Sentences with phrase «indirect aerosol forcing»

I started by regressing on all nine series: there are separate series for direct and indirect aerosol forcing.

[14] In particular, use of RF (or, a fortiori, iRF) for indirect aerosol forcing [giving RFaci] is inappropriate.

When Aldrin adds a fixed cloud lifetime effect of -0.25 W / m ^ 2 forcing on top of his variable parameter direct and (1st) indirect aerosol forcing, the mode of the sensitivity PDF increases from 1.6 to 1.8.

That results in the data maximum likelihoods for direct and indirect aerosol forcing being in the upper tails of the priors, biasing the aerosol forcing estimation to more negative values (and hence biasing ECS estimation to a higher value).

The (posterior) mean estimated by the study was circa -0.3 W / m ^ 2 for indirect aerosol forcing and -0.4 W / m ^ 2 for direct.

The probabilistic analyses of DAI reported in this section draw substantially on (subjective) Bayesian probabilities to describe key uncertainties in the climate system, such as climate sensitivity, the rate of oceanic heat uptake, current radiative forcing, and indirect aerosol forcing.

The top three curves show total anthropogenic forcing assuming central values for all components other than indirect aerosol forcing.

The effect on radiative forcing of assuming different values for indirect aerosol forcing.

The bottom three curves show the history of indirect aerosol forcing used in the top three curves.

The effect on global - mean temperature of assuming a large value for indirect aerosol forcing (viz. − 1.8 W / m2 in 2005, the 95th percentile value according to the IPCC AR4) compared with temperatures for the central indirect forcing estimate (− 0.7 W / m2) and a less extreme maximum of − 1.1 W / m2.

To do so we assume that all anthropogenic forcings except indirect aerosol forcing are given their central values, and consider a range of values for the reference (2005) indirect forcing amount.

When Aldrin adds a fixed cloud lifetime effect of -0.25 W / m ^ 2 forcing on top of his variable parameter direct and (1st) indirect aerosol forcing, the mode of the sensitivity PDF increases from 1.6 to 1.8.

Table 1 and Figure 15 (2nd panel) of the Supplementary Material show that a wide prior extending from -0.3 to -1.8 W / m ^ 2 (corresponding to the AR4 estimated range) was used for indirect aerosol forcing.

The (posterior) mean estimated by the study was circa -0.3 W / m ^ 2 for indirect aerosol forcing and -0.4 W / m ^ 2 for direct.

In fact one point you made 2 posts ago — that the aerosol and indirect aerosol forcings seem fudged to make the curve fit — I think that is a strong possibility.

Not exact matches

The AR5 gives a value for 1850 aerosol forcing (relative to 1750)(Annex II, Table AII.1.2) of -0.178 W / m ² for direct + indirect (radiation + clouds).

Steven J. Ghan • Contributing Author, Working Group I, «Aerosols, Their Direct and Indirect Effects,» IPCC Third Assessment Report (2001) • Contributing Author, Working Group I, «Radiative Forcing of Climate Change,» IPCC Third Assessment Report (2001).

When extra forcing of -0.25 or -0.5 W / m ^ 2 is added his prior mean total aerosol forcing is very substantially more negative than -0.7 W / m ^ 2 (the posterior mean without the extra indirect forcing).

But, given the revised aerosol forcing estimates given in the AR5 WG1 SOD, there is no justification at all for increasing the prior for aerosol indirect forcing prior by adding either -0.25 or -0.5 W / m ^ 2.

Most studies consider a range of anthropogenic forcing factors, including greenhouse gases and sulphate aerosol forcing, sometimes directly including the indirect forcing effect, such as Knutti et al. (2002, 2003), and sometimes indirectly accounting for the indirect effect by using a wide range of direct forcing (e.g., Andronova and Schlesinger, 2001; Forest et al., 2002, 2006).

We don't know the total forcing that well, primarily because we don't know the aerosol (direct or indirect) effects.

It is rather surprising that adding cloud lifetime effect forcing makes any difference, insofar as Aldrin is estimating indirect and direct aerosol forcings as part of his Bayesian procedure.

The total of -0.7 W / m ^ 2 is the same as the best observational (satellite) total aerosol adjusted forcing estimate given in the leaked Second Order Draft of AR5 WG1, which includes cloud lifetime (2nd indirect) and other effects.

As noted above, two independent analyses [64], [72] yield a total (direct plus indirect) aerosol forcing in the past decade of about − 1.5 W / m2, half the magnitude of the GHG forcing and opposite in sign.

The indirect aerosol effect on clouds is non-linear [1], [76] such that it has been suggested that even the modest aerosol amounts added by pre-industrial humans to an otherwise pristine atmosphere may have caused a significant climate forcing [59].

Earth's measured energy imbalance has been used to infer the climate forcing by aerosols, with two independent analyses yielding a forcing in the past decade of about − 1.5 W / m2 [64], [72], including the direct aerosol forcing and indirect effects via induced cloud changes.

There are indeed uncertainties in aerosol forcing (not just the indirect effects) and, especially in the earlier part of the 20th Century, uncertainties in solar trends and impacts.

While there is good data over the last century, there were many different changes to planet's radiation balance (greenhouse gases, aerosols, solar forcing, volcanoes, land use changes etc.), some of which are difficult to quantify (for instance the indirect aerosol effects) and whose history is not well known.

Based on NASA's CMIP5 forcing model, year 2012 has a greenhouse forcing of 3.54 Wm2, ozone has 0.45 Wm2, atmospheric aerosols have -0.89 Wm2 combined direct / indirect, and land use has -0.19 Wm2, all based on iRF.

Inclusion of calculated indirect effects from aerosols for instance or if unknown / un-included forcings are significant this may lead to more model - obs disagreements.

The top panel shows the direct effects of the individual components, while the second panel attributes various indirect factors (associated with atmospheric chemistry, aerosol cloud interactions and albedo effects) and includes a model estimate of the «efficacy» of the forcing that depends on its spatial distribution.

The expected global average direct + indirect forcings for aerosols vary between -1.0 (Japan) and -1.4 W / m2 (Hansen, IPCC) for the past centuries and -0.9 to -1.3 W / m2 for future (2050, 2100) emissions (Canada).

It predicts an annual global mean first indirect forcing of -1.5 W m - 2 from an anthropogenic sulfate burden of 0.59 Tg S. Most of the cooling occurs in norhtern hemisphere (NH), where most anthropogenic sources of aerosol are located.

Some of these forcings are well known and understood (such as the well - mixed greenhouse gases, or recent volcanic effects), while others have an uncertain magnitude (solar), and / or uncertain distributions in space and time (aerosols, tropospheric ozone etc.), or uncertain physics (land use change, aerosol indirect effects etc.).

While this does not invalidate the aerosol indirect effect at all, it underlines the limitations in using satellite observed changes in droplet size to compute the aerosol indirect forcing.

Assuming a Northern Hemisphere to Southern Hemisphere ratio of 2:1 for the aerosol indirect effect, this would imply a globally - averaged forcing of -1.5 Wm - 2.

Indirect aerosol effect - Aerosols may lead to an indirect radiative forcing of the climate system through acting as cloud condensation nuclei or modifying the optical properties and lifetime ofIndirect aerosol effect - Aerosols may lead to an indirect radiative forcing of the climate system through acting as cloud condensation nuclei or modifying the optical properties and lifetime ofindirect radiative forcing of the climate system through acting as cloud condensation nuclei or modifying the optical properties and lifetime of clouds.

Given our very short and spotty data on the relative abundance (or importance) of the majority of these aerosols, and given our very poor understanding of the direct, indirect, and side effects of the majority of these aerosols, any numbers that anyone generates about their abundance, importance, or total radiative forcing are going to be a SWAG.

Hansen,» Aerosol climate forcing today is inferred to be -1.6 ± 0.3 W / m2, implying substantial aerosol indirect climate forcing via cloud cAerosol climate forcing today is inferred to be -1.6 ± 0.3 W / m2, implying substantial aerosol indirect climate forcing via cloud caerosol indirect climate forcing via cloud changes.

Note, OA stands for Other Anthropogenic factors, primarilly the aerosol direct and indirect effects and Land Use Change, all of which are negative forcings.

Additionally, changes in anthropogenic sulfate aerosol forcing have been proposed as the dominant cause of the AMV and the historical multidecadal variations in Atlantic tropical storm frequency, based on some model simulations including aerosol indirect effects.

adding two variables that were requested in the ACCMIP Word document but not explained in the spreadsheet: the longwave and the shortwave cloud radiative forcing with reference (fixed) composition, for diagnosis of aerosol indirect effect.

As I have pointed out before, it seems to me that a fair evaluation of climate models is impossible when there remains vast uncertainty in aerosol forcing (direct and indirect), and substantial uncertainty in cloud effects.

Note that most models do not use other forcings described in Chapter 6 such as soot, the indirect effect of sulphate aerosols, or land - use changes.

«Here, it is sufficient to note that many of the 20CEN / A1B simulations neglect negative forcings arising from stratospheric ozone depletion, volcanic dust, and indirect aerosol effects on clouds... It is likely that omission of these negative forcings contributes to the positive bias in the model average TLT trends in Figure 6F.

But including aerosol indirect effects on radiative forcing has made it easier to generate a greater variety of 20th century simulations without affecting other aspects of the climate simulation as strongly.

Earth's measured energy imbalance has been used to infer the climate forcing by aerosols, with two independent analyses yielding a forcing in the past decade of about − 1.5 W / m2 [64], [72], including the direct aerosol forcing and indirect effects via induced cloud changes.

In the period 1910 to 1945 the reflective aerosol and indirect aerosol effects combined look to almost cancel out the forcing from GHG's.

Climate scientist Kevin Trenberth also notes that the change in the estimated aerosol forcing is mainly associated with indirect aerosol effects, but half of GCMs don't include these indirect effects, and those that do actually tend to simulate less warming.

I think it could produce useful predictions but major uncertainties need to be addressed; aerosols, BC, maybe GCRs, indirect solar forcings, etc..