The Influence of Local Rainy and Dry Seasons on the Diurnal Temperature Range in Nigeria

This study analyzed the impact of the local dry and rainy seasons on diurnal temperature range (DTR), for each major climatic zone of Nigeria namely the tropical monsoon, tropical savannah and semi-arid, using meteorological data from thirteen observation stations for the period 1981 to 2021. DTR was computed from the difference of minimum temperature from maximum temperature and yearly and forty one years’ monthly averages of DTR and rainfall were computed and plotted in different graphs. The overall results from each climatic zone showed that DTR fluctuates with the seasons and there is an inverse relationship between DTR and rainfall whereby the value of DTR decreases as the rainy season approaches but increases as the rainy season departs ushering in the dry season or conversely DTR increases as the dry season approaches and decreases as the dry season departs ushering-in the rainy season. Secondly, the average yearly patterns of rainfall and DTR are roughly and oppositely shaped parabolas where the peak value of rainfall is diametrically opposite to the trough value of DTR and the least or nil volume of rainfall corresponds to the highest value of DTR. Thirdly, due to the yearly seasonal cycle of dry and rainy seasons in Nigeria coupled with the inverse relationship between DTR and Rainfall, the seasonal plot of DTR and rainfall is also cyclic in pattern with DTR cycle lagging 180 degrees with the rainfall cycle and the intersection of the two cycles represents the departure of one season and onset of another season while each half-cycle represents either the dry or rainy season. Fourthly, the dependence of DTR on any season at hand in Nigeria makes DTR season-forcing. This fourth result is underpinned by a result that showed that the 1981 and 2021 patterns of DTR and 1981 and 2021 patterns of rainfall when compared were similar, the differences were in the volume of rainfall which was due to climate change that has taken place over the four decades and which also impacted DTR since DTR varies inversely with rainfall. Finally and notwithstanding the common grounds of the results stated above, the result further showed that each climatic zone of Nigeria reacts differently to the local and global climate changes leading to the magnitude of DTR and the volume of rainfall being different across climatic zones, with rainfall volume and duration decreasing towards the arid North from the Coastal South while contrariwise DTR increases towards the arid North from the Coastal South.

Precipitation Changes in Wet and Dry Seasons over the 20th Century Simulated by Two Versions of the FGOALS Model

Seasonal precipitation changes over the globe during the 20th century simulated by two versions of the Flexible Global Ocean-Atmosphere-Land System （FGOALS） model are assessed. The two model versions differ in terms of their AGCM component, but the remaining parts of the system are almost identical. Both models reasonably reproduce the mean-state features of the timings of the wet and dry seasons and related precipitation amounts, with pattern correlation coefficients of 0.65-0.84 with observations. Globally averaged seasonal precipitation changes are analyzed. The results show that wet sea- sons get wetter and the annual range （precipitation difference between wet and dry seasons） increases during the 20th century in the two models, with positive trends covering most parts of the globe, which is consistent with observations. However, both models show a moistening dry season, which is opposite to observations. Analysis of the globally averaged moisture budget in the historical climate simulations of the two models shows little change in the horizontal moisture advection in both the wet and dry seasons. The globally averaged seasonal precipitation changes are mainly dominated by the changes in evaporation and vertical moisture advection. Evaporation and vertical moisture advection combine to make wet seasons wetter and enhance the annual range. In the dry season, the opposite change of evaporation and vertical moisture advection leads to an insignificant change in precipitation. Vertical moisture advection is the most important term that determines the changes in precipitation, wherein the thermodynamic component is dominant and the dynamic component tends to offset the effect of the thermodynamic component.

Water discharge changes of the Changjiang River downstream Datong during dry season

Based on hydrometric data and extensive investigations on water-extracting projects, this paper presents a preliminary study on water discharge changes between Datong and Xuliujing during dry season. The natural hydrological processes and human factors that influence the water discharge are analyzed with the help of GIS method. The investigations indicate that the water-extracting projects downstream from Datong to Xuliujing had amounted to 64 in number by the end of 2000, with a water-extracting capacity up to 4,626 m 3 /s averaged in a tidal cycle. The water extraction from the Changjiang River has become the most important factor influencing the water discharge downstream Datong during dry season. The potential magnitude in water discharge changes are estimated based on historical records of water extraction and a water balance model. The computational results were calibrated with the actual data. The future trend in changes of water discharge into the sea during dry season was discussed by taking into consideration of newly built hydro-engineering projects. The water extraction downstream Datong in dry season before 2000 had a great influence on discharges into the sea in the extremely dry year like 1978-1979. It produced a net decrease of more than 490 m 3 /s in monthly mean discharges from the Changjiang into the sea. It is expected that the water extraction will continually increase in the coming decades, especially in dry years, when the net decrease in monthly mean water discharge will increase to more than 1000 m 3 /s and will give a far-reaching effect on the changes of water discharge from the Changjiang into the sea.

Aerosol Optical Properties and Radiative Impacts in the Pearl River Delta Region of China during the Dry Season

Aerosol optical properties and direct radiative effects on surface irradiance were examined using seven years （2006-2012） of Cimel sunphotometer data collected at Panyu--the main atmospheric composition monitoring station in the Pearl River Delta （PRD） region of China. During the dry season （October to February）, mean values of the aerosol optical depth （AOD） at 550 nm, the Angstrom exponent, and the single scattering albedo at 440 nm （SSA） were 0.54, 1.33 and 0.87, respectively. About 90% of aerosols were dominated by fine-mode strongly absorbing particles. The size distribution was bimodal, with fine-mode particles dominating. The fine mode showed a peak at a radius of 0.12 μm in February and October （- 0.10 μm3 μm-2）. The mean diurnal shortwave direct radiative forcing at the surface, inside the atmosphere （FATM）, and at the top of the atmosphere, was -33.4± 7.0, 26.1 ± 5.6 and -7.3 ±2.7 W m-2, respectively. The corresponding mean values of aerosol direct shortwave radiative forcing per AOD were -60.0 ±7.8, 47.3 ± 8.3 and -12.8 ±3.1 W m-2, respectively. Moreover, during the study period, FATM showed a significant decreasing trend （p 〈 0.01） and SSA increased from 0.87 in 2006 to 0.91 in 2012, suggesting a decreasing trend of absorbing particles being released into the atmosphere. Optical properties and radiative impacts of the absorbing particles can be used to improve the accuracy of inversion algorithms for satellite-based aerosol retrievals in the PRD region and to better constrain the climate effect of aerosols in climate models.

Wet and Dry Season Effects on Select Soil Nutrient Contents of Upland Farms in North Bank Region of the Gambia

The study was conducted in three villages of North Bank Region of the Gambia in 2013 and 2014. We examined wet and dry season effects on select soil nutrient contents of upland farms in North Bank Region of the Gambia. The objective was to evaluate changes in soil nutrient contents in both wet and dry seasons. Soil samples were collected from three RCBD upland fields with three replications at a depth of 0 - 15 cm and analyzed for pH, Soil Organic Carbon (SOC), and soil moisture content. The gravimetric method of moisture estimation was used. The results showed that soil moisture content, soil TN, and soil pH are significantly different (P < 0.05) during the two seasons. There was no significant difference in SOC between the two seasons in the study area. The study concluded that soil nutrients were more readily available during the wet season than during the dry season probably because there is more soil moisture available in the wet season that facilitates soil nutrient release. The study concludes that soil moisture has to be available in order for some select soil nutrients to be released for plant uptake.

Changes of Dry-wet Climate in the Dry Season in Yunnan(1961-2007)

Factor analysis was used to investigate the changes of dry-wet climate in the dry season in Yunnan during 1961-2007 based on observed data from 15 stations.Three common factors were extracted from the 9 climatic factors.The results showed that the dry-wet climate has evidently changed since the early 1960s.The general trends in the changes of drywet climate were described as slight decrease in humidity and gradual enhancement in drought intensity.The climate during 1960s-1980s was under weak-medium drought.But since early 1990s,dry conditions have markedly strengthened and continued due to uneven temporal distribution of rainfall and climate warming.

Water relations balance parameters of 30 woody species from Cerrado vegetation in the wet and dry season

The water relations balance parameters of plant tissue have been determined under field condition.They are the osmotic potentials at saturation (nsat), the osmotic potentials at the turgid loss point (ntlp), modulusof elasticity and the water saturation deficiency at turgid loss point (Wsdtlp) of 30 adult woody species fromCerrado vegetetion (neotropical savanna) in the wet and dry seasons of Brazil. And the changing patterns of Sevalues of each species have been compared and analyzed in different methods. The mean values of nsat, ntlp, and Wsdtlp of 30 species in the wet season were -2.11 MPa, -2.50 MPa, 19.66 MPa and 10.27 % respectively.Responding to water stress in the dry season, the values of nsat of 24 species, the ntlp and the of 17 speciesthe Wsdtpl of 6 species significantly went down or up comparing with those in the wet season (P < 0.05)- Only 3species had not changed their water parameters significantly any more. The mean values of nsat, ntlp, andWsdtlp of 30 species were adjusted to be -2.28 MPa, -2.84 MPa, 18.58 MPa and 8.19 % respectively. The species that have lower values on the mt have higher vaIues on e. Contrary, the specles that have higher valueson the nsat have lower values on . The special strategies of 30 Cerrado species have been divided. into 3 typesin Cluster Analysis Method. Every type has the distinct water balance mechanism and the parameter-adjustingpattern.

Effects of protein and mineral supplementation on the performance of lactating dairy cows gobra and crossbreed guzerat during the dry season in senegal

The purpose of this study carried out in the township of Dahra was to access the effect of dry season protein and mineral supplementation of Gobra and Crossbreed Guzerat cows on milk production. The experimental design is a completely randomized block. The treatments were: supplement of molasse-urea blocks with supplement of hay;supplement of molasse-urea blocks without any hay;no supplement of molasse-urea blocks and supplement of hay;no supplement of molasse-urea block without any hay. For each breed, the treatments were replicated three times on a lot of cows with the similar zootechnic parameters. A total of twelve lactating cows per breed were then used. The supplement of block + hay has significantly (p < 5%) allowed obtaining the largest average daily quantity of milk: 1.9 ± 0.7L/day/cow and 2.4 ± 0.8 L/day/cow respectively in Gobra and Crossbreed Gobra*Guzerat. The increases in production compared to the control treatment (without supplement) are 52.63% and 100% respectively in the breed Gobra and Gobra*Guzerat. The supplement of hay comes in the second place and contributes to an additional production of 66.66% in both breeds of cow. Then, the supplement of block follows and it allows increasing the production of 44.44% and 50% respectively in Gobra and Crossbreed. In both races, the supplement of block + hay has allowed obtaining the highest profits of $1.6/L/day/cow for Gobra and $ 2.8/L/day/cow for the Crossbreed, that equals to an increase by $ 0.3 and $ 0.9 compared to the control treatment. The supplement of hay and the block supplement have respectively given a profit of 0.4 and $ 0.3/L/day/cow in Gobra and 0.6 and $ 0.4/L/day/cow in the Crossbreed. The adoption of supplementation molasse-urea block + hay by producers appears an alternative to boost milk production in dry season.

Investigating the Apparent Link between Cosmic Ray Muon Flux, Sudden Stratospheric Warming and Dry Season Rainfall over Jamaica

The Jamaican primary dry season extends from November-April with the driest period being January-March each year. Examination of the rainfall records over several decades reveal months that experienced a sharp increase in rainfall while sometimes they are drier than normal. During this dry season, some of the weather systems that impact the island significantly are cold fronts, highs pressure systems and troughs that migrate from the mainland USA. Major Sudden Stratospheric Warmings (SSW) occur routinely north of 60&#176;N and severely impact weather over the North American continent. The islands of the Greater Antilles also experience inclement weather during this period as weather systems migrate southwards and impact the Caribbean. Severe winter weather due to the increase frequency and intensity of storms related to SSW events over North America is important to the Jamaican economy as tourists escape harsh winters by travelling to the island. Predicting the variability of rainfall during the primary dry season is therefore important as it has significant implications for event planning, tourism and agriculture. Cosmic-ray Muon flux has been found to be positively correlated with the atmospheric effective temperature used to indicate the occurrence of SSW events. Current research investigates the relationship between cosmic-ray Muon flux, SSW events and primary dry season rainfall. Our findings suggest that a significant change in rainfall occur over Jamaica during the primary dry season on average 29 days after the central date or on average 15 days after the SSW events end. Our study also suggests apparent similarities in the behaviour of cosmic-ray Muon flux over Jamaica to those when major SSW occurs at high latitudes. We therefore argue that the Muon detectors at low latitudes have practical use with respect to identifying SSWs and merits further study.

On the Causes of the Minor Dry Season over the Coastal Region of the Northern Gulf of Guinea

Along the littoral shelf of northern coast of the Gulf of Guinea (GG), a minor dry season of the rainfall regime is concomitantly observed with the occurrence of a major coastal upwelling in July-August-September (JAS). It was then supposed that this upwelling drives that minor dry season. But no previous studies have tried to understand this minor dry season and, this study is the first focusing on this question. The investigations undertaken to explain this dry season on the Ivorian littoral shelf with the ERA-Interim data from the European Centre for Medium Range Weather Forecasts over the 1980-2016 period have shown that the minor dry season is driven by the Northward migration of the Inter Tropical Convergence Zone (ITCZ) during this period and, enhanced by the occurrence of the major coastal upwelling of the northern GG at the same time. These two phenomena interact as follow: i) the ITCZ is located in JAS far in the north cutting off convective processes along the coast, ii) the air on the coastal region is poor in humidity, iii) the air temperature on the bordering region of the GG is cooled by the coastal upwelling to value less than 26°C and not favorable for providing convection.

Runoff characteristics in flood and dry seasons based on wavelet analysis in the source regions of the Yangtze and Yellow rivers

By decomposing and reconstructing the runoff information from 1965 to 2007 of the hydrologic stations of Tuotuo River and Zhimenda in the source region of the Yangtze River, and Jimai and Tangnaihai in the source region of the Yellow River with db3 wavelet, runoff of different hydrologic stations tends to be declining in the seasons of spring flood, summer flood and dry ones except for that in Tuotuo River. The declining flood/dry seasons series was summer 〉 spring 〉 dry; while runoff of Tuotuo River was always increasing in different stages from 1965 to 2007 with a higher increase rate in summer flood seasons than that in spring ones. Complex Morlet wavelet was selected to detect runoff periodicity of the four hydrologic stations mentioned above. Over all seasons the periodicity was 11-12 years in the source region of the Yellow River. For the source region of the Yangtze River the periodicity was 4-6 years in the spring flood seasons and 13-14 years in the summer flood seasons. The differences of variations of flow periodicity between the upper catchment areas of the Yellow River and the Yangtze River and between seasons were considered in relation to glacial melt and annual snowfall and rainfall as providers of water for runoff.

Contemporary climate infuence on variability patterns of Anadenanthera colubrina var.cebil,a key species in seasonally dry tropical forests

The distribution of many plant species has been shaped by climate changes,and their current phenotypic and genetic variability refect microclimatically suitable habitats.This study relates contemporary climate to variability patterns of phenotypic traits and molecular markers in the Argentinean distribution of Anadenanthera colubrina var.cebil,as well as to identify the most relevant phenotypic trait or molecular marker associated with those patterns.Individuals from four populations in both biogeographic provinces,Paranaense and Yungas,were investigated.Multivariate analyses and multiple linear regressions were carried out to determine relationships among phenotypic traits and nuclear microsatellites,respectively,to climatic variables,and to identify the phenotypic traits as well as nuclear microsatellite loci most sensitive to climate.Two and three clusters of individuals were detected based on genetic and phenotypic data,respectively.Only clusters based on genetic data refected the biogeographic origin of individuals.Reproductive traits were the most relevant indicators of climatic effects.One microsatellite locus Ac41.1 appeared to be non-neutral presenting a strong correlation with climate variable temperature seasonality.Our findings show complex patterns of genetic and phenotypic variability in the Argentinean distribution of A.colubrina var.cebil related to the present or contemporary climate,and provides an example for an integrative approach to better understand climate impact on contemporary genetic and phenotypic variability in light of global climate change.

Carbon stocks in a highly fragmented landscape with seasonally dry tropical forest in the Neotropics

Background:Global modeling of carbon storage and sequestration often mischaracterizes unique ecosystems such as the seasonally dry tropical forest of the central region of the Gulf of Mexico,because species diversity is usually underestimated,as is their carbon content.In this study,aboveground and soil carbon stocks were estimated to determine the climate mitigation potential of this highly degraded landscape(<25%of forest cover).Results:Tree species in the study area had carbon content values that were 30%–40%higher than the standard value proposed by the IPCC(i.e.,50%).Tropical oak forest in the region,despite its restricted distribution and low species richness,accounted for the highest mean carbon stocks per unit area.The main factors driving spatial variability in carbon stocks were:maximum precipitation,soil organic matter,clay and silt content.No strong relationship was found between aboveground carbon stocks and soil organic carbon in the study area.Quanti-fication of carbon stocks is an important consideration in the assessment of the conservation value of remnants of native vegetation in human-modified landscapes.Conclusions:This study demonstrates the importance of the highly fragmented tropical dry regions of the Neo-tropics in maintaining landscape functionality and providing key ecosystem services such as carbon sequestration.Our results also highlight how crucial field-based studies are for strengthening the accuracy of global models.Furthermore,this approach reveals the real contribution of ecosystems that are not commonly taken into account in the mitigation of climate change effects.

Seasonal Dynamics of the Soil Moisture in Yuanmou Dry-Hot Valley of Yunnan

[ Objective] The research aimed to study seasonal dynamics of the soil moisture in Yuanmou Dry-Hot Valley of Yunnan. [ Method] We investigated soil moisture in rainy season in Yuanmou Dry-Hot Valley. By combining completed research about soil moisture in dry season, data in rainy and dry seasons were contrasted to study seasonal dynamics of the soil moisture in the zone. [ Resultl Soil moisture in rainy season increased with the depth of soil, but would decrease within 1.0 m below the root layer. The soil moisture of grassland was higher than that of the woodland, while soil moisture of the savanna was higher than that of the woodland but lower than that of the grassland. In addition, compared with soil mois- ture in dry season, it is clear that to avoid forming permanent soil desiccation, based on soil and hydrology conditions in Yuanmou, it is better to plant grass not tree in Yuanmou when we do something about ecological restoration. [ Condusion] The research had certain guidance significance for planting agricultural and economic crops and carrying out ecological restoration in Yuanmou Dry-Hot Valley.

基于氡同位素示踪的洞庭湖区枯水期湖水与地下水交互作用研究

洞庭湖区水系发达,水文地质条件复杂,人类活动强烈,地表水和地下水的水力联系变化频繁,其研究的难度以及由此造成的研究不足影响了对湖区地下水赋存和运动规律的深入认识。本文以洞庭湖整体为研究对象,采用水位动态分析和氡(222 Rn)同位素示踪法,定性和定量研究枯水期洞庭湖区地表水与地下水的交互作用关系与交互通量。枯水期洞庭湖区水位和氡浓度空间分布特征指示研究区内地下水向湖水排泄,尤以东洞庭湖最为显著。氡箱模型计算结果显示枯水期地下水排泄222 Rn通量为455.09 Bq/(m^(2)·d),占总输入222 Rn通量的60.07%,地下水排泄总量为0.29×10^(8)m^(3)/d,平均排泄速率为56.27 mm/d,地下水排泄对湖水的贡献率为7.04%。敏感性分析表明:风速、地下水和湖水222 Rn浓度以及湖面面积等参数较为敏感,合理布置取样点并提高敏感参数测量准确度能提高模型计算结果的可靠度。氡同位素示踪法物理意义明确、操作过程简便,是研究复杂区域地下水补、径、排特征的有效方法。研究成果一定程度上提供了洞庭湖区水量均衡的更多认识,可为洞庭湖区地下水资源评价和管理提供参考。

Formula for Determining Number of Basic Seedlings at Scattered-Planting with Seedling Dry-Raised on Plastic Trays in Double-Season Rice

The tiller emergence in seedling nursery beds and field, and panicle formation in the field were investigated under scattered-planting with seedling dry-raised on plastic trays in double-season rice. A significant difference was noted in the non-synchronously-emerged tillers （the tillers that formed from latent buds and did not emerge following the normal tillering law on seedling nursery beds and recovered to grow after scattered-planting or transplanting） as well as the percentage of the available synchronously-emerged tillers between seedlings raised on plastic trays under dry-land conditions （DPT） and seedlings raised on nursery beds under wetland conditions （WB）. The seedlings under DPT had some non-synchronously-emerged tillers, but those under WB had not. Therefore, the traditional formula for determining the number of rice seedlings was improved, and the formula for determining the number of basic seedlings under scattered planting with DPT in double-season rice was introduced. For early rice, it was X=Y/{（I＋t1r1）[1＋（N-n-SN）Rr2]＋（SN-3-t1）R2r5}, and for late rice, it was X=Y/{（1＋t1r1）[1＋（N-n-SN）Rr2]＋（N-n-SN-3）Rr2R1r3＋（SN-3-t1）R2r5}. Where, X represents reasonable number of basic seedlings per unit area at scattered-planting; Y, number of fitting panicles per unit area; t1, total number of tillers per plant; r1, percentage of the total available tillers; N, total number of leaves of the main culm; n, total number of elongated internodes in the main culm; SN, seedling leaf ages at scattered-planting; R, percentage of the primary tillers emerged in available node-position; r2, percentage of the available primary tillers; R1, percentage of the secondary tillers in the field （except the secondary tillers of the seedlings）; r3, percentage of the available secondary tillers; R2, percentage of the asynchronously-emerged tillers after scattered-planting; r5, percentage of the available non-synchronously-emerged tillers after scattered-planting.

鄂尔多斯盆地二叠系盒8段河流扇沉积模式及勘探意义

根据野外露头及岩心的分析化验资料,在源-汇系统分析的基础上,对鄂尔多斯盆地二叠系盒8段的古气候环境及沉积相特征进行了详细研究。研究结果表明:(1)鄂尔多斯盆地二叠系盒8段Sr/Cu的值多大于10,V/Cr值多小于2.0,地层厚度差小于30 m,未出现明显的突变,古沉积坡度为0.5°~1.0°,古地貌开阔平缓且无明显坡折带,沉积水体较浅,是在古气候干旱、古地形平缓的背景下,受阶段性洪水作用主导的事件沉积。(2)盒8段沉积期,盆地不存在大面积汇水区,沉积体系中河流并未进入湖泊水体,而是向东南流出盆地或是消失在内陆干旱地区,全盆地以洪泛平原沉积为主,表现为河道与泛滥平原交互分布的沉积格局,形成了河流扇沉积模式。(3)湖水进退往复,洪水期与枯水期间歇发育,洪水期多期次决口河道接力搬运使得粗粒级砂岩向湖盆长距离延伸,枯水期发育厚层泥质沉积可作为区域性盖层,形成了良好的储盖组合,勘探潜力大。