Abstract:

Sunlight irradiance is a source of energy for life on Earth but it can also be a stressor at high dose; marine systems are no exception. Irradiance varies spatially, temporally and with the water bio-optical characteristics and depth, and this variability is expected to increase with climate change. Therefore, quantifying the exposure of living organisms or of particles in the ocean is key to accurately address light-related processes affecting them. Yet, current irradiance exposure estimates are static and neglect the movements of ocean currents or of organisms controlling their vertical distribution. This dataset was generated with the first numerical model capable of tracking the cumulative irradiance of moving particles in a moving ocean. Our novel biophysical modeling framework explicitly estimates the exposure to solar energy irradiance by encompassing ocean circulation modeling output, individual particles’ behavior, and time-varying irradiance from a global environmental model. Several examples of particle trajectories and their exposure to UV radiation are provided for five regions of the global ocean. One set of simulations models virtual organisms, with and without diurnal vertical migration (DVM), which are released as a cohort and tracked for seven days. An additional simulation modeled the passive drift of particles, such as microplastics, drifting in the ocean. In this case, the particles were released in a transect across the Atlantic and tracked for a full year.

Suggested Citation:

Faillettaz, Robin, Ana C. Vaz, Christina Pasparakis, Martin Grosell, and Claire B. Paris. 2021. Effect of trajectory on particles' cumulative solar radiation exposure simulated by the Connectivity Model System (CMS) model, 2018-01-15 to 2018-12-30. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/X8GVY03Y

Purpose:

The in-situ estimates of UV-exposure in the upper ocean have been limited to either discrete one-dimensional (1D) local measurements or large-scale two-dimensional (2D) averaging, reducing local Spatio-temporal variability. We provide a modeling framework to understand oceanic particles’ cumulative responses to solar radiation, combining realistic radiation levels and the motion of both the particles and their environment.

Data Parameters and Units:

Time [YYYY-MM-DD HH:MM:SS], longitude [degrees], latitude [degrees N], depth [m], dist (distance traveled, [km]), exitcode (particle status, [0 to -5]), releaseDate [YYYY-M-DD HH:MM:SS], ID [numeric], simulation (alpha label including region and DVM or NoDVM), releasedepth [m], dvm (diurnal vertical migration, [DVM or release depth]), region [Nor, AtlW, AtlE, Ind, Atlantic Gyre, Pac], uva (UVA radiation, [W/m^2]).

Methods:

We developed a four-dimensional Lagrangian biophysical model that incorporates the time-varying irradiance from the NAVy Global Environment Model (NAVGEM; Hogan et al., 2014), the ocean transport and turbulence from the Mercator Global ¼° model, and particles’ characteristics and behavior. Using in-situ measurements of UV-A in the upper ocean from BGC (Biogeochemical-Argo) floats, we estimate the UV-A penetration in the water column of five regions: the Nordic Sea (NOR), the Sargasso Sea (western Atlantic, ATLW), the eastern equatorial Atlantic (ATLE), the equatorial Pacific (PAC) and the southern Indian Ocean (IND). We modeled moving planktonic propagules undertaking diel vertical migrations and abiotic particles persisting in the environment (such as microplastics), all of which may be affected by projected increases in UV radiation reaching Earth’s surfaces. The diel vertical migration (DVM) was modeled as a probability distribution, with 50% of the population at or above 5 m and all above 15 m; rise rates of 0.33 cm/s resulted in a maximum travel time of 2.5 hours from 30 m, the deepest position of particles during the day. The UVA exposure was implemented as the annual mean attenuation coefficient, modeled as a linear regression of the measured radiation at a particular wavelength (380 nm for UVA) against pressure. The five oceanic regions were bounded as Nordic Seas: 60°N to 73°N and 0°E to 20°E; West Atlantic: 19°N to 29°N and 58°W to 68°W; East Atlantic: 6°N to 16°N and 21°W to 31°W; Pacific: 13°S to 23°S and 148°W to 158°W; and South Indian: 44°S to 54°S and 70°E to 80°E. The NAVGEM atmospheric forcing model is located at https://www.hycom.org/dataserver/navgem and the Mercator Global ¼° model at https://datastore.cls.fr/catalogues/mercator-model-psy3v3/. The solar radiation module code for CMS will be available at Github. The main CMS code may be found at github.com/beatrixparis/connectivity-modeling-system.

Provenance and Historical References:

Hogan, T.F., Liu, M., Ridout, J.A., Peng, M.S., Whitcomb, T.R., Ruston, B.C., Reynolds, C.A., Eckermann, S.D., Moskaitis, J.R., Baker, N.L. and McCORMACK, J.P., 2014. The navy global environmental model. Oceanography, 27(3), pp.116-125.

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