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））

Analyzed PeriodAnalyzed PeriodOctober 1, 1994 – March 31, 1999 (5 Cold Seasons)October 1, 1994 – March 31, 1999 (5 Cold Seasons)

Analyzed RegionAnalyzed Region2020N - 65N - 65N, 100N, 100E - 180E - 180EE

26)φ(t6)-φ(t

sin

60sin

12

6)P(t6)-P(t (Bergeron) Rate Deepening

Deepening Rate 1 Bergeron and Continuing at least 24 hours

at t Latitude : (t) (hour),at t (hPa) Pressure Level Sea : P(t)

Slide 1

Explosively Deepening Explosively Deepening CycloneCyclone

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

O-LO-L) Type) Type2.2. Pacific Ocean – Ocean Pacific Ocean – Ocean

((PO-OPO-O) Type) Type

Sea of Japan

Sea of Okhotsk

NorthwesternPacific Ocean

Total : 224 casesTotal : 224 cases

Slide 2

Explosively Deepening Cyclone TypeExplosively Deepening Cyclone Type

TOTALTOTAL：：224224

Slide 3

OJ： 42

PO-L： 50

PO-O： 110

OJ OJ TYPETYPE

PO-L PO-L TYPETYPE

PO-O PO-O TYPETYPE

Rapid DeepeningRapid DeepeningSea of Japan or Sea of OkhoSea of Japan or Sea of Okhotsktsk

FormationFormationLandLand

Rapid DeepeningRapid DeepeningNorthwestern Pacific OceanNorthwestern Pacific Ocean

FormationFormationLandLand

Rapid DeepeningRapid DeepeningNorthwestern Pacific OceanNorthwestern Pacific Ocean

FormationFormationOceanOcean

Slide 4

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)

Synoptic EnvironmentSynoptic Environment ↓↑ ↓↑

Cyclone Meso-scale StructureCyclone Meso-scale StructureLatent Heat Release

Slide 8

Numerical Studies of Extreme Numerical Studies of Extreme CasesCases

Focused on the Latent Heat ReleaseFocused on the Latent Heat Release

• OJ TYPEOJ TYPE 00UTC February 27, 1999 (1.84 Bergeron)00UTC February 27, 1999 (1.84 Bergeron)

• PO-L TYPEPO-L TYPE 18UTC February 10, 1998 (2.54 Bergeron)18UTC February 10, 1998 (2.54 Bergeron)

• PO-O TYPEPO-O TYPE 00UTC December 31, 1997 (2.96 Bergeron)00UTC December 31, 1997 (2.96 Bergeron)

Slide 9

PSU-NCAR MM5 version PSU-NCAR MM5 version 3.6.13.6.1

Horizontal GridHorizontal Grid• Domain 1 : 200×160 (45 km)Domain 1 : 200×160 (45 km)• Domain 2 : 301×271 (15 km)Domain 2 : 301×271 (15 km)

Vertical Levels : 23 Sigma levelVertical Levels : 23 Sigma levelInitial / Initial / Boundary Conditions :Boundary Conditions : JMA GANAL JMA GANALSea Surface Temperature : Reynolds SSTSea Surface Temperature : Reynolds SSTMicrophysicsMicrophysics

• Domain 1 : Simple Ice SchemeDomain 1 : Simple Ice Scheme (Vapor, Cloud Water, Rain Water, Cloud Ice, Snow)(Vapor, Cloud Water, Rain Water, Cloud Ice, Snow)• Domain 2 : Mixed-phase Scheme (+ Supercold Water)Domain 2 : Mixed-phase Scheme (+ Supercold Water)

Cumulus Parameterization : Grell’s SchemeCumulus Parameterization : Grell’s Scheme

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

Mass ExtensionMass Extension

Upper-level Vorticity AdvectionUpper-level Vorticity Advection

Early and Late WinterEarly and Late WinterMedium Deepening RateMedium Deepening Rate

Zonally Stretched Jet StreamZonally Stretched Jet StreamMedium Continental Cold Air Medium Continental Cold Air

Mass ExtensionMass Extension

Mid-WinterMid-WinterLargest Deepening RateLargest Deepening Rate

Strong Jet StreamStrong Jet StreamLarge Continental Cold Air Large Continental Cold Air

Mass ExtensionMass Extension

Large Latent Heat ReleaseLarge Latent Heat Release

Effect of Effect of

Latent HeatLatent Heat Smallest Smallest MediumMedium LargestLargestReleaseRelease Slide 18