Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userEstimation of Evapotranspiration of Palmyra Oasis by Energy Balance method «Analaitical and Experemental Study»
تقدير الانفضاج التبخري لواحة تدمر بطريقة موازنة الطاقة «دراسة تحليلية و تجريبية»
1269
0 24
0
(
0
)
Created by
Ask ChatGPT about the research
أجريت حسابات مستمرة للانفضاج التبخري (ET أو LE) باسـتخدام طريقـة Covariance Eddy و طريقة موازنة الطاقة خلال أكثر من سنة فوق غطاء نباتي غير متجانس في نظام بيئي يمثل واحة جافة في وسط صحراء سورية. إن طريقة الري السائدة هي الغمر التقليدي، و بتـواتر لتوزيـع الميـاه كـل 28 يوماً. ركز العمل على دراسة التغيرات الفصلية لموازنة الطاقة خلال سنتين، مع تركيز خـاص علـى تأثيرات الهطول المطري، و سرعة الرياح، و الموازنة الإشعاعية على الانفضاج التبخري. كان الانفـضاج. لقد ظهر التأثير المهم لأمطار الشتاء في LE حتى في أثناء تطبيق 1 - التبخري الأعظمي فقط day.mm 5 الري. بينت مقارنة حالتين مختلفتين في حزيران 2002 و حزيران 2003 وجود زيادة بمقدار %13 في قيم G-Rn/ LE .لقد وجدت القيم الأعظمية للمتوسطات الساعية للانفضاج التبخري عند سرعة رياح قرابـة . يشير هذا إلى أنه عندما يتجاوز المتطلب التبخري للهواء (أو عجز ضغط بخار الماء vpd (حداً 1-s.3m معيناً يغلق النبات مساماته بهدف تقليل معدل فقد الماء بالنتج. أظهرت نتائج التحقق من موازنة الطاقـة وجود فروقات معنوية في ميل علاقة LE+H مقابل G-Rn بين الشهر الحار و الشهر البارد، و يعزى ذلك إلى الموازنة الإشعاعية الخاصة بالمناطق الصحراوية.
Continuous calculations of evapotranspiration (LE) using eddy covariance method and energy budget were performed over more than one year above the heterogeneous canopy of an arid oasis ecosystem in the central Syrian desert. Irrigation practice was traditional flooding with a 28 days turn of water delivery. The work focuses on seasonal variations of energy budget over a 2 years period with emphasis on effects of rainfall, wind speed and radiative budget on evapotranspiration. Maximum evapotranspiration was only 5mm/day. Even under irrigation practices, winter rainfall seems to have an important impact on LE: comparisons of two situations in June 2002 and June 2003 showed an increase of 13% in values of LE/Rn-G. Maximum averaged hourly values of evapotranspiration were found for wind speed values closed to 3m/s. This suggests that when the evaporative demand from the air (or vapour pressure deficit (vpd) ) is increasing above a certain limit, the vegetation closes its stomata and reduces transpiration. Results from the energy balance closure showed significant differences in the slope of H+LE against Rn-G relationships between cold and hot month which was explained by specific radiative budget of desert areas.
References used
ANTHONI, P., LAW, B.E., UNSWORTH, M.J., VONG, R.J., 2000. Variation in net radiation over heterogeneous surfaces: measurements and simulations in a juniper-sagebrush ecosystem. Agricultural and Forest Meteorology, 102: 275-286
BLANEY, H.F., CRIDDLE, W.D., 1962. Determining consumptive use and irrigation water requirements. USDA (ARS) technical Bulletin, 1275, 59pp
BRUTSAERT, W., 1982. Evaporation into the Atmosphere, D. Reidel Publishing company, Holland, 299 pp
rate research
Read More
In this work, we have found exact traveling wave solutions for generalized Fitzhug-
Nagumo equation with arbitrary constant coefficients, by using the homogeneous balance
method, The obtained results shows that these solutions changes with the spec
ials solution
of Ricati ODE with arbitrary constant coefficients , and shows that this method is simple,
direct and very efficient for solving this kind of nonlinear PDEs, It can be applied to
nonlinear PDEs which frequently arise in engineering sciences, mathematical physics and
other scientific real-time applications fields.
Atmospheric temperature increases after sunrise to reach its maximum at
approximately ٢ hours from midday. The temperature variation curve agrees
with the intensity curve of incident solar radiation on the earth surface, but
with delay time (tow h
our) proportional to the parameters atmosphere and
materials.
During eclipse of sun, the intensity of solar radiation decreased, and as a
consequence, this affects many atmospheric processes, such as temperature of
air and wind cycles. These changes can be studied as variations of solar
radiation density, which occurs in the short time of the eclipse.
These variations can be observed by a spectroscopic study, was the subject
of the Damascus university scientific group to studying the total eclipse in Ain-
Dewar, which is located at northeast of Syria on ١١-th of August ١٩٩٩.
The variations happened in solar spectrum and in the earth atmosphere
were recorded and discussed in detail. The recorded diagrams and spectrum
were analyzed for the estimation of the magnitude of radiation energy, which
was screened during eclipse. They result in the estimation of energy loss by the
atmosphere and its parameters like temperature and wind movement.
It was shown, that ٦٠٪ of the total solar energy were screened during
eclipse, and this was sufficient to cause many changes in wind velocity and
temperature of the atmosphere. Because of the eclipse line and neighboring
areas considered to be connected with thermodynamic system, thus the energy
changes will decrease in the atmosphere, Sowe didn’t calculate it.
Evapotranspiration forms one of the hydrology cycle elements that it's hard to
measure its actual amounts in the field conditions, so it’s estimated by calculations of
experimental relations that depend on climatic elements data. These estimations
include
different errors because of approximation processes. The research goals to accurate
estimation of the monthly reference evapotranspiration amount in Safita area (on the east
coast of the Mediterranean Sea), and the research depends on the technique of Artificial
Neural Network (ANN), and the mathematical model was built by the
(nftool), which is one of the Matlab tools, depending on monthly air temperature and
relative humidity data which were taken from Safita meteorological station, and the data of
monthly pan evaporation (Class A pan) has been used, after modifying its results, for the
purpose of checking the performance accuracy of the network, by using Simulink
technique, which is existing in Matlab Programs Package. The results of the research
verify that a multi-layer ANN of error Back-propagation algorithm gives a good result in
estimating monthly reference Evapo-transpiration for the used data group.
In this work, we recorded the alpha spectra of radium-226 and amrecium-241 sources using a semiconductor detector and Rutherford scattering chamber. We also measured the energy loss of alpha particles in gold foil (target) and in aluminum foil as a f
unction of alpha energy and as a function atomic number Z of the target. Comparison between experimental and theoretical results show a good agreemen.
This research includes analytical study by Finite Element Method about the effect of
earthquakes in the stability of ALBASEL DAM, so we have set a numerical model suitable
by using programs Slope/W, Quake/W. We run the model and we got the results
of the
simulation, which summarized in calculation factors of safety for verification the final
stability of the dam under the effect of different intensity earthquakes. And then were
compared between the two cases static and dynamic model showing the effect of the shear
variables of the soil angle of internal friction and tendency of slops dam and the different
situations of the lake water levels and the high of dam in addition to the effect of the
construction material of the dam on the stability of the body of the dam.
After the study each case depending on the parameters, that are entered, and based
on the resulting factors of safety, the diagrams are painted to appear the positive or the
negative effects to increase or decrease any variable of the dam variables in each of the
static case and the dynamic case. And then we studied the effect of seismic Amplification
resulting from the body of the dam on both the two horizontal and vertical component of
seismic acceleration. The results will help us in a perfect choice for variables of
Embankment dams for design.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
