the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Modelling of atmospheric concentrations of fungal spores: a two-year simulation over France using CHIMERE
Abstract. Fungal spore organic aerosol emissions have been recognised as a significant source of particulate matter as PM10; however, they are not widely considered in current air quality models. In this work, we have implemented the parametrisation of fungal spore organic aerosol (OA) emissions introduced by Heald and Spracklen (2009) (H&S) and further modified by Hoose et al. (2010) in the CHIMERE regional chemistry-transport model. This simple parametrisation is based on two variables which are leaf area index (LAI) and specific humidity. We have validated the geographical and temporal representativeness of this parametrisation on a large scale by using yearly polyol observations and primary biogenic organic aerosol factors from PMF analysis at 11 French measurement sites. For a group of sites in northern and eastern France, the seasonal variation of fungal spore emissions, displaying large summer and small winter values, is correctly depicted. However, the H&S parametrisation fails to capture fungal spore concentrations for a smaller group of Mediterranean sites with less data availability both in terms of absolute values as well as seasonal variability, leading to strong negative biases especially during the autumn and winter seasons occur. Two years of CHIMERE simulations with the H&S parametrisation have shown a significant contribution of fungal spore OA to PM10 mass, lower than 10 % during winter, and reaching up to 20 % during summer in high emission zones, especially over large forested areas. In terms of contribution to organic matter (OM) concentrations, the simulated fungal spore contribution in autumn is as high as 40 % and reaches at most 30 % of OM for other seasons. As a conclusion, the fungal spore OA contribution to total OM concentrations is shown to be substantial enough to be considered as a major PM10 fraction and shall then be included in state-of-the-art chemistry transport models. The H&S parametrisation shows satisfactory results over northern and eastern France, but may underestimate concentrations for Mediterranean areas that may indicate missing factors influencing emissions or a missing source of spores.
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Status: open (until 28 May 2024)
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RC1: 'Comment on egusphere-2024-698', Anonymous Referee #1, 23 Apr 2024
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This manuscript explores fungal spore concentrations over France. The paper describes efforts: (1) to implement an existing scheme for fungal spores into the regional CHIMERE model (2) to evaluate the resulting simulation with 2 years of surface observations from 11 diverse sites in France and (3) to estimate the importance of this source to total OA and PM10. The objective and methods are straight-forward and the results are generally clearly described. I provide suggestions largely to clarify the methods and results.
- Line 43: suggest replace “shall” with “should”
- Lines 44-47: This abstract text is repetitive, and I recommend it be cut.
- Line 51: Inappropriate references for the text. The two references use AMS observations which measure particles less than ~1 um, not PM10. Pai et al. do not show an underestimate of in situ observations.
- Line 90: typo? Remove “the variability”
- Lines 113-114: The number of data points seems like excessive detail that bogs down the introduction
- Line 179-182: PMF is also commonly used for source apportionment of online measurements (such as AMS). Suggest you re-phrase.
- Table 1: Provide units or more details in caption for the column “PMF” and “Polyols”. Are these number of samples?
- Line 231: The reference Fountoukis and Nenes (2007) refers to ISORROPIA II – either correct the text to refer to this version or cite the original reference for ISORROPIA I
- Section 2.2.1: should also describe the simulation of other PM10 components (e.g. BC, dust, sea salt) since PM10 simulations are included in the manuscript.
- Table 2: This provides extraneous or duplicative information from the text. Suggest cut.
- Line 271: reference for this sentence?
- Equation 1: why are there multiple constants (c, 5, 1.5x10-2) rather than integrating these into a single constant?
- Line 291: please include units for density
- Lines 290-292: What size of fungal spore is assumed for this conversion? Are the spores treated as a size distribution or monodisperse?
- Line 298: are the fungal spores treated as soluble?
- Section 3.1 discussion of lifetime: Lifetime depends on the assumed size and solubility of the aerosol. These model assumptions should be described (see previous comments) and the lifetime diagnosed for the specific simulation. In particular, line 341 “Despite little transport” has not been shown. Are there any spores aloft in the simulation? Any transported to the eastern boundary of the domain?
- Line 445: It seems odd to end the discussion of Figure 4 without discussing the outliers Aix and Nice. This comes later in the text, so the authors may wish to explicitly tell the reader that they will discuss these outliers in Section 3.2.2, or move this discussion forward.
- Line 460: why do the authors use MFE here when using MFB in Figure 4. I suggest harmonizing for consistent statistical metrics.
- Figure 5 and lines 539-546: Please include all sites with long-term measurements discussed in the text in Figure 5.
Citation: https://doi.org/10.5194/egusphere-2024-698-RC1
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