Methane and hydrogen photochemistry

Methane is an important greenhouse gas that is emitted at the Earth's surface through biological activity in swamps, marshes, rice paddies, lakes and oceans. It is also a product in emissions from agriculture, animal husbandry, mining, landfills and volcanoes. Tropospheric methane concentrations have increased from about 0.70 ppmv pre-1980 to 1.75 ppmv in 1998 (IPCC 2001). About half of the current emissions are of anthropogenic origin. Methane is removed from the atmosphere primarily through...

FL SxeTx6112

Is the direct solar flux, at optical depth rx, normal to the direction of incidence defined by po, the cosine of the solar zenith angle. SqX is the incoming solar spectral flux (erg cm-2 s-1 pm-1) at the Earth's orbit. We note that the phase function is divided by 4n sr so that SiX(p) has units of radiance (erg cm-2 s-1 If we take positive in the downwards direction (increasing optical depth), integrate over the incoming direction and use the Eddington approximation Ix Jx + 3pHx, eqn (3.89), we...

A 2A0S f32477

For values of w < 10, the above series converges after 25 terms with an error less than 1 . For values w > 10 the absorptance can be computed, with a maximum error of 3 , from the expression A 2A0S(0.7523b3 2 + 0.6513b1 2 + 0.3013b-1 2 + 0.1231), (4.78) where b ln w, based on an asymptotic expansion for single lines given in Struve and Elvey (1934). Thus, given the total line strength of the band, k, or band strength, the absorber amount (in units corresponding to the band strength), the...

Info

Projected emissions of carbon dioxide (in units of 1012 tonnes of carbon per year) from fossil-fuel burning for four future emission scenarios, together with estimated emissions from 1850-2000. Crown copyright (UK Met Office Hadley Centre 2005). surface air temperature is accompanied by more frequent extreme high and less frequent extreme low temperatures. There is a decrease in diurnal temperature range in many areas, with nighttime lows increasing more than daytime highs. Results...

Hp Sx395

On using the Eddington approximation we obtain ld2'd 2X) JX(tx) Sx(Tx). (3.103) Substituting for the source function for coherent and isotropic scattering we have l f1 C1 )(Mrx) Bx(rx)), (3.104) which has the form of a steady-state diffusion equation. The above equation can then be solved for the mean radiance J by any standard technique given the boundary conditions at the surface and deep in the atmosphere (see Chapter 6). 3.5.7 The Schuster-Schwarzschild approximation Another approach for...

Shortwave aerosol radiative forcing

The SW aerosol radiative forcing, AF, or more precisely the 'aerosol flux change', is the effect of aerosols on the SW radiation budget at TOA, at the Earth's surface, or within the atmosphere, and it is given by where Fi and Fciear i are the SW radiative fluxes with and without the presence of aerosols, respectively. The index i involves various aerosol forcings defined in terms of the corresponding SW fluxes. The forcings AFTOa, AFatmo, AFsurf, and AFnsurf, represent the effect of aerosols on...

Scat nr2 QScatrN rdr660

The asymmetry factor, g, can be computed from 3 -Zsn-Re awaw+1 + 6 6n+1J (6.61) where a* denotes the complex conjugate of a. We recall that the complex conjugate of a complex number is obtained by replacing i by i, wherever it occurs (implicitly or explicitly), and that the product of a complex number and its conjugate is equal to the square of its magnitude. In Fig. 6.5, we present the variation of Qscat as a function of the size parameter x, for n 1.4. We see that if the scattering particle...

Tables Of Reactions

Table B.1 Photoionization rates and products of atmospheric species, based on the quiet-Sun irradiance in the ultraviolet and visible spectral regions at the top of the atmosphere, for global mean conditions. N2 N(2D) + N+ + e NO NO+ + e O O+ + e N N+ + e N(2D) N+ + e He He+ + e Table B.2 Total photodissociation and photoionization rates of atmospheric species, based on the quiet-Sun irradiance in the ultraviolet and visible spectral regions at the top of the atmosphere, for global mean...

Detection of climate change

The application of the instruments described in the previous sections to studying the processes involved in climate change is fairly obvious. For example, absolute radiometers (ACRIM) measure the output of the Sun broadband radiometers (ERBE, GERB, CERES) monitor the Earth's radiation budget spec-troradiometers (ATSR, MODIS, HIRS, AIRS) measure surface and atmospheric temperatures interferometers (IRIS, ATM OS, TES) measure composition, including greenhouse-gas amounts. Collectively and in...

Sea surface temperature ATSR

The surface temperature of the Earth's oceans is a key climate parameter and also a tracer for warm and cold currents near the surface. Again, rather precise measurements are required, with precisions of < 0.1 K and absolute accuracies of better than 0.5 K. Achieving these fairly demanding values from space is made particularly difficult by the presence of the intervening atmosphere, which has absorption features even in the most transparent spectral windows, plus very variable attenuation...

Atmospheric Physics And Thermodynamics

The atmosphere is a thin shell of gas held gravitationally to the planet and having a thickness of only about 1 of the radius of the solid body. Its original composition, drawn from the solar nebula from which the Sun and the planets formed, will have included many more light elements, especially hydrogen and helium, than are found today, and a complicated evolutionary process, still not fully understood, was involved in the progression from one to the other. Key stages in the evolution of the...

G

6.7.4 Atmospheres with clouds and aerosols The atmosphere can be divided into layers whose individual optical depth is evaluated, according to its properties, from t Tcs Tca Taers Taera Tma + tr, (6.150) where tcs is the cloud-scattering optical depth, Tca is the cloud-absorption optical depth, raers is the aerosol-scattering optical depth, Taera is the aerosol-absorption optical depth, Tma is that for molecular absorption, and tr is that for Rayleigh or molecular scattering. The single...

Bibliography

Tables of bimolecular diffusion coefficients can be found in Vargaftik, and in Mason and Marrero. For more details regarding molecular diffusion in the atmosphere see Banks and Kockarts and for the mathematical theory of diffusion see crank. Atmospheric chemistry texts include Mcewan and phillips Brasseur and Solomon Hobbs Seifeld and pandis Jacob Warnek. For more details on dry surface deposition of molecules see Wesely Wesely and Hicks ganzeveld and Lelieveld for wet and dry deposition see...

Outgoing solar radiation at TOA

We present global distribution results of the outgoing solar radiation at TOA based on a deterministic radiative-transfer model on a mean monthly and 2.5 x 2.5 longitude-latitude resolution, spanning the 14-year period from January 1984 through December 1997. The model uses data from the ISCCP D2-series supplemented by water-vapour and temperature data taken from NCEP NCAR. Model input data were also taken from other global databases, such as TIROS-TOVS, ISLSCP, and GADS. The model computations...

Model input data

In order to calculate the longwave and shortwave radiation budgets using the models described in Chapters 4 and 6, various atmospheric, cloud and surface properties are required. These are listed in Table 8.1. Table 8.1 Input data required to model the Earth's radiation budget. For clouds the data required are for each cloud type (low, middle and high-level). Cloud properties Atmospheric properties Surface properties Cloud amounts Scattering optical depth Absorption optical depth Cloud-top...

Hz LEMsw1119

Where F(z)gW is the net downwelling solar radiation flux at level z, p is the atmospheric density and cp the atmospheric specific heat capacity at constant pressure. In Fig. 11.4 is given the mean global vertical heating rate due to solar radiation absorption for an RC model with mean cloud cover of 0.5, surface albedo of 0.1, with the relative humidity falling with altitude according to (Man-abe and Whetherald 1967) rh vh Ps '02 p ps > 0.02 (11.20) with a surface relative humidity of 0.8,...

Climate Observations By Radiometryspectrometry

Quantitative and spectroscopic measurements of radiation are at the heart of observations made to understand and monitor the climate system (Fig. 10.1). The time-dependent complexity of the system under observation requires that the measurements span the globe, including the vertical dimension. Many of the important processes, for example those involved in ozone depletion, are associated with transient dynamical phenomena and occur on local and diurnal scales, calling for high-resolution...

A ko T [M

B a k (T), c log b, d (1 + c2)-1 and f is a constant that for atmospheric conditions a value of about 0.6 adequately fits the reaction data. There are simpler limiting forms for kf depending whether or not we have low or high pressure. At low pressures If the number density M of the catalytic third body is in units of molecules cm 3 then the units of ko are cm6 cm3 molecules 1 s 1. Usually, ko(300), ka 2006, IUPAC 2006, NIST 2006). while the units of kare (300), n and m are tabulated (JPL In...

Terrestrial radiation transfer in GCMs

11.4.3.1 HadAM3 Scheme The longwave fluxes are calculated by a two-stream approximation, where the spectrum is divided into 8 bands with the following boundaries (in cm-1) 0-400 400-550 550-800 (excluding 590-750) 590-750 800-1200 (excluding 990-1120) 990-1120 1200-1500 and 1500-3000. Gaseous absorption data are again derived from HITRAN and continuum absorption by water vapour is treated using a continuum model. 11.4.3.2 NCAR CAM 3.0 Scheme Longwave absorption by ozone and carbon dioxide is...

The shortwave radiation budget at surface

Figure 8.16 shows the geographical distribution, on a 2.5x2.5 degree resolution, of the 17-year (1984-2000) average downwelling shortwave radiation (DSR) at flg. 8.16. Long-term (1984-2000) average global distribution of downward shortwave radiation (W m 2) at the Earth's surface for the month of January. (Hatzianastas-siou et al. 2005) flg. 8.16. Long-term (1984-2000) average global distribution of downward shortwave radiation (W m 2) at the Earth's surface for the month of January....

F vnAAOs

The above series converges very slowly for y > 10 and for this range of values, wD can be evaluated, with a relative error < 1 , from the truncated series wB(v(y)) v +--- +- , (4.43) where v(y) i lny. The Lorentz equivalent width can be computed from Table 4.1 The coefficients b and c used to evaluate the Ladenburg-Reiche function L(x) for x < 7 using eqn (4-45). (Vardavas 1993) where x(a,y) y (2a Tr) and L(x) is the Ladenburg-Reiche function given by L(x)...

O2 hv O3P O3P750

With atomic oxygen in the ground state. This Herzberg dissociation continuum is weak, extends from 185 nm to 242 nm, and is the main source of O atoms for altitudes below 60 km in the Earth's atmosphere. The absorption cross-section of O2 as a function of wavelength for the Herzberg continuum is given in Fig. 7.4. FlG. 7.3. Idealized potential energy curves for O2 and vibrational-rotational energy levels, with dissociation limits at 7.047 and 5.080 eV. Bound-bound transitions from Xto B3 -...

[1 wl togc2 ts tajj

And the cloud single scattering albedo is with ts and Ta being the scattering and near-infra-red absorption cloud optical depths, respectively, while the asymmetry factor gc is set to a lower value of about 0.8. The cloud absorption is then given by a rc 1 Rirc tirc. 6.5 Aerosol absorption and scattering A major difference between aerosols and greenhouse gases is that aerosols have a much shorter atmospheric lifetime (from 10 4 days for natural, to tens of days for anthropogenic aerosols)...

NSTp i Afi Y666

Thus, we can write 2nNSTP V A2 If we replace k in the expression for the cross-section we have Table 6.2 Coefficients for computing the Rayleigh scattering cross-section. Table 6.2 Coefficients for computing the Rayleigh scattering cross-section. and so the cross-section (cm2 ) can be computed from

B2 a21 e2

E(year) eo - 7.22 x 10V(year - 2000), FlG. 5.15. The celestial sphere and the plane of the ecliptic. FlG. 5.15. The celestial sphere and the plane of the ecliptic. where year is years AD. The arc SD 6 is the solar declination with a maximum value equal to e. The arc YD a is called the right ascension of the Sun, and corresponds to the solar longitude as measured on the celestial equator, measured from the vernal equinox where a 0. Thus, a and 6 define the coordinates of the Sun, point S, on the...