the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 10 Jul 2025
Improvements on the BRAMS wildfire-atmosphere modelling system
Abstract. Wildfire smoke significantly perturbs atmospheric composition and radiative balance, with implications for air quality, weather, and climate. Accurately simulating smoke–radiation–convection interactions remains a scientific challenge, particularly at meso-local scales. This study presents developments in the BRAMS v6.0 modelling system, including the integration of crown fire spread into SFIRE and dynamic coupling of fire-emitted smoke fluxes. These enhancements enable physically consistent simulations of wildfire behaviour, smoke emissions, and their radiative impacts.
The model couples fire spread and heat release to compute Fire Radiative Power (FRP), which drives smoke emissions in real time. These are fully integrated with aerosol–radiation interactions and atmospheric chemistry. The system was applied to the 15 October 2017 wildfire in central Portugal using high-resolution simulations.
Model performance was evaluated against MERRA-2 aerosol optical depth (AOD). Simulations reproduced key features of smoke transport and optical properties, including extinction and absorption coefficients at 400, 550, and 700 nm, as well as their spectral dependence. Results confirmed the dominance of organic carbon in extinction and validated the use of 550 nm as representative for smoke optical depth. Absorption reached 8 m⁻1 at 550 nm and led to vertical displacements of CAPE and CIN layers up to 200 m. Inversion layers responded to plume heating, exhibiting radiative lid effects that suppressed vertical mixing.
These findings demonstrate the potential of the enhanced BRAMS system to simulate coupled fire–atmosphere processes, contributing to improved forecasting of smoke behavior and understanding of wildfire-induced thermodynamic and radiative impacts.
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RC1: 'Comment on egusphere-2025-2495', Anonymous Referee #1, 22 Aug 2025
The manuscript by Menezes et al. proposes a modeling methodology with BRAMS to provide the simulation of fire spread, smoke injection height, fine mode aerosol concentration and radiative impacts and thermodynamics impact. In order to do so, BRAMS model was updated, including the integration of a crown fire spread behaviour model, which allows the simulation of fire propagation on standing trees, and the implementation of fire radiative power calculations in the SFIRE model. The study is interesting and it fits the journal scope. However, major revision is necessary in order to improve the final version and to clarify some aspects.
First of all, some of the results are compared with MERRA-2 reanalysis products. It is mentioned (lines 298 and 299) that monthly mean results of MERRA-2 products were compared with AERONET retrievals. Considering SSA in particular, was the MERRA-2 result also compared with AERONET retrievals? As detailed below, some inconsistencies were observed. Finally, please, consider increasing the font size of Figures 9 and 10 and verify if the isolines of CAPE in the vertical profiles of the Figure 9 are correct. I had difficulty in interpreting the results just looking at the figures.
Specific comments and technical corrections:
line 42 - GFED, CAMS-GFAS - What do the acronyms mean?
line 58 - replace “originates” by “originated”.
line 68 - include “the” in “increases the heat release…”
line 84 - replace smoke-related aerosols by smoke-related aerosol optical properties.
line 106 - Give the meaning of the acronyms CPTEC and USP.
lines 166, 167, 171 (Eq. 1). Please, verify the subscripts of I and R (initialization x inicialization, respectively). The correct answer should be initialization, unless the authors have a reason to differentiate them. If so, a brief explanation is necessary.
line 400 - please add references discussing the spectral region where OC and BC present higher absorption efficiency.
lines 408 and 411 - Use of AOD x AOT. I recommend using only AOD - aerosol optical depth. Please, check the manuscript thoroughly. Also, in lines 411-412, the authors mention that MERRA-2 estimates AOD at 500 nm, while BRAMS calculates SOD at 550 nm. Given that smoke optical depth varies spectrally, please, clarify if the comparison between these variables was made at different wavelengths (500 nm x 550 nm).
lines 452, 720 and 751 - is there any reason to include all the authors of Menezes et al. (2024) paper? Please, just refer to Menezes et al. (2024).
line 485 - the correct acronym is AOD, instead of TOA. Please, refer to the previous comment.
line 486 - what do you mean by biomass fuel models?
line 487 - it is not only during the flaming phase that aerosol particles are emitted, but during the combustion process. Please, rephrase.
line 520 - add a dot signal after wavelength.
line 521 - rephrase “Understanding the spectral behaviour of smoke aerosols is essential for interpreting optical depth measurements” to “Understanding the spectral behaviour of smoke aerosol optical properties is essential for interpreting optical depth measurements”.
line 522 - what do the authors mean by spectrally integrated SOD?
Figure 3 - Please verify the top numbers in the vertical colorbar (2502.00 and 5000.00) representing SOD values. From the maps, MERRA-2 AOD higher values were observed in the northern part of the region, while SOD highest values were observed between 39.8° and 40° N at 15:00, moving to the north later, reaching 40.3° N at 21:00, when both AOD and SOD presented similar patterns (six hours later only). From the discussion presented in lines 542 to 552, how do the authors explain the high AOD values, above 1.3, further north at 15:00? As discussed, if MERRA-2 did not fully capture the peak of the fresh fire emission, shouldn’t we expect low AOD values at 15:00 everywhere in the map? Or does that mean that MERRA-2 fire source is located further north? From the color gradient, it seems that the peak of AOD from MERRA-2 is further north outside the presented map. Maps at 15:00 in Figure 4 seems to confirm this.
lines 579-580 - Even though OC/BC ratio is higher during the smoldering combustion phase compared to the flaming, OC concentration is always higher than BC for most of the vegetation types, independently of the combustion phase. According to the review by Reid et al. (2005), the exceptions are forest debris and herbaceous fuel.
Figure 6 - The numerical scale of the vertical colorbar must be verified (Simulated single scattering albedo). SSA can vary only between 0 and 1. The top left map (from 15:00) shows lower SSA values from MERRA-2 in the southeastern portion of the map, increasing towards the northern region. Maps generated for later times also show lower SSA values in the southeastern region. Does it mean that MERRA-2 is not reproducing the smoke event accordingly? If not, maybe it is not a good reference for comparison.
lines 687-688 - Please add the references of the mentioned studies.
Figure 8 - It is not clear what the authors mean by "Fire-weighted smoke absorption", whose value can reach 60000 W/m2, according to the presented scale. Sertã time zone is UTC + 1, thus, the absorbed solar irradiance should be close to zero at 17:00 UTC and zero at 21:00 UTC (i. e., no absorbed irradiance, since no solar radiation is available), as shown in the map of No Fire - Fire change in downwelling flux. In the longwave spectrum, by contrast, please confirm if the correct variable is "Fire-weighted smoke absorption” or “Fire-weighted smoke emission", i. e. the irradiance emitted by the smoke plume due to its higher temperature compared to the surrounding environment.
line 735 - replace "shown” by "shows”.
lines 737-738- Discussing Figure 9, it is mentioned “while CAPE and CIN isolines are superimposed: dashed yellow lines indicate the fire simulation and solid orange lines represent the no-fire scenario”. But in the legend, it says: “Dashed black lines indicate the fire simulation, while dashed orange lines represent the no-fire scenario”. What do the authors mean by “superimposed” in the context? Looking at Figure 9, I couldn’t identify the superposition of CAPE and CIN, since it seems they were plotted separately. How can one distinguish the differences of Fire x No-Fire for CAPE in the profiles? Moreover, it is very difficult to read the information in Figure 9, as the font size is too small (the same for Figure 10). Please, consider increasing the font size.
line 764 - the mentioned wavelength is 400 nm, but in the legend, it says 700 nm.
lines 766 to 768 - The spectral dependency is also a result of the smoke particle size distribution, concentrated in the fine mode.
Citation: https://doi.org/10.5194/egusphere-2025-2495-RC1 -
RC2: 'Comment on egusphere-2025-2495', Anonymous Referee #2, 27 Aug 2025
I have several concerns with this paper – I am recommending a “soft reject” – the paper needs significant modification to be suitable for publication, but with updates and improvements may be publishable. There are important aspects to the methodology which need to be better explained, and some of the analysis seems to be flawed. My detailed comments follow.
Please see the attached pdf file. I needed to include a figure in the review.
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