A todo esto, entre los
pronósticos de junio de los expertos, han acertado la extensión media mensual según el NSIDC (4.9 millones de km2) tres de los 16 participantes, que daremos por "ganadores". Habrá que releer la argumentación de sus pronósticos:
Arbetter et al. (North American Ice Service/National Ice Center); 4.9 Million Square Kilometers; Statistical/Heuristic
Despite the reasonably large current extent (14.665 million km2) and compact concentration (12.461 million km2) in late April, the projected extent for mid-September is another near-record low (4.852 million km2). The most compact ice is on the Canadian side of the Arctic Ocean, while the pack on the Siberian side is diffuse (1-3/10th concentration).
Gauthier et al. (Canadian Ice Service); 4.9 Million Square Kilometers; Heuristic/Empirical
The Canadian Ice Service (CIS) is predicting the minimum arctic sea ice extent to be less than 5 million square kilometres in September 2010. A value equal to or slightly greater than the average extent observed in September 2008 is expected. This value (4.7 ≤ x <5.0 million square kilometres) will make the arctic sea ice extent in September 2010 the third lowest in the 1979-2010 record. Although the extent of the Arctic Ocean multi-year ice pack at the beginning of May 2010 was greater than the extents witnessed at the beginning of May in 2007, 2008, and 2009 (the result of new areas of second and third year ice), multi-year ice floe concentrations within the pack in 2010 were less than those of previous years—the result of extensive fracturing and the repeated formation of large open water leads within the multi-year ice pack during the winter months of 2010.
Wu and Grumbine (National Oceanographic and Atmospheric Administration, NOAA); 4.9 Million Square Kilometers; Statistical and Modeling
Note: this value is an average of two estimates:
* Model Prediction for September 2010 average ice extent: 5.13 million km2, standard deviation 0.25 million km2
* Statistical: 4.78 million km2, 0.45 million km2 sdev
Two approaches are used, statistical and modeling. The statistical approach continues from Grumbine in 2009. The approach is to consider the growth of open water as proceeding according to a population growth (positive feedback of more open water leading to more open water) with a constraint. The model prediction is based on the coupled Air-Sea-Ice Climate Forecast System (CFS) at NCEP. These predictions are based on the CFS Reanalysis and Reforecast model. An ensemble of 24 forecasts were made to provide estimates of mean and model variability. At this lead time, the model shows a consistent high bias in its forecasts of September ice extent. We have, therefore, attempted bias correction.