Through
an ensemble modeling approach, we were able to show that without anthropogenic effects, the droughts in the southwestern United States would have been less severe,» says co-author Axel Timmermann, Director of the newly founded IBS Center for Climate Physics, within the Institute for Basics Science (IBS), and Distinguished Professor at Pusan National University in South Korea.
Through
an ensemble modelling approach, we were able to show that without anthropogenic effects, the droughts in the southwestern United States would have been less severe,» said Axel Timmermann, who directs a centre for climate physics at Pusan National University in South Korea.
Not exact matches
A large
ensemble of Earth system
model simulations, constrained by geological and historical observations of past climate change, demonstrates our self ‐ adjusting mitigation
approach for a range of climate stabilization targets ranging from 1.5 to 4.5 °C, and generates AMP scenarios up to year 2300 for surface warming, carbon emissions, atmospheric CO2, global mean sea level, and surface ocean acidification.
This new
approach did not specify any of the observed outcomes and left the existing
model projections from the CMIP5
ensemble untouched.
As IPCC, in a search for objectivity in uncertainty assessment, has turned more to describing uncertainty in terms of the characteristics of
ensembles of
model outcomes, the deficiency in such an
approach (its exclusion or limited treatment of systemic, structural uncertainty in
models) has become increasingly apparent to the community (Winsberg 2010; Knutti et al. 2008; Goldstein and Rougier 2009).
Because the
models are not deterministic, multiple simulations are needed to compare with observations, and the number of simulations conducted by
modeling centers are insufficient to create a pdf with a robust mean; hence bounding box
approaches (assessing whether the range of the
ensembles bounds the observations) are arguably a better way to establish empirical adequacy.
This
approach provides a hybrid assessment of the combined influence of anthropogenic climate change [determined from the
ensemble - mean of the CESM - LE or from the multi-
model Coupled
Model Intercomparison Project phase 5 (CMIP5) archive (Taylor et al. 2012)-RSB- and observed NAO variability on climate over the coming decades.
I could understand the
ensemble approach if the
models are simulating relatively orthogonal (and uncoupled) facets of the climate.
The results of this observationally - based estimate are similar to those obtained directly from the CESM
ensemble, attesting to the fidelity of the
model's representation of the NAO and the utility of this
approach.
crandles - In your example the things the plane
models are trying to simulate are somewhat orthogonal, so the
ensemble approach makes some sense.
The
ensemble member
approach is commonly used to approximate a measure of uncertainty in
modeled results.
ly weren't able to re-run
ensembles of these
models with different parameter values, so instead, we just used a simple pattern - scaling
approach to fit them to the data.
In Sect. 2, we describe the
model ensembles and the application of the rank histogram
approach, including a description of the statistical method used to define the reliability of
model ensembles from the rank histogram, and a method for handling uncertainties in the observations.
One
approach is to use an MME, which consists of simulations contributed by different
models of climate research institutes from around the world, often referred to as an «
ensemble of opportunity».
In the present study, simulations of the present - day climate by two kinds of climate
model ensembles, multi-
model ensembles (MMEs) of CMIP3 and single
model ensembles (SMEs) of structurally different climate
models, HadSM3 / CM3, MIROC3.2, and NCAR CAM3.1, are investigated through the rank histogram
approach.
This idea of a «statistically indistinguishable»
ensemble is common in the field of weather forecasting and other
ensemble prediction fields, and under this paradigm the reliability of
model ensembles can be evaluated through the rank histogram
approach (Anderson 1996) whereby the distribution of the observed occurrence of an event in the prediction
ensembles is evaluated.
We also check the validity of the rank histogram
approach by comparing the
model - data difference with the
ensemble spread through calculating the root mean square
model - data difference (RMSE), and the standard deviation of the
ensemble (SD).