DOI: 10.17604/jmtk-yb12
title: Data for atmospheric transport of North African dust-bearing supermicron freshwater diatoms to South America: implications for iron transport to the equatorial North Atlantic Ocean

description: The equatorial North Atlantic Ocean (NAO) is a nutrient-limited ecosystem that relies on the deposition of long-range transported iron (Fe)-containing aerosols to stimulate primary productivity. Using microscopy, we characterized supermicron and super-coarse mode African aerosols transported to the western NAO in boreal winter/spring. We detected three particle types including African dust, primary biological aerosol particles, and freshwater diatoms (FDs). FDs contained 4% Fe by weight due to surficial dust inclusions that may be susceptible to chemical processing and dissolution. FDs were typically larger than dust particles and comprised 38% of particles between 10 and 18 μm in diameter. The low density, high surface-area-to-volume ratio, and large aspect ratios of FD particles suggest a mechanism by which they can be carried great distances aloft. These same properties likely increase the residence time of FDs in surface waters thereby increasing the time for Fe dissolution and their potential impact on marine biogeochemical cycles.

This data is associated with the article: Barkley, A.E., Olson, N.E., Prospero, J.M., Gatineau, A., Panechou, K., Maynard, N.G., China, S., Ault, A.P. & Gaston, C.J. (2021). Atmospheric transport of North African dust-bearing supermicron freshwater diatoms to South America: implications for iron transport to the equatorial North Atlantic Ocean. Accepted to Geophysical Research Letters (GRL).
description: ## Description of the datasets
The `data/` folder contains three data sets. `ds01` contains information regarding sampling collection dates and times. `ds02` contains particle diameters for each particle analyzed in this study. `ds03` contains the data used to make Figure 4 in the main manuscript. 

## Metadata of the trajectory file
ds01 is a *csv* file that contain 7 columns. Column 1 names the sampling location, whereby 'CAY' represents Cayenne, French Guiana. Column 2 and 4 show the start and end date of collection, respectively, and is in the format dd-mmm-yy (e.g. 04-feb-16). Columns 3 and 5 show sample collection start and stop time, respectively, and is in local time to Cayenne, French Guiana (GMT-3) in the format 'HH:MM' (e.g. 14:33). NA represents data that is not available.  Column 6 shows the total air volume pulled for each sample and is in meters cubed (m^3). Column 7 shows dust mass concentration for each sample (micrograms per meter cubed (ug m^-3).

ds02 is a *csv* file that contains 3 columns. The first column names the particle type. The second column gives particle length along the longest axis (Dmax) in micrometers (um). Column 3 shows projected area diameter (Dpa) in micrometer (um). Column 4 shows aerodynamic diameter (Da) in micrometer. Further discussion of Dmax, Dpa, and Da is located in Section S2.2 in the Supporting Information.

ds03 is a *csv* file that contains 3 columns. Column 1 contains particle type. Column 2 shows particle length along the longest axis (Dmax) in micrometer (um) and the width (W) of the particle at the longest axis that is perpendicular to Dmax in micrometer (um).