Multi-model ensembles are shown in red, and
the single model ensembles (perturbed physics and multi-physics ensembles) are shown in blue.
For
the single model ensembles (HadCM3 - AO, HadSM3 - AS, NCAR - A, MIROC5 - AO, MIROC3 - AS, MIROC - MPE - A), p value calculated from the Chi square statistics of the «ends» component (metric of U-shape) are shown.
In addition to the MMEs, some modelling centres have, over the last decade, developed ensembles based on a single model (
single model ensembles, SMEs).
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.
Here we extend the evaluation to those variables and analyse several ensembles; two multi-model ensembles (MMEs) from CMIP3 and four structurally different
single model ensembles (SMEs, sometimes also referred to a perturbed physics or perturbed parameter ensembles) with different ranges of climate sensitivity.
For example in the case of Knutti et al. (2006), a strong relationship between current behaviour and equilibrium climate sensitivity, that is found to hold across
a single model ensemble, has no skill in predicting the climate sensitivity of the members of the CMIP3 ensemble.
Not exact matches
Because climate studies using multi-
model ensembles are generally superior to
single model approaches43, all nine fire weather season lengths for each location were averaged into an
ensemble mean fire weather season length, hereafter referred to as «Fire Weather Season Length» (See Supplementary Methods).
The nostalgic
ensemble drama revolves around the efforts of a neurotic
single - mom (Annette Bening) to parent a naive 15 year - old (Lucas Jade Zumann) in dire need of a role
model.
You can ameliorate this a little by only selecting a
single ensemble member from each
model (e.g. only the red dots, or only blue dots, or randomly selecting from each
ensemble etc.) before doing any analysis.
I did so, and in so doing pointed out a number of problems in the M&N paper (comparing the
ensemble mean of the GCM simulations with a
single realisation from the real world, and ignoring the fact that the
single GCM realisations showed very similar levels of «contamination», misunderstandings of the relationships between
model versions, continued use of a flawed experimental design etc.).
So, small (a degree or so) variations in the global mean don't impact the global sensitivity in either toy
models,
single GCMs or the multi-model
ensemble.
With «mean climate», surely the
model ensemble mean is meant, however the «real data» to base the tuning on by definition is restricted to the
single realisation of Earth's climate (including cloud cover caused by, for instance, multi-decadal oscillations instead of AGW feedback).
The throughput is equivalent to having about 20
single - processor experiments running continuously throughout the time, highlighting the power of the Grid to enable
ensemble studies with Earth system
models.
Careful calibration and judicious combination of
ensembles of forecasts from different
models into a larger
ensemble can give higher skill than that from any
single model.
We find that the year - to - year variability of each feedback process in this
single model is comparable to the
model - to -
model spread in feedback strength of the CMIP3
ensemble.
The «
ensemble» methodology currently in use is to use a
single run from a diversity of
models, graph these and take a mean.
Given that it seems that averages of
ensembles of
model results is the only accepted method of presenting results of chaotic response for practical use, what is gained by attempting to tune a
single «realization».
Several
ensembles of
model responses are used, including two
single -
model large
ensembles.
Additionally, multi-member
ensemble integrations have been run with
single models with the same forcing.
The IPPC opportunistic
ensemble uses a
single solution from 50 odd
models — a solution arbitrarily chosen from 1000's of plausible solutions, graphed together and a fake statistics fabricated over the top.
The use of
single runs of multiple
models is known as an opportunistic
ensemble.
Reading the report shows that this is the output of an
ensemble; not a
single model.
Using a
single model, and perturbing the inputs (either at the start or during simulation) generates a true
ensemble.
Bob, the graph to which you linked presents another example of an
ensemble of climate
model results versus the actual
single realization with the average and range of the
models displayed.
Below is a perturbed physics
ensemble (PPE) from a
single model using a mid-range no mitigation emissions scenario.
Of course, a
single model run from this
ensemble would have no hope of resolving the actual climate due to chaos and the initial conditions problem.
We assess this possibility using an
ensemble of 30 realizations of a single global climate model [the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM1) Large Ensemble experiment («LENS»)-RSB-(29)(Materials and M
ensemble of 30 realizations of a
single global climate
model [the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM1) Large Ensemble experiment («LENS»)-RSB-(29)(Materials and Meth
model [the National Center for Atmospheric Research (NCAR) Community Earth System
Model (CESM1) Large Ensemble experiment («LENS»)-RSB-(29)(Materials and Meth
Model (CESM1) Large
Ensemble experiment («LENS»)-RSB-(29)(Materials and M
Ensemble experiment («LENS»)-RSB-(29)(Materials and Methods).
Where we are instead is opportunistic
ensembles with a range of
single solutions chosen from amongst many feasible and divergent solutions of many different
models.
One might, possibly, generate a
single model that generates an
ensemble of predictions by using uniform deviates (random numbers) to seed «noise» (representing uncertainty) in the inputs.
* An
ensemble is a
single model created for making predictions.
Furthermore, different SMEs may use different strategies for varying parameters values such that, even using the same
single model structure, different
ensembles can show quite different behaviour (Collins et al. 2010, hereafter C10, Yokohata et al. 2010, hereafter Y10).
Nature provides only one
single realization of many possible realizations of temperature variability over time from a whole distribution of possible realizations of a chaotic system for the given climate conditions, whereas the
ensemble mean of
models is an average over many of the possible realizations (117
model simulations in this case).
Note that it uses an
ensemble of
models as contrasted to the
single one used in the study you cited.
Let me explain: If I can say anything for sure, it's that I don't want anyone to take a precooked climate projection — whether a
single model or a multi-
model ensemble, probabilistic or not — and run with it.
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.
In this combined
ensemble, we make no adjustment or allowance for the possibility that some
models may be particularly closely related to one another, for example consecutive generations from a
single modelling centre.
Taking «
ensembles» of
single runs of different
models is worthless until the probability has been established for individual
models.