Performance of the Global Forecast System's medium-range precipitation forecasts in the Niger river basin using multiple satellite-based products

Accurate weather forecast information has the potential to improve water resources management, energy, and agriculture. This study evaluates the accuracy of medium-range (1–15 d) precipitation forecasts from the Global Forecast System (GFS) over watersheds of eight major dams (Selingue Dam, Markala Dam, Goronyo Dam, Bakolori Dam, Kainji Dam, Jebba Dam, Dadin Kowa Dam, and Lagdo Dam) in the Niger river basin using NASA's Integrated Multi-satellitE Retrievals (IMERG) Final Run merged satellite gauge rainfall observations. The results indicate that the accuracy of GFS forecast varies depending on climatic regime, lead time, accumulation timescale, and spatial scale. The GFS forecast has large overestimation bias in the Guinea region of the basin (wet climatic regime), moderate overestimation bias in the Savannah region (moderately wet climatic regime), but has no bias in the Sahel region (dry climate). Averaging the forecasts at coarser spatial scales leads to increased forecast accuracy. For daily rainfall forecasts, the performance of GFS is very low for almost all watersheds, except for Markala and Kainji dams, both of which have much larger watershed areas compared to the other watersheds. Averaging the forecasts at longer timescales also leads to increased forecast accuracy. The GFS forecasts, at 15 d accumulation timescale, have better performance but tend to overestimate high rain rates. Additionally, the performance assessment of two other satellite products was conducted using IMERG Final estimates as reference. The Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) merged satellite gauge product has similar rainfall characteristics to IMERG Final, indicating the robustness of IMERG Final. The IMERG Early Run satellite-only rainfall product is biased in the dry Sahel region; however, in the wet Guinea and Savannah regions, IMERG Early Run outperforms GFS in terms of bias.

A quantitative synthesis of Holocene vegetation change in Nigeria (Western Africa)

Understanding long-term (centennial–millennial scale) ecosystem stability and dynamics are key to sustainable management and conservation of ecosystem processes under the currently changing climate. Fossil pollen records offer the possibility to investigate long-term changes in vegetation composition and diversity on regional and continental scales. Such studies have been conducted in temperate systems, but are underrepresented in the tropics, especially in Africa. This study attempts to synthesize pollen records from Nigeria (tropical western Africa) and nearby regions to quantitatively assess Holocene regional vegetation changes (turnover) and stability under different climatic regimes for the first time. We use the squared chord distance metric (SCD) to assess centennial-scale vegetation turnover in pollen records. Results suggest vegetation in most parts of Nigeria experienced low turnover under a wetter climatic regime (African Humid Period), especially between ~8000 and 5000 cal year BP. In contrast, vegetation turnover increased significantly under the drier climatic regime of the late-Holocene (between ~5000 cal year BP and present), reflecting the imp role of moisture changes in tropical west African vegetation dynamics during the Holocene. Our results are consistent with records of vegetation and climatic changes in other parts of Africa, suggesting the Holocene pattern of vegetation change in Nigeria is a reflection of continental-scale climatic changes.

Mechanical Calculation of Flexible Wires Taking into Account Taps to Electrical Apparatuses

A method is proposed for the mechanical calculation of flexible wires of substation in the presence of one tap to an electrical apparatus located in the middle of the span, taking into account its real location. The technique takes into account the presence of tension insulators strings, different heights of the suspension of wires. The loads on the conductor and tap depend on the climatic regime and take into account wind and icy conditions, as well as temperature changes. The transition to another climatic regime is performed by solving the equation of state, taking into account the coefficients of the horizontal and vertical load of the given and initial regimes. Formulas are given for calculating load factors that take into account weight, wind and ice cover loads on wires and insulator strings, as well as the slope of the span. They are calculated for each climatic mode based on the actual location of the tap to the electrical apparatus and the forces from it to the busbar. It is shown that the calculation results are in good agreement with the proposed method and the computer program. Formulas are given for calculating the sag and horizontal deviations of the wires when the tap is located in the middle of the span. A method is proposed for calculating the components of the forces on the busbar from the tap, taking into account its real location in substation. Formulas for calculating these components are given for different variants of the tap orientation. Knowledge of the values of the components of concentrated forces from the tap allows to increase the accuracy of calculating the sag and tension of the substation wires. Formulas are given for calculating the coefficients of increasing the sag, taking into account the components of the forces from the tap.

Антропология холода: естественные низкие температуры в традиционной системе жизнеобеспечения якутов (XIX в. – 30-е гг. ХХ в.)

Goals. The study aims to determine the influence of a complex of cryogenic factors (snow, ice, permafrost, cold in general) on traditional household and sociocultural practices of the Yakuts including benefits that some representatives of this ethnic group have learned to derive from winter climatological conditions. Materials and Methods. The work analyzes archival materials, scientific literature and the author’s field data. The most important elements of the methodological toolkit are sociocultural analysis and basic principles of cryosophy that suggest analysis of the phenomena of the ‘cold world’ in terms of their resource potential. Results. The paper shows positions (impacts) of low temperatures and accompanying phenomena when it comes to choose a place of location for a winter settlement and layout a farmstead (availability of a reservoir that does not freeze over the winter to its bottom, relative remoteness of permafrost soils from the surface, creation of open spaces for a better view, etc.), and the former’s influence on the architecture and functionality of residential and household buildings. The work introduces certain characteristics of deep freeze practices used for storing and cooking food, employment of cryogenic phenomena and processes for sanitary and hygienic purposes. Special insight is made into the significance of ‘cold’ practices in household activities. Specifically, the study shows that in farming and cattle breeding cryogenic phenomena were used for irrigation of agriculturally used areas, livestock feeding and threshing arrangements. Moreover, the specific climatic regime made it possible to apply quite a range of unique approaches to fishing and hunting. However, one of the most important results obtained during this study is the conclusion — confirmed by definite examples — that the Yakuts practiced conscious control over cryogenic processes in household activities. Conclusions. Based on the above, the paper concludes it is largely due to cold that a big complex of elements of the traditional life sustenance system of the Yakuts had emerged — to further essentially shape the latter’s most representative ethnocultural features.

A Review of two Middle Jurassic Theropod Tracksites Discovered in the 1980s from Sichuan Basin

Tracks from two sites in the Middle Jurassic Xintiangou Formation in the Wuma Village area, Wuhuang Township, Zizhong have been known and intermittently studied and excavated since the 1980s. The track-bearing surfaces were exposed by a combination of natural weathering and deliberate excavation by residents in a rural agricultural area. The surfaces were used as “threshing floors” for the processing of agricultural crops in an area subject to weathering under a humid sub-tropical climatic regime. Despite the negative effects of weathering on the quality of track preservation, the sites are historically significant in Chinese ichnology as the type areas for many controversially named theropod ichnotaxa. Subsequent researchers challenged the ichnotaxonomy as provincial and over-split, suggesting that many of the tracks, belong to well-known Lower Jurassic ichnogenera. The present study reviews these two sites, providing new information, and confirming that the tracks belong to the ichnogenera Grallator, Eubrontes and Kayentpus which are typical of the globally widespread Lower Jurassic tetrapod biochron. This suggests the Middle Jurassic ichnofauna in Sichuan is like Lower Jurassic ichnofaunas elsewhere. Previous efforts to transfer the ichnospecies to globally, better-known ichnogenera were important in reducing ichnogenus diversity, but did not reduce ichnosepcies diversity. Herein the ichnotaxa are reviewed and it is shown that the ichnospecies names have no utility for comparative study or in assessing assemblage diversity, or biochron composition. It is therefore proposed that the multiple ichnospecies names proposed based on tracks from these two localities can mostly be accommodated under the labels Grallator isp. indet., and Eubrontes isp. indet.

Simultaneous Effects of the Climate Change and the Recent Hydromorphological Modification of Vridi Channel (Côte d'Ivoire) on Some Its Hydrochemical Characteristics

This work aims to assess the simultaneous effects of the climate change and the hydromorphological modification of Vridi channel on its hydrochemistry. To best estimate, this fact, the seasonal dynamic of the particle size distribution, pH, redox potential, salinity, conductivity, moisture and organic matter contents of Vridi channel sediments have been followed and compared during two different annual periods, where the climate and the hydromorphology of this estuary have been different. The first annual period, covering the period from April 2014 to March 2015, has been characterized by a climatic regime close to the climatic normal of the study area and, this channel had its former hydromorphology. The second period annual, covering the period from October 2018 to September 2019, has been marked by a disruption of the climatic regime throughout Côte d'Ivoire, and this channel presented its modified hydromorphology. A monthly sampling has been done in this channel during each annual period. All These physical and chemical parameters have been determined by the corresponding AFNOR standards. Results have shown that these superficial sediments, with a predominantly sandy texture over the period from April 2014 to March 2015, have presented a texture predominantly of silt and clays over the period from October 2018 to September 2019. The climate change and the recent hydromorphological modification of this ecosystem had simultaneous very few effects on their pH and redox potential over the study period. On the other hand, they have caused an important increase in their salinity, moisture and organic matter contents and, a decrease in their electrical conductivity over the period from October 2018 to September 2019 relative to those determined in these substrates over the period of April 2014 to March 2015. This fact has certainly affected its biodiversity, especially that of its benthic fauna.

Phytoperiphyton of watercourses from the White Sea Basin (Murmansk District, Republic of Karelia, Russia)

The results of phytoperiphyton studies in 92 watercourses of the White Sea basin are summarized and analyzed. Totally 540 taxa with a rank below the genus were identified. They belong to six divisions: Cyanophyta – 76, Ochrophyta – 374, Euglenophyta – 3, Dinophyta – 4, Rhodophyta – 8 and Chlorophyta – 75. Diatoms, cyanobacteria and chlorophytes form the basis of the species diversity (> 90%) in all studied rivers. The predominance of these groups reflects the specificity of the phytoperiphyton in the river systems of the boreal and subarctic zones. Leading families are Naviculaceae (174 species), Achnanthaceae (45), Desmidiaceae (43) and Fragilaceaceae (36). Together they cover 337 species or 65% of the total number of species found. The group of leading genera (187 species, 35%) includes Eunotia – 36 species, Achnanthes – 33, Navicula – 48, Pinnularia – 39, and Cymbella – 31 species. The heterogeneity of the climatic regime in the study area determines the simultaneous presence in the algae flora of widespread eurythermic species characteristic of the taiga zone, stenothermic rheophiles of alpine origin and the boreal complex typical of wetlands. The dominant complex is represented by a small number of species resistant to dynamic water loading. It is noted that the ecological-geographical spectra of algae are dominated by widespread oligogalobic species, acidophilic or indifferent to the pH of the medium. The relative importance of indicator species in the formation of groupings allows to refer the waters of the studied watercourses and reservoirs to the second class of purity.

Remarks on Science, Epistemology and Education in Bruno Latour’s Down to Earth

In Down to Earth: Politics in the New Climatic Regime (2018), Bruno Latour argues that any effort to sustain life in the critical zone of our planet must leave behind the modern epistemologies, which reify and partition nature and science. In order to clear the ground for a proper descriptive stance, he dismisses ‘the view from nowhere’ and corresponding epistemic notions such as ‘Galileism’. I demonstrate why Latour’s fight against ‘the view from nowhere’ is misguided and wrong in the details. At best, his critique is largely irrelevant for the constructive use of science and education in ‘the climate war’.