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![Page 1: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/1.jpg)
“Nature Run” Diagnostics
Thomas Jung
ECMWF
![Page 2: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/2.jpg)
Another “Nature Run”
• A large set of seasonal TL511L91 integrations has been carried out for many summers and winters:– NDJFM 1990-2005– JJASON 1990-2005
• Data have been archived on PL and SFC levels only (6-hourly)
• Advantage: We get an idea of the climate of IFS cycle 31R1 at TL511 used to carry out the “Nature Run”
![Page 3: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/3.jpg)
Extratropical Cyclones
![Page 4: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/4.jpg)
Vorticity Histograms: Extratropical Cyclone Tracks
Histogram: Intensity
0 5 10 15 20Vorticity (10 5̂ s -̂1)
0
500
1000
1500
2000
2500
3000
Nu
mb
er
of C
ase
s
EC-T511
ERA-40
![Page 5: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/5.jpg)
Maximum Vorticity Histograms:Extratropical Cyclone Tracks
EC-T511
ERA-40
Histogram: Maximum Intensity
0 5 10 15 20Maximum Vorticity (10 6̂ s -̂1)
0
50
100
150
200
Nu
mb
er
of C
ase
s
![Page 6: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/6.jpg)
Number of Extratropical Cyclones
Number of VO Maxima (er40 DJFM 1990-2005)
-2
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Number of VO Maxima (etn8-er40 DJFM 1990-2005)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0.5
1
1.5
2
2.5
3
3.5
Number of VO Maxima (eut3-er40 DJFM 1990-2005)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0.5
1
1.5
2
2.5
3
3.5
Number of VO Maxima (eut3-etn8 DJFM 1990-2005)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0.5
1
1.5
2
2.5
3
3.5
Number of VO Maxima (er40 DJFM 1990-2005)
-2
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Number of VO Maxima (etn8-er40 DJFM 1990-2005)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0.5
1
1.5
2
2.5
3
3.5
Number of VO Maxima (eut3-er40 DJFM 1990-2005)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0.5
1
1.5
2
2.5
3
3.5
Number of VO Maxima (eut3-etn8 DJFM 1990-2005)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0.5
1
1.5
2
2.5
3
3.5
Life time: 2 days or longer; Minimum migration: 1000km
ERA40 EC-T511 - ERA40
![Page 7: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/7.jpg)
Mean Intensity of VO Maxima (er40 DJFM 1990-2005)
-1.2
1.2
1.8
2.4
3
3.6
4.2
4.8
5.4
6
6.6
7.2
7.8
8.4
9
Mean Intensity of VO Maxima (etn8-er40 DJFM 1990-2005)
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0.2
0.4
0.6
0.8
1
1.2
1.4
Mean Intensity of VO Maxima (eut3-er40 DJFM 1990-2005)
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0.2
0.4
0.6
0.8
1
1.2
1.4
Mean Intensity of VO Maxima (eut3-etn8 DJFM 1990-2005)
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0.2
0.4
0.6
0.8
1
1.2
1.4
Mean Extratropical Cyclone Intensity
Life time: 2 days or longer; Minimum migration: 1000km
ERA40 EC-T511 - ERA40
Mean Intensity of VO Maxima (er40 DJFM 1990-2005)
-1.2
1.2
1.8
2.4
3
3.6
4.2
4.8
5.4
6
6.6
7.2
7.8
8.4
9
Mean Intensity of VO Maxima (etn8-er40 DJFM 1990-2005)
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0.2
0.4
0.6
0.8
1
1.2
1.4
Mean Intensity of VO Maxima (eut3-er40 DJFM 1990-2005)
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0.2
0.4
0.6
0.8
1
1.2
1.4
Mean Intensity of VO Maxima (eut3-etn8 DJFM 1990-2005)
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0.2
0.4
0.6
0.8
1
1.2
1.4
![Page 8: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/8.jpg)
Mean Growth-Rate
Life time: 2 days or longer; Minimum migration: 1000km
ERA40 EC-T511 - ERA40Mean Growth-Rate of VO Maxima (er40 DJFM 1990-2005)
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Mean Grow th-Rate of VO Maxim a (etn8-er40 DJFM 1990-2005)
-0.35
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Mean Grow th-Rate of VO Maxim a (eut3-er40 DJFM 1990-2005)
-0.35
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Mean Grow th-Rate of VO Maxim a (eut3-etn8 DJFM 1990-2005)
-0.35
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Mean Growth-Rate of VO Maxima (er40 DJFM 1990-2005)
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Mean Grow th-Rate of VO Maxim a (etn8-er40 DJFM 1990-2005)
-0.35
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Mean Grow th-Rate of VO Maxim a (eut3-er40 DJFM 1990-2005)
-0.35
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Mean Grow th-Rate of VO Maxim a (eut3-etn8 DJFM 1990-2005)
-0.35
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0.05
0.1
0.15
0.2
0.25
0.3
0.35
![Page 9: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/9.jpg)
Summary: Extratropical Cyclones 31R1 @ T511 (DJFM)
• Synoptic activity (extratropics):– Generally well represented– Distribution of storm frequency quite realistic– Problems in the Gulf Stream/Kurushio area?– Too many systems in the eastern Atlantic
(blocking)
![Page 10: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/10.jpg)
Tropical Cyclones & African Summer Monsoon in T511 Run
![Page 11: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/11.jpg)
Tropical Cyclone Tracks (Atlantic)
10°N10°N
20°N 20°N
30°N30°N
40°N 40°N
100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W 0°
0°
10°N10°N
20°N 20°N
30°N30°N
40°N 40°N
100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W 0°
0°
10°N10°N
20°N 20°N
30°N30°N
40°N 40°N
100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W 0°
0°
10°N10°N
20°N 20°N
30°N30°N
40°N 40°N
100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W 0°
0°
10°N10°N
20°N 20°N
30°N30°N
40°N 40°N
100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W 0°
0°
10°N10°N
20°N 20°N
30°N30°N
40°N 40°N
100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W 0°
0°
10°N10°N
20°N 20°N
30°N30°N
40°N 40°N
100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W 0°
0°
10°N10°N
20°N 20°N
30°N30°N
40°N 40°N
100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W 0°
0°
2005 2006
TL511
TL255
TL159
TL95
![Page 12: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/12.jpg)
TS Cat 1 Cat 2 Cat 3 Cat 4 Cat 5Tropical storm intensity
0
1
2
3
4
5
6
7
8
9
10
Nu
mb
er
of t
rop
ica
l sto
rms
Atlantic tropical storm intensity1990-2006
T95T159T255T511T159 CY30R2OBS
TS Cat 1 Cat 2 Cat 3 Cat 4 Cat 5Intensity
0
1
2
3
4
5
6
7
8
Nu
mb
er
of T
rop
ica
l Sto
rms
Eastern North Pacific tropical storm intensity1990-2006
T63T159T255T511T159 CY30R2Obs
Resolution and Intensity of Tropical Storms
![Page 13: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/13.jpg)
Synoptic Activity: Vrot @ 700hPa (JJAS)
(a) STD Lowpass Vrot er40 (700hPa 6-9 1990-2006)
0.25
1
3
5
7
9
(b) STD Highpass Vrot er40 (700hPa 6-9 1990-2006)
0.25
1
3
5
7
9
(c) Diff STD Lowpass Vrot etup-er40 (700hPa 6-9 1990-2006)
-2.1
-1.5
-0.9
-0.3
0.3
0.9
1.5
2.1
(d) Diff STD Highpass Vrot etup-er40 (700hPa 6-9 1990-2006)
-2.1
-1.5
-0.9
-0.3
0.3
0.9
1.5
2.1
TL511-ERA40
(a) STD Lowpass Vrot er40 (700hPa 6-9 1990-2006)
0.25
1
3
5
7
9
(b) STD Highpass Vrot er40 (700hPa 6-9 1990-2006)
0.25
1
3
5
7
9
(c) Diff STD Lowpass Vrot etie-er40 (700hPa 6-9 1990-2006)
-2.1
-1.5
-0.9
-0.3
0.3
0.9
1.5
2.1
(d) Diff STD Highpass Vrot etie-er40 (700hPa 6-9 1990-2006)
-2.1
-1.5
-0.9
-0.3
0.3
0.9
1.5
2.1
ERA40
![Page 14: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/14.jpg)
Zonal Mean Zonal Wind: AEJ Area
0O 10ON 20ON 30ON 40ON
1000
800
600
400
200
(a) Average Zonal Mean Zonal Wind (ERA40)
-17.5
-15
-12.5
-10
-7.5
-5
-2.5
2.5
5
7.5
10
12.5
15
17.5
0O 10ON 20ON 30ON 40ON
1000
800
600
400
200
(b) Average Zonal Mean Zonal Wind (T255)
-17.5
-15
-12.5
-10
-7.5
-5
-2.5
2.5
5
7.5
10
12.5
15
17.5
0O 10ON 20ON 30ON 40ON
1000
800
600
400
200
(c) Average Zonal Mean Zonal Wind (T511)
-17.5
-15
-12.5
-10
-7.5
-5
-2.5
2.5
5
7.5
10
12.5
15
17.5
0O 10ON 20ON 30ON 40ON
1000
800
600
400
200
(d) Difference (T255-ERA40)
-7
-6
-5
-4
-3
-2
-1
1
2
3
4
5
6
7
0O 10ON 20ON 30ON 40ON
1000
800
600
400
200
(e) Difference (T511-ERA40)
-7
-6
-5
-4
-3
-2
-1
1
2
3
4
5
6
7
0O 10ON 20ON 30ON 40ON
1000
800
600
400
200
(f) Difference (T511-T255)
-7
-6
-5
-4
-3
-2
-1
1
2
3
4
5
6
7
![Page 15: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/15.jpg)
200 hPa Velocity Potential
-12
-12-6
-6
-6
0
0
0 6
6
6
Velocity Potential 200hPa er40 (6-9 1990-2005)
-3
0
0
0
0
3
3
Velocity Potential 200hPa etup-er40 (6-9 1990-2005)
ERA40
T511 - ERA40
![Page 16: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/16.jpg)
Summary: Tropical Cyclones 31R1 @ T511 (DJFM)
• T511 model produces quite realistic frequency of occurrence of TS/Hurricanes in the Atlantic.
• North African Monsoon too strong + northward shifted.
• AEJ is too weak (problem at higher resolution).• Perhaps slightly too much AEW activity.• Strong problems in the western tropical Pacific
(too little atmospheric upwelling). Problem larger at higher resolution.
![Page 17: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/17.jpg)
Some Other Issues: Model Climate 31R1 @ T511
• Amplitude of the MJO is underestimated (better in recent cycles but still an issue).
• Convectively coupled Kelvin waves in the tropics are underestimated (better from 32R3 onwards).
• Too little (much) precipitation over the tropical continents (oceans) (improved in recent cycles).
• No QBO• Euro-Atlantic blocking significantly
underestimated (large improvements in 33R1).• Anti-cyclonic circulation bias in the North Pacific
(fixed in 32R3)
![Page 18: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/18.jpg)
Tropical Cyclones: 32R3 vs 32R2
![Page 19: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/19.jpg)
Tropical Waves: OLRA (JJA)Power: Symmetric Tropical OLRA (noaa)
-20 -10 0 10 20Westward Modes Wavenumber Eastward Modes
0.0
0.1
0.2
0.3
0.4
0.5
Fre
quen
cy (C
PD
)
Power: Symmetric Tropical OLRA (ewdd)
-20 -10 0 10 20Westward Modes Wavenumber Eastward Modes
0.0
0.1
0.2
0.3
0.4
0.5
Fre
quen
cy (C
PD
)
Power: Symmetric Tropical OLRA (ewdf)
-20 -10 0 10 20Westward Modes Wavenumber Eastward Modes
0.0
0.1
0.2
0.3
0.4
0.5
Fre
quen
cy (C
PD
)
OBS
32R2 32R3
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Tropical Cyclones Frequencies (Annual Mean)
80°S80°S
70°S 70°S
60°S60°S
50°S 50°S
40°S40°S
30°S 30°S
20°S20°S
10°S 10°S
0°0°
10°N 10°N
20°N20°N
30°N 30°N
40°N40°N
50°N 50°N
60°N60°N
70°N 70°N
80°N80°N
20°E
20°E 40°E
40°E 60°E
60°E 80°E
80°E 100°E
100°E 120°E
120°E 140°E
140°E 160°E
160°E 180°
180° 160°W
160°W 140°W
140°W 120°W
120°W 100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W
6.6 6.9 12.88.4 3.1 15.719.6 32.3 28.26.2 12.2 5.2
16.5 9.2 13 10.8 11 8.8 4.7 7.1 5.8
Ensemble size = 1Forecast start reference is 01/11/YYYYTropical Storm FrequencyECMWF Seasonal Forecast
Annual Mean
CY32R2 CY32R3 OBS
Note: TL159L91
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Tropical Cyclones Frequencies (Annual Mean)
Tropical storm frequency
80°S80°S
70°S 70°S
60°S60°S
50°S 50°S
40°S40°S
30°S 30°S
20°S20°S
10°S 10°S
0°0°
10°N 10°N
20°N20°N
30°N 30°N
40°N40°N
50°N 50°N
60°N60°N
70°N 70°N
80°N80°N
160°W
160°W 140°W
140°W 120°W
120°W 100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W 0°
0° 20°E
20°E 40°E
40°E 60°E
60°E 80°E
80°E 100°E
100°E 120°E
120°E 140°E
140°E 160°E
160°E
< 1 1.. 2 2.. 3 3.. 4 4.. 5 5.. 6 6.. 7 7.. 8 8.. 9 > 9
Tropical storm frequency
80°S80°S
70°S 70°S
60°S60°S
50°S 50°S
40°S40°S
30°S 30°S
20°S20°S
10°S 10°S
0°0°
10°N 10°N
20°N20°N
30°N 30°N
40°N40°N
50°N 50°N
60°N60°N
70°N 70°N
80°N80°N
160°W
160°W 140°W
140°W 120°W
120°W 100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W 0°
0° 20°E
20°E 40°E
40°E 60°E
60°E 80°E
80°E 100°E
100°E 120°E
120°E 140°E
140°E 160°E
160°E
< 1 1.. 2 2.. 3 3.. 4 4.. 5 5.. 6 6.. 7 7.. 8 8.. 9 > 9
Tropical storm frequency
80°S80°S
70°S 70°S
60°S60°S
50°S 50°S
40°S40°S
30°S 30°S
20°S20°S
10°S 10°S
0°0°
10°N 10°N
20°N20°N
30°N 30°N
40°N40°N
50°N 50°N
60°N60°N
70°N 70°N
80°N80°N
160°W
160°W 140°W
140°W 120°W
120°W 100°W
100°W 80°W
80°W 60°W
60°W 40°W
40°W 20°W
20°W 0°
0° 20°E
20°E 40°E
40°E 60°E
60°E 80°E
80°E 100°E
100°E 120°E
120°E 140°E
140°E 160°E
160°E
<-2 -2..-1.5 -1.5..-1 -1..-0.5 -0.5..0.5 0.5..1 1..1.5 1.5..2 > 2
32R1 32R3
32R3-32R1
![Page 22: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/22.jpg)
Tropical Cyclones in Recent Model Cycles
• Generally there is an increase in the number/intensity of tropical cyclones/hurricanes.
• Particularly lower resolution versions perform better than older cycles (e.g., US landfall).
• Large increases in the western tropical Pacific (partly due changes in the large-scale atmospheric circulation). Too large?
![Page 23: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/23.jpg)
Tropical Cyclone Forecasts:
T799 vs T511
![Page 24: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/24.jpg)
948
T511 L60 20050828 00UTC ECMWF FC t+36 VT: 20050829 12UTC Surf: MSL
942
T799 L91 20050828 00UTC ECMWF FC t+36 VT: 20050829 12UTC Surf: MSL
963
T511 L60 20050826 12UTC ECMWF FC t+72 VT: 20050829 12UTC Surf: MSL
944
T799 L91 20050826 12UTC ECMWF FC t+72 VT: 20050829 12UTC Surf: MSL
Forecasts of Katrina for Monday 29 Aug. 12 UTC
T511 T799
t+36 t+36
t+72 t+72
Observed SLP: 922 hPa
![Page 25: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/25.jpg)
969
T511 L60 20050922 12UTC ECMWF FC t+36 VT: 20050924 00UTC Surf: MSL
971
T799 L91 20050922 12UTC ECMWF FC t+36 VT: 20050924 00UTC Surf: MSL
983
T511 L60 20050921 00UTC ECMWF FC t+72 VT: 20050924 00UTC Surf: MSL
976
T799 L91 20050921 00UTC ECMWF FC t+72 VT: 20050924 00UTC Surf: MSL
Forecasts of Rita for Saturday 24 Sep. 12 UTC
T511 T799
t+36 t+36
t+72t+72Observed SLP: 930 hPa
![Page 26: “Nature Run” Diagnostics Thomas Jung ECMWF. Another “Nature Run” A large set of seasonal T L 511L91 integrations has been carried out for many summers.](https://reader036.fdocuments.in/reader036/viewer/2022062718/56649e7f5503460f94b83393/html5/thumbnails/26.jpg)
Sensitivity to Horizontal Resolution
• Short-range and medium-range forecasts suggest that T799, if anything, produces stronger hurricanes than T511.
• Resolution studies, however, suggests, that some aspects of the tropical climate (i.e., beyond the medium-range) of 31R1 deteriorate when increasing horizontal resolution (T159->T511). So it may be possible that T799 performs worse than T511.
• In the extratropics the largest changes occur when going from T95 to T159. Rather little changes occur beyond T159 (T159->T511). Hence, it seems reasonable to assume that T511 and T799 perform similar.