Baker: Glacier Monitoring Internship Report: Grand Teton National Park, GLACIER MONITORING INTERNSHIP REPORT: GRAND TETON NATIONAL PARK, 2015 EMILY BAKER UNIVERSITY OF COLORADO-BOULDER BOULDER, CO BACKGROUND is changing. A series of high-snow winters and cloudy, The small glaciers of Grand Teton National cool summer years cause glaciers to grow, while low- Park (GTNP) are iconic landmarks, enhancing the snow winters and clear, hot summer years cause experience of millions of visitors to the park each year. glaciers to shrink. Changes in glacial extent and They are valuable far beyond their beauty, and play a volume are good indicators of multi-year climate critical role in the park’s unique high-elevation trends. ecosystems. Recent studies of glacial extents in GTNP Glaciers act as water towers of the mountain show significant and rapid retreat of glaciers in all ecosystem, storing winter precipitation as ice which areas. On-the-ground estimates of glacier volume, can be utilized slowly over the summer months, as it yearly volume changes and glacial motion are not yet slowly melts to become runoff. Glacial melt controls studied; this research aims to fill this gap. Here, we stream temperatures, enhances late-season streamflow detail the development of a simple mass-balance volumes, and is a critical input for many high- (overall ice melt or accumulation) monitoring protocol elevation plant and animal communities. Additionally, for reference glaciers in GTNP, using readily available change in glacier volume serves as a multi-year record equipment currently owned by GNTP, which can be of climate, and gives a stark illustration of how climate performed in-house, with existing NPS expertise and equipment. Published by Wyoming Scholars Repository, 2015 1 University of Wyoming National Park Service Research Center Annual Report, Vol. 38 [2015], Art. 20 MEASUREMENT OBJECTIVES Glacier Size o What is the volume of the glacier? o What is the surface area of glacier? Change in Volume o How much did the glacier grow or melt, since last measured? o Why: summer temperatures, date of snow melt-off, or incoming sun (cloudiness)? Movement o Is the glacier moving? If not, it is no longer technically a glacier, but stagnant ice. o How far did it move? o What time of year did it flow fastest? TOOLS Repeat photo monitoring points Thermistors (air temperature sensors) Pyranometer (solar radiation / sunlight energy sensor) Time lapse cameras (daily photos) 2 Baker: Glacier Monitoring Internship Report: Grand Teton National Park, Energy Balance Melt Modeling [푇퐹 + 푆푅퐹(1 − 훼)퐺]푇 푇>푇푡 푀 = { 0 푇<푇푡 Vs. Sun Air Temperature Mapping grade GPS: Geo X7 METHODS this surface from year-to-year allows for calculation of change in volume. Glacier areal extent Absolute volume of the glacier can be Glacier area can be mapped in three ways: determined with use of a Ground Penetrating Radar using remotely sensed aerial imagery (i.e., satellite, or unit, which maps the depth to bedrock underneath the airplane), using orthorectified ground-based ice. Cooperation with partners at the University of photography (i.e., repeat photo monitoring points), or Colorado is pending to use a GPR unit in the Fall 2015 directly mapping glacier margins with a GPS unit. survey of Middle Teton Glacier, and thus map the Recent research has used available historical aerial bedrock and measure true glacier volume. Bedrock photography (Reynolds 2012, Tootle 2010) but needs to be mapped only once with a GPR; subsequent reported difficulties distinguishing ice from snow, and years with different ice surfaces will still have the remained unable to correlate change in glacier area same underlying bedrock surface. Ideally, a GPR with available climate forcings (PRISM). Our survey would be completed at each glacier of interest, deployment of high-elevation, glacier-adjacent for knowledge of true remaining ice volume. temperature sensors and pyranometer will allow for However, estimates of ice volume change are not partitioning of observed melt into that caused by affected by knowing absolute size of the glacier. higher air temperatures vs. incoming shortwave solar Rather, knowledge of absolute volume allows for radiation, and additionally allow for re-analysis of better estimates of glacial longevity (i.e., how long it PRISM data, with the potential of using enhanced will likely survive, under current or projected climate PRISM to review and improve this earlier work on conditions). Melt rates and ice volume are the two key historical glacial area change. variables needed to estimate how long a glacier will survive. Change in glacier area can be analyzed as frequently as data are available: either whenever late- Glacier movement season (early September) aerial imagery is flown; yearly, based upon field photo-monitoring points; or A glacier is defined by its motion; a glacier yearly, based upon field-surveyed GPS glacial which is no longer flowing is technically a body of margins. stagnant ice (also known as perennial snow and ice), and no longer a glacier. Recent studies on GTNP Glacier volume and volume change glaciers have focused on aerial extent, and not motion. We do not currently know how fast the glaciers are Surface elevations on reference glaciers will flowing, or even if flow is occurring at all. This is be taken with a GPS survey on an annual basis, or especially true of rock-covered glaciers (Petersen) and multi-year basis, as GIS and Climbing Ranger staff portions of glaciers which are rock covered (lower time allows. A high density of points collected on the lobe of the Middle Teton Glacier), where crevasses glacier surface allows for computation of a complete, (also an indicator of recent motion) cannot be interpolated glacier surface elevation. Comparison of observed. Motion will be quantified using time lapse Published by Wyoming Scholars Repository, 2015 3 University of Wyoming National Park Service Research Center Annual Report, Vol. 38 [2015], Art. 20 photography. Moultrie brand time-lapse cameras have melting, even if the summer was quite cloudy? We can been deployed at glaciers of interest, during the answer these questions using two known inputs: summer of 2015, at stable locations, allowing for incoming solar radiation (measured at the Lower continuous monitoring of the glacier from a static Saddle & Kelly Teton Science School pyranometers), point. The cameras are programmed to take three daily and high-elevation air temperature (our adjacent photos, which should yield at least one per day where thermistors). With these, we can construct a modified clouds do not obscure the field of view. Compiling degree day glacier melt model. Academic researchers daily images gives a time-lapse video of glacier commonly apply full energy-balance models motion and melting over the course of the summer – containing information on latent heat fluxes, longwave including dates when snow melts from the surface of radiation, and surface albedo, but that work is beyond the glacier, and ice (as opposed to seasonal snow) the scope of this project, mostly due to increased cost begins melting. Measurement of two fixed points in of instrumentation, and higher uncertainties associated image background, and distance from camera, will with model parameterization (including estimates of allow calculation of flow rates, using basic surface roughness, surface emissivity, and other trigonometry. quantities that are difficult to measure accurately in the field). Additionally, glacier movement will be measured directly using markers placed on the ice Temperature-index models are widely used surface. Rocks wrapped with surveyor’s tape were operationally, by NOAA and the USGS for snowmelt placed on the surface of the Middle Teton Glacier on runoff forecasting. A modified degree day model July 2, 2015, and their location measured with the allows for use of a temperature-indexed model, while mapping grade GPS unit. Measuring the location of incorporating information about incoming solar these fixed points on the glacier’s surface will allow radiation and allowing us to partition melt into that calculation of annual flow at 3 fixed points along its caused primarily by higher temperatures from that surface, and provide a check on the accuracy of photo- caused by incoming sunlight energy. A modified derived estimates of motion. Depending on the degree day model has far lower data requirements than frequency of surface marker re-visitation, sub-annual an energy-balance model, incorporates data on solar measurement of flow rate can be calculated, radiation – known to be the dominant source of melt approximate timing of maximum flow rate can be energy on most glaciers— and has a stronger physical determined, and potentially correlated with climate basis than simple temperature-only index models. variables (solar radiation and air temperature). High Additionally, the inclusion of a solar input term has flow rates are known to coincide with times where been shown to improve melt modeling substantially more melt is present at the glacier’s bed surface, across varied ecosystems (e.g., Hock 1999, Pellicotti lubricating bedrock friction and speeding flow. 2005). Knowing timing of maximum flow rates would give information on the timing of maximum glacial melt. This modeling portion of the project is under Otherwise, glacial melt volumes are measured only development in conjunction with collaborators at the once per year, with information available on timing of Institute of Arctic and Alpine Research (INSTAAR) at maximum melt rates. the University of Colorado, and the North Cascades National Park Service Complex (NOCA). Its Determining the cause of melt— Modified degree development will follow collection of data from day modeling summer 2015, and will take a form similar to [푇퐹 + 푆푅퐹(1 − 훼)퐺]푇 푇>푇푡 Multiple years of surface elevation 푀 = { measurements on index glaciers allows us to calculate 0 푇<푇푡 changes in ice volumes. The first surface elevation survey was conducted on Schoolroom Glacier in where TF and SRF are empirical coefficients for summer 2014; the second will be conducted on Middle temperature factor and shortwave radiation factor, G is Teton Glacier in summer 2015.