Category
Number of Points for Each Experiment
MethodsMethods
Regular vs No Coast vs No MountainsRegular vs No Coast vs No Mountains 24 hr and 48 forecasts24 hr and 48 forecasts
24 hr vs 48 hr forecasts24 hr vs 48 hr forecasts ETA and GFSETA and GFS
OverallOverall
24 hr Mean Difference24 hr Mean Difference
24 hr Total Mean DifferenceStation - Model
-2
-1
0
1
2
3
4
5
6
Regular No Coast No Mountains
Category
Diffe
ren
ce (m
m)
ETA
GFS
Regular: Mean Difference (24 hr)Station - Model
-20
-100
10
20
3040
50
6070
80
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Diffe
ren
ce
(m
m)
No Coast: Mean Difference (24 hr)Station - Model
-20-10
010
2030
4050
6070
80
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Diffe
ren
ce
(m
m)
No Mountains: Mean Difference (24 hr)Station - Model
-20
-10
010
20
30
40
5060
70
80
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Diffe
ren
ce
(m
m)
24 hr Standard Deviation24 hr Standard Deviationof the Mean Differenceof the Mean Difference
24 hr Total Standard Deviation of Mean Difference
0
5
10
15
20
25
Regular No Coast No Mountains
Category
Devia
tio
n (m
m)
ETA
GFS
No Coast: Standard Deviation of Mean Difference (24 hr)
0
5
10
15
20
25
30
35
40
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Dev
iatio
n (m
m)
Regular: Standard Deviation of Mean Difference (24 hr)
0
5
10
15
20
25
30
35
40
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Dev
iatio
n (m
m)
No Mountains: Standard Deviation of Mean Difference (24 hr)
0
5
10
15
20
25
30
35
40
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Dev
iatio
n (m
m)
48 hr Mean Difference48 hr Mean Difference
48 hr Total Mean Difference
-2
-1
0
1
2
3
4
5
6
Regular No Coast No Mountains
Category
Diffe
ren
ce (m
m)
ETA
GFS
Regular: Mean Difference (48 hr)Station - Model
-20
-10
010
20
30
40
5060
70
80
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Diffe
ren
ce
(m
m)
No Coast: Mean Difference (48 hr)Station - Model
-20
-100
10
20
3040
50
6070
80
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Diffe
ren
ce
(m
m)
No Mountains: Mean Difference (48 hr)Station - Model
-20
-10
0
10
20
30
40
50
60
70
80
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Diffe
ren
ce (m
m)
48 hr Standard Deviation 48 hr Standard Deviation of the Mean Differenceof the Mean Difference
48 hr Total Standard Deviation of Mean Difference
0
5
10
15
20
25
Regular No Coast No Mountains
Category
Devia
tio
n (m
m)
ETA
GFS
Regular: Standard Deviation of Mean Difference (48 hr)
0
5
10
15
20
25
30
35
40
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Deiv
atio
n (m
m)
No Mountains: Standard Deviation of Mean Difference (48 hr)
0
5
10
15
20
25
30
35
40
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Dev
iatio
n (m
m)
No Coast: Standard Deviation of Mean Difference (48 hr)
0
5
10
15
20
25
30
35
40
Overall 0-10 mm 10-20 mm 20-50 mm 50+ mm
Station Rainfall Category
Dev
iatio
n (m
m)
Categorical SummaryCategorical Summary
OverallOverall RegularRegular No CoastNo Coast No MountainsNo Mountains
Mean DifferenceMean Difference
(lowest)(lowest)
24 hr24 hrGFSGFS
(3.27 mm)(3.27 mm)
GFSGFS
(4.37 mm)(4.37 mm)
ETAETA
(1.67 mm)(1.67 mm)
48 hr48 hrGFSGFS
(2.19 mm)(2.19 mm)
GFSGFS
(3.19 mm)(3.19 mm)
ETAETA
(3.04 mm)(3.04 mm)
Standard Standard Deviation of Deviation of
Mean DifferenceMean Difference
(lowest)(lowest)
24 hr24 hrETAETA
(4.43 mm)(4.43 mm)
ETAETA
(5.13 mm)(5.13 mm)
TIETIE
(.90 mm)(.90 mm)
48 hr48 hrETAETA
(3.39 mm)(3.39 mm)
ETAETA
(4.28 mm)(4.28 mm)
TIETIE
(.10 mm)(.10 mm)
24 hr vs 48 hr Forecasts24 hr vs 48 hr ForecastsTotal Mean Difference
-2
-1
0
1
2
3
4
5
6
Regular No Coast No Mountains
Category
Dif
fere
nc
e (m
m)
Total Standard Deviation of Mean Difference
0
5
10
15
20
25
Regular No Coast No Mountains
Category
Devia
tio
n (m
m)
Total Correlation
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Regular No Coast No Mountains
Category
Co
rrela
tio
n
24 hr ETA24 hr ETA 48 hr ETA48 hr ETA
24 hr GFS24 hr GFS 48 hr GFS48 hr GFS
ConclusionsConclusions
Mean differences increase with Mean differences increase with increasingly large eventsincreasingly large events
Standard deviations of mean difference Standard deviations of mean difference increase with increasingly large eventsincrease with increasingly large events
ConclusionsConclusions
RegularRegular Overall Overall GFSGFS smaller mean difference smaller mean difference Overall Overall ETAETA smaller standard deviation of the mean difference smaller standard deviation of the mean difference
No CoastNo Coast Overall Overall GFSGFS smaller mean difference smaller mean difference Overall Overall ETAETA smaller standard deviation of mean difference smaller standard deviation of mean difference
No MountainsNo Mountains Overall Overall ETAETA smaller mean difference smaller mean difference Overall Overall ETAETA and and GFSGFS have identical standard deviations of have identical standard deviations of
mean differencemean difference
ConclusionsConclusionsETA 48 hr forecasts more accurate than ETA 48 hr forecasts more accurate than
the ETA 24 hr forecaststhe ETA 24 hr forecastsKnown initialization problems….additional 24 hrs Known initialization problems….additional 24 hrs
for spinupfor spinup
ETA forecasts precipitation in the region ETA forecasts precipitation in the region better than the GFSbetter than the GFS
Mean differences: both < Mean differences: both < ±±6 mm6 mmStandard Deviations: both > 15 mm, ETA ~ 5 mm Standard Deviations: both > 15 mm, ETA ~ 5 mm
lowerlowerCorrelations: ETA .25-.30, GFS near zeroCorrelations: ETA .25-.30, GFS near zero
Thank YouThank You
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