Presentation on theme: "Demons and Butterflies Beating predictability theory--long-range forecasts of hurricanes by 2025? Richard Anthes VI Congreso Cubano de Meteorologia 30."— Presentation transcript:
Demons and Butterflies Beating predictability theory--long-range forecasts of hurricanes by 2025? Richard Anthes VI Congreso Cubano de Meteorologia 30 November 2011
"Everything proceeds mathematically... if someone could have a sufficient insight into the inner parts of things, and in addition had remembrance and intelligence enough to consider all the circumstances and take them into account, he would be a prophet and see the future in the present as in a mirror." Gottfried Leibniz ( )
The Marquis de Laplace dreamed of an intelligent being (an intellect, later dubbed Laplace's Demon) who knew the positions and velocities of every single atom and used Newton's equations of motion to predict the future of the entire universe. Pierre-Simon Laplace ( ) "We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at any given moment knew all of the forces that animate nature and the mutual positions of the beings that compose it, if this intellect were vast enough to submit the data to analysis, could condense into a single formula the movement of the greatest bodies of the universe and that of the lightest atom; for such an intellect nothing could be uncertain and the future just like the past would be present before its eyes."
Niels Bohr ( ) “Prediction is difficult, especially the future.”
Does the flap of a butterfly’s wing in Brazil set off a tornado in Texas?
“It is doubtful whether a sufficient number of simultaneous initial observations will ever be available … for these scales, although some mesoscale variability may be revealed by satellites. However, nonlinear processes are capable of producing smaller scale information in the forecast than is present in the initial conditions, as long waves interact to produce energy in shorter waves. Furthermore, a realistic treatment of local forcing in the models will allow mesoscale perturbations to develop from initial conditions that are representative of larger scales. Thus we hypothesize that in many synoptic situations, if the local forcing is modeled correctly, the details of the initial perturbations are not particularly important.” Anthes and Warner Monthly Weather Review, August 1978 But scale interactions go both ways!
Examples of medium- and long-range predictions of hurricanes
Hurricane Katrina 2005
Katrina eyewall Cat Aug 2005
11 How much more accurate can hurricane forecasts become? Can they be forecast a month in advance?
Mobile Radar Hurricane Katrina Reflectivity at Landfall 29 Aug Z 4 km WRF, 62 h forecast
Hurricane Katrina 2005 WRF initialized 00 UTC 27 Aug Composite Radar Observations 72 h forecast
Tropical cyclone formation in climate model “September 2000” NCAR’s WRF nested within the Earth System Model starting January 1, 1995 Courtesy Cindy Bruyere and Greg Holland, NCAR
Bo-Wen Shen et al., JGR, 115, D14102, doi: /2009JD013140, day forecast of genesis of Cyclone Nargis (2008) 00GMT 22 Apr-00UTC 29 Apr
10 year statistics Improved high resolution climate models can predict correct frequency of tropical cyclone formation
New Observations can improve predictions Impact of GPS Radio Occultation Data on Tropical Cyclone Genesis Hurricane Ernesto 2006
Radio Occultation-A new way of obtaining accurate and precise profiles of temperature and water vapor in all weather
NCAR 4-Day Ernesto (2006) Forecasts Y.-H. Kuo (NCAR), 2007 Forecast with GPS Forecast without GPS The Actual Storm
Caribbean Ground-based GPS Network Under NSF sponsorship, UCAR has established a ground-based GPS network over the Caribbean to support hurricane research. The color-coded PW estimates from GPS stations in the Caribbean, Gulf of Mexico, and Mexico are overlaid upon a GOES infrared channel 4 (IR4) image on September 1, In this image, hurricane Gustav is approaching the Louisiana coast and tropical storm Hanna is positioned over Grand Turk.
Summary There is evidence that greatly improved forecasts of tropical cyclone tracks and intensity are predictable days in advance Realizing this potential will require – High-resolution global models—probably 4 km or better – Improved physics in models—cloud physics and radiation – Interactive ocean-atmosphere models – Improved initial conditions in atmospheric temperature, water vapor and winds-satellite observations – Improved data assimilation techniques – Faster computers