scholarly journals Contrasting controls on Congo Basin evaporation at the two rainfall peaks

2020 ◽  
Author(s):  
David Crowhurst ◽  
Simon Dadson ◽  
Jian Peng ◽  
Richard Washington
Keyword(s):  
Sensible Heat Flux ◽  
Vapour Pressure Deficit ◽  
Lower Surface ◽  
Congo Basin ◽  
Shortwave Radiation ◽  
Net Radiation ◽  
Area Index ◽  
The North ◽  
North Eastern ◽  
Main Component

AbstractEvaporation is a crucial driver of Congo Basin climate, but the dynamics controlling the seasonality of basin evaporation are not well understood. This study aims to discover why evaporation on the basin-wide average is lower at the November rainfall peak than the March rainfall peak, despite similar rainfall. Using 16-year mean LandFlux-EVAL data, we find that evaporation is lower in November than March in the rainforest and the eastern savannah. The ERA5-Land reanalysis, which effectively reproduces this pattern, shows that transpiration is the main component responsible for lower evaporation in these regions. Using ERA5-Land, we find the following contrasting controls on transpiration, and therefore evaporation, at the two rainfall peaks: (a) In the northern rainforest, there is lower leaf area index (LAI) in November, driven by lower surface downward shortwave radiation (DSR), and lower vapour pressure deficit (VPD) in November, driven by lower sensible heat flux that results from lower net radiation. The combination of lower LAI and VPD explains lower transpiration, and therefore lower evaporation, in November. (b) In the southern rainforest, and in the north-eastern savannah, there is lower LAI in November, driven by lower surface DSR, and this explains lower transpiration, and therefore lower evaporation, in November. (c) In the south-eastern savannah, there is lower LAI in November, driven by lower volumetric water content (VWC), and this explains lower transpiration, and therefore lower evaporation, in November. Collectively, these contrasting controls at the two rainfall peaks explain why the basin-wide average evaporation is lower in November than March.

scholarly journals A database of water and heat observations over grassland in the north-east of Japan

2018 ◽  
Vol 10 (4) ◽  
pp. 2295-2309 ◽  
Author(s):  
Wenchao Ma ◽  
Jun Asanuma ◽  
Jianqing Xu ◽  
Yuichi Onda
Keyword(s):  
Heat Flux ◽  
Time Series ◽  
Wind Speed ◽  
Sensible Heat Flux ◽  
Soil Heat Flux ◽  
Shortwave Radiation ◽  
Sensible Heat ◽  
Net Radiation ◽  
North East ◽  
The North

Abstract. A highly valuable database of long-term hydrometeorological measurements is presented, containing in situ observations for a period of 37 years from a well-maintained grassland in the north-east of Japan. The observations include shortwave radiation, net radiation, air and dew point temperatures at three elevations, soil temperature at four depths, sensible heat flux, soil heat flux, wind speed, relative humidity, air pressure and precipitation. The heights of measurements are 1.6, 12.5 and 29.5 m above ground, with the soil-layer observations at depths of 0.02, 0.1, 0.5 and 1 m. This high-quality database includes four temporal resolutions of 10 s, 0.5 h, 1 h and 24 h, with the hourly data presented here. Monthly and annual statistics are presented at the database web page of the Center for Research in Isotopes and Environmental Dynamics and Prediction of the University of Tsukuba, http://doi.org/10.24575/0001.198108. We validated the data by comparing them with published data from the local meteorological agency in Tateno operated by the Japan Metrological Agency, including the average, maximum and minimum values of air temperature, shortwave radiation, wind speed, relative humidity and precipitation. We have generated a daily downward longwave radiation time series with a method developed by Kondo and Xu (1997) based on the observations from the database. This constructed time series agrees well with observations collected between 2002 and 2006, as evaluated based on the values of the Nash–Sutcliffe efficiency (=0.947) and percent bias (=1.486). For the whole database, annually averaged values show a positive trend in precipitation, air temperature, shortwave radiation, net radiation and sensible heat flux over the past 37 years, with a negative trend detected for wind speed, soil heat flux and soil temperature.

scholarly journals A database of water and heat observations over grassland in the north-east of Japan

2018 ◽  
Author(s):  
Wenchao Ma ◽  
Jun Asanuma ◽  
Jianqing Xu ◽  
Yuichi Onda
Keyword(s):  
Heat Flux ◽  
Time Series ◽  
Wind Speed ◽  
Sensible Heat Flux ◽  
Soil Heat Flux ◽  
Shortwave Radiation ◽  
Sensible Heat ◽  
Net Radiation ◽  
North East ◽  
The North

Abstract. A highly valuable database of long-term hydro–meteorological measurements is presented, containing in situ observations for a period of 37 years from well-maintained grassland in the north-east of Japan. The observations include the shortwave radiation, net radiation, the air and dew point temperatures at three elevations, the soil temperature at four depths, the sensible heat flux, soil heat flux, wind speed, relative humidity, air pressure and precipitation. The heights of measurements are 1.6 m, 12.5 m and 29.5 m above ground, with the soil-layer observations at depths of −0.02 m, −0.1 m, −0.5 m and −1 m. This high-quality database includes the four temporal resolutions of 10 s, 0.5 h, 1 h and 24 h, with the hourly data presented here. The monthly and annual statistics are presented at the database web page of the Center for Research in Isotopes and Environmental Dynamics and Prediction of the University of Tsukuba, http://doi.org/10.24575/0001.198108 . We have validated the data quality by comparing with published data from the local meteorological agency in Tateno operated by the Japan Metrological Agency, including the average, maximum and minimum values of air temperature, shortwave radiation, wind speed, relative humidity, and precipitation. We have generated a daily downward longwave radiation time series with a method developed by Konto and Xu (1997) based on the observations from the database. This constructed time series agrees well with observations collected between 2002 to 2006, as evaluated based on the values of the Nash–Sutcliffe efficiency (=0.947) and the percent bias (=1.486). For the whole database, annually averaged values give an obvious positive trend in the precipitation, air temperature, shortwave radiation, net radiation and sensible heat flux over the previous 37 years, with a negative trend detected for the wind speed, soil heat flux and soil temperature.

scholarly journals Development of the leaf area and the productivity structure of the sunflower hybrids in the north-eastern Forest-Steppe of Ukraine

2019 ◽  
pp. 33-39
Author(s):  
М.М. Sakhoshko ◽  
M.I. Kravchenko ◽  
V.M. Yatsenko ◽  
I.O. Kolosok
Keyword(s):  
Leaf Area ◽  
Field Experiments ◽  
Unit Area ◽  
Geographical Area ◽  
Main Element ◽  
Forest Steppe ◽  
Area Index ◽  
The North ◽  
North Eastern ◽  
Sunflower Crop

At the present stage, the model of leaf plant development is increasingly considered as the main element of genotypes adaptation to specific cultivation conditions, geographical area, etc. Under these conditions, the potential of the hybrid, the range of its adaptation to environmental conditions is determined by the level of interaction between the development of the assimilation apparatus and the generative organs. An urgent task aimed at improving the productivity of sunflower crop due to the use of genotypes adapted to the conditions of the north-eastern Forest-Steppe and Polyssya of Ukraine is to identify typical schemes of interaction of photosynthetic potential and parameters of plant productivity and crop yields. The studies were conducted in accordance with the program for the development of a variety model for the conditions of the north-eastern Forest-Steppe and Polyssya of Ukraine. Field experiments were carried out in 2016‒2019 at the Sumy National Agrarian University and the Institute of the Agriculture of North East of Ukraine. In the studies, 28‒56 hybrids of different originators were tested annually. Sunflower was cultivated according to the technology recommended for the area, with pre-harvesting density of 60 thousand plants / ha. Harvesting was done manually, from two central rows of a 4-rows plot. The results were processed using the Statistics package. The data on yield indices and values of leaf area coefficient (LAC) of crop for groups of varieties separated by the duration of growing season were analyzed. It was found that the increasing of leaf area was accompanied by an increasing of yield in case of comparing groups with dates of technological maturation until 20 August, 1 September and 10 September. In all cases, the maximum value of the leaf area index ranged from 3.12‒3.52 m2/m2. These dynamics of indicators indicated to the regulatory nature of the values of leaf area coefficient (LAC) of modern sunflower crop and the absence of genotypes (or conditions) capable of maintaining these values at the level of more than 3.3‒3.5 m2/m2. According to the analysis of correlation pleiades, the presence of several levels was found and the relative independence of the relationships between the group of parameters, determining the morphological structure of plants and the vertical structure of crop and the group of parameters, characterizing the content of chlorophyll and its concentration per unit area of leaf surface. In practical terms, the results of the analysis indicated the potential informative nature of the complex use of parameters characterizing the morpho-structure of plants, primarily the index of leaf area and the index of chlorophyll concentration per unit area. In order to isolate the typical schemes characteristic of different levels of adaptation to the conditions of the zone, data on 29 sunflower hybrids distributed in the region were clustered. The results of the analysis allowed to distinguish three significantly different algorithms for the realization of the vegetative and generative potential of sunflower hybrids in the area of the north-eastern Forest-Steppe of Ukraine. It has been established that one of the factors for successful realization of the generative potential of sunflower hybrids in the conditions of the zone is the ability to preserve and (in some cases) to improve the structure of relations between the dynamics and parameters of the plant leaf apparatus and the parameters of their generative development.

Taxonomic challenges in freshwater fishes: a mismatch between morphology and DNA barcoding in fish of the north-eastern part of the Congo basin

2015 ◽  
Vol 16 (1) ◽  
pp. 342-352 ◽  
Author(s):  
Eva Decru ◽  
Tuur Moelants ◽  
Koen De Gelas ◽  
Emmanuel Vreven ◽  
Erik Verheyen ◽  
...  
Keyword(s):  
Dna Barcoding ◽  
Freshwater Fishes ◽  
Congo Basin ◽  
The North ◽  
North Eastern ◽  
North Eastern Part

scholarly journals Validation of the Deardorff model for estimating energy balance components for a sugarcane crop

2008 ◽  
Vol 65 (4) ◽  
pp. 325-334 ◽  
Author(s):  
Glauco de Souza Rolim ◽  
João Francisco Escobedo ◽  
Amauri Pereira Oliveira
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Latent Heat ◽  
Sensible Heat Flux ◽  
Reference Level ◽  
Sensible Heat ◽  
Net Radiation ◽  
Area Index ◽  
Sugarcane Crop ◽  
Aerodynamic Method

The quantification of the available energy in the environment is important because it determines photosynthesis, evapotranspiration and, therefore, the final yield of crops. Instruments for measuring the energy balance are costly and indirect estimation alternatives are desirable. This study assessed the Deardorff's model performance during a cycle of a sugarcane crop in Piracicaba, State of São Paulo, Brazil, in comparison to the aerodynamic method. This mechanistic model simulates the energy fluxes (sensible, latent heat and net radiation) at three levels (atmosphere, canopy and soil) using only air temperature, relative humidity and wind speed measured at a reference level above the canopy, crop leaf area index, and some pre-calibrated parameters (canopy albedo, soil emissivity, atmospheric transmissivity and hydrological characteristics of the soil). The analysis was made for different time scales, insolation conditions and seasons (spring, summer and autumn). Analyzing all data of 15 minute intervals, the model presented good performance for net radiation simulation in different insolations and seasons. The latent heat flux in the atmosphere and the sensible heat flux in the atmosphere did not present differences in comparison to data from the aerodynamic method during the autumn. The sensible heat flux in the soil was poorly simulated by the model due to the poor performance of the soil water balance method. The Deardorff's model improved in general the flux simulations in comparison to the aerodynamic method when more insolation was available in the environment.

scholarly journals The Evaluation of the Concentration of Bivalent Basic Cations in Surface Water of the National Nature Reserve Čičov Oxbow

2017 ◽  
Vol 20 (2) ◽  
pp. 28-34
Author(s):  
Jaroslav Noskovič ◽  
Mária Babošová ◽  
Jana Ivanič Porhajašová
Keyword(s):  
Nature Reserve ◽  
Lower Surface ◽  
Average Concentration ◽  
Magnesium Concentration ◽  
Reference Period ◽  
National Nature Reserve ◽  
The North ◽  
North Eastern ◽  
Sampling Points ◽  
Basic Cations

Abstract During the years 2013–2014, the concentrations of bivalent basic cations Ca2+ and Mg2+ were evaluated in the water of the Čičov tributary, which belongs to the National Nature Reserve of the basin of the river Danube. On the basis of the results obtained, it can be stated that the average concentration of calcium for the whole reference period was 59.63 mg.dm−3. Minimum average concentration depending on the time of sampling was found in November (48.42 mg.dm−3) and maximum in July (70.73 mg.dm−3). We assume that this above average concentrations in the summer could be due to the lower surface of the water due to higher evaporation. Depending on the places of sampling points, the lowest average concentration (58.10 mg.dm−3) for the whole reference period was at the mouth of the Čilizian brook and the top (60.32 mg.dm−3) in the first side shoulder. The analysis of variance detected highly statistically significant effect of the year and month of collection on changes in the concentration of calcium. The average concentration of magnesium for the whole reference period was 14.54 mg.dm−3. As for the time of collection, the highest average concentrations for the entire observation period were found during the summer, with the maximum average concentration in July (16.94 mg.dm−3) and minimum in February (10.81 mg.dm−3). The lowest average magnesium concentration for the entire reference period, regarding to the sampling points, was measured in the north-eastern part of the nature reserve (14.28 mg.dm−3) and the highest one at the mouth of the Čilizian brook into the National Nature Reserve (14.72 mg.dm−3).

Discussion on “The grinding wheel and production” at the North-Eastern Section of the Institution

1942 ◽  
Vol 21 (8) ◽  
pp. 315
Author(s):  
Bowen ◽  
Vickery ◽  
Buchanan ◽  
Swallow ◽  
Perks ◽  
...  
Keyword(s):  
Grinding Wheel ◽  
The North ◽  
North Eastern

The influence of submesoscale eddies on hydrochemical parameters and structural and functional characteristics of phytoplankton in the north-eastern part of the Black Sea

2019 ◽  
pp. 24-40
Author(s):  
Sergey B. Kuklev ◽  
Vladimir A. Silkin ◽  
Valeriy K. Chasovnikov ◽  
Andrey G. Zatsepin ◽  
Larisa A. Pautova ◽  
...  
Keyword(s):  
Anticyclonic Eddy ◽  
The Black Sea ◽  
Hydrochemical Parameters ◽  
North East ◽  
The North ◽  
Seasonal Thermocline ◽  
North Eastern ◽  
Quantitative Indicators ◽  
The City ◽  
North Eastern Part

On June 7, 2018, a sub-mesoscale anticyclonic eddy induced by the wind (north-east) was registered on the shelf in the area of the city of Gelendzhik. With the help of field multidisciplinary expedition ship surveys, it was shown that this eddy exists in the layer above the seasonal thermocline. At the periphery of the eddy weak variability of hydrochemical parameters and quantitative indicators of phytoplankton were recorded. The result of the formation of such eddy structure was a shift in the structure of phytoplankton – the annual observed coccolithophores bloom was not registered.

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