PIC v1.3: comprehensive R package for computing permafrost indices with daily weather observations and atmospheric forcing over the Qinghai–Tibet Plateau
An R package was developed for computing permafrost indices (PIC v1.3) that integrates meteorological observations, gridded meteorological datasets, soil databases, and field measurements to compute the factors or indices of permafrost and seasonal frozen soil. At present, 16 temperature- and de...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-06-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://www.geosci-model-dev.net/11/2475/2018/gmd-11-2475-2018.pdf |
| Summary: | An R package was developed for computing permafrost indices (PIC v1.3) that integrates meteorological observations, gridded
meteorological datasets, soil databases, and field measurements to compute
the factors or indices of permafrost and seasonal frozen soil. At present, 16
temperature- and depth-related indices are integrated into the PIC v1.3 R package
to estimate the possible trends of frozen soil in the Qinghai–Tibet Plateau
(QTP). These indices include the mean annual air temperature (MAAT), mean
annual ground surface temperature (MAGST), mean annual ground temperature
(MAGT), seasonal thawing–freezing <i>n</i> factor (<i>n</i><sub>t</sub>∕<i>n</i><sub>f</sub>),
thawing–freezing degree-days for air and the ground surface
(DDT<sub>a</sub>∕DDT<sub>s</sub>∕DDF<sub>a</sub>∕DDF<sub>s</sub>),
temperature at the top of the permafrost (TTOP), active layer thickness (ALT),
and maximum seasonal freeze depth. PIC v1.3 supports two computational modes,
namely the stations and regional calculations that enable statistical
analysis and intuitive visualization of the time series and spatial
simulations. Datasets of 52 weather stations and a central region of the QTP
were prepared and simulated to evaluate the temporal–spatial trends of
permafrost with the climate. More than 10 statistical methods and a
sequential Mann–Kendall trend test were adopted to evaluate these indices in
stations, and spatial methods were adopted to assess the spatial trends.
Multiple visual methods were used to display the temporal and spatial
variability of the stations and region. Simulation results show extensive
permafrost degradation in the QTP, and the temporal–spatial trends of the
permafrost conditions in the QTP are close to those of previous studies. The
transparency and repeatability of the PIC v1.3 package and its data can be
used and extended to assess the impact of climate change on permafrost. |
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| ISSN: | 1991-959X 1991-9603 |