scholarly journals Processes controlling the vertical aerosol distribution in marine stratocumulus regions – a sensitivity study using the climate model NorESM1-M

2021 ◽  
Vol 21 (1) ◽  
pp. 577-595
Author(s):  
Lena Frey ◽  
Frida A.-M. Bender ◽  
Gunilla Svensson
Keyword(s):  
Vertical Distribution ◽  
Radiative Forcing ◽  
Climate Model ◽  
Cloud Microphysics ◽  
Aerosol Extinction ◽  
Shallow Convection ◽  
Marine Stratocumulus ◽  
Aerosol Emission ◽  
Aerosol Distribution ◽  
The Vertical Distribution

Abstract. The vertical distribution of aerosols plays an important role in determining the effective radiative forcing from aerosol–radiation and aerosol–cloud interactions. Here, a number of processes controlling the vertical distribution of aerosol in five subtropical marine stratocumulus regions in the climate model NorESM1-M are investigated, with a focus on the total aerosol extinction. A comparison with satellite lidar data (CALIOP, Cloud–Aerosol Lidar with Orthogonal Polarization) shows that the model underestimates aerosol extinction throughout the troposphere, especially elevated aerosol layers in the two regions where they are seen in observations. It is found that the shape of the vertical aerosol distribution is largely determined by the aerosol emission and removal processes in the model, primarily through the injection height, emitted particle size, and wet scavenging. In addition, the representation of vertical transport related to shallow convection and entrainment is found to be important, whereas alterations in aerosol optical properties and cloud microphysics parameterizations have smaller effects on the vertical aerosol extinction distribution. However, none of the alterations made are sufficient for reproducing the observed vertical distribution of aerosol extinction, neither in magnitude nor in shape. Interpolating the vertical levels of CALIOP to the corresponding model levels leads to better agreement in the boundary layer and highlights the importance of the vertical resolution.

scholarly journals Investigating processes that control the vertical distribution of aerosol in five subtropical marine stratocumulus regions – A sensitivity study using the climate model NorESM1-M

2019 ◽  
Author(s):  
Lena Frey ◽  
Frida A.-M. Bender ◽  
Gunilla Svensson
Keyword(s):  
Vertical Distribution ◽  
Radiative Forcing ◽  
Climate Model ◽  
Sensitivity Study ◽  
Cloud Microphysics ◽  
Orthogonal Polarization ◽  
Aerosol Extinction ◽  
Shallow Convection ◽  
Marine Stratocumulus ◽  
The Vertical Distribution

Abstract. The vertical distribution of aerosols plays an important role in determining the effective radiative forcing from aerosol–radiation and aerosol–cloud interactions. Here, a number of processes controlling the vertical distribution of aerosol in five subtropical marine stratocumulus regions in the climate model NorESM1-M are investigated, with a focus on the total aerosol extinction. A comparison with satellite lidar data (CALIOP, Cloud-Aerosol Lidar with Orthogonal Polarization) shows that the model underestimates aerosol extinction throughout the troposphere, especially elevated aerosol layers in the two regions where they are seen in observations. It is found that the shape of the vertical aerosol distribution is largely determined by the aerosol emissions and removal processes in the model, primarily through the injection height, emitted particle size, and wet scavenging. In addition, the representation of vertical transport related to shallow convection and entrainment are found to be important, whereas alterations in aerosol optical properties and cloud microphysics parameterizations have smaller effects on the vertical aerosol extinction distribution. However, none of the alterations made are sufficient for reproducing the observed vertical distribution of aerosol extinction, neither in magnitude nor in shape. Interpolating the vertical levels of CALIOP to the corresponding model levels, leads to a better agreement in the boundary layer and highlights the importance of the vertical resolution.

scholarly journals Airborne lidar study of the vertical distribution of aerosols over Hyderabad, an urban site in central India, and its implication for radiative forcing calculations

2006 ◽  
Vol 24 (10) ◽  
pp. 2461-2470 ◽  
Author(s):  
H. Gadhavi ◽  
A. Jayaraman
Keyword(s):  
Vertical Distribution ◽  
Radiative Forcing ◽  
Central India ◽  
Airborne Lidar ◽  
Urban Site ◽  
Transfer Model ◽  
Aerosol Extinction ◽  
Vertical Profiles ◽  
Flight Duration ◽  
The Vertical Distribution

Abstract. Use of a compact, low power commercial lidar onboard a small aircraft for aerosol studies is demonstrated. A Micro Pulse Lidar fitted upside down in a Beech Superking aircraft is used to measure the vertical distribution of aerosols in and around Hyderabad, an urban location in the central India. Two sorties were made, one on 17 February 2004 evening hours and the other on 18 February 2004 morning hours for a total flight duration of four hours. Three different algorithms, proposed by Klett (1985), Stephens et al. (2001) and Palm et al. (2002) for deriving the aerosol extinction coefficient profile from lidar data are studied and is shown that the results obtained from the three methods compare within 2%. The result obtained from the airborne lidar is shown more useful to study the aerosol distribution in the free troposphere than that obtained by using the same lidar from ground. Using standard radiative transfer model the aerosol radiative forcing is calculated and is shown that knowledge on the vertical distribution of aerosols is very important to get more realistic values than using model vertical profiles of aerosols. We show that for the same aerosol optical depth, single scattering albedo and asymmetry parameter but for different vertical profiles of aerosol extinction the computed forcing values differ with increasing altitude and improper selection of the vertical profile can even flip the sign of the forcing at tropopause level.

Observation and Study of Summer Aerosol by APL Lidar at Beijing

2014 ◽  
Vol 641-642 ◽  
pp. 1209-1215
Author(s):  
Hui Yang ◽  
Xue Song Zhao ◽  
Jun Jun Zong ◽  
Cao Fang Lv
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Planetary Boundary Layer ◽  
Layer Structure ◽  
Aerosol Extinction ◽  
Observation Site ◽  
Extinction Coefficients ◽  
Aerosol Distribution ◽  
The Vertical Distribution

The vertical distribution of aerosol extinction coefficients, and relativity between aerosol and BC the within summer planetary boundary layer (PBL) over the observation site are shown in this paper. The data indicates that the aerosol is almost trapped within PBL and troposphere layer is rather stable and the main composition of aerosol in Beijing is BC. The multi-layer structure of the aerosol distribution is obvious.

Winter PBL Aerosol Profiles at Bejing

2013 ◽  
Vol 791-793 ◽  
pp. 992-997
Author(s):  
You Ming He ◽  
Hui Yang ◽  
De Bin Yan ◽  
Pei Bin Chen ◽  
Jie Song Ye ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Planetary Boundary Layer ◽  
Layer Structure ◽  
Aerosol Extinction ◽  
Observation Site ◽  
Extinction Coefficients ◽  
Measurement Site ◽  
Aerosol Distribution ◽  
The Vertical Distribution

The vertical distribution of aerosol extinction coefficients within winter planetary boundary layer (WPBL) over the observation site are shown in this paper, and the heights of PBL are discussed. The data indicates that the aerosol over the measurement site is almost trapped within PBL and troposphere layer and is rather stable, and the multi-layer structure of the aerosol distribution is obvious.

How detailed do cloud microphysics need to be in climate models?

2021 ◽  
Author(s):  
Ulrike Proske ◽  
Sylvaine Ferrachat ◽  
David Neubauer ◽  
Ulrike Lohmann
Keyword(s):  
Radiative Forcing ◽  
Climate Models ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Computing Time ◽  
Cloud Microphysics ◽  
Model Response ◽  
Microphysical Processes ◽  
Improved Accuracy

<p>Clouds are of major importance for the climate system, but the radiative forcing resulting from their interaction with aerosols remains uncertain. To improve the representation of clouds in climate models, the parameterisations of cloud microphysical processes (CMPs) have become increasingly detailed. However, more detailed climate models do not necessarily result in improved accuracy for estimates of radiative forcing (Knutti and Sedláček, 2013; Carslaw et al., 2018). On the contrary, simpler formulations are cheaper, sufficient for some applications, and allow for an easier understanding of the respective process' effect in the model.</p><p>This study aims to gain an understanding which CMP parameterisation complexity is sufficient through simplification. We gradually phase out processes such as riming or aggregation from the global climate model ECHAM-HAM, meaning that the processes are only allowed to exhibit a fraction of their effect on the model state. The shape of the model response as a function of the artificially scaled effect of a given process helps to understand the importance of this process for the model response and its potential for simplification. For example, if partially removing a process induces only minor alterations in the present day climate, this process presents as a good candidate for simplification. This may be then further investigated, for example in terms of computing time.<br>The resulting sensitivities to CMP complexity are envisioned to guide CMP model simplifications as well as steer research towards those processes where a more accurate representation proves to be necessary.</p><p> </p><p><br>Carslaw, Kenneth, Lindsay Lee, Leighton Regayre, and Jill Johnson (Feb. 2018). “Climate Models Are Uncertain, but We Can Do Something About It”. In: Eos 99. doi: 10.1029/2018EO093757</p><p>Knutti, Reto and Jan Sedláček (Apr. 2013). “Robustness and Uncertainties in the New CMIP5 Climate Model Projections”. In: Nature Climate Change 3.4, pp. 369–373. doi: 10.1038/nclimate1716</p>

scholarly journals Numerical framework and performance of the new multiple-phase cloud microphysics scheme in RegCM4.5: precipitation, cloud microphysics, and cloud radiative effects

2016 ◽  
Vol 9 (7) ◽  
pp. 2533-2547 ◽  
Author(s):  
Rita Nogherotto ◽  
Adrian Mark Tompkins ◽  
Graziano Giuliani ◽  
Erika Coppola ◽  
Filippo Giorgi
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Regional Climate ◽  
Cloud Microphysics ◽  
Microphysics Scheme ◽  
Additional Information ◽  
Mixing Ratios ◽  
Multiple Phase ◽  
Realistic Representation ◽  
And Performance

Abstract. We implement and evaluate a new parameterization scheme for stratiform cloud microphysics and precipitation within regional climate model RegCM4. This new parameterization is based on a multiple-phase one-moment cloud microphysics scheme built upon the implicit numerical framework recently developed and implemented in the ECMWF operational forecasting model. The parameterization solves five prognostic equations for water vapour, cloud liquid water, rain, cloud ice, and snow mixing ratios. Compared to the pre-existing scheme, it allows a proper treatment of mixed-phase clouds and a more physically realistic representation of cloud microphysics and precipitation. Various fields from a 10-year long integration of RegCM4 run in tropical band mode with the new scheme are compared with their counterparts using the previous cloud scheme and are evaluated against satellite observations. In addition, an assessment using the Cloud Feedback Model Intercomparison Project (CFMIP) Observational Simulator Package (COSP) for a 1-year sub-period provides additional information for evaluating the cloud optical properties against satellite data. The new microphysics parameterization yields an improved simulation of cloud fields, and in particular it removes the overestimation of upper level cloud characteristics of the previous scheme, increasing the agreement with observations and leading to an amelioration of a long-standing problem in the RegCM system. The vertical cloud profile produced by the new scheme leads to a considerably improvement of the representation of the longwave and shortwave components of the cloud radiative forcing.

scholarly journals The vertical distribution of ozone instantaneous radiative forcing from satellite and chemistry climate models

2011 ◽  
Vol 116 (D1) ◽  
Author(s):  
A. M. Aghedo ◽  
K. W. Bowman ◽  
H. M. Worden ◽  
S. S. Kulawik ◽  
D. T. Shindell ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Radiative Forcing ◽  
Climate Models ◽  
The Vertical Distribution

scholarly journals On the spatial variability of the regional aerosol distribution as determined from ceilometers

2020 ◽  
Author(s):  
Matthias Wiegner ◽  
Alexander Geiß ◽  
Ina Mattis ◽  
Fred Meier ◽  
Thomas Ruhtz
Keyword(s):  
Vertical Distribution ◽  
Mixing Layer ◽  
Data Set ◽  
Integrated Backscatter ◽  
Aerosol Distribution ◽  
Mixing Layer Height ◽  
Aerosol Sources ◽  
The Mean ◽  
Two Parameters ◽  
The Vertical Distribution

Abstract. Measurements of the vertical distribution of aerosol particles are typically only available at selected sites leaving the question of their representativeness for urban and regional scales unanswered. As a contribution to solve this problem we have investigated ceilometer signals from two testbeds in Munich and Berlin, Germany. For each testbed measurements of 24 months from 6 ceilometers were available. This constitutes a unique data set, in particular as the same type of instruments are deployed and the same data evaluation schemes applied. Two parameters are discussed: the mixing layer height (MLH) as an indicator for the vertical distribution and the integrated backscatter as a proxy for the amount of aerosols in the mixing layer. The MLH was determined by the COBOLT algorithm, the integrated backscatter from the Klett (backward and forward) inversion scheme. It was found that the mean difference of the MLH at two sites within a testbed typically only varies by less than 50 m, slightly increasing with the distance of the corresponding sites. Almost 60 % of all intercomparisons agree within ±100 m. MLHs are typically correlated with R > 0.9 in particular for the Berlin-testbed. With respect to the integrated backscatter the correlation is in the range of 0.7 < R < 0.9. This is expected from the diversity of local aerosol sources within a given testbed. We conclude from our data that the MLH determined from a single ceilometer is applicable for a whole metropolitan area. However, the integrated backscatter of particles within the mixing layer exhibits a variability of 15–25 % suggesting that one ceilometer is not representative, especially if atmospheric processes shall be investigated.

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