Imagine what you could learn about a far-off landscape by looking at it through a telescope. Now imagine what you could learn by looking at pieces of that landscape through a microscope. What if you did both? What could you learn then?
Chris Arp, hydrology and ecosystems researcher with WERC, thinks you can learn a lot by combining far-off imagery with up-close, in-depth study. His chosen landscapes are lake-rich ones, referred to as lake districts, and thanks to recent funding from the Alaska NASA EPSCoR office at UAF, he’ll conduct research on those landscapes through his project, “Analysis of lake ice-out timing within and among lake districts of Alaska.”
Arp’s project will combine analysis of satellite imagery of numerous lake districts throughout the state with on-the-ground data measurements of lakes in the Minto Flats lake district to gain in-depth knowledge of the characteristics such areas. Specifically, Arp will observe ice-out, or the moment in the spring when lake ice melts or breaks up enough to expose lake waters. Depending on lake size and depth, and spring weather patterns, ice-out can happen over several days or several weeks.
“One of the things we’ll be doing is trying to establish a relationship between the sequences of ice-out timing from large to small lakes and how this progresses among lake districts throughout Alaska,” Arp explained.
Why is that important? Arp said he and other researchers in fields such as hydrology, permafrost and climate change are interested in learning more about various ecosystems and the seasonality of landscape elements such as lakes. Gaining a better understanding of lakes and their interactions with surrounding ecosystems could allow researchers to better predict how those ecosystems will respond to anticipated changes in climate.
Courtesy Chris Arp
A new reseach project led by Chris Arp will take a closer look at ice-out timing among lake districts in Alaska. Previous ice-out data was gathered using satellite imagery.
“Phenology, which involves seasonal timing, like ice-out, is a big one we want to look at because it has important implications to other ecosystem processes,” he said.
The goal is to learn how the timing of lake ice-out varies among these lake-rich regions of Alaska and how this pattern has changed over the last decade. According to his original proposal, Arp’s project aims to answer two “big” questions that fit into NASA’s earth science research mission: 1. How is the global earth system changing? and 2. How will the earth system change in the future?
“We’re tracking how ice-out varies in areas and if it’s changing over time in Alaska,” Arp said.
Keeping track of ice-out timing is important, Arp explained, because it represents an important seasonal threshold that affects the landscape. If this period becomes earlier or later each spring, it may “affect a bunch of different things within the environment,” he said, such as evaporation and energy balance.
Arp categorized the importance of ice-out analysis into three key areas: Climate and energy balance, habitat, and carbon and carbon release.
First, energy balance: “Energy is reflected from the lake (when ice is present) and stored when the lake is ice free,” he said.
More energy stored means higher temperatures and more changes to the habitat in the lake ecosystem.
“It affects the habitat because once lakes become ice-free they are available for migratory water fowl, and temperature changes alter other life conditions, such as for fish and plankton. There is a relevance to quit a few different areas of interest.”
Another key factor is how lakes impact underlying permafrost. Below larger lakes, permafrost thaws. Arp said lakes represent key areas of permafrost degradation, which leads to the release of carbon.
“If lakes become ice free earlier and store more energy, this potentially allows further degradation to occur,” Arp explained, noting the subsequent carbon release is considered a contributor to climate change.
Arp said ice-out timing has already been identified by other researchers as an important response to climate change. Several key studies have documented earlier lake ice-out across Canada and at individual lakes in northern regions worldwide. For his own study, Arp said he will “be looking at a relatively short time period to better understand spatial patterns and processes with the goal of eventually tracking longer term trends in Alaska.”
Arp said he’d like to first understand what ice-out timing is expected to be across lake-rich areas in Alaska, then predict how that may change in the future and track it. Studying lake districts, which he said cover about 16 percent of the state, compared to other landscapes dominated by elements like mountains offers important information. That is partly because landscapes with expansive surface waters may respond differently to climate change, in part because of things like ice.
For Arp, though, the important part is just getting out to do the research.
Courtesy Chris Arp
Satellite images of the Minto Flats lake district, May 2007.
“It’s been a long-time interest of mine to be able to analyze the ice and lake ecosystems in these areas, specifically in Minto Flats because I haven’t done any work there before,” Arp said. “But it is the closest lake district to Fairbanks, so of course it makes sense to set up (field work) there.”
The field work in Minto Flats will offer in-depth datasets for comparison with coarser satellite imagery. Arp plans to use a combination of time lapse cameras and light and temperature sensors placed on the surface of the lakes to record the exact timing of ice-out.
“So we’ll know more exactly when it happens and get a more accurate understanding of the meltout process relative to weather patterns,” Arp said.
Satellite imagery has been used for some time to offer insight into lake ice-out, but Arp explained having “ground-truthing” is really essential for interpretation of observations from the satellite technology.
“For one thing, cloud cover interferes (with this satellite imagery). That’s a major limitation of that approach. You could have a month-long period of cloud cover,” he said. “Also it only works for big lakes because of resolution issues.”
Combining these two approaches will provide depth and breadth: Remote sensing will be conducted on 11 to 20 of the major lake districts in the state (Arp worked with United States Geological Survey researcher Ben Jones to identify the districts in Alaska in 2008). The remote sensing will offer a look at “a bunch of places over a long period of time,” Arp said, and the ground-truthing will offer the in-depth perspective.
Lake districts included in the study will likely include the North Slope, Yukon-Kuskokwin Delta, Denali, Yukon Flats, Koyukuk, the Mat-Su Valley and Kenai. Are explained because many of the more than 400,000 lakes in Alaska are concentrated in these lake districts, these are obvious places to study for projects like his.
The opportunity to see those lake districts first hand is part of what keeps Arp impassioned about his research.
“I’m enthusiastic about all of these lake-rich areas. Eventually I’d like to work in all of the lake districts in the state,” Arp said. “That’s one of my goals.”
Lakes will remain an interesting area of study with regard to climate change, Arp explained, because in boreal and Arctic climates subject to changes in climate, “we expect big changes in patters within the ecosystems such as lake ice-out.” Arp hopes this project will lead to more detailed studies that address how changes in ice-out timing affect other aspects of lake ecosystems and regions where lakes are very abundant.
In the meantime, Arp is happy to explore some of his own motivations for being in the field.
“For me, just getting to be out there, learning how lakes were formed, how they’ve changed over time, that’s the important part,” he said. “Essentially most lakes were created catastrophically, either by glaciers, shifts in rivers, or tectonics. So in areas with so many lakes, I wonder why these different areas came to have so many lakes, how long they will persist and whether new lake districts will be formed elsewhere.”
These musing lead Arp to his own Big Question:
“So I wonder, or try to understand, what are these lake districts going to look like 10,000 years from now? I think that’s just fascinating.”
