Water Balance and Thermal Regime of Lakes in Antarctic Oases

The chapter aims to revise the capabilities of a water balance modelling approach to be applied on climate-related or practical studies of lakes located in specific conditions of Antarctica. The seasonal water balance equation (WBaL) of a lake was suggested for the lakes located in the vicinity of the Antarctic scientific stations: Bellinshausen, Progress and Maitri. First, the methods and models used to evaluate the income and outcome terms of the WBaL from minimal observational datasets are considered. Then the historical observations available on the lakes Kitezh, Priyadarshini, Stepped, Nella, Progress and Reid are described based on the technical reports of the Finnish, Indian and Russian Antarctic research programmes and from open source publications. Finally, practical recommendations on improving temporal hydrological network are formulated to give a simple solution for the seasonal water balance studies of the Lake Priyadarshini

Evaporation over a glacial lake in Antarctica

The study provides estimates of summertime evaporation over a glacial lake located in the Schirmacher oasis, Dronning Maud Land, East Antarctica. Lake Zub (alternately named Lake Priyadarshini and referred to throughout as Lake Zub/Priyadarshini) is the second-largest lake in the oasis, and its maximum depth is 6 m. The lake is also among the warmest glacial lakes in the oasis, and it is free of ice during almost 2 summer months. The summertime evaporation over the ice-free lake was measured using the eddy covariance method and estimated on the basis of five indirect methods (bulk-aerodynamic method and four combination equations). We used meteorological and hydrological measurements collected during a field experiment carried out in 2018. The eddy covariance method was considered the most accurate, and the evaporation was estimated to be 114mm for the period from 1 January to 7 February 2018 (38 d) on the basis of this method. The average daily evaporation was 3.0mmd-1 in January 2018. During the experiment period, the largest changes in daily evaporation were driven by synoptic-scale atmospheric processes rather than local katabatic winds. The bulk-aerodynamic method suggests the average daily evaporation is 2.0mmd-1, which is 32% less than the results based on the eddy covariance method. The bulk-aerodynamic method is much better in producing the day-to-day variations in evaporation compared to the combination equations. All selected combination equations underestimated the evaporation over the lake by 40 –72 %. The scope of the uncertainties inherent in the indirect methods does not allow us to apply them to estimate the daily evaporation over Lake Zub/Priyadarshini. We suggested a new combination equation to evaluate the summertime evaporation over the lake’s surface using meteorological observations from the nearest site. The performance of the new equation is better than the performance of the indirect methods considered. With this equation, the evaporation over the period of the experiment was 124 mm, which is only 9% larger than the result according to the eddy covariance method

Newly identified climatically and environmentally significant high-latitude dust sources

Dust particles from high latitudes have a potentially large local, regional, and global significance to climate and the environment as short-lived climate forcers, air pollutants, and nutrient sources. Identifying the locations of local dust sources and their emission, transport, and deposition processes is important for understanding the multiple impacts of high-latitude dust (HLD) on the Earth\u27s systems. Here, we identify, describe, and quantify the source intensity (SI) values, which show the potential of soil surfaces for dust emission scaled to values 0 to 1 concerning globally best productive sources, using the Global Sand and Dust Storms Source Base Map (G-SDS-SBM). This includes 64 HLD sources in our collection for the northern (Alaska, Canada, Denmark, Greenland, Iceland, Svalbard, Sweden, and Russia) and southern (Antarctica and Patagonia) high latitudes. Activity from most of these HLD sources shows seasonal character. It is estimated that high-latitude land areas with higher (SI ≥0.5), very high (SI ≥0.7), and the highest potential (SI ≥0.9) for dust emission cover >1 670 000 km$^{2}$, >560 000 km$^{2}$, and >240 000 km$^{2}$, respectively. In the Arctic HLD region (≥60$^{∘}$ N), land area with SI ≥0.5 is 5.5 % (1 035 059 km$^{2}$), area with SI ≥0.7 is 2.3 % (440 804 km$^{2}$), and area with SI ≥0.9 is 1.1 % (208 701 km$^{2}$). Minimum SI values in the northern HLD region are about 3 orders of magnitude smaller, indicating that the dust sources of this region greatly depend on weather conditions. Our spatial dust source distribution analysis modeling results showed evidence supporting a northern HLD belt, defined as the area north of 50$^{∘}$ N, with a “transitional HLD-source area” extending at latitudes 50–58∘ N in Eurasia and 50–55$^{∘}$ N in Canada and a “cold HLD-source area” including areas north of 60$^{∘}$ N in Eurasia and north of 58$^{∘}$ N in Canada, with currently “no dust source” area between the HLD and low-latitude dust (LLD) dust belt, except for British Columbia. Using the global atmospheric transport model SILAM, we estimated that 1.0 % of the global dust emission originated from the high-latitude regions. About 57 % of the dust deposition in snow- and ice-covered Arctic regions was from HLD sources. In the southern HLD region, soil surface conditions are favorable for dust emission during the whole year. Climate change can cause a decrease in the duration of snow cover, retreat of glaciers, and an increase in drought, heatwave intensity, and frequency, leading to the increasing frequency of topsoil conditions favorable for dust emission, which increases the probability of dust storms. Our study provides a step forward to improve the representation of HLD in models and to monitor, quantify, and assess the environmental and climate significance of HLD

Newly identified climatically and environmentally significant high-latitude dust sources

Peer reviewe

The origins and spread of domestic horses from the Western Eurasian steppes

This is the final version. Available on open access from Nature Research via the DOI in this recordData availability: All collapsed and paired-end sequence data for samples sequenced in this study are available in compressed fastq format through the European Nucleotide Archive under accession number PRJEB44430, together with rescaled and trimmed bam sequence alignments against both the nuclear and mitochondrial horse reference genomes. Previously published ancient data used in this study are available under accession numbers PRJEB7537, PRJEB10098, PRJEB10854, PRJEB22390 and PRJEB31613, and detailed in Supplementary Table 1. The genomes of ten modern horses, publicly available, were also accessed as indicated in their corresponding original publications57,61,85-87.NOTE: see the published version available via the DOI in this record for the full list of authorsDomestication of horses fundamentally transformed long-range mobility and warfare. However, modern domesticated breeds do not descend from the earliest domestic horse lineage associated with archaeological evidence of bridling, milking and corralling at Botai, Central Asia around 3500 BC. Other longstanding candidate regions for horse domestication, such as Iberia and Anatolia, have also recently been challenged. Thus, the genetic, geographic and temporal origins of modern domestic horses have remained unknown. Here we pinpoint the Western Eurasian steppes, especially the lower Volga-Don region, as the homeland of modern domestic horses. Furthermore, we map the population changes accompanying domestication from 273 ancient horse genomes. This reveals that modern domestic horses ultimately replaced almost all other local populations as they expanded rapidly across Eurasia from about 2000 BC, synchronously with equestrian material culture, including Sintashta spoke-wheeled chariots. We find that equestrianism involved strong selection for critical locomotor and behavioural adaptations at the GSDMC and ZFPM1 genes. Our results reject the commonly held association between horseback riding and the massive expansion of Yamnaya steppe pastoralists into Europe around 3000 BC driving the spread of Indo-European languages. This contrasts with the scenario in Asia where Indo-Iranian languages, chariots and horses spread together, following the early second millennium BC Sintashta culture

Thermal regime and components of water balance of lakes in Antarctica at the Fildes peninsula and the Larsemann Hills

Thermal regime and water balance components of 12 lakes located at two different parts of the Antarctic (the Fildes peninsula in the Maritime Antarctic and the Larsemann Hills in the continental Antarctica) were studied using the observations from three field campaigns in 2012–2014. The morphometric characteristics of the studied lakes were updated with GPS/echo-sounding surveys, and changes in the length, width and volume of the lakes were revealed in comparison with the previous surveys. The thermal regime of the lakes was also studied by modelling, applying the lake model FLake, which is widely used in different environmental applications but was tested for the first time in the Antarctic conditions. In contrast to boreal lakes, for lakes in Antarctica the modelling results by FLake appeared to be sensitive to the light extinction coefficient. According to simulations, all lakes were mixed down to the bottom for the whole summer; however, the reasons for this are different for shallow and deep lakes. The sensitivity of different methods to calculate evaporation, by the Dalton-type empirical equation and by the atmospheric surface layer block of FLake, was studied. For endorheic lakes, the sensitivity appeared to be large, up to 47% of the total seasonal water volume change, which assumes that FLake has the potential to be used in hydrological applications to calculate evaporation. Seasonal variations of the volume of the lakes in the continental Antarctica are larger than in the Maritime Antarctic. Usually, small and medium-sized lakes accumulate or redistribute water during the warm season. However, the systems of big lakes also release the stored water through the mechanism of abrupt jumps, which simultaneously cause the inflow into the sea of huge amounts of fresh water during short time intervals

The probabilistic hydrological model MARCS (MARkov Chain System): the core code

<p>The MARCS model simulates three statistical moments of annual runoff based on a mean annual precipitation for any projected period period of 20-30 years in the future. To run the MARCS model, non-central moments of annual runoff are calculated from historical time series observed in a gauging site for a period in the past considered as a reference period. For the reference period, a mean annual precipitation is calculated from observations, and it is expressed in mm year^-1. For the projected period, a mean of annual precipitation is calculated from output of any global/regional climate model, and it is expressed in mm year^-1. The MARCS model simulates non-central moments as well as mean value of annual runoff, coefficients of variation (CV) and coefficients of skewness (CS) for the projected period considered.<br> The code of the model core (model_core.py) is supported by two files, which were used in an example embedded to the code. For the reference period, the non-central moments of annual runoff were calculated from observed time series extracted from the Global Runoff Data Center, GRDC, 56068 Koblenz, Germany (6233410.mon), and mean of precipitation was calculated from the dataset of NOAA/OAR/ESRL PSD, Boulder, Colorado, USA at a grid node nearest to the watershed centroid (6233410_pre_obs.txt).</p

Newly identified climatically and environmentally significant high-latitude dust sources

Peer reviewe

Population genomics of post-glacial western Eurasia

Western Eurasia witnessed several large-scale human migrations during the Holocene1-5. Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes-mainly from the Mesolithic and Neolithic periods-from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a 'great divide' genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 BP, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 BP, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a 'Neolithic steppe' cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations