Sentences with phrase «of radiative feedbacks»

Rose, B.E.J., L. Rayborn * and N. Feldl, Understanding the Dependence of Radiative Feedbacks and Clouds on the Spatial Structure of Ocean Heat Uptake.

It's not quantitative for several reasons (ocean heat uptake, the dependence of radiative feedbacks on the spatial structure of the SST changes, etc).

Roy Spencer and William Braswell, «On the Diagnosis of Radiative Feedback in the Presence of Unknown Radiative Forcing,» Journal of Geophysical Research, v. 115, August 24, 2010 38.

Spencer, R.W., and Braswell, W. D. (2010) On the diagnosis of radiative feedback in the face of unknown radiative forcing, Journal of Geophysical Research, 114, D16109.

Their method of overcoming this (which is quite an important bias towards high sensitivity, see «Spencer, R. W., and W. D. Braswell (2010), On the diagnosis of radiative feedback in the presence of unknown radiative forcing, J. Geophys.

Spencer cites: Spencer & Braswell, 2010: «On the Diagnosis of Radiative Feedback in the Presence of Unknown Radiative Forcing» JGR, for his latest work.

Not exact matches

Acting as a safety valve of sorts, this response creates a negative radiative feedback that allows more of the accumulating heat to be released into space through the top of the atmosphere.

This was revealed through a key aspect of the simulation called radiative feedback, which accounted for the way X-rays emitted by the black hole affected distant gas.

Continuous measurements was used for the first time to estimate the direct radiative feedback of natural aerosols

(Top left) Global annual mean radiative influences (W m — 2) of LGM climate change agents, generally feedbacks in glacial - interglacial cycles, but also specified in most Atmosphere - Ocean General Circulation Model (AOGCM) simulations for the LGM.

The mechanism for reducing anthropogenic global warming, initiated through radiative forcing of greenhouse gases, is to stop emissions and reduce their concentration in the atmosphere to levels which do not stimulate carbon feedbacks.

Tsushima, Y., A. Abe - Ouchi, and S. Manabe, 2005: Radiative damping of annual variation in global mean surface temperature: Comparison between observed and simulated feedback.

Jerome Fast has lead a team of PNNL scientists that have contributed a gas - phase chemistry mechanism, an sectional aerosol model, cloud chemistry, cloud - aerosol interactions, and radiative feedback processes into the chemistry version of Weather Research and Forecasting (WRF - chem) model.

Peters, M.E., and C.S. Bretherton, 2005: A simplified model of the Walker circulation with an interactive ocean mixed layer and cloud - radiative feedbacks.

The regional climate feedbacks formulation reveals fundamental biases in a widely - used method for diagnosing climate sensitivity, feedbacks and radiative forcing — the regression of the global top - of - atmosphere radiation flux on global surface temperature.

However, in view of the fact that cloud feedbacks are the dominant contribution to uncertainty in climate sensitivity, the fact that the energy balance model used by Schmittner et al can not compute changes in cloud radiative forcing is particularly serious.

I think the actual point that we were making was that the cloud feedback (how clouds change as a function of the temperature, circulation, humidity etc., and how that impacts the radiative balance) is not being calculated here.

Nevertheless, the results described here provide key evidence of the reliability of water vapor feedback predicted by current climate models in response to a global perturbation in the radiative energy balance.»

Abstract:» The sensitivity of global climate with respect to forcing is generally described in terms of the global climate feedback — the global radiative response per degree of global annual mean surface temperature change.

Since OHC uptake efficiency associated with surface warming is low compared with the rate of radiative restoring (increase in energy loss to space as specified by the climate feedback parameter), an important internal contribution must lead to a loss rather than a gain of ocean heat; thus the observation of OHC increase requires a dominant role for external forcing.

He goes so far as to say that the IPCC is biased against «internal radiative forcing,» in favor of treating cloud effects as feedback.

On the possibility of a changing cloud cover «forcing» global warming in recent times (assuming we can just ignore the CO2 physics and current literature on feedbacks, since I don't see a contradiction between an internal radiative forcing and positive feedbacks), one would have to explain a few things, like why the diurnal temperature gradient would decrease with a planet being warmed by decreased albedo... why the stratosphere should cool... why winters should warm faster than summers... essentially the same questions that come with the cosmic ray hypothesis.

Alternatively, more direct observations of that radiative imbalance would be nice, or better theoretical and observational understanding of the water vapor and cloud feedbacks, or more paleoclimate data which can give us constraints on historical feedbacks, but my guess is that ocean heat content measurements would be the best near term bet for improving our understanding of this issue.

In the recently published report of the intergovernmental panel on climate change (IPCC), 6 out of 20 climate models showed a positive and 14 a negative cloud radiative feedback in a doubled CO2 scenario.»

Gavin disputes that the main driver of the sea ice retreat is the albedo flip, but we are seeing not only polar amplification of global warming but positive feedback, which would not be explained simply by radiative forces and ocean currents.

CO2 ppm effects a radiative forcing in W / m ^ 2 and temperature response to forcing in K is mediated by a host of feedbacks and heat capacities.

In Spencer and Braswell (2008), and to an even greater extent in his blog article, Spencer tries to introduce the rather peculiar notion of «internal radiative forcing» as distinct from cloud or water vapor feedback.

Abstract:» The sensitivity of global climate with respect to forcing is generally described in terms of the global climate feedback — the global radiative response per degree of global annual mean surface temperature change.

It is the net overall feedback to increased radiative forcing that is important and we are way way short of understanding how these operate.

so when i'm talking to people out there and they can produce a stupid list of dissenting scientists, i can't explain to them about the radiative proberties of co2 and feedbacks and so on.

Since many of these processes result in non-symmetric time, location and temperature dependant feedbacks (eg water vapor, clouds, CO2 washout, condensation, ice formation, radiative and convective heat transfer etc) then how can a model that uses yearly average values for the forcings accurately reflect the results?

We also know that there must be positive feedbacks in order for Earth to be at its current temperature — you wouldn't get 33 degrees of warming from just the intrinsic radiative properties of the greenhouse gasses.

(57k) When I state that the equilibrium climatic response must balance imposed RF (and feedbacks that occur), I am referring to a global time average RF and global time average response (in terms of radiative and convective fluxes), on a time scale sufficient to characterize the climatic state (including cycles driven by externally - forced cycles (diurnal, annual) and internal variability.

Starting from an old equilbrium, a change in radiative forcing results in a radiative imbalance, which results in energy accumulation or depletion, which causes a temperature response that approahes equilibrium when the remaining imbalance approaches zero — thus the equilibrium climatic response, in the global - time average (for a time period long enough to characterize the climatic state, including externally imposed cycles (day, year) and internal variability), causes an opposite change in radiative fluxes (via Planck function)(plus convective fluxes, etc, where they occur) equal in magnitude to the sum of the (externally) imposed forcing plus any «forcings» caused by non-Planck feedbacks (in particular, climate - dependent changes in optical properties, + etc.).)

The stratosphere will, absent sustained non-radiative perturbations (see 57i), approach radiative equilibrium on a time scale under a year (Holton, «An Introduction to Dynamic Meteorology», 1992, p. 410), so taking stratospheric adjustment to instantaneous stratospheric forcing first and then applying the adjusted tropopause - level forcing to the troposphere + surface and stratospheric feedbacks is similar to the actual order of events in reality.

So there is little evidence of the cloud radiative feedback that may keep the Arctic temperate in future being a major player now.

Obviously, sensitivity to radiative forcing of greenhouse gases (not water vapor, but CO2 and CH4) can't include feedbacks of those same gases — those are defined as forcings in such a sensitivity.

First, for changing just CO2 forcing (or CH4, etc, or for a non-GHE forcing, such as a change in incident solar radiation, volcanic aerosols, etc.), there will be other GHE radiative «forcings» (feedbacks, though in the context of measuring their radiative effect, they can be described as having radiative forcings of x W / m2 per change in surface T), such as water vapor feedback, LW cloud feedback, and also, because GHE depends on the vertical temperature distribution, the lapse rate feedback (this generally refers to the tropospheric lapse rate, though changes in the position of the tropopause and changes in the stratospheric temperature could also be considered lapse - rate feedbacks for forcing at TOA; forcing at the tropopause with stratospheric adjustment takes some of that into account; sensitivity to forcing at the tropopause with stratospheric adjustment will generally be different from sensitivity to forcing without stratospheric adjustment and both will generally be different from forcing at TOA before stratospheric adjustment; forcing at TOA after stratospehric adjustment is identical to forcing at the tropopause after stratospheric adjustment).

It should not be so hard to accept that doubling the concentration of a gas that interacts with earth's radiative output (which is orders of magnitude larger than any other energy loss), over time and with feedbacks included, can change change the surface temperature by about 1 %.

Within a convecting layer, convective fluxes can also be part of the response, but where convection is bounded within a layer, the layer as a whole must respond with radiation to radiative forcings and feedbacks.)

The equilbrium global time average response (on a time scale sufficient to characterize externally - forced cycles (day, year) and internal varibility) to an imposed global time average radiative forcing is a change that balances the externally imposed forcing plus any non-Planck feedbacks (where the Planck response is part of the response to the other feedbacks.

So really it's the gain of the temperature - convection feedback that's at stake, and if it were high enough to fully offset all radiative effects on temperature, there'd be some obvious symptoms — low natural variability and glacial cycles perfectly correlated with insolation perhaps.

IF the rise in temperature is caused by the radiative absorbtion by 390ppm of GHG (I agree), then the proposed increase in convective feedback is spread out over a MILLION ppm of air.

What ARM meant: To unravel the uncertainties in cloud feedbacks it was necessary to obtain simultaneous measurements of a broad range of parameters relative to clouds and their impact on the radiative energy balance.

``... Using radiative kernels (43, 44) and the changes in specific humidity in the CMIP5 4 × CO2 forcing experiments, we calculate an SW water vapor feedback of +0.3 ± 0.1 W m − 2 K − 1.

and seen that even a large part of skeptics agree on many issues and the approximate of the direct radiative forcing of CO2 belongs to those issues (while the feedbacks certainly do not).

The radiative forcing due to CO2 may serve as an amplifier of initial orbital forcing, which is then further amplified by fast atmospheric feedbacks (39) that are also at work for the present - day and future climate.

«Climate Change and Cloud Feedback: The Possible Radiative Effects of Latitudinal Redistribution.»

Once triggered, the radiative effects of H2O are completely overwhelmed by the storms, resulting in a very strong localized negative feedback.

The large spread in cloud radiative feedbacks leads to the conclusion that differences in cloud response are the primary source of inter-model differences in climate sensitivity (see discussion in Section 8.6.3.2.2).