Pingback: Huge efficacy of land use forcing in one GISS - E2 - R simulation: is
an ocean model error involved?
Not exact matches
Based on
model experiments, it has been suggested that
errors resulting from the highly inhomogeneous distribution of
ocean observations in space and time (see Appendix 5.
As stated in the paper, that could reflect an
error in the land temperature reconstruction (too cold), an
error in the
ocean reconstruction (not cold enough) or an
error in the
models land /
ocean ratio.
The sampling
error can be large as results from realistic
ocean model consistently show.
Missing pieces and small
errors can pose difficulties when
models of sub-systems such as the
ocean and the atmosphere are coupled.
[Response: At the dawn of coupled
modelling,
errors that arose in separate developments of
ocean and atmospheric
models lead to significant inconsistencies between the fluxes that each component needed from the other, and the ones they were getting.
While impressive, this may be due to an
error in the forcings combined with compensating
errors in the climate sensitivity (2.7 C for a doubling of CO2 in this
model) or the mixing of heat into the deep
ocean.
The claim to get around the two problems of an geometric increase in
error, and using absolute values of temperature that are not Earth's, is the argument that the
model ensemble got the heat transfer correctly in atmosphere and in the
ocean.
What politician is going to claim a Nature journal article is full of
errors, or that the Russell
ocean model has serious problems which lead to nutty GCM behavior?
So
errors that would be almost undetectable if either the atmosphere or
ocean were
modelled independently can become quite serious when the two are coupled together.
These scaling factors compensate for under - or overestimates of the amplitude of the
model response to forcing that may result from factors such as
errors in the
model's climate sensitivity,
ocean heat uptake efficiency or
errors in the imposed external forcing.
When
ocean models were first coupled to atmospheric
models well over a quarter century ago, systematic
errors in each component near their interface led to sizeable drift and unrealistic climate simulations.
The US CLIVAR Eastern Tropical
Oceans Synthesis (ETOS) Working Group was formed to promote collaboration in the southeast oceanic basins, coordinate a
model assessment of surface flux
errors for the equatorial Atlantic, identify recent
model improvements and common and persistent
model errors, and provide recommendations of cases for community simulation and evaluation using eddy - permitting
ocean models.
We need to be careful focussing upon «trends» — it can lead to serious
errors of context — and this underlies the entire «global warming» thesis which relies upon computer
models with entirely false (i.e. non-natural) notions of an equilibrium starting point and calculations of trend — this conveniently ignores cycles, and it has to because a) there are several non-orbital cycles in motion (8 - 10 yr, 11, 22, 60, 70, 80, 400 and 1000 - 1500) depending on
ocean basic, hemisphere and global view — all interacting via «teleconnection» of those
ocean basins, some clearly timed by solar cycles, some peaking together; b) because the cycles are not exact, you can not tell in any one decade where you are in the longer cycles.
To estimate the uncertainty range (2σ) for mean tropical SST cooling, we consider the
error contributions from (a) large - scale patterns in the
ocean data temperature field, which hamper a direct comparison with a coarse - resolution
model, and (b) the statistical
error for each reconstructed paleo - temperature value.
Over the next 3 years the
Ocean Colour Climate Change Initiative project aims to: Develop and validate algorithms to meet the
Ocean Colour GCOS ECV requirements for consistent, stable,
error - characterized global satellite data products from multi-sensor data archives; Produce and validate, within an R&D context, the most complete and consistent possible time series of multi-sensor global satellite data products for climate research and
modelling; Optimize the impact of MERIS data on climate data records; Generate complete specifications for an operational production system; Strengthen inter-disciplinary cooperation between international Earth observation, climate research and
modelling communities, in pursuit of scientific excellence.
It occurs to me to wonder whether this
error in the GISS - E2 - R
ocean mixing parameterisation, which gave rise to AMOC instability in the Pliocene simulation, might possibly account for the
model's behaviour in LU run 1.
Applications such as the forcing of ice —
ocean models are sensitive to the
errors in reanalyses.
Moreover,
models that strive to incorporate everything, from aerosols to vegetation and volcanoes to
ocean currents, may look convincing, but the
error range associated with each additional factor results in near - total uncertainty.
The figure above compares the average track forecast
errors in the Atlantic
Ocean basin during the past six hurricane seasons for the most reliable computer
models available to the National Hurricane Center during this period.
TOAA is also relevant to reducing the large
errors associated with numerical calculation in climate
models of the transfer of heat and moisture between
ocean and atmosphere.
A recent study by C10 analysed a number of different climate variables in a set of SMEs of HadCM3 (Gordon et al. 2000, atmosphere —
ocean coupled version of HadSM3) from the point of view of global - scale
model errors and climate change forcings and feedbacks, and compared them with variables derived from the CMIP3 MME. Knutti et al. (2006) examined another SME based on the HadSM3
model, and found a strong relationship between the magnitude of the seasonal cycle and climate sensitivity, which was not reproduced in the CMIP3 ensemble.
Xie (June 2008): The Tropical Eastern Pacific Seasonal Cycle: Assessment of
Errors and Mechanisms in IPCC AR4 Coupled
Ocean — Atmosphere General Circulation
Models.
I have just discovered (from Chandler et al 2013) that there was an
error in the
ocean model in the version of GISS - E2 - R used to run the CMIP5 simulations.
Looking at the last decade, it is clear that the observed rate of change of upper
ocean heat content is a little slower than previously (and below linear extrapolations of the pre-2003
model output), and it remains unclear to what extent that is related to a reduction in net radiative forcing growth (due to the solar cycle, or perhaps larger than expected aerosol forcing growth), or internal variability,
model errors, or data processing — arguments have been made for all four, singly and together.
My
error was in assuming that the
model output (which were in units W yr / m2) were scaled for the
ocean area only, when in fact they were scaled for the entire global surface area (see fig. 2 in Hansen et al, 2005).
Although the science of regional climate projections has progressed significantly since last IPCC report, slight displacement in circulation characteristics, systematic
errors in energy / moisture transport, coarse representation of
ocean currents / processes, crude parameterisation of sub-grid - and land surface processes, and overly simplified topography used in present - day climate
models, make accurate and detailed analysis difficult.
In an article from November 5, 2008, Josh Willis states that the world
ocean actually has been warming since 2003 after removing Argo measurement
errors from the data and adjusting the measured temperatures with a computer
model his team developed.