Towards Unified Online-Coupled Aerosol Parameterization for the Brazilian Global Atmospheric Model (BAM): Aerosol–Cloud Microphysical–Radiation Interactions

Round 1

Reviewer 1 Report

Review of the manuscript
“Towards unified online-coupled aerosol parameterization for 2 the Brazilian global atmospheric model (BAM): Part I. aerosol-3 cloud microphysical-radiation interactions” by Jayant Pendharkar, Silvio Nilo Figueroa, Angel Vara-Vela, R. Phani Murali Krishna, Daniel Schuch, Paulo Yoshio Kubota, Débora Souza Alvim, Eder Paulo Vendrasco, Helber Barros Gomes, Paulo Nobre1, Dirceu Luís Herdies

 

Natural and anthropogenic aerosols of South America have a wide variety of sources and sinks. Their variability in space and time is characterized by high intensity.  In addition, they differ significantly from aerosols of other continents. The manuscript considers the results of numerical simulation based on modernized Brazilian global atmospheric model allowing for these types of aerosols. Thus, the results of numerical simulation based on the modernized Brazilian global atmospheric model reported in the manuscript are of great interest to the scientific community. 

In my understanding, the issues considered in the manuscript are far from issues of remote sensing. The publication of the manuscript in MDPI Remote Sensing may lead to the situation that the paper presenting interesting results appears unavailable to a wide range of readers. I’d recommend the authors to publish the manuscript in MDPI Atmosphere, whose subject area corresponds closely to the topic of the reviewed manuscript. 

If the authors insist on publication in MDPI Remote Sensing, then they need to relate their results to the issues of remote sensing in Introduction and Conclusion. In addition, it is also necessary to formulate clearly the novelty brought by the obtained results to remote sensing.  In this case, the manuscript can be considered as multidisciplinary and will be of interest to experts in the field of remote sensing.

Author Response

Attached file.

Author Response File: Author Response.docx

Reviewer 2 Report

Initial results of implementing an online-coupled aerosol-cloud microphysical-radiation interaction model are presented. The Brazilian global atmospheric model uses an aerosol module based on a modal representation with microphysical processes. Mass and number mixing ratios, along with dry and wet radii, are predicted for various aerosol types. The changes in cloud droplet number concentrations are evaluated by physically parameterizing aerosol activation. Besides, vertical mixing, ice nucleation, and radiative optical properties are computed. The simulated spatial patterns of surface mass and number concentrations are compared with satellite observations for JFM 2014 and JAS 2019. The global means of simulated shortwave and longwave cloud radiative forcing are comparable with observations, though the simulated cloud cover is notably over-predicted. Potential areas for improvement are identified for further development. Although this model study is still in its initial phase, the model development focusing on the Brazilian atmosphere will be informative for researchers in the relevant community. The manuscript is well organized, though the authors should consider the following issues for clarifying the standpoint and improving the presentation.

(major)

1. As the title of this manuscript suggests, the purpose of this work is to develop a Brazilian global atmospheric model. The results are presented for two time periods (three months each, representing the wet and biomass-burning seasons) as global distributions for a number of parameters involved. The essential question about this research is whether the authors intend to develop a model that aims to improve the accuracy over the southern hemisphere (SH) or not. If so, at least some figures should indicate the improvements as compared with previous results in SH. If not, it is indispensable to describe the superiority of the present approach over the existing global models. This aspect is not clear and should be stated explicitly in both the Abstract and Introduction, based on the outcomes of this research, even if the work is still in progress.

 2. The current Introduction is too long. Inserting an appropriate table or a figure (and shortening the text accordingly) will benefit the reader regarding various types of atmospheric models and parameterizations so far developed in close relation to the current paper. Also, at around L198, adding a figure explaining the development of both BAM and AMIC will facilitate readability.

 3. Considering the initial stage of this comprehensive simulation, it is questionable to exhibit all the simulation results in the Results section (Figures 1-9 and Tables 2-4) since many of the results seem to be tentative at this stage. Therefore, it would be informative and meaningful to separately show the results that have proven to be acceptable and that have to be improved in the future. Moreover, it is required to describe how to implement the improvements, whether input data or atmospheric processes are considered more responsible for the discrepancies from observations.

 4. A conclusion section is needed, even if this is Part I of a series of papers. The section should summarize the major points found in the course of the research described so far. Also, if permitted, showing a list of abbreviations will help the reader since there are so many of them in the text.

 5. Please examine the relevance of the following publications. The WRF-Chem approach can yield results on atmospheric conditions that can be compared with the present work, so these two papers should be added to the reference list.

 L. Liu, Y. Cheng, et al., Impact of biomass burning aerosols on radiation, clouds, and precipitation over the Amazon: relative importance of aerosol–cloud and aerosol–radiation interactions, Atmos. Chem. Phys., 20, 13283–13301, https://doi.org/10.5194/acp-20-13283-2020, 2020.

 E. D. S. F. Duarte, P. Franke, et al., Evaluation of atmospheric aerosols in the metropolitan area of São Paulo simulated by the regional EURAD-IM model on high-resolution. Atmospheric Pollution Research, 12(2), 451-469. https://doi.org/10.1016/j.apr.2020.12.006, 2021.

 6. Some parts of the current manuscript show apparent deviation from the standard usage of English syntax and punctuation. Some examples are listed below, but not all because they are numerous. Please revise the manuscript carefully to improve its quality.

 (minor)

L18-20 “Mass and number mixing ratios, along with dry and wet radii of black carbon, particulate organic matter, secondary organic aerosols, sulfate, dust, and sea salt aerosols are predicted.” – “Mass and number mixing ratios, along with dry and wet radii, are predicted for black carbon, particulate organic matter, secondary organic aerosols, sulfate, dust, and sea salt aerosols.”

L25 “short wave and long wave” – “shortwave and longwave”

L26-27 “30% respectively.” – “30%, respectively.”

L36 “Aerosols serves as ...” – “Aerosols serve as ...”

L39 “after the discovery; several centers” –“after the discovery, several centers”

L47-48 “In unified online-coupled model, aerosol module is integrated into the GCM allowing ...” – “In a unified online-coupled model, an aerosol module is integrated into the GCM, allowing ...”

L74 “yield” – “yields”

L99-100 “SS scatter light and also serve as CCN and hence representing ...” – “SS aerosols scatter light and also serve as CCN, and hence, representing ...”

L119-120 “the model simulated absorbing AOD is ...” – “the model-simulated absorbing AOD is ...”

L121 “the multi-model mean show ...” – “the multi-model mean shows ...”

L128, L153, etc. “online coupled” – “online-coupled”

L133  “550nm” – “550 nm”

L141 “Carbon Monoxide (CO)” – “carbon monoxide (CO)”

L192 “the direct and indirect effect of aerosols” – “the direct and indirect effects of aerosols”

L233, L259, etc. “Köhler theory” – “the Köhler theory”

L251-252 Why is it justified to assume “new particle nucleation and coagulation are not performed in the cloudy subarea”?

L264 “a 2-mode lognormal size distribution” – “a two-mode lognormal size distribution”

L266 “m−3) respectively for” – “m−3), respectively, for”

L267 Please spell out “AG00” with a reference.

L272 “supersaturations are low affecting” – Please paraphrase this part.

L280 “The formation of ice crystal involve” – “The formation of an ice crystal involves”

L281 “and Meyers et al.’ [85] deposition nucleation” – Please paraphrase this part.

L304-305 “R-package eixport [90], each variable contains” – Please paraphrase this part.

L329 “a 4-mode configuration” – “a four-mode configuration

L333 “SMT mode” – Please add a reference or spell it out.

L346 “in next version” – “in the next version”

L349 Please rephrase “burdens.” (aerosol loading?)

L449 “m3” – “m^3” (superscript); the same applies to Figs. 3 and 4.

L496 Fig. 5a: Please indicate “%” for CLDF and “g m^-2” for LWP. The same applies to Fig. 5b.

L655 “season in the Amazon during which …” – “season in the Amazon, during which …”

L678-680 “Simulated cloud properties: shortwave cloud optical depth, cloud fraction and cloud liquid water path have shown …” – Please paraphrase this part.

L686-687 “JAS 2019 respectively.” – “JAS 2019, respectively.”

 

Author Response

Attached file.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have responded reasonably to the comments on the previous version of this manuscript. Including an intense biomass burning episode of August 2019 is suitable for highlighting the capability of the BAM model in simulating the advection and uplifting features. For further improving the presentation, please consider the flowing technical issues.

L16 The abbreviation of BAM should appear here, not later at L28.

L35 The term “cloud processing” is somewhat ambiguous. Please paraphrase this part.

L62 “… lists few studies” – “… lists a few studies”

L134 “computational resources for example, using … “ – “computational resources, for example, using …”

L162 “given the dynamics and …” – “given the fact that the dynamics and …”

L169 – 170 “Comparing with previous results from existing global aerosol models require …” – “Comparing with previous results from existing global aerosol models requires …”

L236-237 “to compute aerosol activation; changes in cloud optical properties and aerosol radiative properties respectively.” – “to compute aerosol activation, changes in cloud optical properties, and aerosol radiative properties, respectively.”

L258 “supersaturations are low affecting …” – “supersaturations are less affecting …” 

L266 “Meyers et al.’ [85] deposition nucleation in mixed phase clouds” – “deposition nucleation in mixed-phase clouds as described (or proposed) by Meyers et al. [85]”

L379 The part “BC and POM are treated in accumulation and primary carbon modes in AMIC” is redundant since the same phrase appears in the next sentence.

L381-382 “The explicit treatment for … result in …” – “The explicit treatments for … result in …”

L383-384 “in the primary carbon mode allowing …” – “in the primary carbon mode, allowing …”

L444-445 “microphysical properties namely, …” – “microphysical properties, namely, …”

L447 “S2 respectively.” – “S2, respectively.”

L451 “over SA i.e., …” – “over SA, i.e., …”: The same applies to L454.

L461 “shortwave cloud optical depth” – “shortwave COD” (see L271.)

L466 “liquid water path” – “LWP” (see L343.)

L471 In subsection 4.3, it is recommended not to omit the unit of W m^-2 in view of the policy of SI (a physical quantity consists of its value and unit.)

L490-491 “corresponding to similar period. Variables evaluated include shortwave cloud radiative forcing (SWCRF); longwave cloud radiative forcing (LWCRF); and outgoing longwave radiation (OLR).” – “corresponding to a similar period. Variables evaluated include shortwave cloud radiative forcing (SWCRF), longwave cloud radiative forcing (LWCRF), and outgoing longwave radiation (OLR).”

L510 “the observed 228.9 Wm-2.” – “the observed value of 228.9 Wm-2.”

L522 It would be better to add a brief explanation of the way these discrepancies could be solved in future work since AOD is the most influential parameter in AMIC.

L568 “populated areas impacting regional weather.” – “populated areas, impacting regional weather.”

L570 “transported down south causing …” – “transported down south, causing …”

L577 “AOD 550nm” – “AOD 550 nm”

L620 “in totality providing …” – “in totality, providing …”

L626 The phrase “between modal” seems to be dangling.

L656-657 “the mass and number distribution …” – “the mass and number distributions …”

L674 The phrase “indicate a possible study to investigate …” should be rephrased with better wording.

Author Response

attached.

Author Response File: Author Response.docx