The Effect of Changes in Cloud Amount on the Net Radiation at the Top of the Atmosphere

Ohring, George; Clapp, Philip F.

doi:10.1175/1520-0469(1980)037<0447:teocic>2.0.co;2

Cited by 109 publications

(42 citation statements)

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“…Therefore, cirrus clouds lead to a positive radiative effect (e.g., a greenhouse effect) and their knowledge and evolution are crucial in the understanding of the Earth's radiative budget (Hartmann and Short, 1980;Ohring and Clapp, 1980;Stephens, 2005;Eguchi et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Impact of cirrus clouds heterogeneities on top-of-atmosphere thermal infrared radiation

Fauchez

Cornet

Szczap³

et al. 2014

Atmos. Chem. Phys.

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Abstract. This paper presents a study of the impact of cirrus cloud heterogeneities on the thermal infrared brightness temperatures at the top of the atmosphere (TOA). Realistic 3-D cirri are generated by a cloud generator based on simplified thermodynamic and dynamic equations and on the control of invariant scale properties. The 3-D thermal infrared radiative transfer is simulated with a Monte Carlo model for three typical spectral bands in the infrared atmospheric window. Comparisons of TOA brightness temperatures resulting from 1-D and 3-D radiative transfer show significant differences for optically thick cirrus (τ > 0.3 at 532 nm) and are mainly due to the plane-parallel approximation (PPA). At the spatial resolution of 1 km × 1 km, two principal parameters control the heterogeneity effects on brightness temperatures: i) the optical thickness standard deviation inside the observation pixel, ii) the brightness temperature contrast between the top of the cirrus and the clear-sky atmosphere. Furthermore, we show that the difference between 1-D and 3-D brightness temperatures increases with the zenith view angle from two to ten times between 0 • and 60 • due to the tilted independent pixel approximation (TIPA).

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Section: Introductionmentioning

confidence: 99%

Impact of cirrus clouds heterogeneities on top-of-atmosphere thermal infrared radiation

Fauchez

Cornet

Szczap³

et al. 2014

Atmos. Chem. Phys.

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“…Cess (1976) has suggested a solarinfrared compensation on a global average, while recently Hartmann and Short (1980) and Ohring and Clapp (1980) have found evidence for a dominant solar effect.…”

Section: Radiation and Cloudsmentioning

confidence: 99%

“…Specifically, for small cloud amounts, broken clouds do have a larger net effect than planiform cloud and vice versa for large cloud amount. The finding should have use in the derivation of the net radiative effect of cloud from satellite measurements (e.g., Ohring and Clapp, 1980).…”

Section: Cloud Amountmentioning

confidence: 99%

On the parameterization of the radiative properties of broken clouds

Schmetz

1984

Tellus A: Dynamic Meteorology and Oceanography

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A onedimensional radiative transfer scheme is presented which accounts for the efTects of broken cloud in the solar and infrared rdition field. The fractional cloud amount is explicitly considered in the two-stream model by treating clouds as the boundary condition between two adjacent atmospheric layers. The scheme accounts for absorption and scattering by gases and aerosols assuming realistic atmospheres. The radiative properties of broken clouds are included in a parameterized form making use of results from three-dimensional radiative transfer models. The radiative characteristics of a cloud field are represented by an average finite cloud whose size or optical thickness grows with increasing cloud amount. This growth is described by a simple mathematical model, and its use yields qualitative agreement between model results and observations for solar radiation.The scheme is then applied to calculate the net radiative effect of broken cloud. Since thecloud size growth with cloud amount implies a non-linear relation between the fractional cloud amount and the radiative properties of the cloud field, the net radiative eff'ect of cloud depends on cloud mount. The idealized model shows that the albedo efTcct (increase of solar reflection with cloud amount) of broken cloud is smaller than that of a plane-paralkl cloud for cloud amounts less than about 0.7. while the opposite is true for larger cloud amounts. The greenhouse efTcct (reduction of the outgoing long-wave flux) of broken cloud is larger than that of a plane-paralkl cloud for small cloud amount and smaller for large cloud amount.An application of the radiation scheme to compute bispectral curves of visibk albedo versus thermal brightness temperature shows that broken cloud layers and unbroken layers with variable optical depths show a similar shape of the bispectral curve.

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“…The Earth's weather and climate are both strongly influenced by clouds (Morgan et al, 2010;Ohring and Clapp, 1980). Cloud droplet number concentration and size can have a significant effect on cloud albedo by changing the amount of reflected shortwave radiation and absorbed longwave radiation (Twomey, 1977;McCormick and Ludwig, 1967).…”

Section: Introductionmentioning

confidence: 99%

Uncertainty in aerosol hygroscopicity resulting from semi-volatile organic compounds

Goulden¹,

Crooks²,

Connolly³

2018

Atmos. Chem. Phys.

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Abstract. We present a novel method of exploring the effect of uncertainties in aerosol properties on cloud droplet number using existing cloud droplet activation parameterisations. Aerosol properties of a single involatile particle mode are randomly sampled within an uncertainty range and resulting maximum supersaturations and critical diameters calculated using the cloud droplet activation scheme. Hygroscopicity parameters are subsequently derived and the values of the mean and uncertainty are found to be comparable to experimental observations. A recently proposed cloud droplet activation scheme that includes the effects of co-condensation of semi-volatile organic compounds (SVOCs) onto a single lognormal mode of involatile particles is also considered. In addition to the uncertainties associated with the involatile particles, concentrations, volatility distributions and chemical composition of the SVOCs are randomly sampled and hygroscopicity parameters are derived using the cloud droplet activation scheme. The inclusion of SVOCs is found to have a significant effect on the hygroscopicity and contributes a large uncertainty. For non-volatile particles that are effective cloud condensation nuclei, the co-condensation of SVOCs reduces their actual hygroscopicity by approximately 25 %. A new concept of an effective hygroscopicity parameter is introduced that can computationally efficiently simulate the effect of SVOCs on cloud droplet number concentration without direct modelling of the organic compounds. These effective hygroscopicities can be as much as a factor of 2 higher than those of the non-volatile particles onto which the volatile organic compounds condense.

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The Effect of Changes in Cloud Amount on the Net Radiation at the Top of the Atmosphere

Cited by 109 publications

References 0 publications

Impact of cirrus clouds heterogeneities on top-of-atmosphere thermal infrared radiation

Impact of cirrus clouds heterogeneities on top-of-atmosphere thermal infrared radiation

On the parameterization of the radiative properties of broken clouds

Uncertainty in aerosol hygroscopicity resulting from semi-volatile organic compounds

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