heat waves gregorio gomez robert sauermann ben lynton

Download HEAT WAVES Gregorio Gomez Robert Sauermann Ben Lynton

Post on 18-Dec-2015

212 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Slide 1
  • HEAT WAVES Gregorio Gomez Robert Sauermann Ben Lynton
  • Slide 2
  • Introduction: What is a heat wave? 2010 Russian Heat Wave 1.Dole et al. (2011): Natural Variability & Omega Blocking 2.Rahmstorf & Coumou (2011): Warming & Frequency 3.Otto et al. (2012): Reconciling 1 & 2 4.Samenow article (2012): Public Perception Debate: Has global warming had an effect on heat waves? http://www.youtube.com/watch?v=hl9WYhYJjqQ Presentation Outline
  • Slide 3
  • Introduction
  • Slide 4
  • 1858, Londons Great Stink 1936, North America Great Depression, drought, dust storms Record temperatures in 12 states, clearing 120 o F 5,000 US and 1,100 Canadian deaths 1995, Chicago 106 o F = average Arizona temperatures 700 deaths in 5 days, infrastructure break down 2003, Western Europe Hottest summer since 1500 A.D. 40,000 deaths + forest fires, glacier floods, crop destroyed Historical Heat Waves History Channel: http://www.history.com/news/history-lists/heat-waves-throughout-history
  • Slide 5
  • 55,000 deaths 25% annual crop production decrease 15 billion USD loss to the Russian economy http://www.youtube.com/watch?v=eCb0pNY5jeE http://www.youtube.com/watch?v=eCb0pNY5jeE 2010 Russian Heat Wave Average climatological seasonal cycle Above average temperature Below average temperatures *National Climatic Data Center: Global Summary of the Day slide 5: note that this graph (and many of the other graphs) are actually temperature anomalies, which the authors do not say in their caption. Recommend replacing their y- axis with one that correctly describes the data Temperature Anomalies (C) Off of average temperature 11/1/09-10/31/10
  • Slide 6
  • The World Meteorological Organization considers a climatic event a heat wave if the local maximum daily temperature exceeds the historical average by 5C for 5 consecutive days. Heat Wave/Dome High pressure in mid/ upper atmosphere (5km) diverts jet stream stifles circulation traps heat on surface Magnified by sun angle, clear skies, and drought (latent heat) What is a Heat Wave? slide 6: remember that you'll want to be able to explain the heat dome, so make sure you all understand it!
  • Slide 7
  • Understanding Statistics: Mean and Variability An increase in the mean raised heat wave frequency Increases in the variability raise hot and cold event frequencies Changes in mean or variability affect heat wave frequency differently slide 7: 'comparison' is showing a change in shape (there's a change in mean and I believe a change in the skew) -- would label correctly, or not include.
  • Slide 8
  • 1. Dole et al. (2011) Randall Dole Fellow of the American Meteorological Society Division Director for the CIRES and IPCC member
  • Slide 9
  • Motivation Cause of 2010 Russian Heat Wave: What were the primary causes for 2010 Western Russian heat wave? Predictability of Russian 2010 Heat Wave: Based on natural and human forcings and observed regional climate trends, could the heat wave have been predicted? slide 9: generally recommend not presenting the conclusions first, rather present motivation and methods, and we'll talk through the conclusions by looking at figures. Folks won't necessarily understand the conclusions bullet points until we've talked about the paper
  • Slide 10
  • Methodology: Data & Models Data Observations Western Russian mean July temperatures Extreme temperature event frequency/variability Datasets NOAA, GHCN, NASA, GISTEMP Model Experiments 1.Simulations to observe trends in heat wave frequency IPCC CMIP3 model 2.Evaluate potential effects of July 2010 boundary conditions AM2.1, MAECHAM5 3.Future global warming effects on heat waves IPCC CMIP3 model slide 10: 'data experiments' doesn't make a lot of sense -- we'd typically say 'data analysis', and you're actually just presenting the datasets they are using. What is the purpose of your underlines? While helpful for highlighting things, they seem to highlight words that are not all in the same category (i.e. frequency/variability vs boundary conditions)
  • Slide 11
  • Western Russia Mean July Temperatures since 1880 No significant temperature change in Western Russia from 1880-2009 Mean regional July temp trend unlikely to have caused 2010 heat wave Western Russia July temp change = -0.1C / 130yrs =.0008 C/yr = July Mean T 2009 July Mean T 1880 (C/130yrs) Western Europe Large temp change (Recall 2003 heat wave)
  • Slide 12
  • Dole finds no shift in the mean
  • Slide 13
  • Western Russia Shows No Increase In Temperature Variability (+) anomalies (-) anomalies No observable trends in Western Russia temperature extremes Temperature variability trend unlikely to have caused 2010 heat wave Mean Temp 1880-2009 2010 slide 14: recommend 'western russia does not show an increase in temperature variability' or similar for title
  • Slide 14
  • Dole finds no change in variance
  • Slide 15
  • Statistical Summary: neither mean nor variability explain 2010 heat wave no statistically significant long-term change is detected in either the mean or variability of Western Russia July temperatures No significant difference in Western Russia temp mean over last 65 years than previous 65 years (t-test) No significant difference in Western Russia temp variability over last 65years than previous 65years (F-Test) 1880-19441945-20091880-19441945-2009
  • Slide 16
  • Omega Blocking Pattern Omega Blocking is a common cause of heat waves Pressure: Low-High-Low High pressure over large latitude Disturbs Jet Stream Difficult for air flow to move from west to east over high pressure hump traps heat Region under Block dry weather, light wind troughs Rain and clouds
  • Slide 17
  • Typical Western Russia Heat Wave Conditions Top 10 Heat Waves exhibit classic omega blocking pattern Top 10 Composite Height of pressure bar anomalies off of 5000m (in 10s of meters) Temp anomalies off of local average surface temperature (C)
  • Slide 18
  • Comparing 2010 with Top 10 2010 Heat Wave Consistent with Top 10 Composite 2010 Heat Wave exhibits classic omega blocking 2010 Heat WaveTop 10 Composite Height of pressure bar anomalies off of 5000m (in 10s of meters) Temp anomalies off of local average surface temperature in (C) Height of pressure bar anomalies off of 5000m (in 10s of meters) Temp anomalies off of local average surface temperature (C)
  • Slide 19
  • Moreover, the Blocking Pattern was not Predictable July 2010 climate conditions GDFL AM2.1 and MAECHAM5 natural and human forcings e.g. SSTs, arctic sea ice 50-member ensemble Inconsistent with blocking Single Model Simulation Qualitatively similar to observations Reflect internal atmospheric variability rather than systematic response to boundary conditions Boundary Conditions could not predict 2010 Blocking Pattern Height of pressure bar anomalies off of 5000m (in 10s of meters) Temperature anomalies off of local average surface temp in (C) Height of pressure bar anomalies off of 5000m (in 10s of meters) Temperature anomalies off of local average surface temp in (C) Boundary Conditions ForcingGDFL AM2.1~ ~ MAECHAM5 NOAA CFS slide 20: would make title more specific, as we're specifically testing if the predictability can come from boundary conditions.
  • Slide 20
  • Not mean shift, Not increased variability, Not Boundary Conditions 2010 Heat Wave not predictable, and likely due to natural variability
  • Slide 21
  • Models predict global increase in the probability of future heat waves Probability of Future Heat Waves on Earth % of 22 CMIP3 models that simulate 10% probability of heat wave occurrence CMIP3 models show increase in heat wave frequency, with uncertain timing due to sensitivity in greenhouse gas concentration predictions
  • Slide 22
  • Conclusions Cause of 2010 Russian Heat Wave: Internal atmospheric variability created an omega blocking period which caused the heat wave. Predictability of 2010 Russian Heat Wave: The 2010 Western Russian heat wave could not have been predicted as there have not been observed changes in mean temperatures or extreme temperature variability, and boundary conditions could not have predicted the omega blocking event. slide 9: generally recommend not presenting the conclusions first, rather present motivation and methods, and we'll talk through the conclusions by looking at figures. Folks won't necessarily understand the conclusions bullet points until we've talked about the paper
  • Slide 23
  • 2. Rahmstorf & Coumou (2011) Stefan Rahmstorf: Paper 2 German climate change advisory council member Author of paleo-climate chapter in 4 th IPCC report Dim Coumou: Paper 2 Potsdam Institute of Climate Impact Research member
  • Slide 24
  • Motivation Heat Wave Frequency : How do warming trends influence the expected number of record breaking and threshold breaking heat waves? Cause of Moscow Heat Wave: What is the probability that local warming trends caused the 2010 Moscow Heat Wave?
  • Slide 25
  • Methodology Data: - NASA Goddard Institute for Space Studies (GISS) annual global temperature (0.09C variability, + 0.70C / last 100 years) - Moscow Weather Station mean July temperature (1.7C variability, + 1.8C / last 100 years) Simulations / Calculations: 1. Generated Gaussian distributions of stationary climate, linearly increasing climate, a