DOI: 10.1594/pangaea.951091
title: Pond measurements of ice and snow thickness, temperature profile and solar radiation in 2021, close to Lake Elmo

description: Continuous observations were made of ice thickness, snow thickness, ice, and water temperatures at 1 ft increments of levels in the pond from surface to bottom, ambient temperatures above the ice surface, incoming shortwave and longwave radiation of the test and control sections. The observations were made from January 13, 2021 to March 20th 2021. The pond used for these observations is situated near Lake Elmo, Minnesota, USA. The pond consists of an artificial excavation lined with 0.045 EDPM film over a geofabric base. The shape is essentially conical with a nominal diameter of 100 ft, depth of 6 ft, and a slope of 1 to 4. A simple bisection using plastic sheeting was made to provide for a single control section and a single test section. The data was collected to experimentally determine effects of surface albedo modification on ice melt and thermodynamic processes of a freshwater pond. In this experiment we applied a coating of reflective hollow glass microspheres to a test section, while leaving a control section unmodified. The data was used to compare the rates of ice melt, albedo and pond water and ice temperatures and energy changes of the test and control section to determine the effectiveness of the surface albedo modification using hollow glass microspheres. To collect data, we used nominally identical sets of instruments for the test and control sides of the pond, to measure temperature, incoming and reflected longwave and shortwave radiation, ice thickness. Each suite was made up of a Raspberry Pi 4B+, two strings of DS18B20 temperature sensors, an apogee SN-500 net radiometer as well as an ice thickness gauge made up of an upwards facing blue robotics Ping sonar positioned in the water below the ice and a snow thickness gauge made up of a downwards facing MaxBotix in-air ultrasonic sensor. The radiometers were positioned on suspension cables along the southwest-northeast axis of the pond about 1 m above the ice and about 4,5 m from the center of the pond. The ice thickness gauges were each positioned about 3.3 meters from the pond center, towards the north on the control side and towards the west on the test side. The temperature sensor strings were of different lengths and designed to measure the temperature of the water in the deeper and more shallow areas of the pond. The longer string used for the deeper, more central area was made up of 7 temperature sensors, one in air close to the termination at the Raspberry Pi, and then 6 others coming up from the bottom each spaced about a foot from one another. The deep sensor strings were deployed through holes drilled in the ice about 2.4 m from the center in the southwest and northeast directions. The strings were positioned so that the topmost sensor of the bottom 6 was at the ice-air interface when testing began in January, and the bottom most sensor was weighed down and close to the bottom.. The shorter temperature sensor string was made up of 4 temperature sensors, each spaced about a foot from one another and positioned closer to the edge of the pond where the topmost sensor was at the ice-air interface and the bottom sensor was close to the bottom. These shallower sensor strings were again deployed via holes drilled in the ice, at about 5.5 m from the pond center in the same directions.