Evaluation of Vertical Refractivity Profile over Microwave Link in Mowe, Nigeria

The radio refractive index structure of the lower section of the atmospheric boundary layer is critical in the planning and construction of microwave communication connections. This study analyses the refractivity profile carried out in Mowe (6.8085° N, 3.4367° E) South – Western Nigeria. Ground measurements of air pressure, temperature, and relative humidity used in this investigation were collected from the rain gauge of the Tropospheric Observatory Data Acquisition Network (TRODAN). The radio refractivity, associated refractivity gradient and climatic factor were computed using data from January 2012 to December 2013. The vertical distributions of radio refractivity were then calculated using these parameters. Seasonal fluctuations in refractivity are visible over the location, with high values in the wet season and low values in the dry season. The findings also suggest that propagation circumstances fluctuate in frequency, with sub-refractive situations being most common between April and September. This is an indication that microwave link in Mowe will suffer higher signal loss during wet season, while the loss may be mild during the dry season. The refractivity values in this study are expected to aid in determining the necessary mitigation to be put in place to reduce loss of signal in Mowe.

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Entomological Studies, relating to Yellow Fever Epidemiology, at Gede and Taveta, Kenya

Bulletin of Entomological Research ◽

10.1017/s0007485300030819 ◽

1955 ◽

Vol 46 (1) ◽

pp. 149-183 ◽

Cited By ~ 25

Author(s):

W. H. R. Lumsden

Keyword(s):

Yellow Fever ◽

Yellow Fever Virus ◽

Sea Water ◽

Dry Season ◽

Natural Environments ◽

Wet Season ◽

Field Surveys ◽

Mount Kilimanjaro ◽

Vertical Distributions ◽

Tree Holes

The theoretical objections to the explanation of the persistence of yellow fever virus in areas subject to a prolonged dry season by cycles involving only mosquitos and wild primates are discussed in relation to the results of field surveys in areas of this type in Kenya. The localities studied were Gede, on the coast about 65 miles north of Mombasa, and Taveta, near Mount Kilimanjaro.The topography, climate, vegetation and human population of the areas are briefly described.Gede was visited towards the end of the dry season, Taveta during the main wet season. Thus most of the data relating to conditions during the dry season are derived from Gede, the results from Taveta being used mainly for comparative purposes. The work included 24-hour baited catches at two levels, moving catches, and larval collections in all the main typical environments.All the species of biting arthropod encountered at each locality are recorded; in each case most were mosquitos.At Gede the only mosquitos which were abundant as biting adults were species which breed in sea water, Aëdes fryeri (Theo.) and A. pembacnsis (Theo.), and they were practically confined to the close vicinity of their breeding places. The vertical distributions and biting-cycles of these species are defined.At Gede, mosquito larvae could readily be obtained by filling tree holes artificially with water but no naturally water-filled tree holes were discovered by intensive searches in all the natural environments present in the area. Nor were any water-containing leaf axils discovered.

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A Variational Approach to Retrieve Rain Rate by Combining Information from Rain Gauges, Radars, and Microwave Links

Journal of Hydrometeorology ◽

10.1175/jhm-d-12-094.1 ◽

2013 ◽

Vol 14 (6) ◽

pp. 1897-1909 ◽

Cited By ~ 25

Author(s):

Blandine Bianchi ◽

Peter Jan van Leeuwen ◽

Robin J. Hogan ◽

Alexis Berne

Keyword(s):

Variational Approach ◽

Rain Rate ◽

Rain Gauge ◽

Sources Of Information ◽

Rain Gauges ◽

Strongly Nonlinear ◽

Using Data ◽

The Cost ◽

Microwave Link ◽

Link Information

Abstract Accurate and reliable rain rate estimates are important for various hydrometeorological applications. Consequently, rain sensors of different types have been deployed in many regions. In this work, measurements from different instruments, namely, rain gauge, weather radar, and microwave link, are combined for the first time to estimate with greater accuracy the spatial distribution and intensity of rainfall. The objective is to retrieve the rain rate that is consistent with all these measurements while incorporating the uncertainty associated with the different sources of information. Assuming the problem is not strongly nonlinear, a variational approach is implemented and the Gauss–Newton method is used to minimize the cost function containing proper error estimates from all sensors. Furthermore, the method can be flexibly adapted to additional data sources. The proposed approach is tested using data from 14 rain gauges and 14 operational microwave links located in the Zürich area (Switzerland) to correct the prior rain rate provided by the operational radar rain product from the Swiss meteorological service (MeteoSwiss). A cross-validation approach demonstrates the improvement of rain rate estimates when assimilating rain gauge and microwave link information.

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What Drives Daily Precipitation Over Central Amazon? Differences Observed Between Wet and Dry Seasons

10.5194/acp-2020-1098 ◽

2020 ◽

Author(s):

Thiago S. Biscaro ◽

Luiz A. T. Machado ◽

Scott E. Giangrande ◽

Michael P. Jensen

Keyword(s):

Satellite Data ◽

Dry Season ◽

Surface Fluxes ◽

Wet Season ◽

Night Time ◽

Central Amazon ◽

Physical Mechanisms ◽

Diurnal Rainfall ◽

Rain Events ◽

Using Data

Abstract. This study suggests a new approach on how diurnal precipitation is modulated by the nighttime events developed over Central Amazon using data from the Observations and Modelling of the Green Ocean Amazon (GoAmazon 2014/5) field campaign in the Central Amazon as well as radar and satellite data. Local observations of cloud occurrences, soil temperature, surface fluxes, and planetary boundary layer characteristics are coupled with satellite data to identify physical mechanisms that control the diurnal rainfall in Amazonas during the wet and dry season. This is accomplished by evaluating the atmospheric properties during the nocturnal periods from the days prior to rainfall and non-raining events. Comparisons between non-rainy and rainy transitions are presented for the wet (January to April) and dry (June to September) seasons. The results suggest that wet season diurnal precipitation is modulated mainly by night-time cloud coverage and local effects such as turbulence, while dry season rain events are mainly controlled by large-meso scale circulation.

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Optimum time for sampling floristic diversity in tropical eucalypt woodlands of northern Queensland

The Rangeland Journal ◽

10.1071/rj04013 ◽

2004 ◽

Vol 26 (2) ◽

pp. 190 ◽

Cited By ~ 5

Author(s):

V. J. Neldner ◽

A. B. Kirkwood ◽

B. S. Collyer

Keyword(s):

Dry Season ◽

Floristic Diversity ◽

Tropical Savannas ◽

Wet Season ◽

Anova Analysis ◽

Ground Flora ◽

Vegetation Sampling ◽

Eucalypt Woodlands ◽

Using Data ◽

Study Sites

The timing of vegetation sampling in highly seasonal environments is one of the critical factors in determining the proportion of the flora captured in a single sampling. Four sites were located within a 20 km radius of Mareeba, north Queensland and sampled every three months for three years. The sites were located in a variety of eucalypt communities and across an altitudinal range from 380 to 840 m above sea level. In these eucalypt communities experiencing highly seasonal rainfall typical of the tropical savannas, vegetation sampling in the early dry season (May) maximises the diversity of flora recorded. The ANOVA analysis showed a significant effect of month of sampling for the number of ground taxa recorded (P < 0.005). There was significant variation (P < 0.005) in species diversity between the sites but in all four study sites the May sampling recorded greater than 84% of the total recorded flora, whereas the November samplings accounted for between 21% and 56% of the flora. This supports the experience of other researchers that a May sampling is near optimum for sampling the ground layer floristic diversity in tropical eucalypt woodlands. Most vegetation survey and mapping data are of necessity collected at less than ideal times of the year due to access and resource issues. Care must be exercised in using data collected in the dry season, as only a limited proportion of the total ground flora is likely to be recorded. Studies designed to capture the full florisitic inventory of species present in these highly seasonal environments need to budget resources and plan to access these environments in the late wet season.

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The seasonal changes of the gut microbiome of the population living in traditional lifestyles are represented by characteristic species-level and functional-level SNP enrichment patterns

BMC Genomics ◽

10.1186/s12864-021-07372-0 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Xue Zhu ◽

Jiyue Qin ◽

Chongyang Tan ◽

Kang Ning

Keyword(s):

Gut Microbiome ◽

Seasonal Changes ◽

Dry Season ◽

Urban Setting ◽

Snp Analysis ◽

Wet Season ◽

Human Gut ◽

Human Gut Microbiome ◽

Genome Level ◽

Prevalent Species

Abstract Background Most studies investigating human gut microbiome dynamics are conducted on humans living in an urban setting. However, few studies have researched the gut microbiome of the populations living traditional lifestyles. These understudied populations are arguably better subjects in answering human-gut microbiome evolution because of their lower exposure to antibiotics and higher dependence on natural resources. Hadza hunter-gatherers in Tanzania have exhibited high biodiversity and seasonal patterns in their gut microbiome composition at the family level, where some taxa disappear in one season and reappear later. Such seasonal changes have been profiled, but the nucleotide changes remain unexplored at the genome level. Thus, it is still elusive how microbial communities change with seasonal changes at the genome level. Results In this study, we performed a strain-level single nucleotide polymorphism (SNP) analysis on 40 Hadza fecal metagenome samples spanning three seasons. With more SNP presented in the wet season, eight prevalent species have significant SNP enrichment with the increasing number of SNP calling by VarScan2, among which only three species have relatively high abundances. Eighty-three genes have the most SNP distributions between the wet season and dry season. Many of these genes are derived from Ruminococcus obeum, and mainly participated in metabolic pathways including carbon metabolism, pyruvate metabolism, and glycolysis. Conclusions Eight prevalent species have significant SNP enrichments with the increasing number of SNP, among which only Eubacterium biforme, Eubacterium hallii and Ruminococcus obeum have relatively high species abundances. Many genes in the microbiomes also presented characteristic SNP distributions between the wet season and the dry season. This implies that the seasonal changes might indirectly impact the mutation patterns for specific species and functions for the gut microbiome of the population that lives in traditional lifestyles through changing the diet in wet and dry seasons, indicating the role of these variants in these species’ adaptation to the changing environment and diets.

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Seasonal Climate Impacts on Vocal Activity in Two Neotropical Nonpasserines

Diversity ◽

10.3390/d13070319 ◽

2021 ◽

Vol 13 (7) ◽

pp. 319

Author(s):

Cristian Pérez-Granados ◽

Karl-L. Schuchmann

Keyword(s):

Air Temperature ◽

Daily Rainfall ◽

Climatic Conditions ◽

Dry Season ◽

Climate Impacts ◽

Calling Behavior ◽

Wet Season ◽

Focal Species ◽

Calling Activity ◽

Vocal Activity

Climatic conditions represent one of the main constraints that influence avian calling behavior. Here, we monitored the daily calling activity of the Undulated Tinamou (Crypturellus undulatus) and the Chaco Chachalaca (Ortalis canicollis) during the dry and wet seasons in the Brazilian Pantanal. We aimed to assess the effects of climate predictors on the vocal activity of these focal species and evaluate whether these effects may vary among seasons. Air temperature was positively associated with the daily calling activity of both species during the dry season. However, the vocal activity of both species was unrelated to air temperature during the wet season, when higher temperatures occur. Daily rainfall was positively related to the daily calling activity of both species during the dry season, when rainfall events are scarce and seem to act as a trigger for breeding phenology of the focal species. Nonetheless, air temperature was negatively associated with the daily calling activity of the Undulated Tinamou during the wet season, when rainfall was abundant. This study improves our understanding of the vocal behavior of tropical birds and their relationships with climate, but further research is needed to elucidate the mechanisms behind the associations found in our study.

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Inorganic Nitrogen Production and Removal along the Sediment Gradient of a Stormwater Infiltration Basin

Water ◽

10.3390/w13030320 ◽

2021 ◽

Vol 13 (3) ◽

pp. 320

Author(s):

Qianyao Si ◽

Mary G. Lusk ◽

Patrick W. Inglett

Keyword(s):

Removal Efficiency ◽

N Mineralization ◽

Inorganic Nitrogen ◽

Dry Season ◽

Pollutant Removal ◽

Net N Mineralization ◽

Wet Season ◽

Inorganic N ◽

N Removal ◽

Stormwater Infiltration

Stormwater infiltration basins (SIBs) are vegetated depressions that collect stormwater and allow it to infiltrate to underlying groundwater. Their pollutant removal efficiency is affected by the properties of the soils in which they are constructed. We assessed the soil nitrogen (N) cycle processes that produce and remove inorganic N in two urban SIBs, with the goal of further understanding the mechanisms that control N removal efficiency. We measured net N mineralization, nitrification, and potential denitrification in wet and dry seasons along a sedimentation gradient in two SIBs in the subtropical Tampa, Florida urban area. Net N mineralization was higher in the wet season than in the dry season; however, nitrification was higher in the dry season, providing a pool of highly mobile nitrate that would be susceptible to leaching during periodic dry season storms or with the onset of the following wet season. Denitrification decreased along the sediment gradient from the runoff inlet zone (up to 5.2 μg N/g h) to the outermost zone (up to 3.5 μg N/g h), providing significant spatial variation in inorganic N removal for the SIBs. Sediment accumulating around the inflow areas likely provided a carbon source, as well as maintained stable anaerobic conditions, which would enhance N removal.

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Seasonal changes in water quality and macrophytes and the impact of cattle on tropical floodplain waterholes

Marine and Freshwater Research ◽

10.1071/mf12114 ◽

2012 ◽

Vol 63 (9) ◽

pp. 788 ◽

Cited By ~ 17

Author(s):

N. E. Pettit ◽

T. D. Jardine ◽

S. K. Hamilton ◽

V. Sinnamon ◽

D. Valdez ◽

...

Keyword(s):

Water Quality ◽

Seasonal Changes ◽

Aquatic Macrophyte ◽

Plant Cover ◽

Critical Role ◽

Dry Season ◽

Nutrient Concentrations ◽

Wet Season ◽

Dry Tropics ◽

The Impact

The present study indicates the critical role of hydrologic connectivity in floodplain waterholes in the wet–dry tropics of northern Australia. These waterbodies provide dry-season refugia for plants and animals, are a hotspot of productivity, and are a critical part in the subsistence economy of many remote Aboriginal communities. We examined seasonal changes in water quality and aquatic plant cover of floodplain waterholes, and related changes to variation of waterhole depth and visitation by livestock. The waterholes showed declining water quality through the dry season, which was exacerbated by more frequent cattle usage as conditions became progressively drier, which also increased turbidity and nutrient concentrations. Aquatic macrophyte biomass was highest in the early dry season, and declined as the dry season progressed. Remaining macrophytes were flushed out by the first wet-season flows, although they quickly re-establish later during the wet season. Waterholes of greater depth were more resistant to the effects of cattle disturbance, and seasonal flushing of the waterholes with wet-season flooding homogenised the water quality and increased plant cover of previously disparate waterholes. Therefore, maintaining high levels of connectivity between the river and its floodplain is vital for the persistence of these waterholes.

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Effects of moisture supply in the dry season and subsequent defoliation on persistence of the savanna grasses Themeda triandra, Heteropogon contortus and Panicum maximum

Australian Journal of Agricultural Research ◽

10.1071/ar9920241 ◽

1992 ◽

Vol 43 (2) ◽

pp. 241 ◽

Cited By ~ 27

Author(s):

JJ Mott ◽

MM Ludlow ◽

JH Richards ◽

AD Parsons

Keyword(s):

Growing Season ◽

Close Correlation ◽

Dry Season ◽

Carbon Gain ◽

Panicum Maximum ◽

Wet Season ◽

Themeda Triandra ◽

Heteropogon Contortus ◽

Moisture Conditions ◽

Sheath Material

The close correlation between grazing-induced mortality and major climatic patterns in Australian savannas, led us to the hypothesis that moisture conditions during the dry, non-growing season could affect sensitivity to grazing in the subsequent growing season. Using three widespread savanna species (Themeda triandra, Heteropogon contortus and Panicum maximum), this hypothesis was tested experimentally and the mechanisms controlling this response examined and quantified. In T. triandra drought during the dry season led to major mortality in defoliated plants in the next growing season. This mortality was caused by a synchrony of tillering at the commencement of the wet season, leaving few buds for replacement once parent tillers were killed by defoliation. T. triandra was also the most sensitive species to defoliation. This sensitivity was due to the poor ability of the plant to maintain positive carbon gain after defoliation. Several factors contributed to this poor ability, including: low total photosynthetic rate, low specific leaf area, and a large proportion of sheath material with poor photosynthetic capacity remaining after cutting. Both H. contortus and P. maximum growing under irrigated and fertilized conditions did not display any effects of previous moisture treatments when defoliated during the next wet season and were much less sensitive to defoliation than T. triandra.

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Crocodylus johnstoni and C. porosus Coexisting in a Tidal River

Wildlife Research ◽

10.1071/wr9830639 ◽

1983 ◽

Vol 10 (3) ◽

pp. 639 ◽

Cited By ~ 27

Author(s):

GJW Webb ◽

SC Manolis ◽

GC .Sack

Keyword(s):

Competitive Exclusion ◽

Dry Season ◽

Tidal River ◽

Main Stream ◽

Wet Season ◽

Seasonal Movements ◽

Crocodylus Johnstoni ◽

Seasonal Factors

A 52.5-km section of the Adelaide River, N.T. (12�13'S., 131�13'E.). was spotlight-surveyed 20 times between June 1979 and September 1981. C, johnstoni (15.3 � 9.2 sighted per survey) were less abundant than C. porosus (137.6 � 36.5 sighted per survey), and were mainly in the upstream 20 km of the survey route (96% of C. johnstoni sightings); here considered a zone of syntopy within the survey route. C. johnstoni congregate in the main stream during the dry season and disperse from it during the wet season, which parallels similar seasonal movements to and from dry-season refuges in non-tidal areas lacking C. porosus. As the dry season progresses, C. johnstoni are located further and further upstream, and this movement (or loss ofanimals) appears unrelated to changes in salinity. Numbers of C.johnstoni within the zone of syntopy are negatively correlated with numbers of C. porosus (r*2 = 0.50, P=0.005). and competitive exclusion may be occurring. Independent of seasonal factors, numbers of C. johnstoni within the zone of syntopy declined with consecutive month (1979-81: r*2=0.47, P= O.004), whereas numbers ofthe more recently protected C, porosus increased (r2 = 0.48, P= 0,006). The location of the syntopic zone was unchanged.

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