«They involve relatively complex processes and rather constrained sets
of uncertain parameters.»
Not exact matches
«The precise
parameters of the U.K.'s future relationship with the European Union remained highly
uncertain and it seemed likely that asset prices would remain sensitive to perceived developments in the outlook in the months ahead,» the Bank
of England said through the minutes
of the policy committee's meeting.
Although estimates
of this
parameter, based on observations, are very
uncertain, observers generally quote values in the range from 50 to 90 kilometres per second per megaparsec.
The nature
of the tuning also matters: allowing an
uncertain parameter to vary within reasonable bounds and picking the value that gives the best result, is quite different to inserting completely artificial fluxes to correct for biases.
In that survey, it was almost universal that groups tuned for radiation balance at the top
of the atmosphere (usually by adjusting
uncertain cloud
parameters), but there is a split on pratices like using flux corrections (2 / 3rds
of groups disagreed with that).
Eight test cases were constructed and an ensemble
of USHCN analyses were undertaken, varying
uncertain parameters within the algorithm.
Assessing the role
of uncertain precipitation estimates on the robustness
of hydrological model
parameters under highly variable climate conditions.
Typically there is also a single
parameter controlling the rate
of ocean heat uptake, and forcings (from aerosols in particular, this forcing being quite
uncertain) can
of course readily be adjusted.
It is pretty clear that the model for the process governing Sun spot occurrence is the correct one, even if the parameterization is somewhat statistically
uncertain (and even if some
parameters may be randomly or deterministically varying slowly and / or narrowly in time, as well as the precise frequency distribution
of noise energy, though we really only care about that within a narrow band around the resonances).
Indefinite time scales, natural contributions, many adjustable
parameters,
uncertain response to CO2, averaging
of model outputs, non linearity, chaos and the absence
of successful predictions are all reasons to continue to challenge the present models.
Even when updated by fnite Bayesian learning,
uncertain structural
parameters induce a critical ìtail fatteningî
of posterior - predictive distributions, Such fattened tails have strong implications for situations, like climate change, where a catastrophe is theoretically possible because prior knowledge can not place su cents ciently narrow bounds on overall damages.
Because
of the sensitivity
of the shelter level temperature to
parameters and forcing, especially to
uncertain turbulence parameterization in the SNBL, there should be caution about the use
of minimum temperatures as a diagnostic global warming metric in either observations or models.»
Climate IAMs have «hundreds
of input
parameters, each
of which is highly
uncertain in the long run.»
The EnKF is used to assimilate seasonally averaged observational data into the model, thereby generating an ensemble
of runs with a range
of values for the
uncertain parameters, all reasonably compatible with present - day climatology.
However, climates at high latitude are known to be very sensitive to orbital
parameters affecting insolation (Ravelo et al., 2004), and thus proxy estimates with
uncertain age constraints are not directly comparable to model simulations that typically span hundreds
of years.
For example, Stainforth et al. (2005) have shown that many different combinations
of uncertain model sub-grid scale
parameters can lead to good simulations
of global mean surface temperature, but do not lead to a robust result for the model's climate sensitivity.
In UKCIP08, for example, we are handling this problem by combining results from two different types
of ensemble data: One is a systematic sampling
of the uncertainties in a single model, obtained by changing
uncertain parameters that control the climate system; the other is a multi-model ensemble obtained by pooling results from alternative models developed at different international centers.
Even the most fundamental quantitative
parameter of all, the forcing factor relating the increase in mean temperature to a doubling
of CO2, lies somewhere between 1 and 3 degrees, and is thus
uncertain to within a factor
of 3.
Lastly, while there are wide variations in plausible scenarios around the future
of the homeownership rate, they require many
uncertain parameters, which makes it difficult to say with much confidence how the homeownership rate will evolve.