1 / 47

The Impacts of Global Scale Climate Variations on Southwest Asia

The Impacts of Global Scale Climate Variations on Southwest Asia. Capt Damon Vorhees, USAF Masters of Science Thesis Research Naval Postgraduate School Advisors: Prof. Tom Murphree Lt Col Karl Pfeiffer, USAF 22 March 2006. Thesis Brief, Capt Damon Vorhees, USAF, March 2006

mufutau-allen
Download Presentation

The Impacts of Global Scale Climate Variations on Southwest Asia

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Impacts of Global ScaleClimate Variations on Southwest Asia Capt Damon Vorhees, USAF Masters of Science Thesis Research Naval Postgraduate School Advisors: Prof. Tom Murphree Lt Col Karl Pfeiffer, USAF 22 March 2006 Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 1

  2. Overview • Motivation • Background • Goals of This Study • Hypothesis • Data and Methods • Geography and Climate of SWA • Results • ENLN • IOZM • MJO • NAO • Summary of Results • Further Study Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 2

  3. Motivation • Long-term mean (LTM) conditions in SWA are well-understood and well-documented • We can significantly improve climo support to warfighters by going beyond our current LTM focus • Example of major climo event missed by LTMs: heavy SWA precip in 2004-05 winter • No DoD studies on SWA conducted using reanalysis data from NCEP/NCAR • Focus on geopolitical situation in SWA—extreme drought from 1998-2001 and ongoing Global War on Terrorism • Bottom line (from topic list): Where anomalous environmental conditions can be identified as either transient or persistent consequences of teleconnection patterns, METOC staffs and operational planners can exploit that information for the complete spectrum of operational impacts. Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 3

  4. Background • Over the last 10-20 years researchers have demonstrated increased predictability on the intraseasonal to interannual timescales based on known climate variations • El Nino-La Nina (ENLN) • Madden Julian Oscillation (MJO) • Indian Ocean Zonal Mode / Indian Ocean Dipole (IOZM / IOD) • North Atlantic Oscillation (NAO) • NCEP/NCAR reanalysis datasets have played a crucial role in improved: • climate analyses • climate forecasts • Climate forecasting (leads of about 1 week to 1 year) is being done within the civilian community (e.g., CPC, CDC, IRI). • Little research has been done with respect to forecasting at these timescales in SWA — either in the civilian or military community Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 4

  5. ENLN and SWA • Recent research by Mariotti and Zeng (2002) and Mariotti et al. (2005) indicates: • During autumn, SWA tends to receive above normal precip during EN years, and below normal precip during LN periods • The opposite anomalies are observed during winter • Mariotti and Zeng (2002) and Mariotti et al. (2005) also noted that: • During periods of above normal precip there was anomalous onshore moisture flux from the Arabian Sea region into SWA • During periods of below normal precip there was offshore moisture flux. • No mechanisms proposed to explain the observed anomalies. They were primarily focused on Europe and the Med • Focusing solely on Iran, Nazemosadat and Cordery (2000) and Nazemosadat and Ghasemi (2004) found the same general trends Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 5

  6. convective region subsidence region MJO Background • MJO is a propagating intraseasonal (1-2 month period) oscillation • Most intense in the tropical Indian and West Pacific Ocean • Propagates eastward at approximately 8 m/s • Consists of a convective and subsidence component • MJO is somewhat predictable at medium and long ranges Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 6 Figure from MR3610 Course Notes

  7. MJO and SWA • Barlow et al. (2005) found: • When the convective phase of the MJO was in the eastern Indian Ocean (IO) (roughly 80-100E), there was below normal precipitation in SWA. • When the subsidence phase was in the same region, there was above normal precip in SWA — 23% increase relative to the daily mean. • They found an upper level tropical Rossby-Kelvin response to increased or decreased convection in the eastern IO. • Upper level response stretches westward to SWA, creating circulation anomalies over the region. • Low level anomalous circulation is opposite to that in the upper levels. Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 7

  8. Tropical Rossby-Kelvin WaveResponse to Tropical Heating anticyclone ridge trough anticyclone cyclone trough ridge cyclone • Based on early work by Matsuno (1966) and Gill (1980) • From Sardeshmukh and Hoskins (1988): “the response in the tropics is typically baroclinic, with flow anomalies at upper levels having an opposite sense to those at lower levels.” The structure in the mid-latitudes is typically equivalent barotropic. Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 8 Figure from MR3610 Course Notes

  9. Goals of This Study • Review existing climate variations and examine their impacts on SWA — bring DoD up to speed on current research • Develop a foundation for climate forecasting for SWA. To accomplish this we focused on two specific topics: • How do climate variations alter atmospheric circulations in and near SWA? • What are the mechanisms by which these anomalous circulations contribute to fall and winter precipitation anomalies in SWA? • Explore the impacts of climate variations on military operations and interests. One of our questions: To what degree can the impacts of climate anomalies could be mitigated by identifying the climate variations ahead of time and accounting for their associated anomalies in SWA during planning? Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 9

  10. Hypothesis • ENLN, MJO, IOZM, and NAO are climate variations known to produce large scale circulation anomalies throughout the troposphere. Given the location of SWA with respect to large scale circulation patterns and moisture sources, we expect these climate variations to produce anomalous precipitation and temperature patterns by changing: • long wave patterns over SWA • moisture transport patterns into SWA from: (a) Indian Ocean and north Africa; (b) central Asia; and (c) N Atlantic - Mediterranean • ENLN, MJO, IOZM, and NAO occur at intraseasonal and interannual timescales and are relatively predictable once initiated. Thus, these climate variations could be useful in improving intraseasonal-interannual forecasts for SWA. Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 10

  11. Data and Methods • Primary dataset: NCEP/NCAR reanalysis • Monthly and daily data — 2.5 degree resolution • Focused on 1960-2005 • GPH/Winds/Specific Humidity/Precipitation Rate/2m Temperature • Thesis investigates ENLN, IOZM, MJO, and NAO • Used Multivariate ENSO Index (MEI) to classify years as either EN/LN/neutral • Picked 15 autumns (Oct-Dec) and 15 winters (Jan-Mar) to composite for each phase of ENLN Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 11

  12. Data and Methods (cont’d) • To measure IOZM, we used the weekly Dipole Mode Index (DMI) from Kevin Vranes at Columbia University — available for 1981-1996 • Composited all days during autumn when IOD > 1.0 • Too few days during autumn when IOD < -1.0 • Real-time Multivariate MJO (RMM) Index from Wheeler and Hendon (2004) was used to identify periods of convection and subsidence in the eastern IO during both autumn and winter. • If MJO persisted in either convective or subsidence phase for seven or more days, these days were included in composite • Calculated seasonal average of NAO index from CPC for each autumn and winter from 1960-2005 • Picked 8 autumns and 10 winters to composite for each phase of NAO — seasonal average of NAO > 1.0 or < -1.0 Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 12

  13. Precipitation in SWA • Majority of precipitation falls between October and March and comes from extratropical cyclones that transit the region • Rainfall is sparse during the remainder of the year in most places — these areas rely on winter rain/snowfall to sustain them throughout the year. • Orography plays a major role in precipitation distribution Annual Precip (mm) Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu Figures from AFCCC (left), IRI (right) 13

  14. Rossby-Kelvin (R-K) anticyclone at 200 hPa is response to • seasonal convection/heating over maritime continent • STJ is part of R-K response • SWA lies under R-K response • Expect SWA to be affected by variations in tropical convection • via variations in R-K response Autumn LTM GPH-Winds at 200 hPa STJ Northern component of Rossby-Kelvin response at 200 hPa Deep convection and heating region Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 14

  15. Rossby-Kelvin (R-K) cyclone at 850 hPa is response to • seasonal convection/heating over maritime continent • Northeasterly trades are part of R-K response • SWA lies under R-K response • Expect SWA to be affected by variations in tropical convection • via variations in R-K response Autumn LTM GPH-Winds at 850 hPa Northern component of Rossby-Kelvin response at 850 hPa Deep convection and heating region Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 15

  16. Warm moist air lies to south and east of SWA • Moisture closely linked to SST • Expect SWA T and precip to be affected by climate variations • that alter tropical surface T (e.g., SST) and low level winds Autumn LTM Temperature and Specific Humidity at Surface (2 m) Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 16

  17. Lower SSTs and decreased convection Autumn El Nino GPH-Wind Anomaliesat 200 hPa Northern component of Rossby-Kelvin response at 200 hPa • Anomalous cyclone over southern Asia is Rossby-Kelvin • response to below normal convection over maritime continent • Note anomalous UL convergence over maritime continent • and northwesterlies over northern IO Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 17

  18. Lower SSTs and decreased convection • Anomalous anticyclone over southern Asia is Rossby-Kelvin response to below normal • convection over maritime continent • Note anomalous LL divergence over maritime continent and southeasterlies over NW IO • Note anomalous onshore southerly flow into and over SWA  more days than normal • with warm, moist onshore flow • This represents anomalous weakening of northeasterly monsoon conditions Autumn El Nino GPH-Wind Anomaliesat 850 hPa Northern component of Rossby-Kelvin response at 850 hPa Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 18

  19. Autumn El Nino Wind & Specific Humidity Anomalies at 850 hPa • R-K response leads to LL southerly anomalies that produce • anomalously warm, moist transports into SWA (and E Africa) • from tropical IO and maritime continent region Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 19

  20. Southerly wind anomaly leads to anomalous moist air advection • from Arabian Sea and NW IO into SWA • Northerly wind anomalies over the Caucuses and Caspian Sea • bring drier air south Autumn El Nino Moisture Advection Anomalies at 850 hPa Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 20

  21. Autumn El Nino Precipitation Rate &Surface Temperature Anomalies • Net result of EN anomalies is general trend during autumn for SWA to be • wetter than normal • Despite northerly wind anomaly over NW Iran and Iraq, there is an • increase in precip as northerly winds run into high terrain in this region • Temperature anomalies better reflection of the wind anomalies Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 21

  22. R-K response leads to NE-erly anomalies that transport dry air • into SWA (and E Africa) from Asia • During LN periods, there is an offshore anomaly in the low • level winds over SWA. • This represents a strengthening of the offshore monsoon • Drier, continental air from the interior of Asia brought into SWA Autumn La Nina Wind and Specific Humidity Anomalies at 850hPa Higher SSTs and increased convection Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 22

  23. Autumn La Nina Precipitation Rate & Surface Temperature Anomalies • Net result of LN anomalies is general trend during autumn for • SWA to be drier and cooler than normal • Southerly wind anomalies lead to slightly warmer conditions • over the Caucuses and the Caspian Sea Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 23

  24. Winter ENLN Anomalies • SWA anomalies tend to be opposite to those observed during the autumn • EN — SWA is drier than normal • LN — SWA is wetter than normal • Precip and temp patterns more complicated than in autumn • This reversal of anomalies could be due to: • Center of activity for ENLN shifting south and east during winter • Westerlies stronger and further south over SWA during winter Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 24

  25. Winter El Nino Precipitation Rate & Surface Temperature Anomalies • Net result of EN anomalies during winter is general trend for • SWA to be drier and cooler than normal • Note generally weaker precip and temp anomalies than in autumn Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 25

  26. Winter La Nina Precipitation Rate & Surface Temp Anomalies • Net result of LN anomalies during winter is general trend • for SWA to be somewhat wetter and cooler than normal Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 26

  27. IOZM Basics Negative IOZM • Cool (warm) SST in the western (eastern) Indian Ocean • Reduced (enhanced) convection over the western (eastern) Indian Ocean Positive IOZM • Warm (cool) SST in the western (eastern) Indian Ocean • Enhanced (reduced) convection over the western (eastern) Indian Ocean cf. Saji et al (1999) Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 27 Figures from: http://www.jamstec.go.jp/frsgc/research/d1/iod/IOD1.html

  28. Autumn Positive IOZM GPH-Wind Anomalies at 200 hPa • Strong Rossby-Kelvin response to decrease in SST/convection • over the eastern IO • Similar patterns to autumn EN case, but anomalies have • strengthened Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 28

  29. Autumn Positive IOZM Wind &Specific Humidity Anomalies at 850 hPa • Strong R-K response leads to southerly anomalies in low levels • that transport warm, moist air into SWA (and E Africa) from • maritime continent and tropical IO Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 29

  30. During strong positive IOZM periods in the autumn, SWA is • generally much wetter and warmer than usual Autumn Positive IOZMPrecip Rate & Surface Temperature Anomalies Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 30

  31. MJO Convective Component in E. IO GPH-Wind Anomalies at 200 hPa • Increase in convection in the eastern IO leads to a prominent • anomalous Rossby-Kelvin response over the maritime continent, IO, • and SWA • Opposite pattern is observed when subsidence component of the • MJO is in the eastern IO Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 31

  32. Note offshore anomalies over and near SWA, similar to • analogous situation for LN in fall MJO Convective Component in E. IO Wind & Spec Hum Anomalies at 850 hPa Convection Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 32

  33. MJO Convective Component in E. IO Precip Rate and Surface Temp Anomalies • Due to circulation anomalies shown in prior slide, SWA tends • to be drier and cooler than normal. • Result of cool, dry continental air advected from Asia Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 33

  34. Note onshore anomalies over and near SWA, similar to • analogous situation for EN in fall MJO Subsidence Component in E. IOWind & Spec Hum Anomalies at 850 hPa Subsidence Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 34

  35. Due to circulation anomalies shown in prior slide, SWA tends to be • warmer and wetter than average • Result of weakened offshore winds  more days with onshore flow • from Arabian Sea MJO Subsidence Component in E. IO Precip Rate and Surface Temp Anomalies Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 35

  36. NAO and SWA • Previous research suggests there is a positive correlation between the NAO and SWA precip during the autumn, and a negative correlation during winter • Research has focused primarily on Med, not SWA • Because the NAO is an extratropical phenomena, there is no associated tropical Rossby-Kelvin response • Our results corroborated previous research and point to moisture transport as an explanation for precip anomalies NAO Negative Phase NAO Positive Phase Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 36 Figure from: resourcescommittee.house.gov/ archives/109/testimony/2005/terrencejoyce.pdf -

  37. Strong anticyclonic anomalies over Europe and S central Asia • Extratropical circulation anomalies have equivalent barotropic • structure  upper and lower level anomalies are similar • Opposite anomalies during winter negative NAO conditions (e.g., • strong troughing and cyclonic flow over Europe- Med) Winter Positive NAO GPH-Wind Anomalies at 200 hPa Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 37

  38. Winter Positive NAO Wind & Specific Humidity Anomalies at 850-hPa • Northerly wind anomalies in the low levels lead to dry, cool air • advection over SWA Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 38

  39. Winter Positive NAO Precip Rate & Surface Temp Anomalies • Net result of winter positive NAO anomalies: SWA tends to be • drier and cooler than normal • For negative NAO case, anomalies are nearly the opposite Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 39

  40. Results Summary • Identified major climate variations that affect SWA --- ENLN, IOZM, MJO, and NAO. • Identified mechanisms by which these climate variations alter SWA circulation and precip patterns in fall-winter Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 40

  41. Mechanisms for Above NormalPrecip in SWA Above Normal Precip L L Below Normal Convection H H Gulf of Mexico – Midwest U.S. analogy • For SWA: Low level anomaly pattern during periods of above normal precip. Pattern occurs during specific seasons and phases of EN/LN, IOZM, MJO, and/or NAO. Example: much of 2004-05 winter • Mechanisms involve teleconnections from tropics and midlatitudes to SWA. • ENLN, IOZM, MJO, and NAO are predictable at leads of one week to six months  SWA precip may be predictable on these time scales. • Next step: develop forecasting system based on these climate variations. Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 41

  42. Mechanisms for Below Normal Precip in SWA H Below Normal Precip L Above Normal Convection • Low level anomaly pattern during periods of below normal precip in SWA. Pattern occurs during specific seasons and phases of EN/LN, IOZM, MJO, and/or NAO. • Mechanisms involve teleconnections from tropics and midlatitudes to SWA. • ENLN, IOZM, MJO, and NAO are predictable at leads of one week to six months  SWA precip may be predictable on these time scales. • Next step: develop forecasting system based on these climate variations. Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 42

  43. Winds, Moist Adv Flooding in Afghanistan and Pakistan, 1-14 February 2005 • Strong, persistent subsidence phase of the MJO over the E. IO • Hypothesize that this played a major role in the heavy rain/snowfall and widespread flooding throughout Pakistan and Afghanistan Precip Fig Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 43

  44. Prototype Operational Product Climo Impacts Forecasts for Operational Planning Impact anomalies: red = worse than normal; white = no change; green = better than normal Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 44 Operational thresholds from AFWA/TN-98/002 Rev 13Jun03

  45. Results Summary • Identified major climate variations that affect SWA --- ENLN, IOZM, MJO, and NAO. • Identified mechanisms by which these climate variations alter SWA circulation and precip patterns in fall-winter • Identified operational impacts and developed prototype products • Cloud cover, ceilings  takeoff/landing, weapon/sensor selection, ISR • Snow cover and snow melt  trafficability and flooding potential • Temperature  impacts on troops & equipment • Long-term forecasting in SWA: look for impacts from tropics Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 45

  46. Suggestion For Future Work • Investigate intraseasonal-interannual prediction during spring and summer and different combinations of months • Explore how the climate variations interact with each other • How to further apply results to military operations? • Work with AFCCC on projects such as Seasonal Prediction Working Group • Guidance and products for use by planners on headquarters staffs • Tailoring existing AFCCC products—OCDS/SOCS/narratives/climograms • Climate briefs for use by AFOG Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 46

  47. Contact Information Capt Damon Vorhees, USAF dcvorhee@nps.edu Prof. Tom Murphree murphree@nps.edu Lt Col Karl Pfeiffer, USAF kdpfeiff@nps.edu Thesis Brief, Capt Damon Vorhees, USAF, March 2006 Naval Postgraduate School, murphree@nps.edu 47

More Related