bluuebunny/crossref_metadata_2025 huggingface dataset:
Spermatozoa Survival Rate in Stored Cock Semen Extended With Diluent Fortified With Natural Antioxidant Sources under Room Temperature
Authors: Ewuola E. O. , Balogun A. S. , Lawanson A. A.
Published: February 2021

An experiment was conducted in a completely randomized design with five treatments in triplicates. Four extenders were formulated: Lake Extender; Coconut water-Orange juice Extender (CWOE), Egg yolk-Tomato juice Extender (EYTE) and Milk based-Carrot Extender (MCE), were used to extend cock semen constituting treatments 2, 3, 4 and 5 respectively, while the control (Treatment 1) was unextended semen. Semen was harvested from 8 proven Isa breeder cocks aged 35-40 weeks, pooled and evaluated. The ejaculate was divided into 5 and each part was extended with the extenders at ratio 1:2 (Semen: Extender). The extended and un-extended semen samples were kept under room temperatures (26.6 27.4°C) with relative humidity of 64.0-74.0% for in vitro assessment at 2 hrs interval until percentage motility was less than 60%. The results showed that the mass activity, sperm motility and percentage livability reduced p<0.05) as the time of storage increased. Mass activities of unextended semen and the one extended with coconut water-orange juice were significantly (P<0.05) higher than that of other treatments at 0 hour period of storage. Sperm motility in treatments 1 (95.0%), 3 (93.3%) and 4 (88.3%) was not significantly (p>0.05) different from one another, but they was significantly (p<0.05) higher than treatments 2 (40.0%) and 5 (71.7%). At 2 hours of storage, the mass activity and percentage sperm motility in treatment 2 were significantly (P<0.05) lower than other treatments, while live sperm cells were significantly lower for Treatment 3 than other treatments. At 4 hours of storage, mass activity and motility were zero in Treatment 2, while Treatment 1 recorded the highest values (66.7% and 93.5% respectively). Percent motility in Treatments 3, 4 and 5 were 55.0, 50.0 and 43.3%, respectively. However, percent live sperm cells were significantly (P<0.05) higher in treatments 2, 4, 5 and 1 than the in treatment 3. Both CWOE and EYTE possessed a good keeping quality for semen storage. The extenders fortified with natural antioxidants can be used for on-farm insemination in poultry within two hours of collection.
Growth performance and blood profile of gestating wad ewes fed dietary supplementation of ammonium sulphate
Authors: Ososanya T. O. , Inyang U. A. , Shehu S. A.
Published: February 2021

The concern raised as a result of antibiotic usage in the livestock industry has necessitated the need for alternative feed additives such as ammonium sulphate. Hence, sixteen West African Dwarf (WAD) ewes averaging 24 kg in weight and aged eighteen months were used to determine the growth performance and blood chemistry of ammonium sulphate supplemented diets. The animals were divided into four groups of experimental diets consisting: D1 (0%) (Control diet), D2 (0.25%), D3 (0.50%) and D4 (0.75%) of ammonium sulphate (AMS) inclusion levels and were randomly allotted in a completely randomized design. They were also synchronized with prostaglandin F2a and naturally mated with four (4) rams of proven fertility when they came on heat. Parameters determined were feed intake, dry matter intake (DMI), gestating weights and gains, and blood haematology and serum biochemistry such as white blood cells (WBC), red blood cell (RBC), packed cell volume (PCV), haemoglobin (HGB), albumin (A), globulin (G), total protein (TP), cholesterol (CHOL), blood urea nitrogen, creatinine (C), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP). The results showed that supplementing AMS in ewe diets generally enhanced (p<0.05) final weight (kg), gestational weight gain (Kg) and average daily weight gain (g). The values ranged from 32.00 – 45.25 Kg; 8.25 - 22.25 Kg; 207.79 -- 267.86 g/d respectively. The feed conversion ratio improved with increasing levels of AMS with animals on D4 recording the least (0.20). Animals on D1 recorded the highest values for PCV, HGB, and RBC while those on D3 had the least. The values were 44.25 and 41.00%; 14.68 and 13.40 g/dl; and 13.02 and 11.86 x 106/mm3 respectively. Animals on D4 recorded the highest values for WBC (5150.50 x 103/mm3). Serum biochemical responses of pregnant sheep indicated significant differences (p < 0.05) of AMS supplementation on TP, A/C ratio, ALP and creatinine values. Animals on D1 recorded the highest values for TP, A/G ratio; ALT, BUN and C while those on D2 were least except for ALT where D3 was least in ALT. The values were 8.68 and 8.15 g/dl; 0.80 and 0.65; 289 and 235.50 I.U/L; 10.75 and 9.75 mg/dl; 1.48 and 1.08 mg/dl respectively. Animals on D2 recorded the highest values for G, ALP and CHOL (4.80 mg/dl; 25.25 1. U/L; and 63.00 mg/dl respectively). Inclusion of AMS improved conversion ratio thereby improving the performance of ewes and thus proved that it could be tolerated up to 0.75% supplementation in diets for ewes.
Energy utilization for body weight gain of ram-lambs fed differently processed breadfruit (Artocarpus altilis) meal in total mixed rations
Authors: Okoruwa M. I.
Published: February 2021

The study was carried out to estimate the energy utilization for body weight gain in West African dwarf ram-lambs fed differently processed breadfruit meal in total mixed rations. Twenty non-castrated ram-lambs, about 7months of age with an average-initial body weight of 6.00±0.55kg, were randomly assigned to four dietary treatments with five ram-lambs per treatment group in a completely randomized design. Ficus foliage with differently processed breadfruit meals and concentrate diet were used as treatment diets. Diet A (50% unpeeled raw breadfruit meal +20% Ficus foliage + 30% concentrate diet) B (50% peeled raw breadfruit +20% Ficus foliage + 30% concentrate diet), C (50% unpeeled soaked breadfruit meal +20% Ficus foliage + 30% concentrate diet) and D (50% unpeeled boiled breadfruit meal + 20% Ficus foliage +30% concentrate diet). Results showed that faecal energy output (999.41 MJ/g/day DM) was significantly (P<0.05) highest in treatment diet A compared with other treatment diets. Ram-lambs on treatment diets B and Chad the significantly highest (P < 0.05) on digestible energy intake (1310.84 and 1295.62 MJ/g/day DM), metabolizable energy intake (1074.89 and 1062.41 MJ/g/day DM), average total weight gain (4.18 und 4.13kg) and average daily weight gain (87.08 and 86.04g) compared with treatment diets A and D. Gross energy intake (4503.00MJ/g/day), average total feed intake (13.68kg), averuge daily feed intake (285.00g) and feed conversion ratio (4.44) were significantly (P < 0.05) better in ram-lambs on treatment diet D. There were no significant (P >0.05) differences in urinary energy loss, metabolizability and initial body weight of ram-lambs. It was therefore concluded that diets B and C enhanced efficiency of energy utilization for body weight gain of ram-lambs.
Adoption of improved fish hatchery production technologies by fish hatchery managers in Oyo state, Nigeria
Authors: Ashely-Dejo S. S. , Omoniyi I. T. , Olaoye O. J. , Fakoya E. O. , Adelaja A. O.
Published: February 2021

This study sought to assess the adoption of improved fish hatchery production technologies and information usage by fish hatchery farmers in Oyo State, Nigeria. Multistage sampling technique was used to select 234 hatchery farmers from Oyo using structured questionnaire from all the four Agricultural Development Programme zones in Oyo State. Data were analyzed using descriptive statistics, mean score and index score. Information on socio economic characteristics revealed that most (88.9%) of the fish hatchery farmers were in the active age bracket of 31-60 years, majority (86.8%) were married male. The mean household size was 7 persons per household with majority (53.4%) having above 6 years of fish hatchery experience. The grand mean score for agencies/channel examined in this study was 1.68, information usage index was 0.56. Levels of awareness were relatively high but there were low adoption rate for some of the fish hatchery production technologies. Based on the available evidences, it was recommended that all fish farmers should be trained on hatchery operations regardless of level of educational status. Therefore, regular workshop should be organized for the producers and the most available and cost effective innovations on hatchery enterprises should be made available to all the categories of fish farmers irrespective of their gender.
Arctic on the verge of an ozone hole?
Authors: Kuttippurath Jayanarayanan , Feng Wuhu , Müller Rolf , Kumar Pankaj , Raj Sarath , Gopikrishnan Gopalakrishna Pillai , Roy Raina
Published: February 2021

Abstract. Severe vortex-wide ozone loss in the Arctic would expose nearly 650 million people and ecosystem to unhealthy ultra-violet radiation levels. Adding to these worries, and extreme weather events as the harbingers of climate change, clear signature of an ozone hole (ozone column values below 220 DU) appeared over the Arctic in March and April 2020. Sporadic occurrences of ozone hole values at different regions of vortex for almost three weeks were found for the first time in the observed history in the Arctic. Furthermore, a record-breaking ozone loss of about 2.0–3.4 ppmv triggered by an unprecedented chlorine activation (1.5–2.2 ppbv) matching to the levels of Antarctic ozone hole conditions was also observed. The polar processing situation led to the first-ever appearance of loss saturation in the Arctic. Apart from these, there were also ozone-mini holes in December 2019 and January 2020 driven by atmospheric dynamics. The large loss in ozone in the colder Arctic winters is intriguing and that demands rigorous monitoring of the region. Our study suggests that the very colder Arctic winters in near future would also very likely to experience even more ozone loss and encounter ozone hole situations, provided the stratospheric chlorine levels still stay high there.
Evolution of OH reactivity in low-NO volatile organic compound photooxidation
investigated by the fully explicit GECKO-A model
Authors: Peng Zhe , Lee-Taylor Julia , Stark Harald , Orlando John J. , Aumont Bernard , Jimenez Jose L.
Published: February 2021

Abstract. OH reactivity (OHR) is an important control on the oxidative capacity in the atmosphere but remains poorly constrained. For an improved understanding of OHR, its evolution during oxidation of volatile organic compounds (VOCs) is a major aspect requiring better quantification. We use the fully explicit Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) model to study the OHR evolution in the low-NO photooxidation of several VOCs, including decane (an alkane), m-xylene (an aromatic), and isoprene (an alkene). Oxidation progressively produces more saturated and functionalized species. Total organic OHR (including precursor and products, OHRVOC) first increases for decane (as functionalization increases OH rate coefficients), and m-xylene (as much more reactive oxygenated alkenes are formed). For isoprene, C=C bond consumption leads to a rapid drop in OHRVOC before significant production of the first main saturated multifunctional product, i.e., isoprene epoxydiol. The saturated multifunctional species in the oxidation of different precursors have similar average OHRVOC per C atom. The latter oxidation follows a similar course for different precursors, involving fragmentation of multifunctional species to eventual oxidation of C1 and C2 fragments to CO2, leading to a similar evolution of OHRVOC per C atom. An upper limit of the total OH consumption during complete oxidation to CO2 is roughly 3 per C atom. We also explore the trends in radical recycling ratios. We show that differences in the evolution of OHRVOC between the atmosphere and an environmental chamber, and between the atmosphere and an oxidation flow reactor (OFR) can be substantial, with the former being even larger, but these differences are often smaller than between precursors. The Teflon wall losses of oxygenated VOCs in chambers result in substantial deviations of OHRVOC from atmospheric conditions, especially for the oxidation of larger precursors, where multifunctional species may suffer near-complete wall losses, resulting in significant underestimation of OHRVOC. For OFR, the deviations of OHRVOC evolution from the atmospheric case are mainly due to significant OHR contribution from RO2 and lack of efficient organic photolysis. The former can be avoided by lowering the UV lamp setting in OFR, while the latter is shown to be very difficult to avoid. However, the former may significantly offset the slowdown in fragmentation of multifunctional species due to lack of efficient organic photolysis.
Recommendations on benchmarks for numerical air quality model applications in China – Part 1: PM2.5 and chemical species
Authors: Huang Ling , Zhu Yonghui , Zhai Hehe , Xue Shuhui , Zhu Tianyi , Shao Yun , Liu Ziyi , Emery Chris , Yarwood Greg , Wang Yangjun , Fu Joshua , Zhang Kun , Li Li
Published: February 2021

Abstract. Numerical air quality models (AQMs) have been applied more frequently over
the past decade to address diverse scientific and regulatory issues
associated with deteriorated air quality in China. Thorough evaluation of a
model's ability to replicate monitored conditions (i.e., a model performance
evaluation or MPE) helps to illuminate the robustness and reliability of the
baseline modeling results and subsequent analyses. However, with numerous
input data requirements, diverse model configurations, and the scientific
evolution of the models themselves, no two AQM applications are the same and
their performance results should be expected to differ. MPE procedures have
been developed for Europe and North America, but there is currently no
uniform set of MPE procedures and associated benchmarks for China. Here we
present an extensive review of model performance for fine particulate matter
(PM2.5) AQM applications to China and, from this context, propose a set
of statistical benchmarks that can be used to objectively evaluate model
performance for PM2.5 AQM applications in China. We compiled MPE
results from 307 peer-reviewed articles published between 2006 and 2019,
which applied five of the most frequently used AQMs in China. We analyze
influences on the range of reported statistics from different model
configurations, including modeling regions and seasons, spatial resolution
of modeling grids, temporal resolution of the MPE, etc. Analysis using a
random forest method shows that the choices of emission inventory, grid
resolution, and aerosol- and gas-phase chemistry are the top three factors
affecting model performance for PM2.5. We propose benchmarks for six
frequently used evaluation metrics for AQM applications in China, including
two tiers – “goals” and “criteria” – where goals represent the
best model performance that a model is currently expected to achieve and
criteria represent the model performance that the majority of studies
can meet. Our results formed a benchmark framework for the modeling
performance of PM2.5 and its chemical species in China. For instance,
in order to meet the goal and criteria, the normalized mean bias (NMB) for
total PM2.5 should be within 10 % and 20 %, while the normalized
mean error (NME) should be within 35 % and 45 %, respectively. The goal
and criteria values of correlation coefficients for evaluating hourly and
daily PM2.5 are 0.70 and 0.60, respectively; corresponding values are
higher when the index of agreement (IOA) is used (0.80 for goal and 0.70 for
criteria). Results from this study will support the ever-growing modeling
community in China by providing a more objective assessment and context for
how well their results compare with previous studies and to better
demonstrate the credibility and robustness of their AQM applications prior
to subsequent regulatory assessments.
The spring transition of the North Pacific jet and its relation to deep stratosphere-to-troposphere mass transport over western North America
Authors: Breeden Melissa L. , Butler Amy H. , Albers John R. , Sprenger Michael , Langford Andrew O'Neil
Published: February 2021

Abstract. Stratosphere-to-troposphere mass transport to the planetary
boundary layer (STT-PBL) peaks over the western United States during boreal
spring, when deep stratospheric intrusions are most frequent. The
tropopause-level jet structure modulates the frequency and character of
intrusions, although the precise relationship between STT-PBL and jet
variability has not been extensively investigated. In this study, we
demonstrate how the North Pacific jet transition from winter to summer leads
to the observed peak in STT-PBL. We show that the transition enhances
STT-PBL through an increase in storm track activity which produces
highly amplified Rossby waves and more frequent deep stratospheric
intrusions over western North America. This dynamic transition coincides
with the gradually deepening PBL, further facilitating STT-PBL in spring. We
find that La Niña conditions in late winter are associated with an
earlier jet transition and enhanced STT-PBL due to deeper and more frequent
tropopause folds. An opposite response is found during El Niño
conditions. El Niño–Southern
Oscillation (ENSO) conditions also influence STT-PBL in late spring or early
summer, during which time La Niña conditions are associated with larger
and more frequent tropopause folds than both El Niño and ENSO-neutral
conditions. These results suggest that knowledge of ENSO state and the North Pacific jet structure in late winter could be leveraged for predicting the
strength of STT-PBL in the following months.
A new measurement approach for validating satellite-based above-cloud aerosol optical depth
Authors: Gatebe Charles K. , Jethva Hiren , Gautam Ritesh , Poudyal Rajesh , Várnai Tamás
Published: February 2021

Abstract. The retrieval of aerosol parameters from passive
satellite instruments in cloudy scenes is challenging, partly because clouds
and cloud-related processes may significantly modify aerosol optical depth
(AOD) and particle size, a problem that is further compounded by 3D
radiative processes. Recent advances in retrieval algorithms such as the
“color ratio” method, which utilizes the measurements at a shorter
(470 nm)
and a longer (860 nm) wavelength, have demonstrated the simultaneous
derivation of AOD and cloud optical depth (COD) for scenes in which absorbing
aerosols are found to overlay low-level cloud decks. This study shows
simultaneous retrievals of above-cloud aerosol optical depth (ACAOD) and
aerosol-corrected cloud optical depth (COD) from airborne measurements of
cloud-reflected and sky radiances using the color ratio method. These
airborne measurements were taken over marine stratocumulus clouds with
NASA's Cloud Absorption Radiometer (CAR) during the SAFARI 2000 field campaign
offshore of Namibia. The ACAOD is partitioned between the AOD below-aircraft
(AOD_cloudtop) and above-aircraft AOD (AOD_sky). The results show good agreement between AOD_sky and
sun-photometer measurements of the above-aircraft AOD. The results also show
that the use of aircraft-based sun-photometer measurements to validate
satellite retrievals of the ACAOD is complicated by the lack of information
on AOD below aircraft. Specifically, the CAR-retrieved AOD_cloudtop captures this “missing” aerosol layer caught between the aircraft
and cloud top, which is required to quantify above-cloud aerosol loading and
effectively validate satellite retrievals. In addition, the study finds a
strong anticorrelation between the AOD_cloudtop and COD for
cases in which COD < 10 and a weaker anticorrelation for COD > 10, which may be associated with the uncertainties in the color
ratio method at lower AODs and CODs. The influence of 3D radiative effects
on the retrievals is examined, and the results show that at cloud troughs, 3D
effects increase retrieved ACAOD by about 3 %–11 % and retrieved COD by
about 25 %. The results show that the color ratio method has little
sensitivity to 3D effects at overcast stratocumulus cloud decks. These
results demonstrate a novel airborne measurement approach for assessing
satellite retrievals of aerosols above clouds, thereby filling a major gap
in global aerosol observations.
Model estimations of geophysical variability between satellite measurements of ozone profiles
Authors: Sheese Patrick E. , Walker Kaley A. , Boone Chris D. , Degenstein Doug A. , Kolonjari Felicia , Plummer David , Kinnison Douglas E. , Jöckel Patrick , von Clarmann Thomas
Published: February 2021

Abstract. In order to validate satellite measurements of
atmospheric composition, it is necessary to understand the range of random
and systematic uncertainties inherent in the measurements. On occasions
where measurements from two different satellite instruments do not agree
within those estimated uncertainties, a common explanation is that the
difference can be assigned to geophysical variability, i.e., differences due
to sampling the atmosphere at different times and locations. However, the
expected geophysical variability is often left ambiguous and rarely
quantified. This paper describes a case study where the geophysical
variability of O3 between two satellite instruments – ACE-FTS
(Atmospheric Chemistry Experiment – Fourier Transform Spectrometer) and
OSIRIS (Optical Spectrograph and InfraRed Imaging System) – is estimated
using simulations from climate models. This is done by sampling the models
CMAM (Canadian Middle Atmosphere Model), EMAC (ECHAM/MESSy Atmospheric
Chemistry), and WACCM (Whole Atmosphere Community Climate Model) throughout
the upper troposphere and stratosphere at times and geolocations of
coincident ACE-FTS and OSIRIS measurements. Ensemble mean values show that
in the lower stratosphere, O3 geophysical variability tends to be
independent of the chosen time coincidence criterion, up to within 12 h; and
conversely, in the upper stratosphere geophysical variation tends to be
independent of the chosen distance criterion, up to within 2000 km. It was
also found that in the lower stratosphere, at altitudes where there is the
greatest difference between air composition inside and outside the polar
vortex, the geophysical variability in the southern polar region can be
double of that in the northern polar region. This study shows that the
ensemble mean estimates of geophysical variation can be used when comparing
data from two satellite instruments to optimize the coincidence criteria,
allowing for the use of more coincident profiles while providing an estimate
of the geophysical variation within the comparison results.
Characterizing water vapour concentration dependence of commercial cavity ring-down spectrometers for continuous on-site atmospheric water vapour isotope measurements in the tropics
Authors: Komiya Shujiro , Kondo Fumiyoshi , Moossen Heiko , Seifert Thomas , Schultz Uwe , Geilmann Heike , Walter David , Lavric Jost V.
Published: February 2021

Abstract. The recent development and improvement of commercial laser-based
spectrometers have expanded in situ continuous observations of water vapour
(H2O) stable isotope compositions (e.g. δ18O and δ2H) in a variety of sites worldwide. However, we still lack
continuous observations in the Amazon, a region that significantly
influences atmospheric and hydrological cycles on local to global scales. In
order to achieve accurate on-site observations, commercial water isotope
analysers require regular in situ calibration, which includes the correction
of H2O concentration dependence ([H2O] dependence) of isotopic
measurements. Past studies have assessed the [H2O] dependence for air
with H2O concentrations of up to 35 000 ppm, a value that is frequently
surpassed in tropical rainforest settings like the central Amazon where we
plan continuous observations. Here we investigated the performance of two
commercial analysers (L1102i and L2130i models, Picarro, Inc., USA) for
measuring δ18O and δ2H in atmospheric moisture at
four different H2O levels from 21 500 to 41 000 ppm. These H2O
levels were created by a custom-built calibration unit designed for regular
in situ calibration. Measurements on the newer analyser model (L2130i) had
better precision for δ18O and δ2H and demonstrated
less influence of H2O concentration on the measurement accuracy at each
concentration level compared to the older L1102i. Based on our findings, we
identified the most appropriate calibration strategy for
[H2O] dependence, adapted to our calibration system. The best strategy
required conducting a two-point calibration with four different H2O
concentration levels, carried out at the beginning and end of the
calibration interval. The smallest uncertainties in calibrating
[H2O] dependence of isotopic accuracy of the two analysers were
achieved using a linear surface fitting method and a 28 h calibration
interval, except for the δ18O accuracy of the L1102i analyser
for which the cubic fitting method gave the best results. The uncertainties in
[H2O] dependence calibration did not show any significant difference
using calibration intervals from 28 up to 196 h; this suggested that one
[H2O] dependence calibration per week for the L2130i and L1102i
analysers is sufficient. This study shows that the cavity ring-down spectroscopy (CRDS) analysers,
appropriately calibrated for [H2O] dependence, allow the detection of
natural signals of stable water vapour isotopes at very high humidity
levels, which has promising implications for water cycle studies in areas
like the central Amazon rainforest and other tropical regions.
Seasonal dependence of the Earth's radiation belt – new insights
Authors: Hajra Rajkumar
Published: February 2021

Abstract. Long-term variations in the relativistic (∼MeV) electrons in the Earth's radiation belt are explored to study seasonal features of the electrons. An L-shell dependence of the seasonal variations in the electrons is reported for the first time. A clear ∼6 month periodicity, representing one/two peaks per year, is identified for 1.5–6.0 MeV electron fluxes in the L shells between ∼3.0 and ∼5.0. The relativistic electron flux variation is strongest during solar cycle descending to minimum phases, with weaker/no variations during solar maximum. If two peaks per year occur, they are largely asymmetric in amplitude. The peaks essentially do not have an equinoctial
dependence. Sometimes the peaks are shifted to solstices, and sometimes only one annual peak is observed. No such seasonal features are prominent for L<3.0 and L>5.0. The results imply varying solar/interplanetary drivers of the radiation belt electrons at different L shells. This has a potential impact on the modeling of the space environment. Plausible solar drivers are discussed.
Multi-sensor analysis of monthly gridded snow precipitation on alpine glaciers
Authors: Gugerli Rebecca , Guidicelli Matteo , Gabella Marco , Huss Matthias , Salzmann Nadine
Published: February 2021

Abstract. Accurate and reliable solid precipitation estimates for high mountain regions are crucial for many research applications. Yet, measuring snowfall at high elevation remains a major challenge. In consequence, observational coverage is typically sparse, and the validation of spatially distributed precipitation products is complicated. This study presents a novel approach using reliable daily snow water equivalent (SWE) estimates by a cosmic ray sensor on two Swiss glacier sites to assess the performance of various gridded precipitation products. The ground observations are available during two and four winter seasons. The performance of three readily-available precipitation data products based on different data sources (gauge-based, remotely-sensed, and re-analysed) is assessed in terms of their accuracy compared to the ground reference. Furthermore, we include a data set, which corresponds to the remotely-sensed product with a local adjustment to independent SWE measurements. We find a large bias of all precipitation products at a monthly and seasonal resolution, which also shows a seasonal trend. Moreover, the performance of the precipitation products largely depends on in situ wind direction during snowfall events. The varying performance of the three precipitation products can be partly explained with their compilation background and underlying data basis.
Technical note: Interpreting pH changes
Authors: Fassbender Andrea J. , Orr James C. , Dickson Andrew G.
Published: February 2021

Abstract. The number and quality of ocean pH measurements have increased
substantially over the past few decades such that trends, variability, and
spatial patterns of change are now being evaluated. However, comparing pH
changes across domains with different initial pH values can be misleading
because a pH change reflects a relative change in the hydrogen ion
concentration ([H+], expressed in mol kg−1) rather than an
absolute change in [H+]. We recommend that [H+] be used in
addition to pH when describing such changes and provide three examples
illustrating why.
Global analysis of short- versus long-term drainage basin erosion
rates
Authors: Chen Shiuan-An , Michaelides Katerina , Singer Michael Bliss , Richards David A.
Published: February 2021

Abstract. Measuring erosion rates, analysing their temporal variations, and exploring environmental controls are crucial in the field of geomorphology because erosion through sediment transport in drainage basins shapes landforms and landscapes. Thus, important insights into landscape controls can be gleaned from analyses of erosion rates measured over different timescales. Suspended sediment flux and in situ cosmogenic radionuclides have been widely used for estimating short- and long-term erosion rates of drainage basins, respectively. Even though analyses of erosion rates have been conducted across the globe, there are still gaps in understanding of the links between environmental controls and erosion rates between timescales, especially the influence of climate, which is complex and covaries with other factors. To begin unpicking controls on landscape evolution across the globe, we compiled short- and long-term erosion rates (estimated from suspended sediment yield and in situ beryllium-10, 10Be, respectively) and analysed their relationships with climate, topography, and anthropogenic activity. The results show that: 1) A non-linear relationship exists between aridity and long-term erosion rates, resulting from the balance between precipitation and vegetation cover; 2) Long-term erosion rates are higher in mid- and high-latitude regions with high humidity, reflecting glacial processes during ice ages; 3) Long-term erosion rates are positively related to the steepness of drainage basins, showing that both climate and topography are the common factors; 4) Human activities increase short-term erosion rates which outweigh natural controls; and 5) The ratios of short- to long-term erosion rates are negatively related to basin area, reflecting the buffering capacity of large basins. These results highlight the complex interplay of controlling factors on land surface processes and reinforce the view that timescale of observation reveals different erosion rates and principal controls.
Evaluation of climate change impact on extreme temperature variability in the Blue Nile Basin, Ethiopia
Authors: Mohamed Mostafa Abdel-Hameed , El-Mahdy Mohamed El-Sayed
Published: February 2021

Abstract. Climate change raises important issues concerning hydrological engineering.
The impact of climate change on important river basins should be
investigated rigorously. Extreme temperature variability has a direct impact
on the hydrological cycle, especially the evaporation component. In this
paper, spatial and temporal patterns of changes in extreme temperatures were
investigated using 10 meteorological stations' data for the period 1950–2018
in the Blue Nile Basin. Long-term trends in the Blue Nile Basin annual and
monthly temperatures were investigated. The statistical significance of the
trend was calculated by applying the Mann–Kendall (MK) test. The analysis of
data was performed using the coefficient of variance and anomaly index. The
results showed that the annual maximum and minimum temperatures were
increasing significantly with a magnitude of 0.037 and
0.025 ∘C per decade respectively in the period from 1950 to
2018. The result of the Mann–Kendall analysis test revealed a marked
increase in the mean maximum and minimum temperature trends over time during
the study period (the minimum temperature rate is more evident than the
maximum). The long-term anomalies of mean annual minimum temperature
revealed the interannual variability while the trend after 1977 was higher
than the long-term average, which is proof of the warming trend's existence
during the last two decades of the 20th century.
A circulation-based performance atlas of the CMIP5 and 6 models
for regional climate studies in the northern hemisphere
Authors: Brands Swen
Published: February 2021

Abstract. Global Climate Models are a keystone of modern climate research. In many applications relevant for decision making, and particularly when deriving future projections with the delta-change method, they are assumed to be perfect. However, these models have not been originally developed to reproduce the regional-scale climate, which is where information is needed in practice. To overcome this dilemma, two general efforts have been made since their introduction in the late 1960ies. First, the models themselves have been steadily improved in terms of physical and chemical processes, parametrization schemes, resolution and complexity, giving rise to the term Earth System Model. Second, the global models' output has been refined at the regional scale using Limited Area Models or statistical methods in what is known as dynamical or statistical downscaling. Both approaches, however, are in principle unable to correct errors resulting from a wrong representation of the large-scale circulation in the global model. Also, dynamical downscaling has a high computational demand and thus cannot be applied to all available global models in practice. On this background, there is an ongoing debate in the downscaling community on whether to thrive away from the model democracy paradigm towards a careful selection strategy based on the global models' capacity to reproduce key aspects of the observed climate. The present study attempts to be useful for such a selection by providing a performance assessment of the historical global model experiments from CMIP5 and 6 based on recurring regional atmospheric circulation patterns (Lamb, 1972). The latest model generation is found to perform better on average, which can be partly explained by a moderately strong statistical relationship between performance and horizontal resolution in the atmosphere. A few models rank favourably over almost the entire northern hemisphere extratropics, but the better models tend to be less complex than others. Model selection should therefore not solely rely on model performance but also on model complexity and a discussion is needed on how to combine these two criteria. Internal model variability only has a small influence on the model ranks. Reanalysis uncertainty is an issue in Greenland and the surrounding seas, the southwestern United States and the Gobi desert, but is otherwise negligible.
A novel causal structure-based framework for comparing a basin-wide water–energy–food–ecology nexus applied to the data-limited Amu Darya and Syr Darya river basins
Authors: Shi Haiyang , Luo Geping , Zheng Hongwei , Chen Chunbo , Hellwich Olaf , Bai Jie , Liu Tie , Liu Shuang , Xue Jie , Cai Peng , He Huili , Ochege Friday Uchenna , Van de Voorde Tim , de Maeyer Philippe
Published: February 2021

Abstract. The previous comparative studies on watersheds were mostly based on the comparison of dispersive characteristics, which lacked systemicity and causality. We proposed a causal structure-based framework for basin comparison based on the Bayesian network (BN) and focus on the basin-scale water–energy–food–ecology (WEFE) nexus. We applied it to the Syr Darya River basin (SDB) and the Amu Darya River basin (ADB), of which poor water management caused the Aral Sea disaster. The causality of the nexus was effectively compared and universality of this framework was discussed. In terms of changes in the nexus, the sensitive factor for the water supplied to the Aral Sea changed from the agricultural development during the Soviet Union period to the disputes in the WEFE nexus after the disintegration. The water–energy contradiction of the SDB is more severe than that of the ADB, partly due to the higher upstream reservoir interception capacity. It further made management of the winter surplus water downstream
of the SDB more controversial. Due to this, the water–food–ecology conflict between downstream countries may escalate and turn into a long-term chronic problem. Reducing water inflow to depressions and improving the planting
structure prove beneficial to the Aral Sea ecology, and this effect of the SDB is more significant. The construction of reservoirs on the Panj River of the upstream ADB should be cautious to avoid an intense water–energy conflict such as the SDB's. It is also necessary to promote the water-saving drip irrigation and to strengthen the cooperation.
Using soil water isotopes to infer the influence of contrasting urban green space on ecohydrological partitioning
Authors: Kuhlemann Lena-Marie , Tetzlaff Doerthe , Smith Aaron , Kleinschmit Birgit , Soulsby Chris
Published: February 2021

Abstract. In cities around the world, urban green spaces provide a range of benefits and ecosystem services. However, recent years have shown how prolonged warm and dry periods can affect urban water resources and lead to water stress in vegetation in urban green spaces, even in temperate regions. Consequently, quantitative knowledge about ecohydrological partitioning in different types of urban green space is crucial for balancing sustainable water needs in cities during future challenges of increasing urbanization and climate warming. Using isotopic tracers in precipitation and soil water, along with conventional hydrometric measurements in a plot-scale study in Berlin, Germany, we investigated water partitioning under different generic types of urban vegetation (grassland, shrub and trees). This allowed for the assessment of urban vegetation effects on evapotranspiration, subsurface flow paths and storage during a prolonged drought period with episodic rainfall. Despite higher soil evaporation losses under urban grassland, higher interception and transpiration likely contributed to slower turnover of soil water and older groundwater recharge under urban trees. Shrub vegetation seemed to be most resilient to prolonged drought periods, with lower evapotranspiration losses. Our results contribute to a better understanding of ecohydrological partitioning under mixed urban vegetation communities and an evidence base for better adaptive management of urban water and irrigation strategies to sustainably meet the water demands of urban green spaces in the future.
Non-classical disproportionation revealed by photo-CIDNP NMR
Authors: Wörner Jakob , Chen Jing , Bacher Adelbert , Weber Stefan
Published: February 2021

Abstract. Photo-chemically induced dynamic nuclear polarization (photo-CIDNP) was used to observe the light-induced disproportionation reaction of 6,7,8-trimethyllumazine starting out from its triplet state to generate a pair of radicals comprising a one-electron-reduced and a one-electron oxidized species. Our evidence is based on the measurement of two marker proton hyperfine couplings, Aiso(H(6α)) and Aiso(H(8α)), which we correlated to predictions from density functional theory. The ratio of these two hyperfine couplings is reversed in the oxidized and the reduced radical species. Observation of the dismutation reaction is facilitated by the exceptional C–H acidity of the methyl group at position 7 of 6,7,8-trimethyllumazine and the slow proton exchange associated with it, which leads to NMR-distinguishable anionic (TML–) and neutral (TMLH) protonation forms.
Sparse 3D reflection seismic survey for deep-targeting iron oxide deposits and their host rocks, Ludvika Mines, Sweden
Authors: Malehmir Alireza , Markovic Magdalena , Marsden Paul , Gil Alba , Buske Stefan , Sito Lukasz , Bäckström Emma , Sadeghi Martiya , Luth Stefan
Published: February 2021

Abstract. Many metallic mineral deposits have sufficient physical property contrasts, particularly density,
to be detectable using seismic methods. These deposits are sometimes significant for our society and
economic growth and can help to accelerate the energy transition towards decarbonization. However,
their exploration at depth requires high-resolution and sensitive methods. Following a series of
2D seismic trials, a sparse, narrow source–receiver azimuth, 3D seismic survey was conducted in
the Blötberget mine, in central Sweden, covering an area of approximately 6 km2 for
deep-targeting iron oxide deposits and their host rock structures. The survey benefited from a
collaborative work by putting together 1266 seismic recorders and a 32 t vibrator,
generating 1056 shot points in a fixed geometry setup. Shots were fired at every 10 m
where possible, and receivers were placed at every 10–20 m. Notable quality data were acquired
despite the area being dominated by swampy places as well as by built-up roads and historical
tailings. The data processing had to overcome these challenges for the static
corrections and strong surface waves in particular. A tailored for hardrock setting and processing workflow was
developed for handling such a dataset, where the use of mixed 2D and 3D refraction static
corrections was relevant. The resulting seismic volume is rich in terms of reflectivity, with clear
southeast-dipping reflections originating from the iron oxide deposits extending vertically and
laterally at least 300 m beyond what was known from available boreholes. As a result, we
estimate potential additional resources from the 3D reflection seismic experiment on the order of
10 Mt to be worth drilling for detailed assessments. The mineralization is crosscut by at least
two major sets of northwest-dipping reflections interpreted to dominantly be normal faults and to be
responsible for much of the lowland in the Blötberget area. Moreover, these
post-mineralization faults likely control the current 3D geometry of the deposits. Curved and
submerged reflections interpreted from folds or later intrusions are also observed, showing the
geological complexity of the study area. The seismic survey also delineates the near-surface
expression of a historical tailing as a by-product of refraction static corrections, demonstrating
why 3D seismic data are so valuable for both mineral exploration and mine planning applications.
Mapping avalanches with satellites – evaluation of performance and completeness
Authors: Hafner Elisabeth D. , Techel Frank , Leinss Silvan , Bühler Yves
Published: February 2021

Abstract. The spatial distribution and size of avalanches are essential parameters for
avalanche warning, avalanche documentation, mitigation measure design and
hazard zonation. Despite its importance, this information is incomplete
today and only available for limited areas and limited time periods. Manual
avalanche mapping from satellite imagery has recently been applied to reduce
this gap achieving promising results. However, their reliability and
completeness have not yet been verified satisfactorily. In our study we attempt a full validation of the completeness of visually
detected and mapped avalanches from optical SPOT 6, Sentinel-2 and radar
Sentinel-1 imagery. We examine manually mapped avalanches from two avalanche
periods in 2018 and 2019 for an area of approximately 180 km2 around
Davos, Switzerland, relying on ground- and helicopter-based photographs as
ground truth. For the quality assessment, we investigate the probability of
detection (POD) and the positive predictive value (PPV). Additionally, we
relate our results to conditions which potentially influence avalanche
detection in the satellite imagery. We statistically confirm the high potential of SPOT for comprehensive
avalanche mapping for selected periods (POD = 0.74, PPV = 0.88) as well
as the reliability of Sentinel-1 (POD = 0.27, PPV = 0.87) for which the
POD is reduced because mainly larger avalanches are mapped. Furthermore, we
found that Sentinel-2 is unsuitable for the mapping of most avalanches due
to its spatial resolution (POD = 0.06, PPV = 0.81). Because we could
apply the same reference avalanche events for all three satellite mappings,
our validation results are robust and comparable. We demonstrate that
satellite-based avalanche mapping has the potential to fill the existing
avalanche documentation gap over large areas, making alpine regions safer.
Evaluating a prediction system for snow management
Authors: Ebner Pirmin Philipp , Koch Franziska , Premier Valentina , Marin Carlo , Hanzer Florian , Carmagnola Carlo Maria , François Hugues , Günther Daniel , Monti Fabiano , Hargoaa Olivier , Strasser Ulrich , Morin Samuel , Lehning Michael
Published: February 2021

Abstract. The evaluation of snowpack models capable of accounting for snow management in ski resorts is a major step towards acceptance of such models in supporting the daily decision-making process of snow production managers. In the frame of the EU H2020 project PROSNOW, a service to enable real-time optimisation of grooming and snow-making in ski resorts was developed. We applied snow management strategies integrated in the snowpack simulations of AMUNDSEN, Crocus and SNOWPACK/Alpine3D for nine PROSNOW ski resorts located in the European Alps. We assessed the performance of the snow simulations for five winter seasons (2015–2020) using both, ground-based data (GNSS measured snow depth) and space-borne snow maps derived from Copernicus Sentinel-2. Particular attention has been devoted to characterize the spatial performance of the simulated piste snow management at a resolution of 10 meters. The simulated results showed a high overall accuracy of more than 80 % compared to the Sentinel-2 data. Moreover, the correlation to the ground observation data was high. Potential sources for the overestimation of the snow depth by the simulations are mainly due to the impact of snow redistribution by skiers or spontaneous local adaptions of the snow management, which were not reflected in the simulations. Subdividing each individual ski resort in differently-sized ski resort reference units (SRU) based on topography showed a slight decrease in mean deviation. Although this work shows plausible and robust results on the ski-slope scale by all three snowpack models, the accuracy of the results is mainly dependent on the detailed representation of the real-world snow management practices in the models. This calls for an assessment of impacts from meteorological station measurements and their interpolations in the ski resorts as well as potential limitations in describing the snow cover, especially managed snow, by simulations.