climate v weather: climate...

10
Climate v Weather: Climate Services Simon Mason [email protected] The Climate-Weather Connection New York, NY, U. S. A., 24 September 2014

Upload: others

Post on 22-May-2020

6 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Climate v Weather: Climate Servicesassets.climatecentral.org/pdfs/ClimateWeek/Mason_Weather_and_climate.pdfClimate v Weather: Climate Services Simon Mason simon@iri.columbia.edu The

Climate v Weather: Climate Services

Simon Mason [email protected]

The Climate-Weather Connection New York, NY, U. S. A., 24 September 2014

Page 2: Climate v Weather: Climate Servicesassets.climatecentral.org/pdfs/ClimateWeek/Mason_Weather_and_climate.pdfClimate v Weather: Climate Services Simon Mason simon@iri.columbia.edu The

2   The  Climate-­‐Weather  Connec2on  

Date:  Friday  24  September  1993  Request:  forecasts  for  Saturday  23  and  30  April  1994  

Climate  Services  

The  academic  The  sleazy  salesman  The  equivocator  The  voice  of  authority  

Page 3: Climate v Weather: Climate Servicesassets.climatecentral.org/pdfs/ClimateWeek/Mason_Weather_and_climate.pdfClimate v Weather: Climate Services Simon Mason simon@iri.columbia.edu The

3   The  Climate-­‐Weather  Connec2on  

Climate  v  Weather  “Climate  is  what  you  expect;  weather  is  what  you  get.”  

Ed  Lorenz  

What  if  you  do  not  know  what  to  expect?  

What  if  you  expect  almost  anything  can  happen?  The  Bri2sh,  he  thought,  must  be  gluSons  for  sa2re:  even  the  weather  forecast  seemed  to  be  some  kind  of  spoof,  predic2ng  every  possible  combina2on  of  weather  for  the  next  twenty-­‐four  hours  without  actually  commiTng  itself  to  anything  specific.  

 David  John  Lodge,    Changing  Places  

Page 4: Climate v Weather: Climate Servicesassets.climatecentral.org/pdfs/ClimateWeek/Mason_Weather_and_climate.pdfClimate v Weather: Climate Services Simon Mason simon@iri.columbia.edu The

4   The  Climate-­‐Weather  Connec2on  

Spot  the  Ball  Compe33on  Where  is  the  ball  now?  

Where  will  it  be  in  20  seconds?  Who  will  win  the  match?  

What  is  the  current  weather?  

What  will  it  be  on  Saturday?  Will  winter  be  unusually  wet?  

Page 5: Climate v Weather: Climate Servicesassets.climatecentral.org/pdfs/ClimateWeek/Mason_Weather_and_climate.pdfClimate v Weather: Climate Services Simon Mason simon@iri.columbia.edu The

5   The  Climate-­‐Weather  Connec2on  

Sources  of  Predictability  

•  We  can  make  forecasts  at  different  2mescales  because  there  are  different  reasons  why  the  predic2ons  can  work:  

–  days:  current  weather  – months:  sea-­‐surface  temperatures  –  years:  sub-­‐surface  ocean  temperatures  

–  decades:  atmospheric  composi2on  

Page 6: Climate v Weather: Climate Servicesassets.climatecentral.org/pdfs/ClimateWeek/Mason_Weather_and_climate.pdfClimate v Weather: Climate Services Simon Mason simon@iri.columbia.edu The

6   The  Climate-­‐Weather  Connec2on  

Making  seasonal  forecasts  I:  Models  of  past  sta3s3cs  -­‐  correla3ons  

How  have  past  El  Niño  events  affected  the  weather?  

 Typical  El  Niño  impacts  during  December  -­‐  February  

Page 7: Climate v Weather: Climate Servicesassets.climatecentral.org/pdfs/ClimateWeek/Mason_Weather_and_climate.pdfClimate v Weather: Climate Services Simon Mason simon@iri.columbia.edu The

7   The  Climate-­‐Weather  Connec2on  

Making  seasonal  forecasts  II:  Models  of  the  physics  –  causa3on  

How  might  this  El  Niño  affect  weather?  

Run  lots  of  forecasts,  ideally  using  a  selec2on  of  models.  Do  many  of  the  forecasts  agree?  

Page 8: Climate v Weather: Climate Servicesassets.climatecentral.org/pdfs/ClimateWeek/Mason_Weather_and_climate.pdfClimate v Weather: Climate Services Simon Mason simon@iri.columbia.edu The

8   The  Climate-­‐Weather  Connec2on  

Do  seasonal  forecasts  work?  

How  well  can  we  predict  seasonal  rainfall  totals?  

Page 9: Climate v Weather: Climate Servicesassets.climatecentral.org/pdfs/ClimateWeek/Mason_Weather_and_climate.pdfClimate v Weather: Climate Services Simon Mason simon@iri.columbia.edu The

9   The  Climate-­‐Weather  Connec2on  

Climate  Services  

It  is  in  the  very  nature  of  probability  that  improbable  things  will  happen.  

 Aristotle,  Rhetoric  

Climate  services  involve  specifying  precisely  how  improbable  the  improbable  is,  by:  •  understanding  the  past;  •  analyzing  the  present;  •  predic2ng  the  future.  

Page 10: Climate v Weather: Climate Servicesassets.climatecentral.org/pdfs/ClimateWeek/Mason_Weather_and_climate.pdfClimate v Weather: Climate Services Simon Mason simon@iri.columbia.edu The

Simon J. Mason [email protected]

web: iri.columbia.edu

@climatesociety  

…/climatesociety