A SPATIO-TEMPORAL FRAMEWORK FOR MODELING ACTIVE LAYER THICKNESS
Other literature type
Streletskiy, D. A.
Nelson, F. E.
Apanasovich, T. V.
(issn: 2194-9050, eissn: 2194-9050)
The Arctic is experiencing an unprecedented rate of environmental and climate change. The active layer (the uppermost layer of soil
between the atmosphere and permafrost that freezes in winter and thaws in summer) is sensitive to both climatic and environmental
changes, and plays an important role in the functioning, planning, and economic activities of Arctic human and natural ecosystems.
This study develops a methodology for modeling and estimating spatial-temporal variations in active layer thickness (ALT) using data
from several sites of the Circumpolar Active Layer Monitoring network, and demonstrates its use in spatial-temporal interpolation.
The simplest model’s stochastic component exhibits no spatial or spatio-temporal dependency and is referred to as the naïve model,
against which we evaluate the performance of the other models, which assume that the stochastic component exhibits either spatial or
spatio-temporal dependency. The methods used to fit the models are then discussed, along with point forecasting. We compare the
predicted fit of the various models at key study sites located in the North Slope of Alaska and demonstrate the advantages of space-time
models through a series of error statistics such as mean squared error, mean absolute and percent deviance from observed data. We find
the difference in performance between the spatio-temporal and remaining models is significant for all three error statistics. The best
stochastic spatio-temporal model increases predictive accuracy, compared to the naïve model, of 33.3%, 36.2% and 32.5% on average
across the three error metrics at the key sites for a one-year hold out period.