Midday atmospheric light during Polar Night.

• Main Authors: Jonathan H. Cohen (7958483), Kim S. Last (11581392), Corie L. Charpentier (3200505), Finlo Cottier (749186), Malin Daase (471602), Laura Hobbs (9152223), Geir Johnsen (257802), Jørgen Berge (235355)
• Format: Other Non-Article Part of Journal/Newspaper
• Language: unknown
• Published: 2021
• Subjects: Physiology; Ecology; Inorganic Chemistry; Environmental Sciences not elsewhere classified; Astronomical and Space Sciences not elsewhere classified; Biological Sciences not elsewhere classified; thysanoessa inermis </; therefore question whether; main migratory species; acoustic field observations; 81 ° n; 5 ° n; arctic ocean extends; light measurements demonstrate; characterize light across; weak midday twilight; div >< p; arctic krill (<; arctic polar night; arctic krill; light plays; polar night; zooplankton community; using electroretinogram; traditional definitions; sun ’; subjective night; photophysiological cycles; north pole; midnight sun; maximum extent; lower latitudes; latitudinal gradient; high latitudes; fundamental role; darkest parts; constant darkness; circadian clock; auroral components; although differences; Arctic; Arctic Ocean; Svalbard; North Pole; Rijpfjorden; Arctic krill; Rijpfjord*; Zooplankton; Thysanoessa inermis
• Online Access: https://doi.org/10.1371/journal.pbio.3001413.s001

Spectral irradiance time series measured north of Rijpfjorden, Svalbard (80° 37.79N 22° 4.14E) on January 15, 2017 over midday period. (a) Solar (black) and lunar (red) altitude during measurements. Lunar phase was a waning gibbous moon, full on January 12. (b) Ratio of 492 nm (solar/lunar light at sensitivity maximum of krill) [ 1 ] and both the 557 nm (green) and 630 nm (red) aurora lines [ 2 ]. (c) Time series of E PAR (400 to 700 nm; upper panel) and 492 nm, 557 nm, and 630 nm light (lower panel). (d) Spectral irradiance at 3 time points during the time series shown in (c); with a running mean and 492 nm peaks (black lines), and aurora lines at 557 nm and 630 nm plotted green and red, respectively. For data, see S1 Data . (DOCX)