An Accurate Parameterization of the Radiative Properties of Water Clouds Suitable for Use in Climate Models

Hu, Yongxiang; Stamnes, Knut

doi:10.1175/1520-0442(1993)006<0728:aapotr>2.0.co;2

Cited by 381 publications

(292 citation statements)

References 0 publications

Supporting

Mentioning

286

Contrasting

Unclassified

Order By: Relevance

“…2.3). The extinction coefficient of cloud droplets at visible wavelengths (including 550 nm) is well approximated by with LWC in g m −3 , r eff the effective radius in µm and l the density of liquid water in g cm −3 (Hu and Stamnes, 1993). The optical depth at visible wavelengths (OD) is obtained by integrating α ext,visible in the vertical.…”

Section: Fog Microphysical Propertiesmentioning

confidence: 99%

Radiation in fog: quantification of the impact on fog liquid water based on ground-based remote sensing

Wærsted¹,

Haeffelin

Dupont

et al. 2017

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. Radiative cooling and heating impact the liquid water balance of fog and therefore play an important role in determining their persistence or dissipation. We demonstrate that a quantitative analysis of the radiation-driven condensation and evaporation is possible in real time using groundbased remote sensing observations (cloud radar, ceilometer, microwave radiometer). Seven continental fog events in midlatitude winter are studied, and the radiative processes are further explored through sensitivity studies. The longwave (LW) radiative cooling of the fog is able to produce 40-70 g m −2 h −1 of liquid water by condensation when the fog liquid water path exceeds 30 g m −2 and there are no clouds above the fog, which corresponds to renewing the fog water in 0.5-2 h. The variability is related to fog temperature and atmospheric humidity, with warmer fog below a drier atmosphere producing more liquid water. The appearance of a cloud layer above the fog strongly reduces the LW cooling relative to a situation with no cloud above; the effect is strongest for a low cloud, when the reduction can reach 100 %. Consequently, the appearance of clouds above will perturb the liquid water balance in the fog and may therefore induce fog dissipation. Shortwave (SW) radiative heating by absorption by fog droplets is smaller than the LW cooling, but it can contribute significantly, inducing 10-15 g m −2 h −1 of evaporation in thick fog at (winter) midday. The absorption of SW radiation by unactivated aerosols inside the fog is likely less than 30 % of the SW absorption by the water droplets, in most cases. However, the aerosols may contribute more significantly if the air mass contains a high concentration of absorbing aerosols. The absorbed radiation at the surface can reach 40-120 W m −2 during the daytime depending on the fog thickness. As in situ measurements indicate that 20-40 % of this energy is transferred to the fog as sensible heat, this surface absorption can contribute significantly to heating and evaporation of the fog, up to 30 g m −2 h −1 for thin fog, even without correcting for the typical underestimation of turbulent heat fluxes by the eddy covariance method. Since the radiative processes depend mainly on the profiles of temperature, humidity and clouds, the results of this paper are not site specific and can be generalised to fog under different dynamic conditions and formation mechanisms, and the methodology should be applicable to warmer and moister climates as well. The retrieval of approximate emissivity of clouds above fog from cloud radar should be further developed.

show abstract

Section: Fog Microphysical Propertiesmentioning

confidence: 99%

Radiation in fog: quantification of the impact on fog liquid water based on ground-based remote sensing

Wærsted¹,

Haeffelin

Dupont

et al. 2017

Atmos. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…In terms of the optical properties of cloud particle, LW emissivity is parameterized depending on cloud water content (Kiehl and Zender 1995), and the corresponding absorption coe‰cient is parameterized as a function of e¤ective radius (Hu and Stamnes 1993, for liquid water clouds, and Ebert and Curry 1992, for ice clouds). Optical depth, single-scattering albedo, and the asymmetry factor in SW are similarly parameterized by cloud water content and e¤ective radius (Slingo 1989, for water clouds and Ebert and Curry 1992, for ice clouds).…”

Section: B Radiationmentioning

confidence: 99%

A New Global Climate Model of the Meteorological Research Institute: MRI-CGCM3 —Model Description and Basic Performance—

Yukimoto¹,

Adachi²,

Hosaka³

et al. 2012

Journal of the Meteorological Society of Japan

698

236

View full text Add to dashboard Cite

A new global climate model, MRI-CGCM3, has been developed at the Meteorological Research Institute (MRI). This model is an overall upgrade of MRI's former climate model MRI-CGCM2 series. MRI-CGCM3 is composed of atmosphere-land, aerosol, and ocean-ice models, and is a subset of the MRI's earth system model MRI-ESM1. Atmospheric component MRI-AGCM3 is interactively coupled with aerosol model to represent direct and indirect e¤ects of aerosols with a new cloud microphysics scheme. Basic experiments for pre-industrial control, historical and climate sensitivity are performed with MRI-CGCM3. In the pre-industrial control experiment, the model exhibits very stable behavior without climatic drifts, at least in the radiation budget, the temperature near the surface and the major indices of ocean circulations. The sea surface temperature (SST) drift is sufficiently small, while there is a 1 W m À2 heating imbalance at the surface. The model's climate sensitivity is estimated to be 2.11 K with Gregory's method. The transient climate response (TCR) to 1 % yr À1 increase of carbon dioxide (CO 2 ) concentration is 1.6 K with doubling of CO 2 concentration and 4.1 K with quadrupling of CO 2 concentration. The simulated present-day mean climate in the historical experiment is evaluated by comparison with observations, including reanalysis. The model reproduces the overall mean climate, including seasonal variation in various aspects in the atmosphere and the oceans. Variability in the simulated climate is also evaluated and is found to be realistic, including El Niñ o and Southern Oscillation and the Arctic and Antarctic oscillations. However, some important issues are identified. The simulated SST indicates generally cold bias in the Northern Hemisphere (NH) and warm bias in the Southern Hemisphere (SH), and the simulated sea ice expands excessively in the North Atlantic in winter. A double ITCZ also appears in the tropical Pacific, particularly in the austral summer.

show abstract

“…The grid-scale cloud optical properties are parameterised as a function of wavelength using the effective droplet radius (Hu and Stamnes, 1993).…”

Section: Model Descriptionmentioning

confidence: 99%

Real-case simulations of aerosol–cloud interactions in ship tracks over the Bay of Biscay

et al. 2015

View full text Add to dashboard Cite

Abstract. Ship tracks provide an ideal test bed for studying aerosol-cloud interactions (ACIs) and for evaluating their representation in model parameterisations. Regional modelling can be of particular use for this task, as this approach provides sufficient resolution to resolve the structure of the produced track including their meteorological environment whilst relying on the same formulations of parameterisations as many general circulation models. In this work we simulate a particular case of ship tracks embedded in an optically thin stratus cloud sheet which was observed by a polar orbiting satellite at 12:00 UTC on 26 January 2003 around the Bay of Biscay.The simulations, which include moving ship emissions, show that the model is indeed able to capture the structure of the track at a horizontal grid spacing of 2 km and to qualitatively capture the observed cloud response in all simulations performed. At least a doubling of the cloud optical thickness was simulated in all simulations together with an increase in cloud droplet number concentration by about 40 cm −3 (300 %) and decrease in effective radius by about 5 µm (40 %). Furthermore, the ship emissions lead to an increase in liquid water path in at least 25 % of the track regions.We are confident in the model's ability to capture key processes of ship track formation. However, it was found that realistic ship emissions lead to unrealistic aerosol perturbations near the source regions within the simulated tracks due to grid-scale dilution and homogeneity.Combining the regional-modelling approach with comprehensive field studies could likely improve our understanding of the sensitivities and biases in ACI parameterisations, and could therefore help to constrain global ACI estimates, which strongly rely on these parameterisations.

show abstract

An Accurate Parameterization of the Radiative Properties of Water Clouds Suitable for Use in Climate Models

Cited by 381 publications

References 0 publications

Radiation in fog: quantification of the impact on fog liquid water based on ground-based remote sensing

Radiation in fog: quantification of the impact on fog liquid water based on ground-based remote sensing

A New Global Climate Model of the Meteorological Research Institute: MRI-CGCM3 —Model Description and Basic Performance—

Real-case simulations of aerosol–cloud interactions in ship tracks over the Bay of Biscay

Contact Info

Product

Resources

About