# Assessment of Frost Depth and Frost Heave in Romania
## 5 Conclusions  
Evaluating soil frost depth is difficult because direct measurements of frost depth are not widely available and those that are available do not date back very far. As frost depth is closely linked to air temperatures, an index that measures how often, and by how much, air temperatures remain below freezing through the winter can serve as a useful proxy measurement for frost depth. The isolines/maps were smoothed using the kriging method. Some caution should be used with spatially interpolated results. The most recognized flaw in this method is that interpolation assumes that the spatial area is homogeneous across the surface.  
The statistical models were calibrated by taking into consideration the yearly average temperatures (Official Gazette of Romania by ANM), the location (geographical coordinates and altitudes for 3186 administrative-territorial units retrieved from the Global Multi-Resolution Terrain Elevation Data 2010), and the average temperature of the coldest quarter for all administrative units of Romania (ECMWF COPERNICUS REPORT, global bioclimatic indicators from 1979 to 2018 derived from reanalysis).  
An accurate estimate of maximum soil frost depth allows for reduced construction costs and proper preparations for future climate conditions. Soil frost depth also has important implications for hydrology, agriculture, and even burials.  
Due to the influence of both the duration and severity of sub-zero temperatures, the warming trends observed in the past three decades are likely to be modifying the freezing patterns of soil and contributing to an increase in the freeze-thaw cycle (FTC). The increase in the FTC can lead to significant structural damage to buildings, roads, and other structures. FTCs have also important implications for hydrology and agriculture.  
In the climatic conditions of Romania, there is an inter-annual very high variability in the dates of the disappearance of the last spring ground frosts and the dates of the occurrence of the first autumn ground frosts, as well as in the number of days with the phenomenon and the duration of frost-free period. The values from the maps represent the worst case scenario expected in each area.  
We retrieved the available data from the National Oceanic and Atmospheric Administration ([[https://www.noaa.gov/](https://www.noaa.gov/)]([https://www.noaa.gov/](https://www.noaa.gov/)), accessed on 5 May 2022) and the National Meteorological Agency (a governmental organization organized under the authority of Romanian Environment Ministry).  
We acknowledge the E-OBS dataset from the EU-FP6 project UERRA ([[https://www.uerra.eu](https://www.uerra.eu)]([https://www.uerra.eu](https://www.uerra.eu)), accessed on 5 May 2022) and the Copernicus Climate Change Service, as well as the data provides by the ECA&D project ([[https://www.ecad.eu](https://www.ecad.eu)]([https://www.ecad.eu](https://www.ecad.eu)), accessed on 5 May 2022).  
Conceptualization, C.A.; methodology, C.A. and R.V.; validation, C.A., A.A. and R.V.; formal analysis, F.P.; investigation, A.A.; data curation, C.A.; writing--original draft preparation, C.A.; writing--review and editing, A.A.; visualization, F.P.; funding acquisition, R.V. All authors have read and agreed to the published version of the manuscript.  
This study received no external funding and the APC was funded by Technical University of Civil Engineering Bucharest.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
The authors declare no conflict of interest.