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1. What is a permafrost evidence?

Is a direct or indirect proof of the presence or absence of permafrost in a specific location obtained by field measures or observations. The Alpine Permafrsot Database (APD) collects Rock Glacier Inventories and the following Permafrost evidence:
- Boreholes Temperature (BH)
- Ground Surface Temperature (GST)
- Surface Movement in periglacial areas (SM)
- Results of Geophysical Prospecting
- Perennial-ice in rock-fall scars, trenches or construction sites
- Other indirect permafrost evidence
 

2. Rock Glaciers Inventories (RGI)

DSC TSANTELEINAThe rock glaciers are landforms commonly associated to the presence (past or current) of permafrost and are studied since many decades. During the last years many rock glacier inventories have been realized throughout the Alps. Most of these RGI have been realized following same or similar criteria and thus can be merged at Alpine lavel. The largest part of RGI realized in the Alps are already collected in the APD.

 

3. Permafrost evidence

3.1. Boreholes temperatures

Temperature measured in boreholes (BH) is  the most reliable evidence of permafrost presence or absence. The minimum requirement for adding a BH evidence in the APD is a borehole depth exeeding the active layer thickness that is reaching at least the top of the permafrost table. Boreholes drilled on steep rock faces and/or located in locations with a strong 3D (topographic) effects are also welcome.The APD does not collects raw borehole data but yearly synthesis means: active layer thickness (ALT) and annual mean temperature at different depths.

3.2. Ground Surface Temperatures

Ground Surface Temperature (GST) is defined as the surface or near-surface temperature of the ground (bedrock or surficial deposit), measured in the uppermost centimeters of the ground. GST is not a direct proof of permafrost existence but it's an important parameter for About Data BHunderstanding the thermal evolution of active layer and frozen ground in general. It can be used for calibrating and validating numerical models and as a proxy for estimating potential permafrost presence or absence in the subsurface. Such estimation has an high degree of uncertainty if GST is measured on flat sites with snow/debris covers while is more realible if GST is measured on steep rock faces where a direct coupling with atmosphere exists. GST has to be distinguished from the Bottom Temperature of Snow cover (BTS), which is the temperature measured at the snow/ground interface in late winter. The APD does not collect raw GST data but the Mean Annual Ground Surface Temperature (MAGST) of a certain depth.

3.3. Surface Movement

Measures of ground surface movements (SM) on rock glaciers and slopes are useful for monitoring the temporal evolution of such creeping phenomena and tracking the potential accelerations induced by global warming. SM can be measured in many different ways (GPS, LIDAR, photogrammetry, ...). The APD collects yearly surface movement data as mean values of the monitoring sites which are usually composed by many measuring points. 

3.4. Geophysical methods

Surface-based geophysical methods are approaches for permafrost characterization. Detection of permafrost and ice from Electrical resistivity/impedance Tomography (ERT/EIT), Ground Penetrating Radar (GPR) or Seismic Refraction (SR) can be included as evidence in the APD. 

3.5. Perennial-ice observations

About Data IceThe presence of massive ice-lenses in periglacial areas can be a direct proof of permafrost occurrence. Such evidence from trenches or construction sites in high-mountain areas can provide useful information. Massive ice can also be observed in rockfall scars and can represents evidence of permafrost.

3.6. Other indirect permafrost evidence

e.g. patterned ground (features produced by the repeated annual freezing and thawing of the active layer in permafrost soils), ...  

 

4. Data upload

The upload of permafrost evidence and rock glacier inventories (RGI) is allowed only to registered data provider.
In case of RGI, data collection is made trough the upload of a rock glacier inventory shapefile (polygons). The publication in the APD takes some days due to system administrators checks and data merging.
Permafrost Evidence upload is done using the field "Add new evidence" in the Evidence map menu. Once a new evidence is inserted and saved, data are verified by the system administrators before publication (see data verification and publication).

 Periodic updates: once per year, APD will send an email to all the data providers asking for BH, GST and SM data yearly updates.

 

5. Data verification and publication

Once submitted, each evidence undergoes different steps of verification before publishing. During this process an evidence can be Public i.e. visible on both the map and the table, or Not-Public that is visible only to data provider and system administrators. These are data verification and publication steps:

- Inserted: the evidence has been saved but not yet confirmed by data provider. The evidence can be further modified by data provider and is Not-Public.

- Under Revision: the evidence has been confirmed by data provider and is waiting the check/approval of system administrators. The evidence is Not-Public and not editable.

- To Be Revised: some inconsistencies have been found by system administrators and some modifications are asked to data provider by email. The evidence is Not-Public and editable. After modifications, data provider confirm the evidence which automatically return Under Revision.

- Approved Incomplete: the evidence has been approved by system administrators but some data need to be added. The evidence is Public and further editable (not all fields).

- Approved Complete: the evidence has been approved by system administrators. The evidence is Public.

 

6. Data dissemination

The files available for downloading are updated once per year with a Versioning Number (VN) and the Release Notes (RN). The VN must always be cited in publications for univocally identifying the dataset while the RN are used for describing the main characteristics of the dataset and provide warnings on known inconsistencies. Refer to Data Policies  for further details.