What is the meaning of radiative forcing?
Radiative forcing is the change in the net, downward minus upward, radiative flux (expressed in Wm−2) at the tropopause or top of atmosphere due to a change in an external driver of climate change such as a change in the concentration of carbon dioxide or the output of the Sun.
Do aerosols have negative radiative forcing?
Aerosols produced by human activity can exert both positive and negative forcing, but it is believed that their overall effect is negative (positive forcing adds heat and tends to warm the climate; negative forcing removes heat and tends to cool the climate).
What is an example of radiative forcing?
For example, anthropogenic increases in carbon dioxide, methane, and nitrous oxide are estimated to account for 2.3 watts per square metre of positive radiative forcing. …
How are aerosols forcing agents?
BC aerosols (soot), formed by incomplete combustion, cause a positive climate forcing by absorbing sunlight and heating the lower atmosphere (12).
What is radiative forcing for kids?
The concept of radiative forcing is fairly straightforward. Energy is constantly flowing into the atmosphere in the form of sunlight that always shines on half of the Earth’s surface. In short, radiative forcing is a direct measure of the amount that the Earth’s energy budget is out of balance.
What is the radiative forcing value?
Radiative forcing is calculated in watts per square meter, which represents the size of the energy imbalance in the atmosphere. NOAA also translates the total radiative forcing of these measured gases into an index value called the Annual Greenhouse Gas Index (right side of Figure 1).
What is aerosol in chemistry?
An aerosol is a collection of solid particles or liquid droplets dispersed in air. Examples include smoke, fog, sea spray and pollution particles from vehicles.
What is aerosol effect?
Aerosols influence climate in two primary ways: by changing the amount of heat that gets in or out of the atmosphere, or by affecting the way clouds form. Aerosols also influence how clouds form and grow. Water droplets coalesce readily around particles, so a particle-rich atmosphere promotes cloud formation.
What do aerosols The atmospheric particles consist of?
Atmospheric aerosols consist of solid/aqueous particles suspended in the atmosphere and are typically of sizes in the range 0.001 μm–10 μm. Aerosols are generated from a wide range of natural and anthropogenic sources.
What effect does aerosol pollution have on climate?
Aerosols can influence the Earth’s climate in two ways. When the sky is clear (devoid of clouds), aerosols can reflect incoming sunlight back to outer space – the direct effect. This blocks part of the energy that would have reached the surface, thus having a cool effect on the climate.
What is aerosol colloid?
A colloidal system in which the dispersed phase is composed of either solid or liquid particles, and in which the dispersion medium is some gas, usually air. Haze, most smokes, and some fogs and clouds may thus be regarded as aerosols. …
What is effective radiative forcing?
Effective radiative forcing (ERF) is now used to quantify the impact of some forcing agents that involve rapid adjustments of components of the atmosphere and surface that are assumed constant in the RF concept (see Box TS. 2).
Which is the best definition of radiative forcing?
Radiative forcing is called instantaneous if no change in stratospheric temperature is accounted for. Radiative forcing from human activity is commonly defined as the change relative to the reference year 1750 and, unless otherwise noted, refers to a global and annual average value.
How is the radiative forcing of the atmosphere calculated?
Radiative forcing can be expressed as the change in the net vertical irradiance within the atmosphere. Radiative forcing is often calculated after allowing for stratospheric temperatures to readjust to radiative equilibrium, while holding all tropospheric properties fixed at their unperturbed values.
Which is better for radiative forcing ERF or RF?
Conversely, ERF is stronger than RF when fast adjustments enhance the initial forcing. Fast adjustments are particularly important for carbonaceous aerosols, and ERF is then a better predictor of the subsequent long-term change in surface temperature than instantaneous RF.
How does radiative forcing affect the climate system?
The climate system results from the coupling of the atmosphere and the ocean. Because the ocean represents 90% of the heat capacity of the climate system, its response to an instantaneous RF is much slower, on the order of decades, than that of the atmosphere, which adjusts within weeks.
