Sentences with phrase «with volcanic aerosols»

I've done it with the ENSO signal once, but I didn't figure out how to do it with the volcanic aerosol signal until just recently, so I'm still working on this one.

Not exact matches

A third key hypothesis involves acidic aerosols released at volcanic sites, such as acid fog, dispersed throughout the atmosphere, and interacting subsequently with the finer components of soil as a source of widespread hydrated iron - sulfate salts.

The models, which factor in natural effects such as solar winds and volcanic eruptions, along with anthropogenic forcings like greenhouse gases and aerosols, match these precipitation variations accurately in trend and reasonably well in magnitude.

Researchers at NASA's Goddard Space Flight Center in Greenbelt, Maryland, are using already available satellite measurements of sulfur dioxide (SO2), a main components of volcanic emissions, along with the more recent ability to map the location and vertical profiles of volcanic aerosols.

Titled «Initiation of Snowball Earth with volcanic sulfur aerosol emissions,» the study posits a hypothesis by two researchers from Harvard University's John A. Paulson School of Engineering and Applied Sciences (SEAS).

There may be reason to strongly suspect that in any sufficiently complicated dynamical system model (such as climate) with stochastic parameters (e.g., exactly when and where a lightning strike starts a major wildfire or a major submarine earthquake perturbs ocean circulation in a region or a major volcanic eruption introduces stratospheric aerosols), it is almost certain that any given run of the model will have periods of significant deviation from the mean of multiple runs.

The causes are however reasonably well identified, a longer period than «usual» of lack of volcanic activity, so a lack of aerosols, combined with solar and CO2, although the latter two factors probably dominated.

The portion associated with short term forcings (solar, unaccounted - for volcanic aerosols, undercounts of Chinese pollution) will depend on their long term evolution — if they stabilise, you'd get a delay.

Positing that there have been any times with zero volcanic aerosols is almost as ludicrous as positing there is no water vapor feedback; neither compares with trying to use them as the basis for a long winded attempt at justification for a wished for «safe» climate sensitivity.

Yet you are also clearly struggling with the idea of volcanic activity replenishing that stock of aerosols.

Again, with arrows: lower volcanic activity — > lower aerosol concentrations — > more sunlight gets in — > more heat

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).

Recently I have been looking at the climate models collected in the CMIP3 archive which have been analysed and assessed in IPCC and it is very interesting to see how the forced changes — i.e. the changes driven the external factors such as greenhouse gases, tropospheric aerosols, solar forcing and stratospheric volcanic aerosols drive the forced response in the models (which you can see by averaging out several simulations of the same model with the same forcing)-- differ from the internal variability, such as associated with variations of the North Atlantic and the ENSO etc, which you can see by looking at individual realisations of a particular model and how it differs from the ensemble mean.

«We found that red - to - green ratios measured in the sunsets of paintings by great masters correlate well with the amount of volcanic aerosols in the atmosphere, regardless of the painters and of the school of painting,» Zerefos said.

Skies polluted by volcanic ash scatter sunlight more, making sunsets show more red; similar results are seen with dust or man - made aerosols.

«We use 1280 years of control simulation, with constant preindustrial forcings including constant specified CO2, and a five - member ensemble of historical simulations from 1850 — 2005 including prescribed historical greenhouse gas concentrations, SO2 and other aerosol - precursor emissions, land use changes, solar irradiance changes, tropospheric and stratospheric ozone changes, and volcanic aerosol (ALL), following the recommended CMIP5 specifications.

We also use five - member ensembles of simulations with greenhouse gas changes only (GHG), volcanic and solar irradiance changes only (NAT), and aerosol changes only (AER) over the period 1850 — 2010.»

Since the last ~ 17 years is the only period with known low volcanic forcing and since aerosol forcing is one of the largest unknowns, that makes the last 17 years the longest useful period of that type.

Two problems with that: warming is not occurring, and they can't determine the effect of the volcanic dust called aerosols.

However, over long time periods, the variation of the global average temperature with CO2 concentration depends on various factors such as the placement of the continents on Earth, the functionality of ocean currents, the past history of the climate, the orientation of the Earth's orbit relative to the Sun, the luminosity of the Sun, the presence of aerosols in the atmosphere, volcanic action, land clearing, biological evolution, etc..

Volcanic aerosols will cool depending on the quantity and duration of their contribution to stratospheric aerosols, with Pinatubo (1991) associated with two to three years of cooling.

Despite differences in volcanic aerosol parameters employed, models computing the aerosol radiative effects interactively yield tropical and global mean lower - stratospheric warmings that are fairly consistent with each other and with observations (Ramachandran et al., 2000; Hansen et al., 2002; Yang and Schlesinger, 2002; Stenchikov et al., 2004; Ramaswamy et al., 2006b); however, there is a considerable range in the responses in the polar stratosphere and troposphere.

In short, radiative forcing from GHGs and volcanic aerosols explains a great deal of the land record with a residual that follows a natural cycle: AMO.

Take a look at Hansen 1993, scaling from radiation changes in last glacial epoch (plain orbital mechanics affecting irradiation), 3 ± 1 °C, Chylek 2007, differences between the Holocene and the last glacial maximum, 1.3 °C to 2.3 °C, and Bender et al 2010, looking at the response from Mount Pinatubo and the volcanic aerosols, with current temperature ranges, 1.7 to 4.1 °C.

If one were to assume that non-volcanic OHC anomalies approximately correlate with ENSO (as the results of Balmaseda et al. seem to confirm), one is left with changes in external forcing which the FR11 method would certainly miss, namely anthropogenic aerosols and recent changes in volcanic aerosols.

We had three major aerosol volcanic eruptions in that period, Agung, El Chinon and Pinatubo doing something with clouds and light availabilty.

The chapter 9 summary also conceded the discrepancy, but attributed it «to a substantial degree» to natural variability, with «possible» contributions from forcing — mentioning aerosols as well as solar and volcanics — and, «in some models», to too strong a response to greenhouse forcing:

There is medium confidence that this difference between models and observations is to a substantial degree caused by unpredictable climate variability, with possible contributions from inadequacies in the solar, volcanic, and aerosol forcings used by the models and, in some models, from too strong a response to increasing greenhouse - gas forcing.

Aerosols from such episodic volcanic events exert a transitory negative RF; however, there is limited knowledge of the RF associated with eruptions prior to Mt. Pinatubo.

If aerosols from volcanic eruption sometimes dim the stratosphere, when they do circulate back out then we are left with dimmer surface albedo.

We know that aerosols trump CO2 both through logic and through the empirical evidence associated with volcanic eruptions.

Third: There was no cooling in the 1920s; in fact that was the start of a multidecadal warming trend that lasted until just after World War II (followed by a brief cooling trend, possibly due to increased aerosols dimming incoming sunlight together with some pretty big volcanic eruptions which did the same thing).

Using CET as supporting evidence, we have shown here that these same 2.5 cycles in the global data are a part of a recurrent oscillation going back at least 350 y, and it is unlikely that they can be attributed to volcanic aerosols, whose eruptions were not periodic nor aligned with the troughs (Fig. 3A).

There have been numerous research papers and reviews published over the past 10 years, including several in prestigious journals such as Nature and Science, that conclude that the observed temperature changes over the past 100 years are consistent with the combined changes in atmospheric aerosols (volcanic and anthropogenic), land surface changes, variations in solar irradiance and increases in greenhouse gases.

Radiative forcing time series for the natural forcings (solar, volcanic aerosol) are reasonably well known for the past 25 years (although these forcings continue to be debated), with estimates further back in time having increasingly large uncertainties.

That may well include increased or decreased natural dust (for natural or unnatural reasons), and definately volcanic aerosols (note that this factor was increasingly negative in the 40's to 60's) along with man - made aerosols.

Forster et al. (2007) described four mechanisms by which volcanic forcing influences climate: RF due to aerosol — radiation interaction; differential (vertical or horizontal) heating, producing gradients and changes in circulation; interactions with other modes of circulation, such as El Niño - Southern Oscillation (ENSO); and ozone depletion with its effects on stratospheric heating, which depends on anthropogenic chlorine (stratospheric ozone would increase with a volcanic eruption under low - chlorine conditions).

The basis for this statement is comparison of global climate model simulations with observations for the 20th century, for simulations conducted with natural forcing (solar and volcanic) only and natural plus anthropogenic forcing (greenhouse gases and anthropogenic aerosol).

What does seem to be known is that aerosols fall out of the lower atmosphere (as high as they can be launched with conventional bombs) in days, and persist for less than 2 years when launched into the stratosphere by a major volcanic event like Pinatubo which was equivalent to several H bombs.

Four distinct mechanisms have been invoked with regards to the climate response to volcanic aerosol RF.

Figure 4 shows that changes in several external forcings over the ETCW could be important, such as: a greenhouse gas increase, a small change in solar irradiance, and a reduction in stratospheric aerosols associated with reduced volcanic activity.

The total forcing Q is known through observation to take large drops after volcanic eruptions (from the volcanic aerosols reflecting away the sunlight), with similarly large and fast recoveries.

DePreSys (18) takes into account the observed state of the atmosphere and ocean in order to predict internal variability, together with plausible changes in anthropogenic sources of greenhouse gases and aerosol concentrations (19) and projected changes in solar irradiance and volcanic aerosol (20).