Active layer and Permafrost monitoring programme in Northern Victoria Land.   Mauro Guglielmin (1) (1) Sciencies Faculty, Insubria University, Via J.H.Dunant 3 21100 Varese Italy

Guglielmin M., Active Layer … Introduction Active layer and permafrost are key indicators of climate change within the cryosphere. The monitoring of these two indicators has been performed and is still going on through several international programmes such as the Circumpolar Active Layer Monitoring (CALM) and Permafrost and Climate in Europe (PACE) that are focussed mainly in the Arctic or in Europe. In Antarctica the data available are very scarce. This paper shows the first results of a programme carried out in Northern Victoria Land and founded by the Italian Antarctic Research Programme since 1996.

Distribution of active layer study sites (+) and boreholes (star) Guglielmin M., Active Layer … + + + + + + + + + + + Distribution of active layer study sites (+) and boreholes (star)

Distribution of active layer study sites (+) and boreholes (star) Guglielmin M., Active Layer … Distribution of active layer study sites (+) and boreholes (star)

Guglielmin M., Active Layer … Study sites location

Guglielmin M., Active Layer … Study sites location

Guglielmin M., Active Layer … Boulder Clay (74°44’45’’S - 164°01’17’’E, at 205 m a.s.l ) Calm Grid ( 100 x 100) and Permafrost station

Oasi (74°42’S – 164°06’E at 80 m a.s.l.) : Guglielmin M., Active Layer … Oasi (74°42’S – 164°06’E at 80 m a.s.l.) : Climate station and Borehole (15.5 m) monitored

Simpson Crags (74°26’S- 164°01’E at 830 m a.s.l.): Guglielmin M., Active Layer … Mount Keinath ( 74° 33’ S – 1 ° E at 1100 m a.s.l.): Permafrost station Simpson Crags (74°26’S- 164°01’E at 830 m a.s.l.): CALM GRID (100 x 100) and Permafrost station

Guglielmin M., Active Layer … Methods In the two grids (100 x 100 m) the measurements have been performed in each grid point, according both to the CALM protocol (Nelson et al., 1998), by annual probing of the maximum thickness of seasonal thaw, and to the RiSCC protocol (Guglielmin, 2003), by annual measurements of temperature at different depths. Permafrost monitoring is going through the automatic measurements of temperature within borehole at different depths from 2 cm to 15.5 m). At the same time the main climatic parameters (i.e. air temperature, solar radiation) are recorded (Guglielmin and Dramis, 1999; Guglielmin, 2003).

Incoming Global Radiation Guglielmin M., Active Layer … Locality N. Ground Temperature Depth (cm) Air Temperature (+1.5 m) Incoming Global Radiation Additional sensors Boulder Clay 6 2, 30, 60,160, 260, 360 Yes no Simpson Crags 2, 30, 160, 260,540,800 Wsd, Sn Mount Keinath 4 2, 30, 60, 100 Oasi 16 2, 30, 60, To 1550 Wsd, Sn, Hum, CNR1

Guglielmin M., Active Layer … Results Summer ground surface temperature (GST) is mainly correlated with air temperature even if, GST at different sites, can be higher or lower than air temperature

Guglielmin M., Active Layer … In winter too GST is well correlated with air temperature and is generally smoothed respect to it. Also during the episodes of sudden strong winds known as “coreless winter” the GST variations are much smaller than air fluctuactions because of the snow fall cover the ground surface during these episodes

Results Snow Cover can influence deeply the GST. Guglielmin M., Active Layer … Results Snow Cover can influence deeply the GST. The manipulation of snow cover carried out at Boulder Clay shows that only 10 cm of snow can decrease the GST until 8 °C on daily average.

Guglielmin M., Active Layer … Vegetation cover exerts a buffering effect on the GST, changing the energy balance and the snow cover permanence and heigth

Impacts of climatic factors on ground surface temperature Guglielmin M., Active Layer … Results Impacts of climatic factors on ground surface temperature - Solar radiation GST seems not to be strongly influenced by the incoming radiation at least on the daily average

Guglielmin M., Active Layer … Example of Radiative Balance and the effect of snow cover recorded during January 2003 at Oasi.

Boulder Clay CALM GRID: surface topography Guglielmin M., Active Layer … Boulder Clay CALM GRID: surface topography

Boulder Clay CALM GRID: albedo (%) Guglielmin M., Active Layer … Albedo (%) Boulder Clay CALM GRID: albedo (%)

Boulder Clay CALM GRID: snow thickness (cm): 1999-2003. Guglielmin M., Active Layer … Snow cover (cm) Boulder Clay CALM GRID: snow thickness (cm): 1999-2003.

Guglielmin M., Active Layer … GST (at 2 cm) Boulder Clay CALM GRID: Ground surface temperature (-2 cm depth) 1999-2003

Temperature at 10 cm of depth Guglielmin M., Active Layer … Temperature at 10 cm of depth Boulder Clay CALM GRID: Ground temperature at 10 cm of depth (1999-2003)

Boulder Clay CALM GRID: active layer thickness (frost probe method) Guglielmin M., Active Layer … Active layer Measured by Frost probe (cm) Boulder Clay CALM GRID: active layer thickness (frost probe method)

Guglielmin M., Active Layer … Active layer measured By linear interpolation of temperature at 10 and 20 cm (only summer 2002 and 2003) Boulder Clay CALM GRID: 0°C isotherm depth (thermal profile extrapolation)

Frost probe: Range: 0-56 Average:38 0°C Isotherm depth: Range:0-86 Guglielmin M., Active Layer … Frost probe: Range: 0-56 Average:38 0°C Isotherm depth: Range:0-86 Average: 32 Boulder Clay CALM GRID:comparison frost probe and thermal extrapolation methods (summer 2002)

Thermal regime measured at Boulder clay station between 27-12-1996 Guglielmin M., Active Layer … Thermal regime measured at Boulder clay station between 27-12-1996 And 16-12-2002 Boulder Clay permafrost station:thermal regime between 2/12/1996 and 16/12/2002

Ground surface temperature Guglielmin M., Active Layer … Results Ground surface temperature GST variations at Boulder Clay permafrost station

Guglielmin M., Active Layer … Synthesis of Mean Annual Ground Temperatures recorded at Boulder Clay . 1999 misses one month of data (november)

Guglielmin M., Active Layer … Temperature profile within Oasi borehole. The shifting of the curves is partially due to the thermal perturbance of the drilling operation only 1 week before the 1999 measurement

Guglielmin M., Active Layer … Conclusions GST is mainly controlled by air temperature although vegetation and snow cover exert an important buffering effect as already known for the Arctic ; Thermal Offset is generally very limited (less than 0.5°C ) and Active Layer thickness is spatially extremely variable because of the high roughness of the surface (that influence strongly both vegetation and snow cover). Permafrost table (PTD) and maximum thawing depths (MTD) can be very different, especially in the coastal areas where the deposits are rich in salt content.

Guglielmin M., Active Layer … Conclusion Active layer thickness with probing is not enough accurate because the lithology is mainly coarse. For Climate monitoring purposes it is recommended the measurement of PTD instead of MTD, because it is easier and more strictly related to GST. Considering the Annual average, the Permafrost thermal regime is almost stable while large variations occur at seasonal scale, especially within active layer. More data are needed both to active layer and permafrost thermal conditions, especially combining areal informations (CALM GRID with RiSCC protocol) and authomatic monitoring of temperature in borehole.

Guglielmin M., Active Layer … Acknowledgments Research was made possible by funds from the projects “Permafrost and Global Change in Antarctica I and II”, supported by Italian National Antarctic Project (PNRA). A special thank for the incredible logistic organization to PNRA and in particular to Ing. Mario Zucchelli that encouraged this research.