Toward the Detection of Permafrost Using Land-Surface Temperature Mapping

Jigjidsurengiin Batbaatar,Alan R Gillespie,Rivka Amit,Gregg Petrie,Ronald S Sletten,Lu Liu,Darío Trombotto Liaudat,Amit Mushkin

doi:10.3390/rs12040695

Abstract

Permafrost is degrading under current warming conditions, disrupting infrastructure, releasing carbon from soils, and altering seasonal water availability. Therefore, it is important to quantitatively map the change in the extent and depth of permafrost. We used satellite images of land-surface temperature to recognize and map the zero curtain, i.e., the isothermal period of ground temperature during seasonal freeze and thaw, as a precursor for delineating permafrost boundaries from remotely sensed thermal-infrared data. The phase transition of moisture in the ground allows the zero curtain to occur when near-surface soil moisture thaws or freezes, and also when ice-rich permafrost thaws or freezes. We propose that mapping the zero curtain is a precursor to mapping permafrost at shallow depths. We used ASTER and a MODIS-Aqua daily afternoon land-surface temperature (LST) timeseries to recognize the zero curtain at the 1-km scale as a “proof of concept.” Our regional mapping of the zero curtain over an area around the 7000 m high volcano Ojos del Salado in Chile suggests that the zero curtain can be mapped over arid regions of the world. It also indicates that surface heterogeneity, snow cover, and cloud cover can hinder the effectiveness of our approach. To be of practical use in many areas, it may be helpful to reduce the topographic and compositional heterogeneity in order to increase the LST accuracy. The necessary finer spatial resolution to reduce these problems is provided by ASTER (90 m).

Highlights

Permafrost, defined as ground that stays below freezing for more than two years, is an integral part of the cryosphere that is predicted to rapidly degrade under current warming climatic conditions (e.g., [1,2])
We developed an algorithm in the MATLAB environment that analyzes the daily Moderate Resolution Imaging Spectroradiometer (MODIS) land-surface temperature (LST) during the first and second six months of the year at each pixel, and tests whether the daily LST satisfies the following rules indicating the occurrence of a zero curtain: (1) LST must be between −3.5 and 3.5 ◦C; (2) The number of consecutive zero-curtain LSTs must be >3; (3) The number of days with missing data between two identified zero-curtain LSTs must be 5
2 PM is near the peak of the diurnal temperature cycle, and thin ice films forming at night will likely not register

Summary

Introduction

Permafrost, defined as ground that stays below freezing for more than two years, is an integral part of the cryosphere that is predicted to rapidly degrade under current warming climatic conditions (e.g., [1,2]). The loss of permafrost affects the regional water balance and changes landscapes and ecosystems in cold regions. Traditional mapping and monitoring techniques of permafrost are accurate but are presently labor-intensive and rely on interpolating small numbers of locally measured data across large areas in order to study regional-scale processes. Remote sensing addresses this difficulty by making spatially dense measurements over vast regions. Previous remote sensing studies have inferred permafrost extent from the instantaneous zero isotherm at the land surface or from changes in the dielectric marking the phase transition of liquid water to ice [8,9,10]

Methods

Results

Conclusion