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This paper gives an overview over all currently available data sets for the European Long-term Ecosystem Research (eLTER) monitoring site Gesäuse-Johnsbachtal. The site is part of the LTSER platform Eisenwurzen in the Alps of the province of Styria, Austria. It contains both protected (National Park Gesäuse) and non-protected areas (Johnsbachtal). Although the main research focus of the eLTER monitoring site Gesäuse-Johnsbachtal is on inland surface running waters, forests and other wooded land, the eLTER whole system (WAILS) approach was followed in regard to the data selection, systematically screening all available data in regard to its suitability as eLTER's Standard Observations (SOs). Thus, data from all system strata was included, incorporating Geosphere, Atmosphere, Hydrosphere, Biosphere and Sociosphere. In the WAILS approach these SOs are key data for a whole system approach towards long term ecosystem research. Altogether, 54 data sets have been collected for the eLTER monitoring site Gesäuse-Johnsbachtal and included in the Dynamical Ecological Information Management System – Site and Data Registry (DEIMS-SDR), which is the eLTER data platform. The presented work provides all these data sets through dedicated data repositories for FAIR use. This paper gives an overview on all compiled data sets and their main properties. Additionally, the available data are evaluated in a concluding gap analysis with regard to the needed observation data according to WAILS, followed by an outlook on how to fill these gaps. [ABSTRACT FROM AUTHOR]

Snow melt is one of the sources of freshwater supply in the late spring and summer in the mountainous regions of Iran, especially in the Urmia Lake Basin (ULB). In this study, past and future droughts of Urmia Lake Basin (ULB) have been studied by analyzing three types of droughts: (i) precipitation-deficit based characterized by the Standardized Precipitation Index (SPI), (ii) precipitation-evapotranspiration based droughts characterized by the Standardized Precipitation and Evapotranspiration Index (SPEI) and (iii) those droughts forced additionally by snow melt using the Snowmelt and Rain Index (SMRI). While reanalysis data ERA5-land describes the past climate, bias-corrected CMIP6 ensemble serves as the data for the future climate. Contrary to the SPI drought index, an increasing trend has been projected both in snowmelt-based (SMRI trend -0.068 units/year) and evapotranspiration-based (SPEI trend -0.079 units/year) drought indices, both for the period 1995–2014 and significant at the 5 % level. This indicates that summer droughts in the ULB will increase in the future, particularly because of increasing evapotranspiration and less snowmelt, while precipitation changes play a minor role. Drought severity will generally increase from the near future (2021–2040) to the far future (2081–2100), particularly forced by snowmelt deficit under the SSP5-8.5 scenario for the far future. Under the present climate, the extent of drought-affected areas is similar for all three types of droughts. However, under future climate drought-affected areas forced by snowmelt deficit will increase from about 20 % in the near future (2021–2040) to 60 % in the far future (2081–2100), showing that snow melt plays a vital role in aggravating the drought over the Basin. A decrease in the Basin's drought trend in the 2080s and later can be seen both for SMRI and SPEI indices under SSP1-2.6, which may be due to the temperature effect on snowmelt and evapotranspiration from the reduction of greenhouse gas emissions in SSP1-2.6 scenario at the end of 21st century. Such a decrease in SMRI and SPEI drought indices can also be seen around the 2090s under the SSP2-4.5 scenario. Results also reveal that the mountainous areas of the Basin will experience much less drought compared to the lowlands (including the lake) and foothills. [ABSTRACT FROM AUTHOR]

Greenland's peripheral glaciers are losing mass at an accelerated rate and are contributing significantly to sea level rise, but only a few direct observations are available. Here, we use the unique combination of high-resolution remote sensing data and direct mass balance observations to separate and quantify the contribution of a singular avalanche event to the mass balance of Freya Glacier (74.38° N, 20.82 W), a small (5.5 km², 2021) mountain glacier in Northeast Greenland. Elevation changes calculated from repeated photogrammetric surveys on 11th -18th August 2013 and on 28th - 31st July 2021 range from -11 m to 18 m, with a glacier-wide mean of 1.56 + 0.10 m (0.85 + 0.20 m w.e.). Somewhat surprisingly, the geodetic mass balance over the full period of 8 years (2013/14 - 2020/21) is slighly positive, (0.25 + 0.21 m w.e.). A main imprint of the near decadal mass balance stems from the exceptional (2.5 standard deviations above average) winter mass balance of 2017/18 with 1.85 + 0.05 m w.e., when in addition to above average precipitation, snow avalanches affected more than one third of the glacier surface and contributed at least 0.31 m w.e. (17%) to the total winter mass balance of 2017/18. We estimate the contribution of avalanches to the accumulated mass balance 2013/14 - 2020/21 as 0.55 m w.e. Without this avalanche event the 8-year mass balance would have been slightly negative, -0.30 m w.e. instead of 0.25 m w.e. Due to a gap in valid observations caused by high accumulation rates and the COVID-19 pandemic the recently reported glacier-wide annual mass balance values now turn out to have a negative bias and demand a thorough reanalysis. Finally, we speculate that the projected future warming increases the likelihood of extreme snowfall events for individual years and thus, may increase the contribution of snow avalanches to the mass balance of mountain glaciers in NE Greenland. [ABSTRACT FROM AUTHOR]

Air temperature inversions, a situation in which atmospheric temperature increases with height, are key components of the Arctic planetary boundary layer. The present study investigates the spatial and temporal variations of temperature inversions over different surface types (rock, gravel, snow, ice) along the Mittivakkat valley (southeast Greenland). For this purpose, 113 vertical profiles with high spatio-temporal resolution of air temperature and relative humidity were collected with unoccupied aerial vehicles (UAVs) during a 13-day field campaign in summer 2019. Air temperature inversions were present in 83% of the profiles, of which 24% were surface-based inversions and 76% were elevated inversions. The proglacial area covered with bare rock and gravel induces surface heating and convection during the day and, through interaction with local circulation patterns, leads to the frequent formation of elevated inversions. In contrast, the glacier surface itself acts as a persistent cooling surface and leads to the formation of surface-based inversions. A low-level fog layer that forms under the inversion layer may be causing non-linear vertical ablation gradients on Mittivakkat Gletsjer. Furthermore, we demonstrate that atmospheric measurements using UAVs can better capture small-scale processes than other products like radiosonde or modeled reanalysis data. [ABSTRACT FROM AUTHOR]