Measurement report: Ice nucleating abilities of biomass burning, African dust, and sea spray aerosol particles over the Yucatan Peninsula


analyze the results presented in this study. MA, BB, and AD refer to marine aerosol, biomass burning, and African dust, respectively. *two samples were collected at different times during the same day. 

Aerosol Type

Place Date 

MA


Calculation of surface active site density (n s )

The methodology employed in this study is based on Si et al. (2018). a) Calculation of the particle density at the sampling RH (ρ p,RH ) 
𝛒 p,RH = 𝛒 w + (𝛒 p,dry -𝛒 w ) 1 gf 3 (𝐒_𝐄𝟏)
where ρw is the density of water and Ρp,dry is the density of the dry particles. 1.87 g cm -3 was used for marine aerosol (Si et al., 2018), 2.5 g cm -3 for dust mineral particles (Wheeler et al., 2015) and 1.25 g cm -3 for biomass burning particles, it is the average between 1.1 g cm -3 and 1.4 g cm -3 reported by Li et al. (2016). gf 3 is the hygroscopic growth factor. This factor was obtained from Ming and Russell (2001), using the mean relative humidity for Sisal in January (65%) and July (95%), and for Merida in May (65%) and July (90%). The particles were assumed to be composed of 30% of organic species. 
b) Calculation of factor (x) that relates the geometric diameter with the aerodynamic diameter. 
𝐃 𝐚𝐞,𝐑𝐇 = 𝐠𝐟 √ 𝛒 p,RH ᵪ𝛒 0 𝐃 𝐠𝐞𝐨,𝐝𝐫𝐲 = 𝐱𝐃 𝐠𝐞𝐨,𝐝𝐫𝐲 (𝐒_𝐄𝟐) 𝐱 = 𝐠𝐟 √ 𝛒 p,RH ᵪ𝛒 0 (𝐒_𝐄𝟑)
where Dae,RH is the aerodynamic diameter at the sampling RH, Dgeo,dry the dry geometric diameter, ᵪ the dynamic shape factor for a non-spherical particle shape, and ρ0 the unit density of 1 g cm -3 . c) Calculation of n s base on the aerodynamic diameters at a given RH. 



  sample holder, and (c) a schematic diagram of a front view of the sample holder. 


Figure S2 .

 S2 Figure S2. Mass concentration of PM 2.5 and chemical elements by XRF (a) BB K P.C* ≥ 0.60, (b) AD Mg P.C ≥ 0.82, Al P.C ≥ 0.94, Si P.C ≥ 0.94, K P.C ≥ 0.86, Ti P.C ≥ 0.89, Fe P.C ≥ 0.88 and, (c) total carbon concentration for BB and AD. * P.C = Pearson correlation 


Figure S4 .

 S4 Figure S4. Surface active site density (ns) as a function of temperature for (a) MA, (b) BB, 55 and (c) AD. Literature data is shown in gray colors. In panel (a), DeMott et al. (2016) (star), McCluskey et al (2018) (dotted line), Gong et al. (2020) (triangle), Si et al. (2018) (black point), Irish et al. (2019) line, Levin et al. (2019) (asterisk) and the colored squares correspond to the MA samples in this study. In panel (b), Grawe et al. (2016) fly ash dry 




  ] is the concentration of INP, Stot,ae,RH the total surface area based on the aerodynamic diameter at the sampling RH, and Ntot the total number of aerosol particles. 


Figure S1. (a) Cold stage showing the sample holder, the heating block, and the cold block (b) a top 

Supplementary information
Fernanda Córdoba, Carolina Ramirez-Romero, Diego Cabrera, Graciela B Raga, Javier Miranda, Harry Alvarez Ospina, Daniel Rosas, Bernardo Figueroa, Jong Sung Kim, Jacqueline Yakobi-Hancock, Talib Amador, Wilfrido Gutierrez, Manuel García, Allan K Bertram, Darrel Baumgardner, Luis A Ladino
Measurement report: Ice nucleating abilities of biomass burning, African dust, and sea spray aerosol particles over the Yucatan Peninsula