An investigation of cloud/radiation interactions using three‐dimensional nephanalysis and earth radiation budget data bases

Koenig, George G.; Liou, Kuo‐Nan; Griffin, Michael K.

doi:10.1029/jd092id05p05540

Cited by 6 publications

(1 citation statement)

References 17 publications

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“…The calculations include the effects of tropospheric clouds, since they reduce the potential for both solar forcing (decreased initial net flux) and infrared forcing (decreased temperature difference between aerosol layer and emitting surface below). Our calculations assume 55% cloud cover and distinguish between low-, mid-, and high-level clouds, based on three dimensional nephanalysis climatological data [Koenig et al, 1987]. The Pinatubo aerosols, as 75% sulfuric acid solution spheres, are placed in the lower stratosphere, using our measurements for optical depth and effective radius (see Table 1).…”

Section: An Investigation Of the Climatic Impact Of The Pinatubosupporting

confidence: 87%

Pinatubo and pre‐Pinatubo optical‐depth spectra: Mauna Loa measurements, comparisons, inferred particle size distributions, radiative effects, and relationship to lidar data

Russell¹,

Livingston²,

Dutton³

et al. 1993

J. Geophys. Res.

220

162

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The Ames airborne tracking sunphotometer was operated at the National Oceanic and Atmospheric Administration (NOAA) Mauna Loa Observatory (MLO) in 1991 and 1992 along with the NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) automated tracking sunphotometer and lidar. June 1991 measurements provided calibrations, optical‐depth spectra, and intercomparisons under relatively clean conditions; later measurements provided spectra and comparisons for the Pinatubo cloud plus calibration checks. June 1991 results are similar to previous MLO springtime measurements, with midvisible particle optical depth τp(λ = 0.526μm) at the near‐background level of 0.012 ± 0.006 and no significant wavelength dependence in the measured range (λ = 0.38 to 1.06μm). The arrival of the Pinatubo cloud in July 1991 increased midvisible particle optical depth by more than an order of magnitude and changed the spectral shape of τp(λ) to an approximate power law with an exponent of about −1.4. By early September 1991, the spectrum was broadly peaked near 0.5 μm, and by July 1992, it was peaked near 0.8 μm. Our optical‐depth spectra include corrections for diffuse light which increase postvolcanic midvisible τp values by 1 to 3% (i.e., 0.0015 to 0.0023). NOAA‐ and Ames Research Center (ARC)‐measured spectra are in good agreement. Columnar size distributions inverted from the spectra show that the initial (July 1991) post‐Pinatubo cloud was relatively rich in small particles (r<0.25μm), which were progressively depleted in the August‐September 1991 and July 1992 periods. Conversely, both of the later periods had more of the optically efficient medium‐sized particles (0.25

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Section: An Investigation Of the Climatic Impact Of The Pinatubosupporting

confidence: 87%

Pinatubo and pre‐Pinatubo optical‐depth spectra: Mauna Loa measurements, comparisons, inferred particle size distributions, radiative effects, and relationship to lidar data

Russell¹,

Livingston²,

Dutton³

et al. 1993

J. Geophys. Res.

220

162

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Development of a two‐dimensional global tropospheric model: Model chemistry

Hough¹

1991

J. Geophys. Res.

177

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A latitudinally averaged two-dimensional model has been used to study the distributions, budgets, and trends of trace gases in the atmosphere from pole to pole and from the surface to 24 km. The chemical mechanism used contains 56 chemical species, including 12 hydrocarbons and 125 chemical and photochemical reactions, as well as wet removal processes and dry deposition. Apart from the stratospheric sources of ozone and nitrogen oxides the model chemistry is driven completely by the time-dependent photolytic processes and the emission of 17 chemical species distributed according to 10 different source categories. Each source category is parameterized as a function of latitude and time of the year. The model results are generally in good agreement with observations, and the model reproduces the observed temporal and spatial variation in the mixing ratios of methane, carbon monoxide, hydrocarbons, and ozone. The global average concentration of the hydroxyl radical in the troposphere is 8.3 x 105 molecules cm -3, in agreement with recent calculations based on budgets and trends for CH3CCI3. Model budgets for NOx, CO, CH 4, H 2 and 0 3 are presented. These show that although the stratospheric source and dry deposition terms for ozone almost balance, the global annual turnover of ozone below 24 km, excluding the O3/NO/NO 2 null cycle, is four times greater than the stratospheric source strength. These budgets also suggest that the observed increase in the mixing ratio of methane may be due not only to an increasing source strength but also to a downward perturbation in the abundance of the hydroxyl radical. 1.Recent work has highlighted the widespread concern with the ways in which man is altering the chemical composition of the global atmosphere [e.g., Rowland and Isaksen, 1988; Isaksen, !988a]. One such area of concern addresses the changes in the composition of the troposphere. These include ttie increasing concentrations of methane [e.g., Rasmussen and Khalil, 1984; Blake and Rowland, 1986; Khalil and Rasmussen, 1987; Ehhalt, 1988], carbon monoxide [e.g., Khalil and Rasmussen, 1988a; Cicerone, 1988], and nitrogen oxides, together with their combined effects on the concentration of ozone and the oxidizing capacity of the troposphere [e.g., Logan, 1985; Feister and Warmbt, 1987; Isaksen and Hov, 1987; Volz and Kley, 1988; Isaksen, 1988b; Hough and Derwent, 1990]. Such changes have implications for biological productivity and human health [Guderian .et al., 1984; Tillon, 1989] as well as contributing to the global warming of the lower atmosphere [e.g., Ramanathan et al., 1985; Bolle et al., 1986; Dickinson and Cicerone, 1986; Ramanathan, 1988; Schneider, 1989]. Much of this work is based on observations made at various locations over a number of years, although models have also been used to examine the chemical processes and changes in atmospheric composition for periods of up to 50 years [Isaksen and Hov, 1987]. A number of different models have been used to study the chemistry of global troposphere and the way in w...

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The potential effects of volcanic aerosols on cirrus cloud microphysics

Jensen

Toon

1992

Geophysical Research Letters

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The potential impact of volcanic aerosols on nucleation of ice crystals in upper tropospheric cirrus clouds is examined from a microphysical perspective. The sulfuric acid aerosols which form in the stratosphere are presumably transported into the troposphere by sedimentation and tropopause folding. The tropospheric volcanic aerosol size distribution is estimated from 10 μm lidar backscatter measurements [Post, 1986] and in situ measurements [Pueschel et al., 1992b], Microphysical simulations suggest that at temperatures below about −50°C the concentration of ice crystals which nucleate may be as much as a factor of 5 larger when volcanic aerosols are present. Our simulations suggest that the presence of volcanic aerosols may increases the net radiative forcing (surface warming) of certain types of cirrus near the tropopause by as much as 8 W/m2. Further observations are required to determine whether these effects actually occur, and their global impact.

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An investigation of cloud/radiation interactions using three‐dimensional nephanalysis and earth radiation budget data bases

Cited by 6 publications

References 17 publications

Pinatubo and pre‐Pinatubo optical‐depth spectra: Mauna Loa measurements, comparisons, inferred particle size distributions, radiative effects, and relationship to lidar data

Pinatubo and pre‐Pinatubo optical‐depth spectra: Mauna Loa measurements, comparisons, inferred particle size distributions, radiative effects, and relationship to lidar data

Development of a two‐dimensional global tropospheric model: Model chemistry

The potential effects of volcanic aerosols on cirrus cloud microphysics

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