WV images, Potential Vorticity and WV images, Potential Vorticity and

Conceptual ModelsConceptual Models

Nuno Moreira (nuno.moreira@meteo.pt)Nuno Moreira (nuno.moreira@meteo.pt)

Instituto de Meteorologia, Lisboa, PortugalInstituto de Meteorologia, Lisboa, Portugal

20032003

WW V images - CharacteristicsV images - Characteristics Water Vapour absorption band : 6 - 7 Water Vapour absorption band : 6 - 7

– WV Meteosat channelWV Meteosat channel– WV 6.2 (5.35 - 7.15 WV 6.2 (5.35 - 7.15 ) from MSG ) from MSG– WV 7.3 (6.85 – 7.85 WV 7.3 (6.85 – 7.85 ) from MSG ) from MSG

Water vapour absorbes Infra-Red radiation Water vapour absorbes Infra-Red radiation emmited by the earth surface and lower emmited by the earth surface and lower cloudsclouds

WV image is “constructed” from the re-WV image is “constructed” from the re-emission by water vapouremission by water vapour

m

m

m

WW V images - CharacteristicsV images - Characteristics

““The instrument measures the humidity The instrument measures the humidity temperature” temperature”

““Topography of water vapour emission”Topography of water vapour emission”

Gray shadesGray shades– Light gray – humidity in the troposphere upper levels Light gray – humidity in the troposphere upper levels – Dark gray - humidity in the troposphere lower levels Dark gray - humidity in the troposphere lower levels

Regions of emission Regions of emission

R.H. =100% -> 250 hPa - 550 hPa R.H. =100% -> 250 hPa - 550 hPa (max: 350 hPa)(max: 350 hPa)

R.H. = 50% -> 250 hPa - 600 hPa R.H. = 50% -> 250 hPa - 600 hPa (max: 400 hPa)(max: 400 hPa)

R.H, = 25% -> 250 hPa - 700 hPa R.H, = 25% -> 250 hPa - 700 hPa (max: 450 hPa) (max: 450 hPa)

(Bader et al, 1995) (Bader et al, 1995)

Regions of emissionRegions of emission

Bader et Bader et al (1995)al (1995)

Water Content in the Water Content in the troposphere troposphere

48.7 % of total water content – below 48.7 % of total water content – below 850hPa850hPa

77.5% of total water content - below 700hPa77.5% of total water content - below 700hPa

92.5% of total water content - below 550hPa 92.5% of total water content - below 550hPa

(NOAA, 1991) (NOAA, 1991)

WW V ImageV Imageand tropospheric levelsand tropospheric levels

Light areas – white / light grayLight areas – white / light gray– Humidity in Humidity in upperupper levels levels– Medium and lowerMedium and lower levels ? levels ?

Dark areas – black/ dark grayDark areas – black/ dark gray– Low humidty in Low humidty in upperupper levels levels– Higher humidity content in Higher humidity content in mediummedium levels levels – LowerLower levels ? levels ?

And a Water Vapour Image ...And a Water Vapour Image ...

… … filter in “whiter shading” filter in “whiter shading”

Fenomena retrieved from Fenomena retrieved from water vapour imagery water vapour imagery

Tropopause folding Tropopause folding Jet streams/streaksJet streams/streaks Vorticity AdvectionVorticity Advection Rapid cyclogenesis (bombs) (?)Rapid cyclogenesis (bombs) (?) Troughs and ridges in upper levelsTroughs and ridges in upper levels Cut-off lows Cut-off lows

Related meteorological Related meteorological parametersparameters

Geopotential (eg. 300 hPa)Geopotential (eg. 300 hPa) Wind field (eg. 300 hPa)Wind field (eg. 300 hPa) Potencial VorticityPotencial Vorticity Tropopause MapTropopause Map

Potential Vorticity Potential Vorticity

Potential Vorticidade in isentropic levels Potential Vorticidade in isentropic levels (constant potential temperature ) (constant potential temperature )

Absolute Vorticity (planetary + relative) Absolute Vorticity (planetary + relative) and static stabilityand static stability

Tropospheric air mass – low (I)PV Tropospheric air mass – low (I)PV Stratospheric air mass – high (I)PVStratospheric air mass – high (I)PV

p

vkfgVPI

Potential VorticityPotential Vorticity

Dynamic Tropopause = 1.5 <-> 3.0 UVP Dynamic Tropopause = 1.5 <-> 3.0 UVP

Advantages of Isentropic Potential Vorticity (IPV)Advantages of Isentropic Potential Vorticity (IPV)– Conservative property over a conservative Conservative property over a conservative

surface surface – Superposition with wind field depicts temporal Superposition with wind field depicts temporal

evolution of Potential Vorticityevolution of Potential Vorticity

However, PV can also be depicted in pressure However, PV can also be depicted in pressure levels !! levels !!

1126101 KgKsmUVP

Tropopause MapTropopause Map

Topography of the Tropopause (isentropic Topography of the Tropopause (isentropic coordenates, isobaric, geopotencial)coordenates, isobaric, geopotencial)

low low -> low Tropopause -> low Tropopause high high -> high Tropopause-> high Tropopause

Advantage Advantage – Quantifies lowest tropopause level Quantifies lowest tropopause level

PV ----> Tropopause MapPV ----> Tropopause Map

Conceptual ModelsConceptual ModelsJet Stream Jet Stream

The definiton …The definiton … Jet streamJet stream

– Upper Tropospheric wind speed > 60 ktUpper Tropospheric wind speed > 60 kt

Jet streakJet streak (= Jet Stream maximum) (= Jet Stream maximum)

– ““wind speed maximum situated along the axis of a wind speed maximum situated along the axis of a jet stream at the level of maximum wind” jet stream at the level of maximum wind”

(Palmén and Newton, 1969)(Palmén and Newton, 1969)

Jet Stream – vertical section Jet Stream – vertical section

Keyser Keyser and and Shapiro Shapiro (1986)(1986)

Jet Stream – vertical sectionJet Stream – vertical section

Holton Holton (1992)(1992)

Jet Stream – vertical sectionJet Stream – vertical section

Met. Met. Office Office (1997)(1997)

Jet Jet Relative Vorticity Relative Vorticity

““Manual of Synoptic Satellite Meteorology–Conceptual Manual of Synoptic Satellite Meteorology–Conceptual Models, v3.0”, ZAMG/KNMI/FMI/EUMETSATModels, v3.0”, ZAMG/KNMI/FMI/EUMETSAT

North H.: North H.: cyclonic side cyclonic side – Positive – Positive Relative Relative VorticityVorticity

South H. : South H. : cyclonic side cyclonic side – Negative – Negative Relative Relative VorticityVorticity

Jet Jet Vorticity advections Vorticity advections

““Manual of Synoptic Satellite Meteorology–Conceptual Manual of Synoptic Satellite Meteorology–Conceptual Models v3.0”, ZAMG/KNMI/FMI/EUMETSATModels v3.0”, ZAMG/KNMI/FMI/EUMETSAT

PVA- Positive PVA- Positive Vorticity Vorticity Advection Advection

NVA - NVA - Negative Negative Vorticity Vorticity AdvectionAdvection

Jet Jet Ageostrophic Wind Ageostrophic Wind Vertical motion Vertical motion

Keyser and Shapiro (1986)Keyser and Shapiro (1986)

gag Vdt

dkf

V

1

Jets and FrontsJets and Fronts

Bluestein Bluestein (1993)(1993)

Conceptual ModelsConceptual ModelsTropopause FoldingsTropopause Foldings

Cut-offCut-off lowslows

Elizaga et Elizaga et al (1996)al (1996)

Lowering Tropopause Lowering Tropopause ----> Vertical Motion----> Vertical Motion

Tropopause Div Q Elbern et al (1998)Elbern et al (1998)

15Oct9315Oct93

Lowering Tropopause Lowering Tropopause ----> Vertical Motion----> Vertical Motion

00 UTC - Ertel Potential Vorticidade 250 hPa

12 UTC – Q-G Forcing Water Vapour Convergence

Romero (2000) Romero (2000) 28 Sep 9428 Sep 94

Conceptual ModelsConceptual Models(rapid) Cyclogenesis (rapid) Cyclogenesis

Hoskins et al (1985)Hoskins et al (1985)

Boyle and Bosart (1986)Boyle and Bosart (1986)

Hirschberg and Fritsch Hirschberg and Fritsch (1991)(1991)

Malardel (2000) Malardel (2000)

And ...And ...

.. Related NEW proposed .. Related NEW proposed symbols ..symbols ..

Adapted from Joly and Santurette (2000) Adapted from Joly and Santurette (2000)

ReferencesReferences Bader, M.J., Forbes, G.S., Grant, J.R., Lilley, R.B. e Waters, A.J., 1995: Images in weather forecasting. Cambridge

University Press, Cambridge, 499 pp. Bechtold, P., 2000: Atmospheric moist convection: effects, concepts and modelling/forecast. Módulo do Curso

“Weather forecasting in the midlatitudes” realizado na MeteoFrance de 4-15 Dezembro 2000 [ver relatório VAP01/01, Instituto de Meteorologia]

Bluestein, H.B., 1993: Synoptic-Dynamic Meteorology in Midlatitudes, Vol.II: Observations and Theory of Weather Systems. Oxford University Press, Oxford, 594 pp.

Boyle, J.S. e Bosart, L.F., 1986: Cyclone-Anticyclone couplets over North America. Part II: Analysis of a major cyclone event over the Eastern United States. Mon. Wea. Rev., 114, 2432-2465.

Elbern, H., Hendricks, J. e Ebel, A., 1998: A climatology of tropopause folds by global analysis. Theor. Appl. Climatology, 59, 181-200.

Elizaga, F., Martin, F., Riosalido R., Carretero, O., Elvira, B. e Garcia, A., 1996: Imágenes de vapor de agua: uso en el diagnostico de niveles altos. IV Simposio Nacional de Predección. Memorial “Alfondo Ascaso”, Madrid, 15-19 Abril 1996, INM.

Grahame, N., 1998: Christmas Eve storm. Review of interesting synoptic cases. Fourth Meeting of the Working Group on Cooperation between European Forecasters (WG CEF). Set. 98 Comunicação oral.

Hirschberg, P.A. e Fritsch, J.M., 1991b: Tropopause ondulations and the development of extratropical cyclones - Part II: Diagnostic Analysis and coceptual model. Mon. Wea. Rev., 119, 518-550.

Hoskins, B.J., McIntyre, M.E. e Robertson, A.W., 1985: On the use and significance of isentropic potencial vorticity maps. Quart. J. Roy. Meteo. Soc., 111, 877-946.

Joly, A e Santurette, P., 2000: Turning dynamical ideas into forecast practice: a proposal for a renewed graphic summary of the synoptic scale situation. Centre National de Recherches Météorologiques, Service Central d´Exploitation Météorologique. Módulo do Curso “Weather forecasting in the midlatitudes” realizado na MeteoFrance de 4-15 Dezembro 2000 [ver relatório VAP01/01, Instituto de Meteorologia]

ReferencesReferences Keyser, D. e Shapiro, M.A., 1986: Review – A review of the structure and dynamics of upper-level frontal zones. Mon.

Wea. Rev., 114, 452-499. Malardel, S., 2000: Weather forecasting in midlatitudes regions - Large scale dynamics in the midlatitudes. Módulo do

Curso “Weather forecasting in the midlatitudes” realizado na MeteoFrance de 4-15 Dezembro 2000 [ver relatório VAP01/01, Instituto de Meteorologia]

Moreira, N., 1999: Utilização de imagens de vapor de água na avaliação de campos previstos por Modelos numéricos. Instituto de Meteorologia.

Morgan,M.C. e Nielson-Gammon, 1998: Using tropopause maps to diagnose midlatitude weather systems. Mon. Wea. Rev., 126, 2555-2579.

NOAA, 1991: Water vapor imagery – Interpretation and applications to weather analysis and forecasting. NOAA Technical report NESDIS 57, National Oceanic and Atmospheric Admnistration, Washington, 213 pp.

Prates, F., 1996: Utilização de cartas de vorticidade potencial isentrópica no diagnóstico dos processos de ciclogénese. Nota Técnica. Instituto de Meteorologia.

Romero, R., 2000: Sensitivity of a heavy rain producing Western Mediterranean cyclone to embedded potencial vorticity anomalies. Submetido ao Quarterly Journal of the Royal Meteorological Society.

Santurette, P., 1998: About new products and new methods for synoptic forecast in Meteo-France. Casos de estudo apresentados no curso sobre previsão na Meteo-France, Dez. 98. Comunicação oral.

ZAMG/KNMI/FMI/EUMETSAT, 2001: Manual of Synoptic Satellite Meteorology – Conceptual Models v3.0. ZAMG/KNMI/FMI/EUMETSAT, 2001: Manual of Synoptic Satellite Meteorology – Conceptual Models v3.0.