2 research outputs found
Pattern change of precipitation extremes in Bear Island
Extreme precipitation in the Arctic region plays a crucial role in global
weather and climate patterns. Bear Island (Bj{\o}rn{\o}ya) is located in the
Norwegian Svalbard archipelago, which is, therefore, selected for our study on
extreme precipitation. The island occupies a unique geographic position at the
intersection of the high and low Arctic, characterized by a flat and
lake-filled northern region contrasting with mountainous terrain along its
southern shores. Its maritime-polar climate is influenced by North Atlantic
currents, resulting in relatively mild winter temperatures. An increase in
precipitation level in Bear Island is a significant concern linked to climate
change and has global implications. We have collected the amount of daily
precipitation as well as daily maximum temperatures from the meteorological
station of Bj{\o}rn{\o}ya located on the island, operated by the Norwegian
Centre for Climate Services for a period spanning from January 1, 1960 to
December 31, 2021. We observe that the trend of yearly mean precipitation
during this period linearly increases. We analyze the recorded data to
investigate the changing pattern of precipitation extremes over the climate
scales. We employ the generalized extreme value distribution to model yearly
and seasonal maxima of daily precipitation amount and determine the return
levels and return period of precipitation extremes. We compare the variability
of precipitation extremes between the two time periods: (i) 1960-1990 and (ii)
1991-2021. Our analysis reveals an increase in the frequency of precipitation
extremes occurrences between 1991 and 2021. Our findings establish a better
understanding of precipitation extremes in Bear Island from a statistical
viewpoint, with an observation of seasonal and yearly variability, especially,
during the period of the last 31 years
Observation of Cloud Base Height and Precipitation Characteristics at a Polar Site Ny-Ă…lesund, Svalbard Using Ground-Based Remote Sensing and Model Reanalysis
Clouds play a significant role in regulating the Arctic climate and water cycle due to their impacts on radiative balance through various complex feedback processes. However, there are still large discrepancies in satellite and numerical model-derived cloud datasets over the Arctic region due to a lack of observations. Here, we report observations of cloud base height (CBH) characteristics measured using a Vaisala CL51 ceilometer at Ny-Ålesund, Svalbard. The study highlights the monthly and seasonal CBH characteristics at the location. It is found that almost 40% of the lowest CBHs fall within a height range of 0.5–1 km. The second and third cloud bases that could be detected by the ceilometer are mostly concentrated below 3 km during summer but possess more vertical spread during the winter season. Thin and low-level clouds appear to be dominant during the summer. Low-level clouds are found to be dominant and observed in 76% of cases. The mid and high-level clouds occur in ~16% and ~7% of cases, respectively. Further, micro rain radar (MRR2) observed enhanced precipitation and snowfall events during the winter and spring which are found to be associated with the lowest CBHs within 2 km from the ground. The frontal process associated with synoptic-scale meteorological conditions explains the variabilities in CBH and precipitation at the observation site when compared for two contrasting winter precipitation events. The findings of the study could be useful for model evaluation of cloud precipitation relationships and satellite data validation in the Arctic environment