Abstract

Abstract. The Tibetan Plateau (TP) has the largest areas of permafrost terrain in the mid- and low-latitude regions of the world. Some permafrost distribution maps have been compiled but, due to limited data sources, ambiguous criteria, inadequate validation, and deficiency of high-quality spatial data sets, there is high uncertainty in the mapping of the permafrost distribution on the TP. We generated a new permafrost map based on freezing and thawing indices from modified Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperatures (LSTs) and validated this map using various ground-based data sets. The soil thermal properties of five soil types across the TP were estimated according to an empirical equation and soil properties (moisture content and bulk density). The temperature at the top of permafrost (TTOP) model was applied to simulate the permafrost distribution. Permafrost, seasonally frozen ground, and unfrozen ground covered areas of 1.06 × 106 km2 (0.97–1.15 × 106 km2, 90 % confidence interval) (40 %), 1.46 × 106 (56 %), and 0.03 × 106 km2 (1 %), respectively, excluding glaciers and lakes. Ground-based observations of the permafrost distribution across the five investigated regions (IRs, located in the transition zones of the permafrost and seasonally frozen ground) and three highway transects (across the entire permafrost regions from north to south) were used to validate the model. Validation results showed that the kappa coefficient varied from 0.38 to 0.78 with a mean of 0.57 for the five IRs and 0.62 to 0.74 with a mean of 0.68 within the three transects. Compared with earlier studies, the TTOP modelling results show greater accuracy. The results provide more detailed information on the permafrost distribution and basic data for use in future research on the Tibetan Plateau permafrost.

Highlights

  • Permafrost is a major component of the cryosphere and is sensitive to climate changes (Wu et al, 2002b; Haeberli and Hohmann, 2008; Li et al, 2008; Gruber, 2012)

  • Relative to the two benchmark maps, the Tibetan Plateau (TP)-2016 result driven by the processed Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperatures (LSTs) in this paper was very sensitive to seasonally frozen ground formed by surface water, and the results show that there are many seasonally frozen ground areas surrounding lakes and major rivers that correspond to the previous studies (Lin et al, 2011; Niu et al, 2011)

  • This study exploited the advantages of the medium spatiotemporal resolution of MODIS LST products to construct a database of mean daily LST of the TP

Read more

Summary

Introduction

Permafrost is a major component of the cryosphere and is sensitive to climate changes (Wu et al, 2002b; Haeberli and Hohmann, 2008; Li et al, 2008; Gruber, 2012). Permafrost and its dynamics complicate the water and energy exchange between soil and atmosphere and thereby introduce greater uncertainty into global climate models (GCMs) that predict climate change (Romanovsky et al, 2002; Smith and Riseborough, 2002; Cheng and Wu, 2007; Riseborough et al, 2008; Zhao et al, 2010). To generate better quantitative simulations, a more accurate TP permafrost distribution is needed. An accurate contemporary permafrost distribution map is important as a baseline with which to estimate future permafrost degradation. A significant amount of research has been conducted on the permafrost distribution of the TP, and many permafrost maps have been compiled to evaluate the distribution and thermal states of permafrost

Objectives
Methods
Results
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call