Study of longwave radiative transfer in stratocumulus clouds by using bin optical properties and bin microphysics scheme

Lábó, Eszter; Geresdi, István

doi:10.1016/j.atmosres.2015.07.016

Cited by 5 publications

(6 citation statements)

References 43 publications

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“…Note that cooling occurs in a narrower layer in the case of the bin scheme. Similar results for the bin radiation scheme compared to the bulk scheme were found for higher CCN concentrations (Lábó and Geresdi, 2016). Contrary to the comparison of the absorption coefficients (Fig.…”

Section: New Results For Longwave Heating Ratessupporting

confidence: 80%

“…A two-dimensional kinematic model was used to simulate the formation of shallow stratocumulus clouds. In this model, a detailed bin microphysical scheme was applied (Lábó and Geresdi, 2016) to prepare the vertical profile of the liquid drops for application in the bin radiation scheme. Vertical transfer of longwave radiation was calculated in each vertical column throughout a domain which included the cloud.…”

Section: New Results For Longwave Heating Ratesmentioning

confidence: 99%

“…This can be explained by the large errors due to observation equipment (pyrometers, Stevens et al, 2003). In addition, the reason for this deviance might be in Duda et al (1991) that they supposed that the shapes of net flux profiles in the clouds are similar even if liquid water contents are different, which is not correct (Lábó and Geresdi, 2016).…”

Section: Comparison With Longwave Cooling Rates In Other Studiesmentioning

confidence: 97%

“…Because longwave cooling rates strongly depend on the liqiud water concentration (LWC) profiles (Lábó and Geresdi, 2016), the maximum liquid water contents are also summarized in Table 1. Table 1.…”

Section: Comparison With Longwave Cooling Rates In Other Studiesmentioning

confidence: 99%

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Numerical modeling of the transfer of longwave radiation in water clouds

Lábó¹,

Geresdi²

2019

Időjárás

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⎯ The strong interaction between the radiation, cloud microphysics, and cloud dynamics requires more advanced radiation schemes in numerical calculations. Detailed (bin) microphysical schemes, which categorize the cloud particles into bin intervals according to their sizes, are useful tools for more accurate simulation of evolution of the hydrometeors. Our research aimed at the development of a new bin radiation scheme based on a commonly used bin microphysical scheme and the implementation of this new scheme into the RRTMG LW longwave radiation-transfer model. We have applied the MADT approximation method to evaluate radiation interaction. The absorption coefficients are calculated by using bin resolved size distribution of water droplets, which is the output of a bin microphysical scheme. The longwave absorption coefficients applied in this new method are in tune with those of a bulk radiation scheme, which is currently used in operational numerical weather prediction models. However, the two schemes gave reasonably different results for longwave radiation cooling rates at stratocumulus cloud tops and fog layers. Unfortunately, only few observation data are available to check our results directly. Indirect evaluation can be based on outputs of numerical radiative transfer models published in various studies since the nineties. Achievements of our research enable more precise calculation of longwave radiation profiles, and better prediction of dynamic and thermodynamic processes in water clouds (e.g., lifetime of stratocumulus clouds, fog evolution, and precipitation formation).

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Section: New Results For Longwave Heating Ratessupporting

confidence: 80%

Section: New Results For Longwave Heating Ratesmentioning

confidence: 99%

Section: Comparison With Longwave Cooling Rates In Other Studiesmentioning

confidence: 97%

Section: Comparison With Longwave Cooling Rates In Other Studiesmentioning

confidence: 99%

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Numerical modeling of the transfer of longwave radiation in water clouds

Lábó¹,

Geresdi²

2019

Időjárás

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“…Thermal cooling rates in stratiform clouds were found to vary between 2 and 40 K h −1 (Feigelson, 1973(Feigelson, , 1984Davies and Alves, 1989;Stephens, 1978). These studies showed that thermal heating and cooling rates depend, e.g., on the liquid water content of a cloud (Feigelson, 1973(Feigelson, , 1984Davies and Alves, 1989;Lábó and Geresdi, 2016) and on the strength of the inversion layer above the clouds (Twomey, 1983). Harshvardhan et al (1981) was one of the first to look at 3-D effects on clouds by applying radiative transfer to a cuboid cloud.…”

Section: Introductionmentioning

confidence: 99%

Effects of 3-D thermal radiation on the development of a shallow cumulus cloud field

et al. 2017

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Abstract. We investigate the effects of thermal radiation on cloud development in large-eddy simulations (LESs) with the UCLA-LES model. We investigate single convective clouds (driven by a warm bubble) at 50 m horizontal resolution and a large cumulus cloud field at 50 and 100 m horizontal resolutions. We compare the newly developed 3-D Neighboring Column Approximation with the independent column approximation and a simulation without radiation and their respective impact on clouds. Thermal radiation causes strong local cooling at cloud tops accompanied by a modest warming at the cloud bottom and, in the case of the 3-D scheme, also cloud side cooling. 3-D thermal radiation causes systematically larger cooling when averaged over the model domain. In order to investigate the effects of local cooling on the clouds and to separate these local effects from a systematically larger cooling effect in the modeling domain, we apply the radiative transfer solutions in different ways. The direct effect of heating and cooling at the clouds is applied (local thermal radiation) in a first simulation. Furthermore, a horizontal average of the 1-D and 3-D radiation in each layer is used to study the effect of local cloud radiation as opposed to the domain-averaged effect. These averaged radiation simulations exhibit a cooling profile with stronger cooling in the cloudy layers. In a final setup, we replace the radiation simulation by a uniform cooling of 2.6 K day −1 . To focus on the radiation effects themselves and to avoid possible feedbacks, we fixed surface fluxes of latent and sensible heat and omitted the formation of rain in our simulations.Local thermal radiation changes cloud circulation in the single cloud simulations, as well as in the shallow cumulus cloud field, by causing stronger updrafts and stronger subsiding shells. In our cumulus cloud field simulation, we find that local radiation enhances the circulation compared to the averaged radiation applications. In addition, we find that thermal radiation triggers the organization of clouds in two different ways. First, local interactive radiation leads to the formation of cell structures; later on, larger clouds develop. Comparing the effects of 3-D and 1-D thermal radiation, we find that organization effects of 3-D local thermal radiation are usually stronger than the 1-D counterpart. Horizontally averaged radiation causes more clouds and deeper clouds than a no radiation simulation but, in general less-organized clouds than in the local radiation simulations. Applying a constant cooling to the simulations leads to a similar development of the cloud field as in the case of averaged radiation, but less water condenses overall in the simulation. Generally, clouds contain more liquid water if radiation is accounted for. Furthermore, thermal radiation enhances turbulence and mixing as well as the size and lifetime of clouds. Local thermal radiation produces larger clouds with longer lifetimes.The cloud fields in the 100 and 50 m resolution simulations develop similarly...

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Numerical prediction of fog: A novel parameterization for droplet formation

Peterka,

Thompson,

Geresdi

2024

Quart J Royal Meteoro Soc

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A novel aerosol activation scheme was developed and implemented into the WRF Thompson–Eidhammer Aerosol‐Aware microphysical module. While in most of the numerical weather prediction (NWP) models the activation is based on updraft velocity, even in the fog, the new parameterization considers the local rate of cooling and water vapor flux in the evaluation of the aerosol activation rate. In addition, diagnostic variables are added to evaluate the visibility reduction due to formation of haze droplets. The impact of changing the activation scheme is demonstrated by a case study of a well‐observed fog event. Data observed during the fog event campaign at Budapest and observed at standard meteorological stations are compared with the output of the numerical model. The results are summarized as follows: (i) the inhomogeneous spatial and temporal distribution of the number concentration of droplets is an inherent characteristic of the new parameterization scheme. (ii) Compared to the prior parameterization based on updraft velocity, the new parameterization scheme increases the number concentration of the droplets significantly, especially at the top of the fog. As a consequence, it reduces the downward short‐wave radiation flux prolonging the lifetime of the fog by about 30–60 min. (iii) Analyses reveal that earlier dissipation of the fog comparing to the observed data cannot be explained only by overestimation of the downward short‐wave radiation flux. (iv) The new method is able to evaluate the reduction of visibility due to haze.

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Study of longwave radiative transfer in stratocumulus clouds by using bin optical properties and bin microphysics scheme

Cited by 5 publications

References 43 publications

Numerical modeling of the transfer of longwave radiation in water clouds

Numerical modeling of the transfer of longwave radiation in water clouds

Effects of 3-D thermal radiation on the development of a shallow cumulus cloud field

Numerical prediction of fog: A novel parameterization for droplet formation

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