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All Months, All Amplitudes (1.00+), All EN/LN/N, No Lag. Categorize by EN, LN and N. Change Phase Only. Change Amplitude Only. Change Season Only. Identify Critical Factors and their NPNA Impacts –. Benchmark Results. Z200 Anomaly. OLR Anomaly. Precip Rate Anomaly.

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Key method composite according to critical factors

All Months, All Amplitudes (1.00+), All EN/LN/N, No Lag

Categorize by EN, LN and N

Change Phase Only

Change Amplitude Only

Change Season Only

Identify Critical Factors and their NPNA Impacts –

Benchmark Results

Z200 Anomaly

OLR Anomaly

Precip Rate Anomaly

Key Method – Composite According to Critical Factors


Comparison of driest and wettest composites ca

Composite of 5 Wettest Periods in CA

Composite of 5 Driest Periods in CA

Comparison of Driest and Wettest Composites - CA

  • Composites based on MJO and wet (dry) conditions in CA-DSW show clear EN (LN) patterns in tropical and northeast Pacific.

  • Onshore/offshore flow anomalies a major contributor to western CONUS precip anomalies.


North Pacific – North American Circulation and Precipitation Anomalies Associated with the Madden-Julian Oscillation

Adam J. Stepanek, Capt, USAF

Co-Advisors: Tom Murphree, Ph.D. & Carlyle Wash, Ph.D.

Naval Postgraduate School - March 6, 2006


Overview of presentation
Overview of Presentation Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Introduction: Motivation / Background

  • MJO Impacts

  • Prior Studies

  • Data

  • Methods

  • Analysis

  • Key Composite Results

  • Individual Cases

  • Summary and Conclusions

  • Future Work

  • References and Acknowledgements


Motivation for research
Motivation for Research Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Desire to increase DoD awareness of tropical-extratropical teleconnections

  • Investigate the potential of the Madden-Julian Oscillation (MJO) as a forecast tool for DoD operations

  • Both tropical and extratropical weather are personal interests, so investigating tropical-extratropical interactions was a good thesis fit


What is the mjo
What is the MJO? Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • The Madden-Julian Oscillation (MJO) is a tropical, quasi-periodic, propagating, intraseasonal oscillation that is most prominent in the equatorial regions of the Indian and Pacific oceans.

    • Convective and subsidence components

    • Eastward propagating (average phase speed 8 m/s)

    • Period of 30-60 days

    • Zonal wavelength 1 phenomenon

    • Major contributor to intraseasonal weather variability (tropics & extratropics)

  • The MJO was first identified by Roland Madden and Paul Julian in a breakthrough paper in 1971.

  • MJO impacts on the North Pacific / North American (NPNA) region have been a research focus over the past decade, but methods for forecasting these impacts are still very limited.


Mjo effects on western conus dod ops
MJO Effects on western CONUS DoD Ops Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • The MJO has been demonstrated to have effects in the extratropics.

  • Anomalous precipitation events in North Pacific –North America (NPNA) have been linked to MJO via teleconnections, including the following high precipitation events in western CONUS:

    • December 2004 – January 2005

    • December 1996 - January 1997 (DoD Humanitarian Missions with flooding in Sierra Nevada Region)

    • January 1995

  • The mechanisms for and the predictability of the NPNA impacts are not well understood.


Prior research on mjo teleconnections
Prior Research on MJO Teleconnections Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Critical studies on MJO teleconnections with a focus on the NPNA region include:

    • Bond and Vecchi (2003) - WA/OR

    • Jones (2000) – central and southern CA

    • Mo and Higgins (1998) – western CONUS

    • Mo and Higgins (1997) – north Pacific (NPAC)

  • Major findings from these studies include:

    • Anomalous precipitation patterns in the western CONUS are highly dependent on the location of MJO anomalous convection, but no clear agreement on specific impacts of each MJO phase

    • MJO teleconnections in the northern hemisphere occur primarily in winter months

    • An active MJO period is more likely to produce extreme precipitation events in the western CONUS

  • However, many variables with potential impacts on MJO teleconnections have not been thoroughly investigated, including

    • Importance of MJO features (amplitude, subsidence portion of MJO, etc.)

    • Seasonal variations

    • El Nino / La Nina interactions


Prior research on mjo teleconnections1

Winter Weather Anomalies Prior to Precipitation Anomalies Associated with the Madden-Julian Oscillation

Heavy West Coast Precip Events

Modeled Response to Tropical Forcing

H

L

L

H

H

= schematic energy propagation

through wave train from east Asia

= anomalous tropical heating

Prior Research on MJO Teleconnections

  • These schematics describe mechanisms by which the MJO impacts the NPNA region. But how often, and just when, do these mechanisms occur in the real world?

Left image from Module 14: Teleconnections, Modern Climatology Course, Prof Tom Murphree, NPS

Right image from: http://www.cpc.ncep.noaa.gov/products/intraseasonal/intraseasonal_faq.html#what


Key hypotheses
Key Hypotheses Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Hypothesis 1: NPNA response to the MJO is sensitive to:

    • MJO Phase

    • MJO Amplitude

    • Season of MJO Occurrence

    • Concurrent state of El Nino / La Nina (EN/LN)

  • Hypothesis 2: By knowing the variables to which the NPNA response is highly sensitive, we can improve forecasts of NPNA circulation and precipitation


Data Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Primary Data

    • NCEP/NCAR Reanalysis Data

      • 200-hPa heights (Z200)

      • Outgoing longwave radiation (OLR)

      • Precipitation rate

    • Unlike prior studies, data was not filtered to highlight only the MJO / intraseasonal signal

  • MJO Index: The Real-time Multivariate MJO (RMM) Index

    • Based upon multiple variables (OLR, U850 winds and U200 winds)

    • Updated on a near real-time basis – critical to use in forecasting

  • El Nino / La Nina (EN/LN) Index: The MEI Index

    • Updated on a bi-monthly basis

    • Based on six oceanic/atmospheric variables in the tropical Pacific


Methods
Methods Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Key Methodology: Composite various atmospheric fields based upon the RMM, especially four factors:

    • MJO Amplitude (high vs. low)

    • Phase of the MJO (1-8)

    • Season of MJO occurrence (OND vs. JFM)

    • El Nino and La Nina background state

  • Also analyze effects of:

    • Lagging the dates within each composite

    • Case following vs non-case following


Methods1
Methods Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Amplitude Based Method (ABM): Composite cases in which for 3 or more consecutive days MJO amplitude met or exceeded a given amplitude

    • Assumption is that a persistent disturbance is needed to excite an extratropical response

    • Each phase is viewed separately (e.g., phase 1 days are not necessarily part of same event as phase 2 days)

  • Case Following Method (CFM): Use specific MJO phase (phase 4) and examine all events meeting ABM standards; trace event through its full lifecycle (phases 1-8)

    • Closer resemblance to real-world analysis of MJO

  • First, create Benchmark Results to do initial assessment of the effects of the four factors on the NPNA response


Methods2
Methods Precipitation Anomalies Associated with the Madden-Julian Oscillation

All Months, All Amplitudes (1.00+), All EN/LN/N, No Lag

Change Phase Only

Categorize by EN, LN and N

Change Amplitude Only

Change Season Only

Investigate Case Following versus Non-Case Following

Investigate Lagging Schemes

Determine Critical Factors and their NPNA Impacts


Benchmark results phase 3 all amplitudes ondjfm en ln n combined

Positive OLR Anomalies = Subsidence Component of MJO Precipitation Anomalies Associated with the Madden-Julian Oscillation

Negative OLR Anomalies = Convective Component of MJO

Benchmark Results: Phase 3 / All Amplitudes / ONDJFM / EN, LN & N Combined

OLR Anomaly

Precip Rate Anomaly

  • Anomalously wet conditions for BC and Pacific Northwest (PNW)


Benchmark results phase 3 all amplitudes ondjfm en ln n combined1
Benchmark Results: Phase 3 / All Amplitudes / ONDJFM / EN, LN & N Combined

200-hPa Anomaly

  • Relatively well-defined wave train from east Asia to NPNA

Approximate Center of MJO Convective Phase

Approximate Center of MJO Subsidence Phase

Energy Propagation through Extratropical Wave Train

Tropical Rossby Wave Response to MJO


Benchmark results phase 3 all amplitudes ondjfm en ln n combined2
Benchmark Results: Phase 3 / All Amplitudes / ONDJFM / EN, LN, & N Combined

Z500 Anomaly

  • Equivalent barotropic structure evident in extratropics

  • Allows interpretation of anomalous low-level flow from upper-level height anomalies

Z850 Anomaly


Impacts of mjo phase on olr anomalies
Impacts of MJO LN, & N CombinedPhase on OLR Anomalies

Ph: 5

Ph: 1

Ph: 6

Ph: 2

Ph: 3

Ph: 7

Ph: 4

Ph: 8


Impacts of mjo phase on z 200 anomalies
Impacts of MJO LN, & N CombinedPhase on Z 200 Anomalies

Ph: 5

Ph: 1

Ph: 6

Ph: 2

Ph: 7

Ph: 3

Ph: 4

Ph: 8


Impacts of mjo phase on the npna response
Impacts of MJO LN, & N CombinedPhase on the NPNA Response

  • Propagation of the convective and subsidence components of the MJO results in changes in the tropical Rossby/Kelvin response.

  • Extratropical wave trains change significantly throughout the lifecycle of the MJO.

  • Anomalies in onshore/offshore flow over the western CONUS are altered as wave trains change.

  • Phase is critical in analyzing MJO teleconnections.


Impacts of mjo amplitude on the npna response
Impacts of MJO LN, & N CombinedAmplitude on the NPNA Response

Phase 3 – All Amplitudes > 1.00

Phase 3 – Low Amplitudes (1.00-1.50)

Phase 3 – High Amplitudes (1.50+)

  • Responses to low to high amplitude events are different in some ways.

  • NPNA differences may lead to differences in western CONUS precipitation.


Impacts of season on npna responses to mjo
Impacts of LN, & N CombinedSeason on NPNA Responses to MJO

Phase 3 – All Seasons (Z200)

Phase 3 – OND Only (Z200)

Phase 3 – JFM Only (Z200)

  • Seasonal differences are not large in this example comparison, but are notable for some other phases.

  • One possible cause of seasonal differences: changes in background flow (e.g., east Asia – north Pacific subtropical jet).


Impacts of el nino la nina on npna response

OLR - All Cases LN, & N Combined

OLR - La Nina Cases

OLR - El Nino Cases

OLR - Neutral Cases

Impacts of El Nino & La Nina on NPNA Response

  • El Nino / La Nina have a large effect on MJO activity through interference with MJO convection (e.g., over maritime continent, MJO phase 3 subsidence is destructively interfered with by La Nina convection).


Impacts of el nino la nina on npna response1

Z200 - All Cases LN, & N Combined

Impacts of El Nino & La Nina on NPNA Response

Z200 - El Nino Cases

Z200 - La Nina Cases

Z200 - Neutral Cases

  • Both tropical and extratropical responses are quite different for EN, LN, and neutral cases.

  • Interference of EN/LN processes with MJO processes may explain differences


Determination of critical factors governing npna response to mjo
Determination of Critical Factors LN, & N CombinedGoverning NPNA Response to MJO

Critical Factors

MJO Phase

Concurrent El Nino / La Nina

Season of MJO Occurrence

  • Some hypotheses appear to be correct, while others still lack solid evidence (e.g., amplitude hypothesis).


Wet dry periods california desert southwest
Wet & Dry Periods: California & Desert Southwest LN, & N Combined

  • Constructed 48 composites of active MJO periods based on 3 critical factors: MJO phase, season, EN/LN/neutral.

  • Composites analyzed to identify conditions most closely associated with precipitation anomalies over western CONUS.

  • Following slides show Z200 and precipitation rate anomalies for conditions under which California - Desert Southwest (CA-DSW) region experienced most positive and most negative precipitation anomalies.

  • Conditions most closely associated with anomalously positive precipitation

    • 1) OND / Neutral – Phase 2

    • 2) OND / Neutral – Phase 6

    • 3) JFM / El Nino – Phase 1

    • 4) JFM / El Nino – Phase 2

    • 5) JFM / El Nino – Phase 7

  • Conditions most closely associated with anomalously negative precipitation

    • 1) OND / El Nino – Phase 4

    • 2) OND / La Nina – Phase 7

    • 3) JFM / La Nina – Phase 3

    • 4) JFM / La Nina – Phase 7

    • 5) JFM / Neutral – Phase 8


Key composites 5 wettest ca composites
Key Composites: 5 LN, & N CombinedWettest CA Composites


Key composites 5 wettest ca composites1
Key Composites: 5 LN, & N CombinedWettest CA Composites

  • Characteristics: Anomalous low positioned to the west and north of CA, with anomalous high to south, sets up anomalously onshore flow between low and high.

  • Generally an east/west or southwest/northeast tilt to the anomalous low, helping to draw in warm, moist air from the tropical regions


Key composites 5 driest ca composites
Key Composites: 5 LN, & N CombinedDriest CA Composites


Key composites 5 driest ca composites1
Key Composites: 5 LN, & N CombinedDriest CA Composites

  • Characteristics: Anomalous high to north and west of CA, with an anomalous low off to south and west, causing offshore flow of dry continental air over CA


Comparison of driest and wettest composites

Composite of 5 LN, & N CombinedWettest Periods in CA

Composite of 5 Driest Periods in CA

Comparison of Driest and Wettest Composites

  • Composites based on MJO and wet (dry) conditions in CA-DSW show clear EN (LN) patterns in tropical and northeast Pacific.

  • Onshore/offshore flow anomalies a major contributor to western CONUS precip anomalies.


Comparison of driest and wettest composites1
Comparison of Driest and Wettest Composites LN, & N Combined

Composite of 5 Wettest Periods in CA

Composite of 5 Driest Periods in CA

  • Large scale factors causing CA-DSW precip anomalies lead to opposite precip anomalies in western Canada.


Npna circulation and precipitation schematics

CA-DSW: Dry Conditions LN, & N Combined

CA-DSW: Wet Conditions

Anomalous Low-level Flow

Anomalous Low-level Flow

L

H

L

H

NPNA Circulation and Precipitation Schematics


Key results
Key Results LN, & N Combined

  • Favorable (F) and unfavorable (U) conditions during MJO activity for fall-winter:

    • Positive precipitation anomalies in CA-DSW:

      F: Early and late phases of MJO

      F: Presence of neutral conditions in OND

      F: Presence of El Nino during JFM

      F: Anomalous wave train from Asia with low over northeast Pacific

      F: SW-NE tilt to anomalous low-high dipole over northeast Pacific

      U: Middle phases of MJO

      U: Presence of LN

    • Negative precipitation anomalies in CA-DSW:

      F: Middle and late phases of MJO

      F: Presence of La Nina

      F: Anomalous high over northeast Pacific

      F: SW-NE tilt to anomalous high-low dipole over northeast Pacific

      U: Early phases of MJO


Key results1
Key Results LN, & N Combined

  • MJO - NPNA teleconnections are very complex.

    • So far, only rudimentary forecasting rules-of-thumb

  • Complexity may be reduced by use of intraseasonal band-pass filter.

    • However, real-world is unfiltered and is what forecasters must deal with


Individual case dec 04 jan 05

MJO convection LN, & N Combined

MJO subsidence

Individual Case: Dec 04 – Jan 05

Precip Rate Anomaly

  • Moderate MJO; phases 3 & 4; OND into JFM; neutral background regime

  • Similar characteristics to wet pattern with SW-NE oriented low near the CA coastline, and precip dipole over western CONUS

  • Strong onshore flow with origins of flow in tropics;


Individual case dec 1996 jan 1997

MJO convection LN, & N Combined

MJO subsidence

Individual Case: Dec 1996 – Jan 1997

Precip Rate Anomaly

  • Very strong MJO; phase 3-8 (select days); OND into JFM; neutral background regime

  • Similar characteristics to wet pattern with SW-NE oriented low near the CA coastline, and precip dipole over western CONUS

  • Strong onshore flow with origins of flow in tropics


Individual case january 1995

MJO convection LN, & N Combined

MJO subsidence

Individual Case: January 1995

Precip Rate Anomaly

  • Moderate MJO; phases 3-5; JFM; El Nino background regime

  • Slightly different orientation of anomalous low, with onshore flow originating in sub-polar regions

  • Duration of onshore flow appears reason for flooding over much of CA; EN influences evident


Additional findings
Additional Findings LN, & N Combined

  • Subsidence Phase of the MJO: Has the ability to cause a significant tropical Rossby wave response and thus influence the extratropical wave train pattern

  • MJO Impacts on Southwest Asia (SWA): Phases 2, 3, 6, & 7 of the MJO can have strong effects on weather in SWA through the Rossby wave response to the convective and subsidence components of MJO

  • MJO amplitude and MJO propagation speed: Stronger MJOs appear to propagate more slowly than do weaker MJOs; may indicate effects of greater atmosphere-ocean coupling for strong MJOs

  • MJO amplitude and persistence of NPNA response: Response is more persistent when amplitude is high; may be related to slower propagation of strong MJOs


Summary and conclusion
Summary and Conclusion LN, & N Combined

  • The relationship between the MJO and NPNA circulation and precipitation anomalies is very complex when looking at non-filtered data, with few, if any, simple rules of thumb to guide forecasters

    • Attempting to base forecasts solely on MJO phase is too simple an approach – other factors are also critical

  • A longer data set appears necessary in order to create more concrete MJO teleconnection rules, especially rules based on ambient background conditions

    • 26 years of data analyzed, but most composites have less than 100 days

  • However, the MJO has the ability to strongly influence the extratropical circulation pattern, and appears to have great potential as a tool for improving extended-range forecasts of the extratropics


Future work
Future Work LN, & N Combined

  • Investigate precipitation anomalies in western CONUS regions through use of a more refined precipitation data set

  • Investigate properties of background flow that contribute to the development of different wave train formations

  • Investigate time evolution of wet and dry composites, especially with respect to background flow patterns


References
References LN, & N Combined

  • Bond, N. A., and G. A. Vecchi, 2003: The Influence of the Madden-Julian Oscillation on Precipitation in Oregon and Washington. Wea. Forecasting, 18, 600-613.

  • Jones, C., 2000: Occurrence of Extreme Precipitation Events in California and Relationships with the Madden Julian Oscillation. J. Climate, 13, 3576-3587.

  • Mo, K. C., and R. W. Higgins, 1998: Tropical Convection and Precipitation Regimes in the Western United States. J. Climate, 11, 2404-2423.

  • Wheeler, M. C., and H. H. Hendon, 2004: An All-Season Real-Time Multivariate MJO Index: Development of an Index for Monitoring and Prediction. Mon. Wea. Rev., 132, 1917-1932.

  • NCEP/NCAR Reanalysis Products constructed at NOAA/CDC: http://www.cdc.noaa.gov/Composites/Day/

  • CPC MJO Index charts available at:

    http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_mjo_index/pentad.html

  • RMM1/RMM2 Index charts available at:

    http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phasediag.list.htm

  • Graphics created using NCL software, available at

  • http://www.ncl.ucar.edu/


Acknowledgements
Acknowledgements LN, & N Combined

  • Co-Advisors: Professor Tom Murphree and Professor Carlyle Wash, NPS, Monterey, CA

  • NCL Assistance: Lt Col Karl Pfeiffer, USAF, NPS, Monterey, CA

  • Important Discussions and Information: Dave Reynolds, NWS, Monterey, CA, and Matthew Wheeler, Australian Bureau of Meteorology


North Pacific – North American Circulation and Precipitation Anomalies Associated with the Madden-Julian Oscillation

Adam J. Stepanek, Capt, USAF

Co-Advisors: Tom Murphree, Ph.D. & Carlyle Wash, Ph.D.

Naval Postgraduate School - March 6, 2006


Overview of presentation1
Overview of Presentation Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Introduction: Motivation / Background

  • MJO Impacts

  • Prior Studies

  • Data

  • Methods

  • Analysis

  • Key Composite Results

  • Individual Cases

  • Summary and Conclusions

  • Future Work

  • References and Acknowledgements


Motivation for research1
Motivation for Research Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Desire to increase DoD awareness of tropical-extratropical teleconnections

  • Investigate the potential of the Madden-Julian Oscillation (MJO) as a forecast tool for DoD operations

  • Both tropical and extratropical weather are personal interests, so investigating tropical-extratropical interactions was a good thesis fit


What is the mjo1
What is the MJO? Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • The Madden-Julian Oscillation (MJO) is a tropical, quasi-periodic, propagating, intraseasonal oscillation that is most prominent in the equatorial regions of the Indian and Pacific oceans.

    • Convective and subsidence components

    • Eastward propagating (average phase speed 8 m/s)

    • Period of 30-60 days

    • Zonal wavelength 1 phenomenon

    • Major contributor to intraseasonal weather variability (tropics & extratropics)

  • The MJO was first identified by Roland Madden and Paul Julian in a breakthrough paper in 1971.

  • MJO impacts on the North Pacific / North American (NPNA) region have been a research focus over the past decade, but methods for forecasting these impacts are still very limited.


Mjo effects on western conus dod ops1
MJO Effects on western CONUS DoD Ops Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • The MJO has been demonstrated to have effects in the extratropics.

  • Anomalous precipitation events in North Pacific –North America (NPNA) have been linked to MJO via teleconnections, including the following high precipitation events in western CONUS:

    • December 2004 – January 2005

    • December 1996 - January 1997 (DoD Humanitarian Missions with flooding in Sierra Nevada Region)

    • January 1995

  • The mechanisms for and the predictability of the NPNA impacts are not well understood.


Prior research on mjo teleconnections2
Prior Research on MJO Teleconnections Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Critical studies on MJO teleconnections with a focus on the NPNA region include:

    • Bond and Vecchi (2003) - WA/OR

    • Jones (2000) – central and southern CA

    • Mo and Higgins (1998) – western CONUS

    • Mo and Higgins (1997) – north Pacific (NPAC)

  • Major findings from these studies include:

    • Anomalous precipitation patterns in the western CONUS are highly dependent on the location of MJO anomalous convection, but no clear agreement on specific impacts of each MJO phase

    • MJO teleconnections in the northern hemisphere occur primarily in winter months

    • An active MJO period is more likely to produce extreme precipitation events in the western CONUS

  • However, many variables with potential impacts on MJO teleconnections have not been thoroughly investigated, including

    • Importance of MJO features (amplitude, subsidence portion of MJO, etc.)

    • Seasonal variations

    • El Nino / La Nina interactions


Prior research on mjo teleconnections3

Winter Weather Anomalies Prior to Precipitation Anomalies Associated with the Madden-Julian Oscillation

Heavy West Coast Precip Events

Modeled Response to Tropical Forcing

H

L

L

H

H

= schematic energy propagation

through wave train from east Asia

= anomalous tropical heating

Prior Research on MJO Teleconnections

  • These schematics describe mechanisms by which the MJO impacts the NPNA region. But how often, and just when, do these mechanisms occur in the real world?

Left image from Module 14: Teleconnections, Modern Climatology Course, Prof Tom Murphree, NPS

Right image from: http://www.cpc.ncep.noaa.gov/products/intraseasonal/intraseasonal_faq.html#what


Key hypotheses1
Key Hypotheses Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Hypothesis 1: NPNA response to the MJO is sensitive to:

    • MJO Phase

    • MJO Amplitude

    • Season of MJO Occurrence

    • Concurrent state of El Nino / La Nina (EN/LN)

  • Hypothesis 2: By knowing the variables to which the NPNA response is highly sensitive, we can improve forecasts of NPNA circulation and precipitation


Data Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Primary Data

    • NCEP/NCAR Reanalysis Data

      • 200-hPa heights (Z200)

      • Outgoing longwave radiation (OLR)

      • Precipitation rate

    • Unlike prior studies, data was not filtered to highlight only the MJO / intraseasonal signal

  • MJO Index: The Real-time Multivariate MJO (RMM) Index

    • Based upon multiple variables (OLR, U850 winds and U200 winds)

    • Updated on a near real-time basis – critical to use in forecasting

  • El Nino / La Nina (EN/LN) Index: The MEI Index

    • Updated on a bi-monthly basis

    • Based on six oceanic/atmospheric variables in the tropical Pacific


Methods3
Methods Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Key Methodology: Composite various atmospheric fields based upon the RMM, especially four factors:

    • MJO Amplitude (high vs. low)

    • Phase of the MJO (1-8)

    • Season of MJO occurrence (OND vs. JFM)

    • El Nino and La Nina background state

  • Also analyze effects of:

    • Lagging the dates within each composite

    • Case following vs non-case following


Methods4
Methods Precipitation Anomalies Associated with the Madden-Julian Oscillation

  • Amplitude Based Method (ABM): Composite cases in which for 3 or more consecutive days MJO amplitude met or exceeded a given amplitude

    • Assumption is that a persistent disturbance is needed to excite an extratropical response

    • Each phase is viewed separately (e.g., phase 1 days are not necessarily part of same event as phase 2 days)

  • Case Following Method (CFM): Use specific MJO phase (phase 4) and examine all events meeting ABM standards; trace event through its full lifecycle (phases 1-8)

    • Closer resemblance to real-world analysis of MJO

  • First, create Benchmark Results to do initial assessment of the effects of the four factors on the NPNA response


Methods5
Methods Precipitation Anomalies Associated with the Madden-Julian Oscillation

All Months, All Amplitudes (1.00+), All EN/LN/N, No Lag

Change Phase Only

Categorize by EN, LN and N

Change Amplitude Only

Change Season Only

Investigate Case Following versus Non-Case Following

Investigate Lagging Schemes

Determine Critical Factors and their NPNA Impacts


Benchmark results phase 3 all amplitudes ondjfm en ln n combined3

Positive OLR Anomalies = Subsidence Component of MJO Precipitation Anomalies Associated with the Madden-Julian Oscillation

Negative OLR Anomalies = Convective Component of MJO

Benchmark Results: Phase 3 / All Amplitudes / ONDJFM / EN, LN & N Combined

OLR Anomaly

Precip Rate Anomaly

  • Anomalously wet conditions for BC and Pacific Northwest (PNW)


Benchmark results phase 3 all amplitudes ondjfm en ln n combined4
Benchmark Results: Phase 3 / All Amplitudes / ONDJFM / EN, LN & N Combined

200-hPa Anomaly

  • Relatively well-defined wave train from east Asia to NPNA

Approximate Center of MJO Convective Phase

Approximate Center of MJO Subsidence Phase

Energy Propagation through Extratropical Wave Train

Tropical Rossby Wave Response to MJO


Benchmark results phase 3 all amplitudes ondjfm en ln n combined5
Benchmark Results: Phase 3 / All Amplitudes / ONDJFM / EN, LN, & N Combined

Z500 Anomaly

  • Equivalent barotropic structure evident in extratropics

  • Allows interpretation of anomalous low-level flow from upper-level height anomalies

Z850 Anomaly


Impacts of mjo phase on olr anomalies1
Impacts of MJO LN, & N CombinedPhase on OLR Anomalies

Ph: 5

Ph: 1

Ph: 6

Ph: 2

Ph: 3

Ph: 7

Ph: 4

Ph: 8


Impacts of mjo phase on z 200 anomalies1
Impacts of MJO LN, & N CombinedPhase on Z 200 Anomalies

Ph: 5

Ph: 1

Ph: 6

Ph: 2

Ph: 7

Ph: 3

Ph: 4

Ph: 8


Impacts of mjo phase on the npna response1
Impacts of MJO LN, & N CombinedPhase on the NPNA Response

  • Propagation of the convective and subsidence components of the MJO results in changes in the tropical Rossby/Kelvin response.

  • Extratropical wave trains change significantly throughout the lifecycle of the MJO.

  • Anomalies in onshore/offshore flow over the western CONUS are altered as wave trains change.

  • Phase is critical in analyzing MJO teleconnections.


Impacts of mjo amplitude on the npna response1
Impacts of MJO LN, & N CombinedAmplitude on the NPNA Response

Phase 3 – All Amplitudes > 1.00

Phase 3 – Low Amplitudes (1.00-1.50)

Phase 3 – High Amplitudes (1.50+)

  • Responses to low to high amplitude events are different in some ways.

  • NPNA differences may lead to differences in western CONUS precipitation.


Impacts of season on npna responses to mjo1
Impacts of LN, & N CombinedSeason on NPNA Responses to MJO

Phase 3 – All Seasons (Z200)

Phase 3 – OND Only (Z200)

Phase 3 – JFM Only (Z200)

  • Seasonal differences are not large in this example comparison, but are notable for some other phases.

  • One possible cause of seasonal differences: changes in background flow (e.g., east Asia – north Pacific subtropical jet).


Impacts of el nino la nina on npna response2

OLR - All Cases LN, & N Combined

OLR - La Nina Cases

OLR - El Nino Cases

OLR - Neutral Cases

Impacts of El Nino & La Nina on NPNA Response

  • El Nino / La Nina have a large effect on MJO activity through interference with MJO convection (e.g., over maritime continent, MJO phase 3 subsidence is destructively interfered with by La Nina convection).


Impacts of el nino la nina on npna response3

Z200 - All Cases LN, & N Combined

Impacts of El Nino & La Nina on NPNA Response

Z200 - El Nino Cases

Z200 - La Nina Cases

Z200 - Neutral Cases

  • Both tropical and extratropical responses are quite different for EN, LN, and neutral cases.

  • Interference of EN/LN processes with MJO processes may explain differences


Determination of critical factors governing npna response to mjo1
Determination of Critical Factors LN, & N CombinedGoverning NPNA Response to MJO

Critical Factors

MJO Phase

Concurrent El Nino / La Nina

Season of MJO Occurrence

  • Some hypotheses appear to be correct, while others still lack solid evidence (e.g., amplitude hypothesis).


Wet dry periods california desert southwest1
Wet & Dry Periods: California & Desert Southwest LN, & N Combined

  • Constructed 48 composites of active MJO periods based on 3 critical factors: MJO phase, season, EN/LN/neutral.

  • Composites analyzed to identify conditions most closely associated with precipitation anomalies over western CONUS.

  • Following slides show Z200 and precipitation rate anomalies for conditions under which California - Desert Southwest (CA-DSW) region experienced most positive and most negative precipitation anomalies.

  • Conditions most closely associated with anomalously positive precipitation

    • 1) OND / Neutral – Phase 2

    • 2) OND / Neutral – Phase 6

    • 3) JFM / El Nino – Phase 1

    • 4) JFM / El Nino – Phase 2

    • 5) JFM / El Nino – Phase 7

  • Conditions most closely associated with anomalously negative precipitation

    • 1) OND / El Nino – Phase 4

    • 2) OND / La Nina – Phase 7

    • 3) JFM / La Nina – Phase 3

    • 4) JFM / La Nina – Phase 7

    • 5) JFM / Neutral – Phase 8


Key composites 5 wettest ca composites2
Key Composites: 5 LN, & N CombinedWettest CA Composites


Key composites 5 wettest ca composites3
Key Composites: 5 LN, & N CombinedWettest CA Composites

  • Characteristics: Anomalous low positioned to the west and north of CA, with anomalous high to south, sets up anomalously onshore flow between low and high.

  • Generally an east/west or southwest/northeast tilt to the anomalous low, helping to draw in warm, moist air from the tropical regions


Key composites 5 driest ca composites2
Key Composites: 5 LN, & N CombinedDriest CA Composites


Key composites 5 driest ca composites3
Key Composites: 5 LN, & N CombinedDriest CA Composites

  • Characteristics: Anomalous high to north and west of CA, with an anomalous low off to south and west, causing offshore flow of dry continental air over CA


Comparison of driest and wettest composites2

Composite of 5 LN, & N CombinedWettest Periods in CA

Composite of 5 Driest Periods in CA

Comparison of Driest and Wettest Composites

  • Composites based on MJO and wet (dry) conditions in CA-DSW show clear EN (LN) patterns in tropical and northeast Pacific.

  • Onshore/offshore flow anomalies a major contributor to western CONUS precip anomalies.


Comparison of driest and wettest composites3
Comparison of Driest and Wettest Composites LN, & N Combined

Composite of 5 Wettest Periods in CA

Composite of 5 Driest Periods in CA

  • Large scale factors causing CA-DSW precip anomalies lead to opposite precip anomalies in western Canada.


Npna circulation and precipitation schematics1

CA-DSW: Dry Conditions LN, & N Combined

CA-DSW: Wet Conditions

Anomalous Low-level Flow

Anomalous Low-level Flow

L

H

L

H

NPNA Circulation and Precipitation Schematics


Key results2
Key Results LN, & N Combined

  • Favorable (F) and unfavorable (U) conditions during MJO activity for fall-winter:

    • Positive precipitation anomalies in CA-DSW:

      F: Early and late phases of MJO

      F: Presence of neutral conditions in OND

      F: Presence of El Nino during JFM

      F: Anomalous wave train from Asia with low over northeast Pacific

      F: SW-NE tilt to anomalous low-high dipole over northeast Pacific

      U: Middle phases of MJO

      U: Presence of LN

    • Negative precipitation anomalies in CA-DSW:

      F: Middle and late phases of MJO

      F: Presence of La Nina

      F: Anomalous high over northeast Pacific

      F: SW-NE tilt to anomalous high-low dipole over northeast Pacific

      U: Early phases of MJO


Key results3
Key Results LN, & N Combined

  • MJO - NPNA teleconnections are very complex.

    • So far, only rudimentary forecasting rules-of-thumb

  • Complexity may be reduced by use of intraseasonal band-pass filter.

    • However, real-world is unfiltered and is what forecasters must deal with


Individual case dec 04 jan 051

MJO convection LN, & N Combined

MJO subsidence

Individual Case: Dec 04 – Jan 05

Precip Rate Anomaly

  • Moderate MJO; phases 3 & 4; OND into JFM; neutral background regime

  • Similar characteristics to wet pattern with SW-NE oriented low near the CA coastline, and precip dipole over western CONUS

  • Strong onshore flow with origins of flow in tropics;


Individual case dec 1996 jan 19971

MJO convection LN, & N Combined

MJO subsidence

Individual Case: Dec 1996 – Jan 1997

Precip Rate Anomaly

  • Very strong MJO; phase 3-8 (select days); OND into JFM; neutral background regime

  • Similar characteristics to wet pattern with SW-NE oriented low near the CA coastline, and precip dipole over western CONUS

  • Strong onshore flow with origins of flow in tropics


Individual case january 19951

MJO convection LN, & N Combined

MJO subsidence

Individual Case: January 1995

Precip Rate Anomaly

  • Moderate MJO; phases 3-5; JFM; El Nino background regime

  • Slightly different orientation of anomalous low, with onshore flow originating in sub-polar regions

  • Duration of onshore flow appears reason for flooding over much of CA; EN influences evident


Additional findings1
Additional Findings LN, & N Combined

  • Subsidence Phase of the MJO: Has the ability to cause a significant tropical Rossby wave response and thus influence the extratropical wave train pattern

  • MJO Impacts on Southwest Asia (SWA): Phases 2, 3, 6, & 7 of the MJO can have strong effects on weather in SWA through the Rossby wave response to the convective and subsidence components of MJO

  • MJO amplitude and MJO propagation speed: Stronger MJOs appear to propagate more slowly than do weaker MJOs; may indicate effects of greater atmosphere-ocean coupling for strong MJOs

  • MJO amplitude and persistence of NPNA response: Response is more persistent when amplitude is high; may be related to slower propagation of strong MJOs


Summary and conclusion1
Summary and Conclusion LN, & N Combined

  • The relationship between the MJO and NPNA circulation and precipitation anomalies is very complex when looking at non-filtered data, with few, if any, simple rules of thumb to guide forecasters

    • Attempting to base forecasts solely on MJO phase is too simple an approach – other factors are also critical

  • A longer data set appears necessary in order to create more concrete MJO teleconnection rules, especially rules based on ambient background conditions

    • 26 years of data analyzed, but most composites have less than 100 days

  • However, the MJO has the ability to strongly influence the extratropical circulation pattern, and appears to have great potential as a tool for improving extended-range forecasts of the extratropics


Future work1
Future Work LN, & N Combined

  • Investigate precipitation anomalies in western CONUS regions through use of a more refined precipitation data set

  • Investigate properties of background flow that contribute to the development of different wave train formations

  • Investigate time evolution of wet and dry composites, especially with respect to background flow patterns


References1
References LN, & N Combined

  • Bond, N. A., and G. A. Vecchi, 2003: The Influence of the Madden-Julian Oscillation on Precipitation in Oregon and Washington. Wea. Forecasting, 18, 600-613.

  • Jones, C., 2000: Occurrence of Extreme Precipitation Events in California and Relationships with the Madden Julian Oscillation. J. Climate, 13, 3576-3587.

  • Mo, K. C., and R. W. Higgins, 1998: Tropical Convection and Precipitation Regimes in the Western United States. J. Climate, 11, 2404-2423.

  • Wheeler, M. C., and H. H. Hendon, 2004: An All-Season Real-Time Multivariate MJO Index: Development of an Index for Monitoring and Prediction. Mon. Wea. Rev., 132, 1917-1932.

  • NCEP/NCAR Reanalysis Products constructed at NOAA/CDC: http://www.cdc.noaa.gov/Composites/Day/

  • CPC MJO Index charts available at:

    http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_mjo_index/pentad.html

  • RMM1/RMM2 Index charts available at:

    http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phasediag.list.htm

  • Graphics created using NCL software, available at

  • http://www.ncl.ucar.edu/


Acknowledgements1
Acknowledgements LN, & N Combined

  • Co-Advisors: Professor Tom Murphree and Professor Carlyle Wash, NPS, Monterey, CA

  • NCL Assistance: Lt Col Karl Pfeiffer, USAF, NPS, Monterey, CA

  • Important Discussions and Information: Dave Reynolds, NWS, Monterey, CA, and Matthew Wheeler, Australian Bureau of Meteorology


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