Sensitivity of Radiative Fluxes to Aerosols in the ALADIN-HIRLAM Numerical Weather Prediction System

Round 1

Reviewer 1 Report

The subject matter is very important and interesting, but the results presented are mainly the results of a numerical experiment.
I think that for scientists dealing only with modeling the article may be too general, while for other scientistsit contains too much detailed results of experiments.
Therefore, I think the article is far too long. I suggest its significant shortening. Authors should select only the most important results and comment on them, and draw conclusions on this basis.
Also, such a large number of detailed figures seems little needed, it is better to choose the most characteristic and discuss them.

Author Response

Reviewer 1:

> Thank you for you critical reading and the suggestion, with which we
agree and reply in detail below after your comments. Please find the
differences between the original and the revised manuscript versions
attached (pdf file by latexdiff).

Open Review
(x) I would not like to sign my review report
( ) I would like to sign my review report
English language and style
( ) Extensive editing of English language and style required
( ) Moderate English changes required
( ) English language and style are fine/minor spell check required
(x) I don't feel qualified to judge about the English language and style
Yes Can be improved Must be improved Not applicable
Does the introduction provide sufficient background and include all relevant references?
(x) ( ) ( ) ( )
Is the research design appropriate?
(x) ( ) ( ) ( )
Are the methods adequately described?
(x) ( ) ( ) ( )
Are the results clearly presented?
( ) ( ) (x) ( )
Are the conclusions supported by the results?
( ) (x) ( ) ( )
Comments and Suggestions for Authors

The subject matter is very important and interesting, but the results
presented are mainly the results of a numerical experiment.

I think that for scientists dealing only with modeling the article may
be too general, while for other scientistsit contains too much
detailed results of experiments.

Therefore, I think the article is far too long. I suggest its
significant shortening. Authors should select only the most important
results and comment on them, and draw conclusions on this basis.

Also, such a large number of detailed figures seems little needed, it
is better to choose the most characteristic and discuss them.

> We have done the following in order to improve the structure and
condense the manuscript in order to better focus on the essential:

- We moved Section 5 and part of Section 2 to an Appendix, which now
gives background information for a reader who is interested in
deeper details of our model, method and data. Reading the Appendix
is not necessary in order to understand the main content and results
of the paper.

- We have shortened the introduction somewhat and made small
rearragements, moving details to the experiment description.

- We separated the experiment description to its own section and
improved its contents concerning the choice of the Badajoz and
Ladoga cases as suggested by the second reviewer.

- We introduced subsections into the long sections of the Results
chapter.

- We removed redundancies and unnecessary repeat of material, improved
formulations and language, checked the consistency of tables and
figures as well as corrected minor mistakes and typos throughout the
text.

- We collected the most used abbreviations to a separate table for the
reference of the reader.

With this, the length of the manuscript in total did not reduce much
but we hope that the better structure did make it more readable and
now allows the reader to focus on the main contents without the need
to follow all details. However, we prefer to keep the details for the
sake of accurate documentation of the suggested renewal of the aerosol
parametrizations and aerosol data usage in HARMONIE-AROME.

Author Response File: Author Response.pdf

Reviewer 2 Report

General overview

Advances in the use of aerosol forecasts by meteorological models are welcome. This is a nice piece of work. The authors themselves assume some limitations (the use of the too-simple HLRADIA radiation scheme, or not considering the indirect effect.)

Other limitation not considered, but mentioned in 5.3 section is the lack of use of the nitrate and ammonium species. However, they represent a major fraction of the aerosol, at least in urban environment and, in spite of their chemical instability, a number models already take them into account.

The examples presented in sections 3.4 and 3.5 are interesting and show the importance of the proper identification of loads of every type of aerosol.

However, all of this issues are still open research areas and the contributions of this manuscript are very significant to me.

Thus, I recommend its publication in “Atmospheres”. Only some changes are advised.

Major changes

Section 5 would be much better located above, for instance, after the introduction.

Why was the Ladoga event chosen? The aerosol load seems to be low. At the Badajoz event the aerosol had a high load of Saharan origin. I think another event with a different kind of aerosol load (for example combustion or urban) would have been much more interesting for the experiment comparison performed in this paper. The authors themselves seem to agree with this (lines 517-526 and Conclusions). Please explain the interest of the Ladoga event, or replace it by another one.

Minor changes

In the introduction I missed some references to other relevant models (WRF-Chem, CAM-Chem). I think the background is very centered in CAMS and HARMONIE.

Please, unify the criteria for naming the parameters. We have: TAUSW, SWTAUA, SSASW, ASYSW…

I find it a bit confusing. Why not something like TAU-SW, TAUA-SW, etc.

Page 5:

Define in more detail the experiments performed for Badajoz and Lake Ladoga in Section 3.1: aerosol load (Saharan intrusion, etc), type of surface (lake, ice, etc…). Computational issues are well detailed in table 1, but not the field conditions.

Line 63: “Prediction” instead of “Predication”

Line 76: Define MMR at the first occurrence of this abbreviation.

Line 92: Definition of HLRADIA and cite 26 better here.

Lines 229-230: “Note that the n.r.t. data used for Badajoz is for a case involving a Saharan dust intrusion while the Ladoga case represents normal background conditions.”

Move this information to Section 3.1

Lines 289-290: “The net SW fluxes for experiment NMMR2 appears between those from the n.r.t experiments and the climatological experiments.”

Is not NMMR2 a n.r.t experiment also? It seems it is. Please, clarify this point.

Line 308: “SSASW varies from 0.78 (NMMR3 for Badajoz and Ladoga)”.

This does not correspond precisely with the values given by Table 4.

Line 332: “Overall, the climatological aerosol concentrations are small at both locations.”

I would not say they are small. Depending on the aerosol type they can be higher than the profiles derived from the nrt data for the cases analyzed, specially for Ladoga.

Line 344: Define SWTAUA at the first occurrence.

Line 417-418: I would remark the very different behaviour of BC in both kinds of experiments at all heights, not only at surface.

Line 469: Check line 469.

Line 555: Erroneous newline.

Line 571: “This makes it”, instead of “This makes is”

Line 651: “...65 vertical levels and” should be “...65 vertical levels were”?

Figure 5: Caption is incomplete. We do not have the same figures as in figure 4.

Comments for author File: Comments.pdf

Author Response

Reviewer 2:

> Thank you for the positive and helpful critical comments. We will
answer them below, replies are inserted between your
comments. Please see the reply to the first reviewer for updates in
the structure and general contents of the manuscript. All
differences between the original and the revised manuscript versions
are shown in the attached pdf file (made with latexdiff).

Open Review
(x) I would not like to sign my review report
( ) I would like to sign my review report
English language and style
( ) Extensive editing of English language and style required
( ) Moderate English changes required
( ) English language and style are fine/minor spell check required
(x) I don't feel qualified to judge about the English language and style
Yes Can be improved Must be improved Not applicable
Does the introduction provide sufficient background and include all relevant references?
( ) (x) ( ) ( )
Is the research design appropriate?
(x) ( ) ( ) ( )
Are the methods adequately described?
( ) (x) ( ) ( )
Are the results clearly presented?
(x) ( ) ( ) ( )
Are the conclusions supported by the results?
(x) ( ) ( ) ( )
Comments and Suggestions for Authors
General overview

Advances in the use of aerosol forecasts by meteorological models are
welcome. This is a nice piece of work. The authors themselves assume
some limitations (the use of the too-simple HLRADIA radiation scheme,
or not considering the indirect effect.)

Other limitation not considered, but mentioned in 5.3 section is the
lack of use of the nitrate and ammonium species. However, they
represent a major fraction of the aerosol, at least in urban
environment and, in spite of their chemical instability, a number
models already take them into account.

> The impact of these species in the radiative transfer in weather
models surely deserves additional study as soon as their
concentration and optical properties will be available. At the
moment we do not have the data and tools to treat them within the
HARMONIE framework.

The examples presented in sections 3.4 and 3.5 are interesting and
show the importance of the proper identification of loads of every
type of aerosol.

However, all of this issues are still open research areas and the
contributions of this manuscript are very significant to me.

Thus, I recommend its publication in “Atmospheres”. Only some changes
are advised.

Major changes

Section 5 would be much better located above, for instance, after the
introduction.

> We moved this section to an appendix, as its aim is to explain the
basic features of the HARMONIE-AROME system, MUSC and the CAMS/ECMWF
data used to a reader who is interested in deeper details that are
necessary to understand the main contents of the paper. We hope this
move is also in line with the suggestion of the first reviever to
focus on essential, remove extra details and shorten the paper.

Why was the Ladoga event chosen? The aerosol load seems to be low. At
the Badajoz event the aerosol had a high load of Saharan origin. I
think another event with a different kind of aerosol load (for example
combustion or urban) would have been much more interesting for the
experiment comparison performed in this paper. The authors themselves
seem to agree with this (lines 517-526 and Conclusions). Please
explain the interest of the Ladoga event, or replace it by another
one.

> Ladoga case was chosen in order to study a "normal", background case
where there is nothing special from the point of aerosols. Quite
often in NWP studies, only extreme situations are chosen for case
studies while in the weather forecasting great majority of cases
represent "business as usual", especially here in the North of
Europe. In addition, we used Ladoga atmospheric and surface state as
the basis for the sensitivity tests where the aerosol conditions
were modified. As we mention in the discussion, there would be
several interesting cases to address in addition to the Saharan dust
event, an we hope to return to them in the future. We now motivate
better the choice of Ladoga in the manuscript and have improved the
description of cases.

Minor changes

In the introduction I missed some references to other relevant models
(WRF-Chem, CAM-Chem). I think the background is very centered in CAMS
and HARMONIE.

> Representative references to WRF-Chem, CAM-Chem, COSMO-ART added as
suggested.

Please, unify the criteria for naming the parameters. We have: TAUSW,
SWTAUA, SSASW, ASYSW…

I find it a bit confusing. Why not something like TAU-SW, TAUA-SW,
etc.

> Thank you, we applied your good suggestion. However, we left AOD and
AOD550 although they also in fact represent TAU and TAU550. This is
because AOD is quite a standard acronym to denote aerosol data. A
couple of errors concerning the use of these acronyms were
corrected. We also made a small table of abbreviations used,
including definition of these variables.

Page 5:

Define in more detail the experiments performed for Badajoz and Lake
Ladoga in Section 3.1: aerosol load (Saharan intrusion, etc), type of
surface (lake, ice, etc…). Computational issues are well detailed in
table 1, but not the field conditions.

> We improved description of the cases, added here also the motivation
(see above)

Line 63: “Prediction” instead of “Predication”
> Corrected

Line 76: Define MMR at the first occurrence of this abbreviation.
> Corrected

Line 92: Definition of HLRADIA and cite 26 better here.
> Corrected

Lines 229-230: “Note that the n.r.t. data used for Badajoz is for a
case involving a Saharan dust intrusion while the Ladoga case
represents normal background conditions.”

Move this information to Section 3.1
> Moved to the renewed description of the cases in the new Section 3

Lines 289-290: “The net SW fluxes for experiment NMMR2 appears between
those from the n.r.t experiments and the climatological experiments.”

Is not NMMR2 a n.r.t experiment also? It seems it is. Please, clarify
this point.

> Yes it is, corrected the formulation by returning the word "other" that
was by mistake skipped.

Line 308: “SSASW varies from 0.78 (NMMR3 for Badajoz and Ladoga)”.
This does not correspond precisely with the values given by Table 4.
> Corrected the text

Line 332: “Overall, the climatological aerosol concentrations are
small at both locations.”

I would not say they are small. Depending on the aerosol type they can
be higher than the profiles derived from the nrt data for the cases
analyzed, specially for Ladoga.

> You are right, improved the presentation of the figure in this paragraph.

Line 344: Define SWTAUA at the first occurrence.
> Corrected

Line 417-418: I would remark the very different behaviour of BC in
both kinds of experiments at all heights, not only at surface.
> Corrected as suggested

Line 469: Check line 469.
> Corrected

Line 555: Erroneous newline.
> Corrected

Line 571: “This makes it”, instead of “This makes is”
> Corrected

Line 651: “...65 vertical levels and” should be “...65 vertical levels were”?
> The text is correct but too complicated, clarified.

Figure 5: Caption is incomplete. We do not have the same figures as in figure 4.
> True, here is one row less. Added own caption for Figure 5.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript has been substantially improved. Thus, I congratulate the authors and recommend its publication in present form.