Characteristics of Cyclones Characteristics of Cyclones over over North-western Pacific Region North-western Pacific Region Yoshio Asuma Yoshio Asuma Division of Earth and Planetary Scien Division of Earth and Planetary Scien ces, ces, Graduate School of Science, Graduate School of Science, Hokkaido University Hokkaido University and and Akira Kuwano-Yoshida Akira Kuwano-Yoshida Earth Simulator Center, Earth Simulator Center, JAMSTEC JAMSTEC
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Characteristics of Cyclones over North-western Pacific Region
Characteristics of Cyclones over North-western Pacific Region. Yoshio Asuma Division of Earth and Planetary Sciences, Graduate School of Science, Hokkaido University and Akira Kuwano-Yoshida Earth Simulator Center, JAMSTEC. Deepening Rate 1 Bergeron and Continuing at least 24 hours. - PowerPoint PPT Presentation
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Characteristics of Cyclones Characteristics of Cyclones over over
North-western Pacific RegionNorth-western Pacific Region
Yoshio AsumaYoshio AsumaDivision of Earth and Planetary Sciences,Division of Earth and Planetary Sciences,
Graduate School of Science,Graduate School of Science,Hokkaido UniversityHokkaido University
andand
Akira Kuwano-YoshidaAkira Kuwano-YoshidaEarth Simulator Center,Earth Simulator Center,
JAMSTECJAMSTEC
1. Introduction Explosively developing cyclones frequently appear over the north-western Pacific Ocean as well as north-western Atlantic Ocean. These cyclones have difficulties to exact forcast and also play an important role for the global vapor and energy transportation point of view. This presentation describes behaviors of cyclones over the north-western Pacific region using JMA global objectively analyzed dataset (GANAL) and would like to show the importance of latent heat release with PSU-NCAR mm5 meso-scale model. 2. Cyclone Characteristics Slide 1 shows the definition of the explosively deepening cyclone, datasets and, analyzing peroid and area. We investigate 5 cold seasons between October and March. 224 explosively deepening cyclones in total were found during the period. Cyclones formed over the land and ocean but they were rapidly deepening over the ocean in the higher latitude than 35N. Cyclones were classified cyclones into three types depending on positions of formation and rapid development: Okhotsk-Japan Sea (OJ), Pacific Ocean-land (PO-L) and Pacific Ocean-ocean (PO-O) cyclones (Slides 2, 3 and 4). OJ cyclones frequently appeared in late fall and had the smallest deepening rate of the three, PO-L cyclones had medium deepening rate and frequently occurred in early and late winter,
and PO-O cyclones mainly occurred in midwinter and had the largest deepening rate (Slides 5 and 6). These characteristics closely connected to the larger scale atmospheric conditions and have an important effect on the latent heat release near the cyclone center (Slides 7 and 8). We discuss the importance of latent heat release with meso-scale model (PSU-NCAR mm5). A most extreme case in each cyclone type was selected for the study (Slide 9). Motel parameters and initial dataset were shown in Slide 10. Calculations were started at 24 hours before maximum deepening and continued for 48 hours (CNTL). CNTL run simulated well each case. Sensivity tests for latent heat release were also conducted (DRY). OJ cyclone: Slide 11: CNTL run simulated well the upper level short-wave trough and jet streak. Low level air parcels turned around cyclone center from the south. Water vapor got into towards cyclone from the south. DRY run showed a little weak cyclone SLP but almost the similar structures as CNTL. Slide 12: CNTL run showed deep cyclone structure but DRY run showed shallower structure. The air parcels in the lower level did not rise higher up.
Slide 17(a): CNTL run followed well the analysis (GANAL). DRY run also followed the analysis but it was not well developed. The differences between CNTL and DRY were not large for OJ cyclones. PO-L cyclone: Slide 13: CNTL run: Cyclone SLP and zonally stretch upper level jet are simulated well. Air parcels in the lower level from the south rose up and vapor was also supplied from the south. The cyclone’s central SLP was weaker in DRY run and zonal winds were strong in the upper level and cyclone circulations did not simulate well in the DRY run. Slide 14: Air parcels in lower level went higher up and showed a deeper structure in CNTL run but they did not go up higher and showed a shallow structure in DRY run. Slide 17(b): CNTL run simulated well the cyclone development but DRY run did not develop well. The differences between CNTL and DRY runs are larger than OJ cyclone but smaller than PO-O cyclone. PO-O cyclone: Slide 15: The cyclone developed under the poleward upper level jet exit. Air parcels in the lower level came from the south and turned around the cyclone center. Large amount of
vapor supplied into the cyclone center from the south in CNTL run. In DRY run, the cyclone did not develop well. Vapor from the south diffused here. We could not identify the northern upper-level jet. Slide 16: The air parcels in CNTL run went up strongly and showed deep convection structure. But in DRY run, they did not go up higher. Slide 17(c): The central SLP followed well the analysis in CNTL run but it did not develop well in DRY run. Differences between CNTL and DRY runs were significant. 3. Conclusions The summaries were illustrated in Slide 18. OJ explosive cyclones tend to occur in late fall with smallest deepening rates. PO-L explosive cyclones are in early and late winter with medium deepening rates. And PO-O explosive cyclones are in the mid-winter with largest deepening rates. The contribution of the latent heat release to the cyclone deepening is largest in PO-O cyclones and smallest in OJ cyclones. These deepening rates are results of cyclone’s synoptic and meso-scale structures. And cyclone developments also affect the larger scale environments.
Definition of Explosively Deepening CycloneDefinition of Explosively Deepening Cyclone (Sanders and Gyakum, 1998)(Sanders and Gyakum, 1998)
Data SourceData SourceJMA Global Objectively Analyzed Dataset JMA Global Objectively Analyzed Dataset (( GANALGANAL))
Rapid Deepening:Rapid Deepening: Higher Latitude thanHigher Latitude than 3535N in LatitudeN in Latitude over the Oceanover the Ocean
Formation:Formation: over the Land and Oceanover the Land and Ocean
Three Types of Cyclone:Three Types of Cyclone:1.1. Okhotsk – Japan Sea Okhotsk – Japan Sea ((OJOJ) Type) Type1.1. Pacific Ocean – Land (Pacific Ocean – Land (PP
Deepening Rate Frequency Deepening Rate Frequency DistributionDistribution
Maximum Maximum Deepening Deepening
RateRate
OJ TypeOJ TypeSmallestSmallest
PO-L TypePO-L TypeMediumMedium
PO-O TypePO-O TypeLargestLargest
Slide 5
Monthly Frequency of Explosive Monthly Frequency of Explosive CyclonesCyclones
Seasonal Seasonal VariationVariation
OJ TypeOJ TypeLate FallLate Fall
PO-L TypePO-L TypeEarly and Late Early and Late
WinterWinter
PO-O TypePO-O TypeMid-WinterMid-Winter
Slide 6
Cyclone Cyclone TypeType
OJ TypeOJ Type (Late Fall)(Late Fall)Short Wave Upper-level TroughShort Wave Upper-level TroughShort Jet StreakShort Jet StreakWeaker Continental Cold Air Mass Weaker Continental Cold Air Mass ExtensionExtension
PO-L TypePO-L Type (Early and Late Winter)(Early and Late Winter)Zonally Stretched Jet StreamZonally Stretched Jet Stream (Strong Zonal Wind Component)(Strong Zonal Wind Component)Medium Continental Cold Air Mass Medium Continental Cold Air Mass ExtensionExtension
PO-O TypePO-O Type (Mid-Winter)(Mid-Winter)Strong Jet Stream Strong Jet Stream (Larger Poleward Component)(Larger Poleward Component)Strongest Continental Cold Air Mass Strongest Continental Cold Air Mass ExtensionExtension
Slide 7
Cyclone Cyclone TypeType
Cold Air Mass over the ContinentCold Air Mass over the ContinentUpper-level Trough Upper-level Trough
Upper-level JetUpper-level Jet↓↓
Cyclone Track and Deepening RateCyclone Track and Deepening Rate(Cyclone type)(Cyclone type)
Calculation was started before 24 hours from the Calculation was started before 24 hours from the maximum deepening rate and continued for 48 homaximum deepening rate and continued for 48 hours.urs.
Sensitivity ExperimentsSensitivity Experiments• CNTL Run : Full Physics CNTL Run : Full Physics • DRY Run : No-latent Heat ReleaseDRY Run : No-latent Heat Release Slide 10
OJ TYPEOJ TYPE
Back Trajectory ended at 850hPaBack Trajectory ended at 850hPa
CNTLCNTL300hPaWinds
PV
SLPRain Water Path
Precip. Water
DRYDRY300hPaWinds
PV
SLPRain Water Path
Precip. Water
Slide 11
OJ TYPEOJ TYPE DRYDRYCNTLCNTL
Slide 12
PO-L TYPEPO-L TYPE CNTLCNTL
Back Trajectory ended at 850hPaBack Trajectory ended at 850hPa
300hPaWinds
PV
SLPRain Water Path
Precip. Water
DRYDRY300hPaWinds
PV
SLPRain Water Path
Precip. Water
Slide 13
PO-L TYPEPO-L TYPE CNTLCNTL DRYDRY
Slide 14
PO-O TYPEPO-O TYPE CNTLCNTL
Back Trajectory ended at 850hPaBack Trajectory ended at 850hPa
300hPaWinds
PV
SLPRain Water Path
Precip. Water
DRYDRY300hPaWinds
PV
SLPRain Water Path
Precip. Water
Slide 15
PO-O TYPEPO-O TYPE CNTLCNTL DRYDRY
Slide 16
1.55 Bergeron0.97 Bergeron
1.24 Bergeron0.72 Bergeron
2.38 Bergeron0.71 Bergeron
OJ OJ TYPETYPE
PO-L PO-L TYPETYPE
PO-O PO-O TYPETYPE
• CNTL runs show CNTL runs show almost exact cyclone’s almost exact cyclone’s central SLPs (GANAL).central SLPs (GANAL).• PO-O cyclonePO-O cyclone shows shows the largest difference the largest difference between CNTL and DRY between CNTL and DRY runs.runs.• PO-L cyclonePO-L cyclone difference difference is the next.is the next.
Slide 17
OJ TYPEOJ TYPE PO-L TYPEPO-L TYPE PO-O TYPE
Late FallLate FallSmallest Deepening RateSmallest Deepening Rate
Short-wave Upper TroughShort-wave Upper TroughWeaker Continental Cold Air Weaker Continental Cold Air