Lake Bonney Autonomous Lake Profiler and Samplers (ALPS): Photosynthetically Active Radiation

Abstract:

Knowledge of the McMurdo Dry Valley (MDV) lakes is limited by winter access, a period which is most relevant in understanding the habitability of other icy worlds and critical to understanding the overall function of these lakes. Owing to the lack of winter access, data that normally require human presence are incomplete. Our goal was to conduct the first year-round investigation of the biogeophysics of these unique lakes. An important part of the McMurdo Long Term Ecological Research (LTER) is evaluating carbon and nitrogen budgets in perennial ice-covered lakes. This data set addresses this core area of research and quantifies the intensity of photosynthetically active radiation (PAR) at specific depths in McMurdo Dry Valley lakes.

Dataset ID:

304

Associated Personnel:

769

770

771

772

773

774

775

Short name:

LIMNO_ALPS_PAR

Data sources:

ALPS_PAR_ELB

ALPS_PAR_WLB

Methods:

Through the ice, wire-walking profilers (McLane Labs Ice Tethered Profilers [ITPs]) were deployed in both lobs of Lake Bonney. Attached to the ITPs was a photosynthetically active radiation sensor (Biospherical instruments Model QCP23000). The ITPs were programmed to profile once daily around regional solar noon. A profile consisted of one downward and one upward movement to the furthest reach of the profilers possible movement, or the bottom of the lake or bottom of the ice, whichever limit came first. During the profiles, conductivity, temperature, salinity and dissolved oxygen readings were recorded every 10 seconds. To convert the raw sensor readings (recorded in sensor output units, millivolts), manufacturer calibration coefficients and fit equations were used.

Instrumentation:

Biospherical instruments Model QCP23000McLane Labs Ice Tethered Profilers