ENSO (El Nino Southern Oscillation)Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Normal Conditions: West Pacific Warm PoolEl Nino ConditionsSlide 11El Nino forecastingSlide 13Slide 14How to measure sea surface temperatures (old school)How to Measure Sea Surface Temperatures from Satellites?Slide 17how to measure ocean temperature at depth ?Historical variationsHow can you Reconstruct ENSO Cycles ?Slide 21Slide 22Slide 23The Southern Oscillation Index (SOI)Slide 25Slide 26ENSO CyclesSlide 28ENSO(El Nino Southern Oscillation)ENVS 110 10-12-2008http://upload.wikimedia.org/wikipedia/commons/1/18/Wiki_plot_03.pnghttp://www.pmel.noaa.gov/pubs/outstand/kess2580/images/fig01.gifhttp://www.sbg.ac.at/ipk/avstudio/pierofun/atmo/el-scans/el-nino1.jpghttp://www.sbg.ac.at/ipk/avstudio/pierofun/atmo/el-scans/walker.jpghttp://www.sbg.ac.at/ipk/avstudio/pierofun/atmo/el-scans/el-nino2.jpgNormal Conditions: West Pacific Warm PoolEl Nino Conditionshttp://www.sbg.ac.at/ipk/avstudio/pierofun/atmo/el-scans/catch.jpgEl Nino forecasting•Careful monitoring of–Oceanic temperatures (satellites)–Strength of trade windssometimes it works – sometimes it doesn’tHow to measure sea surface temperatures (old school)•automated buoys (get spot measurement, often temperature profile)→ buoy arrays•temperature recorders in the water intakes of big ships→ variable locations, sampling depth might not be constant (loaded vs. empty vessel) but greater geographical coverageHow to Measure Sea Surface Temperatures from Satellites?•infrared radiationproblem: cannot see through clouds, aerosols•electromagnetic radiation at other wavelengths–microwave radiation (can see through clouds and aerosols, but is scattered by raindrops)http://www.sciencemag.org/cgi/content/full/288/5467/847how to measure ocean temperature at depth ?•warm water is less dense → takes up more space (floats on top of colder water)•sea surface rises•50 m of 1C warmer water raises sea surface by approximately 1 cm•after lots of correlations, corrections and other trickery → get temperature distribution with depthHistorical variationsRed: El NinoBlue: La NinaHow can you Reconstruct ENSO Cycles ?•Expressed as:–sea surface temperature anomalies–air temperature, atmospheric pressure anomalies in Pacific–precipitation ?–economic effects ?–climate effects outside equatorial Pacific?Where is atmospheric pressure high, where is it low ?source: http://www.worldatlas.com/webimage/countrys/islands/pacifics/tahiti.htmDarwin TahitiThe Southern Oscillation Index (SOI)expresses difference in barometric pressure between Australia (Darwin) and Thaitiseveral ways to calculatePdiff = MSLPThaiti - MSLPDarwinsustained negative values: El Ninosustained positive values: La Ninadiff di ffdiff(p p )SOI 10*(p )s-=Source: Commonwealth of Australia 2006, Bureau of Meteorology (ABN 92 637 533 532)http://www.bom.gov.au/climate/current/soi2.shtml (accessed 3/13/06)ENSO Cycles•El Nino – La Nina phenomenon is cyclical•Note timescales involved•How rapidly does atmosphere change ?•How rapidly do oceans change ?•Oceans are a good place to look for drivers of short term climate