Glacier algal abundance, photophysiology, pigmentation, bio-optical properties growth and impacts to albedo in the Greenland Ice Sheet Dark Zone, July-August 2016

Instrumentation: Algal cell abundance was quantified using a Fuchs-Rosenthal haemocytometer (Lancing, UK) on a LeicaDM 2000 epifluorescence microscope with attached MC120 HD camera (Leica, Germany). Photophysiology was assessed using a Water-PAM fluorometer with attached cuvette system (Walz GmBH, Germany). Algal pigmentation was assessed using a combination of High-Performance Liquid Chromatography (HPLC) using an Agilent 1100 HPLC equipped with a diode-array detector, and spectrophotometric wave-scans using a WPA Light-Wave II UV/Visible spectrophotometer (Biochrom, UK). Albedo modelling was achieved using the radiative transfer model BioSNICAR-GO. GrIS surface ice broadband albedo for June, July and August 2016 were derived from clear-sky MODIS MOD10A1 satellite observations at 500 m horizontal resolution. Glacier algal biomass was modelled in GrIS surface ice forced by hourly snowpack thickness, shortwave-down radiation and air temperature from re-analysis outputs produced by the regional climate model MARv3.8.1 forced with ERA -Interim at 20km resolution.