Sentences with phrase «of snow albedo»

By contrast, the inclusion in the Historical simulation forcing values of Snow Albedo BC forcing does not cause a bias since its effects on GMST and heat uptake are reflected in the Historical simulations; likewise for the trivially small (< 0.0025 W / m2) orbital forcing.

Models indicate increased boreal forest reduces the effects of snow albedo and causes regional warming.

If you have six feet of snow or three inches of snow the albedo doesn't change.

Development and validation of a snow albedo algorithm for the MODIS instrument.

Not exact matches

They found that in regions where the amount of snowfall was low and any snow that did settle was sublimating away, enough dust would have accumulated to change the surface albedo sufficiently so that the Earth absorbed sunlight and thawed (Journal of Geophysical Research — Atmospheres, DOI: 10.1029 / 2009jd012007, in press).

The new study by Stefanie Lutz, postdoc at the German Research Centre for Geosciences GFZ and at the University of Leeds, shows a 13 per cent reduction of the albedo over the course of one melting season caused by red - pigmented snow algal blooms.

It has been known for quite some time that red pigmented snow algae blooming on icy surfaces darken the surface which in turn leads to less albedo and a higher uptake of heat.

The research showed that, compared to pure snow and ice, the reflectivity of the glacier (known as the «albedo») can be reduced by up to 80 % in places where coloured microbial populations are extremely dense, leading to the darkening of the glacier surface.

The albedo of newly fallen snow may approach 90 per cent, while the far - more - absorbent surface of seawater has a low albedo.

The albedo of fresh snow is typically between 80 and 90 percent whereas the albedo of the ocean surface is less than 20 percent.

With the albedo of older snow and ice at about 0.6, the open ocean will absorb more heat than the ice capped ocean.

Abstract: Black carbon (BC) from biomass and fossil fuel combustion alters chemical and physical properties of the atmosphere and snow albedo, yet little is known about its emission or deposition histories.

I guess I am surprised that with better understanding of the importance of water vapor feedback, sulfate aerosols, black carbon aerosols, more rapid than expected declines in sea ice and attendant decreases in albedo, effects of the deposition of soot and dust on snow and ice decreasing albedo, and a recognition of the importance of GHGs that were probably not considered 30 years ago, that the sensitivity has changed so little over time.

Due to the positive feedback caused by the high albedo of snow and ice, susceptibility to falling into snowball states might be a generic feature of water - rich planets with the capacity to host life.

Astronomers also measured how much of the Sun's light Makemake's surface reflects, the albedo, to be 0.77 which is similar to dirty snow and greater than Pluto's, but smaller than that of Eris.

Roesch, A., 2006: Evaluation of surface albedo and snow cover in AR4 coupled climate models.

With higher precipitation, portions of this snow may not melt during the summer and so glacial ice can form at lower altitudes and more southerly latitudes, reducing the temperatures over land by increased albedo as noted above.

The importance of orbital variations, of the greenhouse gases CO2, CH4 and N2O, of the albedo of land ice sheets, annual mean snow cover, sea ice area and vegetation, and of the radiative perturbation of mineral dust in the atmosphere are investigated.

Model performance in reproducing the observed seasonal cycle of land snow cover may provide an indirect evaluation of the simulated snow - albedo feedback under climate change.

Specifically, increasing the snow albedo delayed the melting of snow and sea ice in spring, which increased the albedo difference to the experiment in which snow grains were assumed spherical.

On the studies of sensitivity based on the last glacial maximum, what reduction in solar forcing is used based on the increased Albedo of the ice - sheets, snow and desert.

This chemical weathering process is too slow to damp out shorter - term fluctuations, and there are some complexities — glaciation can enhance the mechanical erosion that provides surface area for chemical weathering (some of which may be realized after a time delay — ie when the subsequent warming occurs — dramatically snow in a Snowball Earth scenario, where the frigid conditions essentially shut down all chemical weathering, allowing CO2 to build up to the point where it thaws the equatorial region, at which point runaway albedo feedback drives the Earth into a carbonic acid sauna, which ends via rapid carbonate rock formation), while lower sea level may increase the oxidation of organic C in sediments but also provide more land surface for erosion... etc..

Everytime it snows, they are back to Albedos of 0.8.

26 Paul W asked, «On the studies of sensitivity based on the last glacial maximum, what reduction in solar forcing is used based on the increased Albedo of the ice - sheets, snow and desert.

The infrared findings indicated that UB313 has a reflectivity, or albedo, of about 60 percent, which is similar to Pluto's and suggested that the two bodies have surfaces are made of very similar materials such as frozen methane and nitrogen snow at a temperature of -248 °C or -418 °F.

In addition, since the global surface temperature records are a measure that responds to albedo changes (volcanic aerosols, cloud cover, land use, snow and ice cover) solar output, and differences in partition of various forcings into the oceans / atmosphere / land / cryosphere, teasing out just the effect of CO2 + water vapor over the short term is difficult to impossible.

[1] CO2 absorbs IR, is the main GHG, human emissions are increasing its concentration in the atmosphere, raising temperatures globally; the second GHG, water vapor, exists in equilibrium with water / ice, would precipitate out if not for the CO2, so acts as a feedback; since the oceans cover so much of the planet, water is a large positive feedback; melting snow and ice as the atmosphere warms decreases albedo, another positive feedback, biased toward the poles, which gives larger polar warming than the global average; decreasing the temperature gradient from the equator to the poles is reducing the driving forces for the jetstream; the jetstream's meanders are increasing in amplitude and slowing, just like the lower Missippi River where its driving gradient decreases; the larger slower meanders increase the amplitude and duration of blocking highs, increasing drought and extreme temperatures — and 30,000 + Europeans and 5,000 plus Russians die, and the US corn crop, Russian wheat crop, and Aussie wildland fire protection fails — or extreme rainfall floods the US, France, Pakistan, Thailand (driving up prices for disk drives — hows that for unexpected adverse impacts from AGW?)

I guess I am surprised that with better understanding of the importance of water vapor feedback, sulfate aerosols, black carbon aerosols, more rapid than expected declines in sea ice and attendant decreases in albedo, effects of the deposition of soot and dust on snow and ice decreasing albedo, and a recognition of the importance of GHGs that were probably not considered 30 years ago, that the sensitivity has changed so little over time.

If this is so, let me ask this simple question: what is the more dominant contributor to the earth's albedo, the 60 - 70 % cloud cover or the various areas of snow / ice?

Our analysis of observations from four years of field experiments indicates that seasonal ice undergoes an albedo evolution with seven phases; cold snow, melting snow, pond formation, pond drainage, pond evolution, open water, and freezeup.

This positive climate feedback is greater than expected from the additional forcing alone, due to amplification by reduced surface albedo through melting of continental snow and decreased sea - ice coverage, especially in the wintertime.

Referring to a 2004 paper examining the impact of soot on albedo, Goddard fabricates a conclusion by Hansen: «In 2004, Dr Hansen... explained that most of Arctic warming and melting is due to dirty snow from soot, not CO2.»

black soot has also been found by a recent university of california study to be the direct cause of the albedo warming effect on the otherwise highly reflective and pristine white arctic ice & snow.

This implies a forcing of 3 W / m2 for albedo changes presumably due to additional ice / snow sheets.

In the NH a lot of land surrounding the arctic ocean is subject to the combination of decrease in seasonal snow cover (with climate warming), and decreasing albedo due to vegetation feedbacks.

, (3) changes in surface albedo of snow & ice due to changes in temperature and deposition of mineral and black carbon particulates, and last, but arguably most significantly (4) the intensity of the positive feedback that comes from the inevitable -LRB-?)

The bottom line is that uncertainties in the physics of aerosol effects (warming from black carbon, cooling from sulphates and nitrates, indirect effects on clouds, indirect effects on snow and ice albedo) and in the historical distributions, are really large (as acknowledged above).

Ecological succession and biological evolution would also provide hysteresis (for example, I read of an idea that under some conditions, bogs will tend to take over forests; these bogs will have a higher albedo than forest when snow falls, thus potentially bringing an ice age...).

On the studies of sensitivity based on the last glacial maximum, what reduction in solar forcing is used based on the increased Albedo of the ice - sheets, snow and desert.

For instance, the effect of soot making snow and sea ice darker has a higher efficacy than an equivalent change in CO2 with the same forcing, mainly because there is a more important ice - albedo feedback in the soot case.

Analysis of observed declines in sea ice and snow coverage from 1979 to 2008 suggests that the NH albedo feedback is between 0.3 and 1.1 W m — 2 °C — 1 (Flanner et al., 2011).

Since it reflects the capacity of the climate system to absorb heat, it may be influenced by the planetary albedo (sea - ice and snow) and ice - caps, which respond to temperature changes.

(In the full 4 - dimensional climate, responses can also tend spread horizontally by convection (advection) and temporally by heat capacity, though «fingerprints» of horizontal and temporal variations in RF (externally imposed and feedback — snow and ice albedo, for example) can remain — this spreading is somewhat different as it relies in part on the circulation already present as well as circulation changes)

The details of the physics of different forcings (i.e. ozone effects due to solar, snow albedo and cloud effects due to aerosols etc.) do vary the feedbacks slightly differently though.

Re 9 wili — I know of a paper suggesting, as I recall, that enhanced «backradiation» (downward radiation reaching the surface emitted by the air / clouds) contributed more to Arctic amplification specifically in the cold part of the year (just to be clear, backradiation should generally increase with any warming (aside from greenhouse feedbacks) and more so with a warming due to an increase in the greenhouse effect (including feedbacks like water vapor and, if positive, clouds, though regional changes in water vapor and clouds can go against the global trend); otherwise it was always my understanding that the albedo feedback was key (while sea ice decreases so far have been more a summer phenomenon (when it would be warmer to begin with), the heat capacity of the sea prevents much temperature response, but there is a greater build up of heat from the albedo feedback, and this is released in the cold part of the year when ice forms later or would have formed or would have been thicker; the seasonal effect of reduced winter snow cover decreasing at those latitudes which still recieve sunlight in the winter would not be so delayed).

It melts without having much cooling effect, and in short order there is net warming because of the reduced albedo of wet snow vs. dry snow and bare rock vs. snow cover.

And all those scientists roaming all over the place up there... wonder what's the albedo differential of yellow snow.

Roesch A. (2006), Evaluation of surface albedo and snow cover in AR4 coupled climate models, J. Geophys.

... A new sea - ice albedo parameterization scheme has been developed and implemented in ECHAM5 general circulation model, and includes important components like albedo decay due to snow aging, ice thickness dependency and an explicit treatment of melt pond albedo.

Global average temperature is lower during glacial periods for two primary reasons: 1) there was only about 190 ppm CO2 in the atmosphere, and other major greenhouse gases (CH4 and N2O) were also lower 2) the earth surface was more reflective, due to the presence of lots of ice and snow on land, and lots more sea ice than today (that is, the albedo was higher).