scholarly journals Evaluation of the Performance of some Evapotranspiration Models at a Tropical Location in Ile – Ife, Nigeria

2020 ◽  
Vol 8 (6) ◽  
Author(s):  
Adekunle B. Toyeje ◽  
Lukman A. Sunmonu ◽  
Ayodele P. Olufemi ◽  
Oladimeji A. Babatunde ◽  
Olawale E. Abiye ◽  
...  
Keyword(s):  
Meteorological Parameters ◽  
Soil Heat Flux ◽  
Meteorological Station ◽  
The Other ◽  
Coefficient Of Determination ◽  
Net Radiation ◽  
Climatic Region ◽  
The Mean ◽  
Reference Et ◽  
Tropical Location

This study evaluates the performance of some evapotranspiration models at Ile – Ife (7o 33’ N, 4o 33’ E) Nigeria. This was to identify suitable evapotranspiration (ET) models at the study site and to provide useful information for standardizing evapotranspiration estimations at a tropical location. Meteorological parameters (wind speed, relative humidity, temperature, solar radiation, soil heat flux, and net radiation) were routinely measured at the Obafemi Awolowo University (OAU) Meteorological Station located within the Teaching and Research Farm of the campus for a period of a month (1st – 29th July 2014). Nine standardized models for the estimation of ET; Penman-Monteith (FAO-56 PM), Priestly-Taylor (PT), Makkink (MAKK), Jensen-Haise (JH), Hargreaves-Samani (HS), Ivanov (IVA), Modified Romanenko (MROM), FAO-24 Radiation (FAO-24 RAD) and Turc (TURC) models were employed. The ET values obtained from these models were then compared to the estimated values obtained from the FAO-56 PM equation recommended as the international standard method for determining reference ET. The estimation of the ET obtained from FAO – 56 PM model ranged between 0.426 – 2.239 mm/day, MAKK, JH, and HS gave estimation closest to this, ranging from 0.544 – 2.272 mm/day. The estimation of ET from other models revealed that PT has the highest value ranging between 1.323 – 6.936 mm/day, followed closely was FAO – 24 RAD with values ranging between 1.197 – 6.500 mm/day, values of IVA model ranged from 0.620 – 1.829 mm/day, MROM value ranged from 1.240 – 3.659 mm/day, TURC has the least value ranging from 0.190 – 0.584 mm/day. Using the result of the mean biased error and regression analysis, JH model compared best with the FAO – 56 PM with coefficient of determination (R2) = 0.927; slope (b) = 0.957; mean biased error (MBE) = 0.133, this was followed closely by HS with value R2 = 0.929; b = 1.199; MBE = - 0.075 and MAKK with the value R2 = 0.931; b = 1.198; MBE = - 0.052. However, the other models showed significant over or underestimation of the ET benchmark values. The performance of the other models showed no improvement after they were recalibrated by adjusting their original coefficients. Thus, six out of the ET models employed in this study [the Priestly-Taylor (PT), Makkink (MAKK), Jensen-Haise (JH), Hargreaves-Samani (HS), FAO-24 Radiation (FAO-24 RAD) and Turc (TURC)] were found suitable for the climatic region of Ile – Ife after the adjustment of their coefficients.

scholarly journals Evaluation of the performances of two rebs net radiometer designs during Nimex at a tropical site in Ile-Ife, Nigeria

2020 ◽  
Vol 22 (2) ◽  
pp. 111-123
Author(s):  
L.A. Sunmonu ◽  
A.I. Ajao ◽  
M.A. Ayoola ◽  
E.O. Ogolo ◽  
O.A. Babatunde ◽  
...  
Keyword(s):  
Longwave Radiation ◽  
Radiation Energy ◽  
Coefficient Of Determination ◽  
Net Radiation ◽  
African Countries ◽  
Term Operation ◽  
The Mean ◽  
Better Than ◽  
Tropical Location

In this study, the performances of two types of Radiation Energy Balance Systems (REBS) net radiometers, a domed (model Q-7.1) and domeless (model NR-LITE) against a reference, four-component net radiometer (model NR01), are evaluated during the conduct of Nigeria  Micrometeorological Experiment (NIMEX) held between May 27 and June 12, 2013 at a tropical location in Ile-Ife, Nigeria. During the daytime, net radiation measurements made by NR-LITE and Q-7.1 showed good agreements with NR01, with coefficient of determination for both > 0.90. The values of the mean and standard deviation for daytime net radiation as  measured by NR01, NR-LITE and Q-7.1 were 257.7 ± 174.7 W m2 , 179.6 ± 129.3 W m2 and 240.6 ± 153.1 W m2 , respectively. At nighttime, NR-LITE net radiometer responded to longwave radiation better than Q-7.1. Adjustments made by linear regression of NR-LITE and Q-7.1 datasets with NR01 produced better fit. Though costs of the two REBS type net radiometers are comparatively the same, Q-7.1 performed better than NRLITE. However, for long-term operation, the Q-7.1 type requires periodic (every 2-3 months) changing of the plastic domes due to ageing and cracking, unlike the NR-LITE. So, the NR-LITE is a preferred option to be adopted by the Weather Services in West African countries for routine measurements of net radiation because it does not require periodic changing of the plastic domes. Keywords: Net radiation; REBS net radiometers; 4-component net radiometer; tropical location.

scholarly journals Soil-Surface Straw Influences Micrometeorological Conditions Affecting Canola Mortality During Nighttime Frosts

2020 ◽  
Vol 12 (11) ◽  
pp. 246
Author(s):  
Samuel Kovaleski ◽  
Arno B. Heldwein ◽  
Genei A. Dalmago ◽  
Jorge A. de Gouvêa ◽  
Gilberto R. da Cunha ◽  
...  
Keyword(s):  
Heat Flux ◽  
Ground Surface ◽  
Soil Surface ◽  
Soil Heat Flux ◽  
Growth Cycle ◽  
The Other ◽  
Net Radiation ◽  
Plant Mortality ◽  
Seedling Mortality ◽  
Micrometeorological Conditions

Our objective was to measure alterations in the micrometeorological conditions surrounding canola seedlings during frost periods, and to quantify seedling mortality as a function of straw distribution on the ground surface. The data was acquired from 15 frosts in 2014. We used four treatments, comprising ground surface without straw (SWS), ground surface entirely straw-covered (SEC), sowing line without straw (SLW), and soil with preexisting surface straw (SES), over three experiments. Net radiation (NR), soil heat flux (G), air (Ta), leaf (Lf), rosette (Tr), and surface temperature (Ts), and plant mortality were evaluated. NR was higher in the SEC treatment and lower in the SLW treatment, whereas G was higher on straw-covered ground; Ts and Ta were lower in the SEC than in the other treatments during the most intense frosts. On 06/19, Tr in the SEC and SLW treatments was -0.66 °C and 0.42 °C, respectively; on 08/14, Lf was -3.62 °C and -2.88 °C in the SEC and SLW treatments, respectively. Plant mortality due to the frost on 06/19 was 30% in the SEC treatment, but 0% in the SLW treatment; the frost of 08/14 caused 33.8% mortality in the SEC treatment and 1.25% in the SLW treatment. This therefore showed that removing straw from the sowing line improved the microclimate around the plants, thus reducing canola mortality at the beginning of the growth cycle, which is when frost events most frequently occur.

scholarly journals Evapotranspiration at Two Mountain Sites During the Vegetation Period

1981 ◽  
Vol 12 (4-5) ◽  
pp. 207-216 ◽  
Author(s):  
M. Staudinger ◽  
H. Rott
Keyword(s):  
Energy Balance ◽  
Vegetation Period ◽  
Test Site ◽  
The Other ◽  
Net Radiation ◽  
Energy Fluxes ◽  
Austrian Alps ◽  
The Mean ◽  
The Village ◽  
Radiation Measurements

Hourly values of evapotranspiration (ET) for the months July to September 1976 and 1977 were calculated from energy balance measurements at two test sites near the village of Obergurgl in the Austrian Alps. One test site was situated at 1,960 m a.s.l. on a cultivated meadow near the timberline, the other test site at 2,580 m a.s.l. was covered with alpine sedges and grasses. Examples of the daily variations and daily sums of the energy fluxes are presented for clear and cloudy days. The mean daily courses of ET at the two test sites are shown for every month of the measurement periods; differences in ET between the two test sites are related to the decrease of transpirating leaf areas with altitude. Monthly sums of ET are presented in relation to net radiation and precipitation; on the average ET was about 30% lower at the higher elevated site. High correlations were found between the daily sums of net radiation and of ET at both sites. This relation can be used for calculating ET from radiation measurements.

An artificially isolated Generation of Tsetse Flies (Diptera)

1946 ◽  
Vol 37 (2) ◽  
pp. 291-299 ◽  
Author(s):  
C. H. N. Jackson
Keyword(s):  
Second Generation ◽  
Meteorological Station ◽  
The Other ◽  
Tsetse Flies ◽  
Glossina Morsitans ◽  
Other Hand ◽  
Perpendicular Distance ◽  
The Mean ◽  
Residual Weight

A generation ofGlossina morsitanswas artificially isolated by allowing emergence for three days in the habitat ofG. swynnertoniandG. pallidipes.Most teneral flies (with chitin unhardened before their first meal) were active on day 2 to 4 from emergence. The non-teneral flies first appeared in numbers when a week old. It is possible that they were somewhat inactive while still fairly young, that is, up to two or three weeks, but this was not proved. They are definitely inactive between the first and second meals. The females, on the other hand, are much more active in the first three weeks of life than later on.The teneral males contained about 12 mg. water, which was increased after several meals to a maximum of about 18 mg. by day 17. Fat started at a mean of 1 1/2 mg., declining to 1 mg. at the first meal, then rising to about 3 mg. at day 17, after which there was no further increase. Residual weight behaved like the water, except that it was relatively very low in teneral flies. The hungry flies which reappear after the first meal have also a relatively low residual weight.In this experiment there was no evidence that smaller flies were at a disadvantage, as has been suspected from other work.With reservations concerned with differences in place and time, the mean age of samples of male flies can be accurately deduced from the wear on the trailing margin of the wing. The females do not wear out their wings so quickly.Males dispersed, in any one direction, to a mean perpendicular distance of 365 yards in a week, 484 yards in two weeks, 772 yards in three weeks, and 941 yards in four weeks.In spite of undoubted interference byG. swynnertoni, a considerable second generation appeared.The females and pupae in nature experienced temperatures approximating to those obtained in a screen at a standard meteorological station: they did not live in specially cool eeoclimates.

scholarly journals Influence of Meteorological Parameters on the Variations of Atmospheric Radionuclides Concentration in Dar es Salaam, Tanzania

2020 ◽  
pp. 1-18
Author(s):  
Dorice Rashid Seif ◽  
Yusuf Ismail Koleleni
Keyword(s):  
Regression Analysis ◽  
Meteorological Parameters ◽  
Activity Concentration ◽  
Absolute Humidity ◽  
Dar Es Salaam ◽  
The Other ◽  
Atmospheric Conditions ◽  
Activity Concentrations ◽  
The Mean ◽  
Atmospheric Concentrations

Atmospheric concentrations of 7Be and 212Pb were measured for 11 years (2008 – 2018) in Dar es Salaam, Tanzania. The mean activity concentrations of 7Be and 212Pb were found to be within the range of 1.29 – 5.71 mBq/m3 and 10.85 – 50.06 mBq/m3, respectively. The annual mean activity concentrations of 7Be and 212Pb were 4.72 ± 1.18 mBq/m3 and 29.76 ± 13.63 mBq/m3, respectively. Distinct annual trends were depicted on 7Be and 212Pb, suggesting that the two radionuclides were affected differently with atmospheric conditions. Monthly atmospheric concentrations of 7Be showed a strong seasonal variation trend with the highest in January and February and lowest in April. 212Pb depicted the highest concentration during June and July and lowest in January and December. The regression analysis for 7Be and 212Pb activity concentrations together with number of meteorological parameters revealed that the relative humidity, rainfall, air temperature, absolute humidity and wind speed are the most significant parameters affecting radionuclides activity concentrations in the atmosphere. The sunspot numbers show 66.7% of its variability with 7Be activity concentration which further suggesting that other parameters may influence its variation. 212Pb, on the other hand, shows only 27.3% of its variability which clearly indicates that the existence of cosmic rays does not affect its activity concentration in the atmosphere.

Multi-Center Study of Thromboplastin Calibration Precision – Influence of Reagent Species, Composition, and International Sensitivity Index (ISI)

1993 ◽  
Vol 69 (01) ◽  
pp. 035-040 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Oral Anticoagulants ◽  
International Normalized Ratio ◽  
The Other ◽  
World Health ◽  
Rabbit Brain ◽  
Sensitivity Index ◽  
Bovine Plasma ◽  
Significant Difference ◽  
The Mean ◽  
International Sensitivity Index

SummaryFour thromboplastin reagents were tested by 18 laboratories in Europe, North-America, and Australasia, according to a detailed protocol. One thromboplastin was the International Reference Preparation for ox brain thromboplastin combined with adsorbed bovine plasma (coded OBT/79), and the second was a certified reference material for rabbit brain thromboplastin, plain (coded CRM 149R). The other two thromboplastin reagents were another rabbit plain brain thromboplastin (RP) with a lower ISI than CRM 149R and a rabbit brain thromboplastin combined with adsorbed bovine plasma (RC). Calibration of the latter two reagents was performed according to methods recommended by the World Health Organization (W. H. O.).The purpose of this study was to answer the following questions: 1) Is the calibration of the RC reagent more precise against the bovine/combined (OBT/79) than against the rabbit/plain reagent (CRM 149R)? 2) Is the precision of calibration influenced by the magnitude of the International Sensitivity Index (ISI)?The lowest inter-laboratory variation of ISI was observed in the calibration of the rabbit/plain reagent (RP) against the other rabbit/plain reagent (CRM 149R) (CV 1.6%). The highest interlaboratory variation was obtained in the calibration of rabbit/plain (RP) against bovine/combined (OBT/79) (CV 5.1%). In the calibration of the rabbit/combined (RC) reagent, there was no difference in precision between OBT/79 (CV 4.3%) and CRM 149R (CV 4.2%). Furthermore, there was no significant difference in the precision of the ISI of RC obtained with CRM 149R (ISI = 1.343) and the rabbit/plain (RP) reagent with ISI = 1.14. In conclusion, the calibration of RC could be performed with similar precision with either OBT/79 or CRM 149R, or RP.The mean ISI values calculated with OBT/79 and CRM 149R were practically identical, indicating that there is no bias in the ISI of these reference preparations and that these reference preparations have been stable since their original calibration studies in 1979 and 1987, respectively.International Normalized Ratio (INR) equivalents were calculated for a lyophilized control plasma derived from patients treated with oral anticoagulants. There were small but significant differences in the mean INR equivalents between the bovine and rabbit thromboplastins. There were no differences in the interlaboratory variation of the INR equivalents, when the four thromboplastins were compared.

Prothrombin Time Standardization: Report of the Expert Panel on Oral Anticoagulant Control

1979 ◽  
Vol 42 (04) ◽  
pp. 1073-1114 ◽  
Keyword(s):  
Prothrombin Time ◽  
Expert Panel ◽  
The Other ◽  
Rabbit Brain ◽  
Calibration Constant ◽  
Freeze Dried ◽  
The Mean ◽  
Point Of Intersection ◽  
And Control ◽  
Standardization Report

SummaryIn collaborative experiments in 199 laboratories, nine commercial thromboplastins, four thromboplastins held by the National Institute for Biological Standards and Control (NIBS & C), London and the British Comparative Thromboplastin were tested on fresh normal and coumarin plasmas, and on three series of freeze-dried plasmas. One of these was made from coumarin plasmas and the other two were prepared from normal plasmas; in each series, one plasma was normal and the other two represented different degrees of coumarin defect.Each thromboplastin was calibrated against NIBS&C rabbit brain 70/178, from the slope of the line joining the origin to the point of intersection of the mean ratios of coumarin/normal prothrombin times when the ratios obtained with the two thromboplastins on the same fresh plasmas were plotted against each other. From previous evidence, the slopes were calculated which would have been obtained against the NIBS&C “research standard” thromboplastin 67/40, and termed the “calibration constant” of each thromboplastin. Values obtained from the freeze-dried coumarin plasmas gave generally similar results to those from fresh plasmas for all thromboplastins, whereas values from the artificial plasmas agreed with those from fresh plasmas only when similar thromboplastins were being compared.Taking into account the slopes of the calibration lines and the variation between laboratories, precision in obtaining a patient’s prothrombin time was similar for all thromboplastins.

Platelet Suruival and Function in Rats with Enhanced Thrombotic Tendency

1985 ◽  
Vol 54 (04) ◽  
pp. 739-743 ◽  
Author(s):  
Federica Delaini ◽  
Elisabetta Dejana ◽  
Ine Reyers ◽  
Elisa Vicenzi ◽  
Germana De Bellis Vitti ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Nephrotic Syndrome ◽  
Platelet Function ◽  
Laboratory Tests ◽  
Thrombus Formation ◽  
The Other ◽  
Mean Survival Time ◽  
The Mean ◽  
And Function ◽  
Thrombotic Tendency

SummaryWe have investigated the relevance of some laboratory tests of platelet function in predicting conditions of thrombotic tendency. For this purpose, we studied platelet survival, platelet aggregation in response to different stimuli, TxB2 and 6-keto-PGFlα production in serum of rats bearing a nephrotic syndrome induced by adriamycin. These animals show a heavy predisposition to the development of both arterial and venous thrombosis. The mean survival time was normal in nephrotic rats in comparison to controls. As to aggregation tests, a lower aggregating response was found in ADR-treated rats using ADP or collagen as stimulating agents. With arachidonic acid (AA) we observed similar aggregating responses at lower A A concentrations, whereas at higher AA concentrations a significantly lower response was found in nephrotic rats, despite their higher TxB2 production. Also TxB2 and 6-keto-PGFlα levels in serum of nephrotic rats were significantly higher than in controls. No consistent differences were found in PGI2-activity generated by vessels of control or nephrotic rats.These data show that platelet function may appear normal or even impaired in rats with a markedly increased thrombotic tendency. On the other hand, the significance of high TxB2 levels in connection with mechanisms leading to thrombus formation remains a controversial issue.

Voronoi Analysis of a Soccer Game

2004 ◽  
Vol 9 (3) ◽  
pp. 233-240 ◽  
Author(s):  
S. Kim
Keyword(s):  
Collective Behavior ◽  
Quantitative Assessment ◽  
The Other ◽  
Analysis Method ◽  
Random System ◽  
Soccer Game ◽  
Voronoi Polygons ◽  
The Mean

This paper describes a Voronoi analysis method to analyze a soccer game. It is important for us to know the quantitative assessment of contribution done by a player or a team in the game as an individual or collective behavior. The mean numbers of vertices are reported to be 5–6, which is a little less than those of a perfect random system. Voronoi polygons areas can be used in evaluating the dominance of a team over the other. By introducing an excess Voronoi area, we can draw some fruitful results to appraise a player or a team rather quantitatively.

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