Alpine glacier surface velocity measurement from UAV imagery – examining the effect of image resolution on the accuracy of results

The reliability and validity of the Glacier Surface Velocity (GSV) measurement results based on remote sensing datasets depends on the quality and spatial resolution of the image used. The typical pixel size of space-borne satellite imagery is often larger than the annual and inter-annual displacement of small alpine debris-covered glaciers. In addition, the pixel size of medium resolution satellite images (10–30 m), limits the size of a feature that can be matched. This is even more of an issue for glaciers located in arid and semi-arid environments (e.g. glaciers in Iran and high mountains of Asia) where flow velocities are not exceeding a few metres per year. Consequently, high-resolution data such as Unmanned Aerial Vehicle (UAV) images are required to calculate the surface velocity of such glaciers. However, the optimal resolution of UAV images is one of the most important challenges in GSV measurement. This paper explores the influence of UAV image resolution on the quality of GSV results. Analysis was carried out at 19 different resolutions of UAV images from 10 to 100 cm with a 5 cm bin over a debris-covered glacier, in Iran. COSI-Corr algorithm was used to perform the image correlation. To evaluate the accuracy of obtained results, manual digitisation was performed and the differences between manual GSV and frequency cross-correlator were assessed for all data sets. Moreover, displacement calculated for a stagnant off-glacier area was evaluated. While the quality of the results of the images between 10 and 30 cm is substantially the same, the obtained results indicate that the best result of GSV was not obtained using the finest image resolution. Results revealed that the highest correspondence between the measured GSV and manual digitisation was obtained in a 30 cm spatial resolution image. In addition, the 30 cm image resolution shows the minimum uncertainty over the off-glacier static area. Obtained results revealed that using too fine resolution images will lead to computational redundancy, while no improvement is observed in the accuracy of GSV results

Nanoliposomal formulation of Ecballium elaterium Extract: Cytotoxic Evaluation against Human Gastric Adenocarcinoma (AGS) Cell Line

Objective(s): The aim of this study was to determine cytotoxic effect of nanoliposomal form of lyophilized aqueous extract of Ecballium elaterium fruit on gastric cell line (AGS) using cell viability tests. Methods: An aqueous extract of the fruits of Ecballium elaterium was prepared. Nanoliposomal form was also prepared by thin-film hydration method and stability size was determined by SEM. The zeta potential and size characterized by Malvern zetasizer. Cytotoxic effect of the nanoliposomes encapsulated the extract on cell line was examined by MTT, Neutral Red and Frame methods. Results: The size of nanoliposomes was 218.2 nm with proper dispersion (PDI=0.3). The morphology of the liposomes was suitable according to SEM image. The IC50 values indicated that the nanoliposomal form of extract was 2-3 times more active than extract alone. The average IC50 values for extract and nanoliposomal form of extract were 1±0.1 and 0.39±0.02 μg/ml, respectively. Conclusions: The results from this study showed that the crude extract and nanoliposomal form extract of Ecballium elaterium have cytotoxicity effect on AGS cell line and these cells were significantly more susceptible to nanoliposomes encapsulated Ecballium elaterium extract than that of the extract itself

Spatio-temporal air quality assessment in Tehran, Iran, during the COVID-19 lockdown periods

Based on ground-based and satellite-based data, spatio-temporal analyses of air quality in Tehran were carried out during the lockdown periods (February-April) in 2020 and 2021. We evaluated the differences in temporal emissions of six air pollutants (NO2, CO, SO2, O3, PM2.5, and PM10) at various time scales, including diurnal, monthly, and relative changes. The results of ground-based measurements indicated that for all pollutants except O3, the magnitude decreased in 2020 (11-42%) compared to the baseline period (2015-2021). As a result of eased restrictions and unfavorable meteorological conditions, the reduction in air pollutants was lower in 2021 (5-32%), and PM2.5 and PM10 levels increased (3.75 and 11.22%). Satellite-based concentrations (NO2, CO, SO2, and AOD) varied from −8 to 54% in 2020 and from −41 to 60% in 2021 compared to 2019 as the pre-lockdown year. Concerning AOD, the trend is consistent with dust events during March and April in our region

Historically unprecedented global glacier changes in the 1 early 21st century

Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass-balance data relating to the impact that glaciers exercise on global sea-level fluctuations or on regional runoff. In this study we provide an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS). The dataset on glacier front variations (∼42 000 since 1600) delivers clear evidence that centennial glacier retreat is a global phenomenon. Intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the Little Ice Age (or Holocene). Glaciological and geodetic observations (∼5200 since 1850) show that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable.Fil: Zemp, Michael. Universitat Zurich; SuizaFil: Frey, Holger. Universitat Zurich; SuizaFil: Gärtner-Roer, Isabelle. Universitat Zurich; SuizaFil: Nussbaumer, Samuel U.. Universitat Zurich; SuizaFil: Hoelzle, Martin. Universite de Fribourg; Suiza. Universitat Zurich; SuizaFil: Paul, Frank. Universitat Zurich; SuizaFil: Haeberli, Wilfried. Universitat Zurich; SuizaFil: Denzinger, Florian. Universitat Zurich; SuizaFil: Ahlstrøm, Andreas P.. Geological Survey Of Denmark And Greenland; DinamarcaFil: Anderson, Brian. Victoria University Of Wellington; Nueva ZelandaFil: Bajracharya, Samjwal. International Centre For Integrated Mountain Development; NepalFil: Baroni, Carlo. Università degli Studi di Pisa; ItaliaFil: Braun, Ludwig N.. Bavarian Academy Of Sciences; AlemaniaFil: Càceres, Bolívar E.. Instituto Nacional de Meteorología E Hidrología; EcuadorFil: Casassa, Gino. Universidad de Magallanes; ChileFil: Cobos, Guillermo. Universidad Politécnica de Valencia; EspañaFil: Dàvila, Luzmila R.. Unidad de Glaciología y Recursos Hídricos; PerúFil: Delgado Granados, Hugo. Universidad Nacional Autónoma de México; MéxicoFil: Demuth, Michael N.. Natural Resources Canada; CanadáFil: Espizua, Lydia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Fischer, Andrea. Osterreichische Akademie Der Wissenschaften; AustriaFil: Fujita, Koji. Nagoya University; JapónFil: Gadek, Bogdan. University Of Silesia; PoloniaFil: Ghazanfar, Ali. Global Change Impact Studies Centre; PakistánFil: Hagen, Jon Ove. University of Oslo; NoruegaFil: Holmlund, Per. Stockholms Universitet; SueciaFil: Karimi, Neamat. Ministry of Energy; IránFil: Li, Zhongqin. Chinese Academy of Sciences; República de ChinaFil: Pelto, Mauri. Nichols College; Estados UnidosFil: Pitte, Pedro Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Popovnin, Victor V.. Moscow State University; RusiaFil: Portocarrero, Cesar A.. Unidad de Glaciología y Recursos Hídricos; PerúFil: Prinz, Rainer. Universidad de Innsbruck; AustriaFil: Sangewar, Chandrashekhar V.. Geological Survey of India; IndiaFil: Severskiy, Igor. Institute Of Geography; KazajistánFil: Sigurdsson, Oddur. Icelandic Meteorological Offic; IslandiaFil: Soruco, Alvaro. Universidad Mayor de San Andrés; BoliviaFil: Usubaliev, Ryskul. Central Asian Institute For Applied Geosciences; KirguistánFil: Vincent, Christian. Laboratory of Glaciology and Environmental Geophysics; Franci

Boost glacier monitoring

Glacier-mass changes are a reliable indicator of climate change. On behalf of the worldwide network of glacier observers, we urge parties to the United Nations Framework Convention on Climate Change to boost international cooperation in monitoring these changes, and to include the results in the Paris agreement’s global stocktake. Since 1960, glaciers have lost more than 9,000 gigatonnes of ice worldwide — the equivalent of a 20-metre-thick layer with the area of Spain. This melting alone — as distinct from that of the Greenland and Antarctic ice sheets — has raised global sea level by almost 3 centimetres, contributing 25–30% of the total rise (M. Zemp et al. Nature 568, 382–386; 2019). The present rate of melting is unprecedented. Several mountain ranges are likely to lose most of their glaciers this century. And we face the loss of almost all glaciers by 2300 (B. Marzeion et al. Cryosph. 6, 1295–1322; 2012). Glacier shrinkage will severely affect freshwater availability and increase the risk of local geohazards. Global sea-level rise will result in the displacement of millions of people in coastal regions and in the loss of life, livelihoods and cultural- heritage sites. The systematic monitoring of glaciers has been internationally coordinated for 125 years. Continuing to do so will document progress in limiting climate change for current and future generations