scholarly journals Variation on Atmospheric Transmittance Solar Radiation at Kathmandu Valley

2020 ◽  
Vol 6 (1) ◽  
pp. 105-112
Author(s):  
P. M. Shrestha ◽  
N. P. Chapagain ◽  
I. B. Karki ◽  
K. N. Poudyal
Keyword(s):  
Water Vapor ◽  
Solar Radiation ◽  
Rayleigh Scattering ◽  
Meteorological Parameters ◽  
Research Work ◽  
Physical Parameters ◽  
Kathmandu Valley ◽  
Gas Mixture ◽  
Affecting Factors ◽  
Atmospheric Transmittance

The daily solar irradiance was measured using CMP6 first class pyranometer at the horizontal surface of Kathmandu Valley (Lat.:-27.7° N, Long.:-85.5° E, Alt. 1350 m above sea level.) from January to December, 2012 (one year). Monthly mean of atmospheric transmittance is calculated based on different meteorological parameters. The effect of different meteorological parameters as well as physical parameters on the atmospheric transmittance of solar radiation was analyzed. The maximum and the minimum monthly mean solar radiation are found to be 21.32 ± 4.14 MJ/m2/day and 10.93 ± 2.03 MJ/m2/day in May and January, respectively. The value of yearly mean solar radiation measures is 16.68 ± 4.60 MJ/m2/day. Similarly, the annual average of atmospheric transmittance value of 0.51 ± 0.12 was obtained that was due to cloudy and more precipitation day during the months of measurements taken. The yearly mean of atmospheric transmittance 0.983, 0.987, 0.698 and 0.889 are found due to Rayleigh scattering followed by ozone, water vapor, gas mixture and aerosols respectively, the maximum atmospheric transmittance due to water vapor and while minimum due to gas mixture. This research work will be beneficial for the further identification of other affecting factors of different parameters for the interaction with radiation at different places of the country.

scholarly journals Study of Affecting Factors of Meteorological Parameters on Solar Radiation in Kathmandu Valley

The Batuk ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 72-80
Author(s):  
Prakash M. Shrestha ◽  
Khem N. Poudyal ◽  
Narayan P. Chapagain ◽  
Indra B. Karki
Keyword(s):  
Solar Radiation ◽  
Meteorological Parameters ◽  
Weather Conditions ◽  
Global Solar Radiation ◽  
Solar Irradiation ◽  
Maximum Temperature ◽  
Affecting Factors ◽  
Air Mass ◽  
High Level ◽  
Relative Sunshine

Solar radiation data are great significance for solar energy systems. This study aimed to estimate monthly and seasonal average daily global solar radiation on a horizontal surface in Kathmandu (27.7oN, 85.5oE, 1350 masl), Nepal, by using CMP6 pyranometer in 2012. The influence of the global solar irradiation from different physical as well as meteorological parameters was analyzed. Besides this, the research highlighted that there is high level of fluctuation of the measured value of global solar irradiance due to local weather conditions. As a result of this measurement, the maximum, minimum monthly and yearly mean solar radiation values were (21.32 ± 4.14) MJ/m2/day in May,(10.93 ± 2.03) MJ/m2/day in January and (16.68 ± 4.60)MJ/m2/day found respectively. Annual average of clearness index, maximum temperature, minimum temperature, relative sunshine hour, air mass are 0.51 ± 0.12, (26.23 ± 4.96)oC, (12.38 ± 6.83)oC, 0.57 ± 0.165 and 1.54 ± 0.42 respectively. There is positive correlation of maximum temperature and negative correlation of air mass with global solar radiation.

scholarly journals Study of Affecting Factors of Meteorological Parameters on Solar Radiation on Pokhara

2020 ◽  
pp. 45-52
Author(s):  
Prakash M. Shrestha ◽  
Jeevan Regmi ◽  
Usha Joshi ◽  
Khem N. Poudyal ◽  
Narayan P. Chapagain ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Negative Correlation ◽  
Meteorological Parameters ◽  
Energy Systems ◽  
Global Solar Radiation ◽  
Maximum Temperature ◽  
Affecting Factors ◽  
Clearness Index ◽  
Annual Average ◽  
Radiation Data

Solar radiation data are of great significance for solar energy systems. This study aimed to estimate monthly and seasonal average of daily global solar radiation on a horizontal surface in Pokhara (Lat.:28.21o N, Long.: 84o E and alt. 827 m above sea level), Nepal, by using CMP6 pyranometer in 2015. As a result of this measurement, monthly and yearly mean solar radiation values were 20.37 ±5.62 MJ/m2/ day in May, 11.37 ± 2.38 MJ/m2/ day in December and 16.82 ±5.24 MJ/m2/ day respectively. Annual average of clearness index and extinction coefficient are 0.51±0.14 and 0.53±0.31 respectively. There is positive correlation of maximum temperature and negative correlation of with global solar radiation.

scholarly journals Estimation of Global Solar Radiation using Modifed Angstrom Empirical formula on the basis of Meterological parameters in Himalaya Region Pokhara, Nepal

2016 ◽  
Vol 11 (1) ◽  
pp. 158-164
Author(s):  
Khem N. Poudyal
Keyword(s):  
Solar Radiation ◽  
Meteorological Parameters ◽  
Research Work ◽  
Global Solar Radiation ◽  
Coefficient Of Determination ◽  
Mean Bias Error ◽  
Bias Error ◽  
Mean Square ◽  
Performance Parameters ◽  
Sunshine Hour

This research work proposes the coefficient equation of modified Angstrom   model using sunshine hour and meteorological parameters for the estimation of global solar radiation in Himalaya Region Pokhara (28.22° N, 83.32° E),  Nepal . This site is about 800.0 m above from the sea level lying just 20.0 km south of the Machhaputre Himalayas.  The model coefficients a and b obtained in this research are 0.43 and 0.23 respectively. The performance parameters of the model are: Root Mean Square Error RMSE = 0.13 MJ/m2 /day, Mean Bias Error MBE= 0.02 MJ/m /day Mean Percentage MPE= 5 percent and coefficient of determination R2 = 0.70. Journal of the Institute of Engineering, 2015, 11(1): 158-164

scholarly journals Estimation of Global Solar Radiation Using Empirical Model on Meteorological Parameters at Simara Airport, Bara, Nepal

2018 ◽  
Vol 14 (1) ◽  
pp. 143-150
Author(s):  
Janaki Awasthi ◽  
Khem Narayan Poudyal
Keyword(s):  
Solar Radiation ◽  
Empirical Model ◽  
Meteorological Parameters ◽  
Research Work ◽  
Winter Season ◽  
Global Solar Radiation ◽  
Measured Data ◽  
Mean Bias Error ◽  
Regression Equations ◽  
Empirical Constants

 This research work purpose to estimate the daily global solar radiation (GSR) using CMP6 pyranometer at low altitude of Simara Airport (lat. 27°9’33” N and long. 84°58’48” E, Alt.137m respectively). The measured data is used to study the diurnal, monthly, and seasonal variation of GSR. The maximum and minimum value of GSR is found at the spring and winter season respectively. A number of multi linear regression equations were developed to predict the relationship between GSR with one or more combinations of meteorological parameters using the regression technique and calculate the empirical constants from Tiwari & Sangeeta model which is the best empirical model among other tested models. The empirical constants and sunshine hour are utilized to estimate the GSR for the years 2009 and 2010 in the Simara Airport. The annual average solar insolation 4.62 and 4.56 k/m2/day is found at Simara Airport for years 2009 and 2010. The performance of each model was analyzed by calculating Root Mean Square Error (RMSE), Coefficient of Determination (R2) Mean Bias Error (MBE), and Mean Percent Error (MPE). The finding empirical constants 0.30 and 0.52 can be utilized to estimate the GSR where there is no measured data of GSR at similar meteorological sites of Nepal.Journal of the Institute of Engineering, 2018, 14(1): 143-150

scholarly journals Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites

2011 ◽  
Vol 4 (10) ◽  
pp. 2273-2292 ◽  
Author(s):  
S. Schweitzer ◽  
G. Kirchengast ◽  
V. Proschek
Keyword(s):  
Wind Speed ◽  
Solar Radiation ◽  
Thermal Radiation ◽  
Rayleigh Scattering ◽  
Infrared Laser ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Wind Speed Profile ◽  
Upper Troposphere ◽  
Trace Species

Abstract. LEO-LEO infrared-laser occultation (LIO) is a new occultation technique between Low Earth Orbit (LEO) satellites, which applies signals in the short wave infrared spectral range (SWIR) within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO) method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity) and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms) of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We conclude that the set of SWIR channels proposed for implementing the LMIO method (Kirchengast and Schweitzer, 2011) provides adequate sensitivity to accurately retrieve eight trace species of key importance to climate and atmospheric chemistry (H2O, CO2, 13CO2, C18OO, CH4, N2O, O3, CO) in the upper troposphere/lower stratosphere region outside clouds under all atmospheric conditions. Two further species (HDO, H218O) can be retrieved in the upper troposphere.

scholarly journals A Feasibility Study for Simultaneous Estimates of Water Vapor and Precipitation Parameters Using a Three-Frequency Radar

2005 ◽  
Vol 44 (10) ◽  
pp. 1511-1525 ◽  
Author(s):  
R. Meneghini ◽  
L. Liao ◽  
L. Tian
Keyword(s):  
Water Vapor ◽  
Rayleigh Scattering ◽  
Pulse Compression ◽  
Pulse Repetition Frequency ◽  
Center Frequency ◽  
Water Vapor Absorption ◽  
Single Antenna ◽  
Vapor Absorption ◽  
The Cost ◽  
Lower Frequencies

Abstract The radar return powers from a three-frequency radar, with center frequency at 22.235 GHz and upper and lower frequencies chosen with equal water vapor absorption coefficients, can be used to estimate water vapor density and parameters of the precipitation. A linear combination of differential measurements between the center and lower frequencies on one hand and the upper and lower frequencies on the other provide an estimate of differential water vapor absorption. The coupling between the precipitation and water vapor estimates is generally weak but increases with bandwidth and the amount of non-Rayleigh scattering of the hydrometeors. The coupling leads to biases in the estimates of water vapor absorption that depend primarily on the phase state and the median mass diameter of the hydrometeors. For a down-looking radar, path-averaged estimates of water vapor absorption are possible under rain-free as well as raining conditions by using the surface returns at the three frequencies. Simulations of the water vapor attenuation retrieval show that the largest source of error typically arises from the variance in the measured radar return powers. Although the error can be mitigated by a combination of a high pulse repetition frequency, pulse compression, and averaging in range and time, the radar receiver must be stable over the averaging period. For fractional bandwidths of 20% or less, the potential exists for simultaneous measurements at the three frequencies with a single antenna and transceiver, thereby significantly reducing the cost and mass of the system.

scholarly journals Attenuation processes of solar radiation. Application to the quantification of direct and diffuse solar irradiances on horizontal surfaces in Mexico by means of an overall atmospheric transmittance

2018 ◽  
Vol 81 ◽  
pp. 93-106 ◽  
Author(s):  
Antonio J. Gutiérrez-Trashorras ◽  
Eunice Villicaña-Ortiz ◽  
Eduardo Álvarez-Álvarez ◽  
Juan M. González-Caballín ◽  
Jorge Xiberta-Bernat ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Atmospheric Transmittance

Effects of aerosols on the solar radiation in mid-hill of Nepal: a case study in the Kathmandu Valley

2016 ◽  
Vol 8 (1) ◽  
pp. 54-62
Author(s):  
M. K. Thapa ◽  
B. K. Bhattarai ◽  
S. Gurung ◽  
B. K. Sapkota ◽  
K. N. Poudyal ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Kathmandu Valley

Actinometry at resorts

1938 ◽  
Vol 34 (2) ◽  
pp. 208-208
Author(s):  
N. I. Kalitin
Keyword(s):  
Water Vapor ◽  
Solar Radiation ◽  
Scattered Radiation ◽  
Radiant Energy ◽  
Influence Of Water

Biomedgiz. Leningrad branch. 1937 208 pp. Pr. 6 rubles. 50 kopecks. The content of the book is much wider than what the reader has a right to expect, judging by its title. The book concerns not only the measurement of radiant energy and touches on not only issues of interest to doctors working in resorts. The properties of solar radiation under various conditions, the influence of water vapor, ozone, dustiness of the atmosphere, the value of scattered radiation reflected from the sky and clouds, which is usually not paid enough attention, all these and many other issues are covered in detail in the book of prof. N.I. Kalitina largely on the basis of her own long-term research.

scholarly journals Comparative Modeling of a Parabolic Trough Collectors Solar Power Plant with MARS Models

Energies ◽  
2017 ◽  
Vol 11 (1) ◽  
pp. 37 ◽  
Author(s):  
Jose Rogada ◽  
Lourdes Barcia ◽  
Juan Martinez ◽  
Mario Menendez ◽  
Francisco de Cos Juez
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Power Plant ◽  
Solar Radiation ◽  
Thermal Energy ◽  
Power Plants ◽  
Solar Power ◽  
Rankine Cycle ◽  
Heat Transfer Fluid ◽  
Solar Field

Power plants producing energy through solar fields use a heat transfer fluid that lends itself to be influenced and changed by different variables. In solar power plants, a heat transfer fluid (HTF) is used to transfer the thermal energy of solar radiation through parabolic collectors to a water vapor Rankine cycle. In this way, a turbine is driven that produces electricity when coupled to an electric generator. These plants have a heat transfer system that converts the solar radiation into heat through a HTF, and transfers that thermal energy to the water vapor heat exchangers. The best possible performance in the Rankine cycle, and therefore in the thermal plant, is obtained when the HTF reaches its maximum temperature when leaving the solar field (SF). In addition, it is necessary that the HTF does not exceed its own maximum operating temperature, above which it degrades. The optimum temperature of the HTF is difficult to obtain, since the working conditions of the plant can change abruptly from moment to moment. Guaranteeing that this HTF operates at its optimal temperature to produce electricity through a Rankine cycle is a priority. The oil flowing through the solar field has the disadvantage of having a thermal limit. Therefore, this research focuses on trying to make sure that this fluid comes out of the solar field with the highest possible temperature. Modeling using data mining is revealed as an important tool for forecasting the performance of this kind of power plant. The purpose of this document is to provide a model that can be used to optimize the temperature control of the fluid without interfering with the normal operation of the plant. The results obtained with this model should be necessarily contrasted with those obtained in a real plant. Initially, we compare the PID (proportional–integral–derivative) models used in previous studies for the optimization of this type of plant with modeling using the multivariate adaptive regression splines (MARS) model.

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