The thermal, anemometric and bioclimatic conditions on the topoclimatic scale were investigated in the summer season in the EbbaValley region in central Spitsbergen. Eight measurement sites, representing different ecosystems and different types of active surfaces typical of Spitsbergen, were chosen and automatic, hourly recorded, measurements were per− formed at the sites between 11 and 25 of July 2009. The analysis of the spatial distribution of the air temperature and thewind−chill temperature, both for the dayswith radiation and non−ra− diation weather, indicates that the most favorable regions in the interior of Spitsbergen are those situated in the shielded central parts of the valleys and in the lower parts of the slopes with southern exposure. The thermal and wind conditions are definitely less favorable at the tops of elevations and on the glacier. Large differences between the air temperature and the wind−chill temperature were noted, particularly during the unfavorable non−radiation weather, on the glacier and on open peaks due to a large horizontal and vertical wind−chill temperature gradient. The thermal inversions observed in the Ebba Valley in July 2009 were not of the typi− cal, glacier katabatic wind origin. They appeared during the western air circulation, which brings advection of cooled air from above the cold waters of Petunia Bay. The cold air pene− trates into the valley and pushes upwards themass of warmer air in the valley, creating a rather thin inversion layer, whose upper edge is marked with thin Stratus clouds.

This article aims to analyse the influence of weather types on meteorological

conditions in Petuniabukta (Svalbard) during July and August of 2016. The paper analyses

the daily courses of air temperature and humidity at four measurement points located on

the west bank of Petuniabukta near Adam Mickiewicz University Polar Station during

two different types of weather conditions: (i) cloudy and windy, (ii) calm and clear.

These weather types, distinguished on the basis of wind speed and cloudiness, allowed

for the creation of composite maps of the synoptic situation (SLP and geopotential

height of 500 hPa distribution) and its anomalies. In the study area, the air temperature

range in windy and cloudy weather conditions was larger (-10°C to 15°C) than that in

sunny and calm weather (0°C to 15°C), which contrasts the range of humidity values.

The diurnal cycle of meteorological elements in sunny and calm days is strongly related

to the sun elevation angle. In the above-mentioned weather types, the air temperature

was higher by several degrees (median 5°C to 8°C) than on windy and cloudy days

(median about 0°C to 6°C) at each measurement point. On days with sunny and calm

weather, a smaller vertical temperature gradient of air is observed (for sunny and calm

days 0.63°C and for windy weather 0.8°C).

This paper constitutes the sensitivity study of application the Polar WRF

model to the Svalbard area with testing selected parameterizations, including planetary

boundary layer, radiation and microphysics schemes. The model was configured, using

three one-way nested domains with 27 km, 9 km and 3 km grid cell resolutions. Results

from the innermost domain were presented and compared against measured wind speed

and air temperature at 10 meteorological stations. The study period covers two months:

June 2008 and January 2009. Significant differences between simulations results occurred

for planetary boundary layer (PBL) schemes in January 2009. The Mellor-Yamada-Janjic

(MYJ) planetary boundary layer (PBL) scheme resulted in the lowest errors for air

temperature, according to mean error (ME), mean absolute error (MAE) and correlation

coefficient values, where for wind speed this scheme was the worst from all the PBL

schemes tested. In the case of June 2008, shortwave and longwave radiation schemes

influenced the results the most. Generally, higher correlations were obtained for January,

both for air temperature and wind speed. However, the model performs better for June

in terms of ME and MAE error statistics. The results were also analyzed spatially, to

summarize the uncertainty of the model results related to the analyzed parameterization

schemes groups. Significant variability among simulations was calculated for January

2009 over the northern part of Spitsbergen and fjords for the PBL schemes. Standard

deviations for monthly average simulated values were up to 3.5°C for air temperature

and around 1 m s-1 for wind speed.