Global and diffuse solar radiant exposures at Pone

Radiation measurements are being carried out at Pune since 1957. The radiation data for the period 1986-90 are studied here with reference to general sky condition and rainfall distribution. Global irradiances show a decrease of about 5 per cent over the last four decades, The diffuse irradiation contributes about 23 per cent to the global irradiance during winter months, Its proportion increases to more than 70 per cent during the monsoon period. The specific rainfall distribution affects both global and diffuse irradiances but in opposite directions, The diffuse irradiance shows increases as the atmospheric transmission decreases, However, the changes found have not become statistically highly significant as yet.

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Effect of Mechanical Ventilation on the Thermal Offset of Pyranometers during Cloud-Free Summer Conditions

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-16-0163.1 ◽

2017 ◽

Vol 34 (5) ◽

pp. 1155-1173 ◽

Cited By ~ 1

Author(s):

G. Sanchez ◽

A. Serrano ◽

M. L. Cancillo

Keyword(s):

Mechanical Ventilation ◽

Solar Radiation ◽

Solar Zenith Angle ◽

Large Range ◽

Absolute Value ◽

Operational Conditions ◽

Global Irradiance ◽

Diffuse Irradiance ◽

The Impact ◽

Radiation Measurements

AbstractThermal offset is a significant source of uncertainty for solar radiation measurements. This study assesses the influence of mechanical ventilation on the daytime thermal offset of pyranometers. Toward this goal, an intensive unprecedented campaign of measurements was conducted in Badajoz, Spain, during four selected summer days under cloud-free conditions, covering a large range of solar zenith angle, irradiance, and temperature. Three leading manufacturers participated in the campaign, providing secondary standard pyranometers and compatible ventilation units. The thermal offset was experimentally measured following the capping methodology. A total of 372 capping events were conducted, the largest number ever reported in the literature. Each pyranometer was tested under different operational conditions (with/without ventilation and measuring global/diffuse irradiance). Results show that mechanical ventilation generally reduces the thermal offset. The magnitude of this reduction is different for each pyranometer model and depends on whether the instrument is shadowed (for measuring diffuse irradiance) or not (for measuring global irradiance). Mechanical ventilation tends to homogenize the temperature around the pyranometer and therefore reduces the impact of environmental conditions on the thermal offset. CMP11 and SPP pyranometers show notable tendencies in the thermal offset even when mechanical ventilation is applied. The Dutton et al. model, which aimed to correct the daytime thermal offset, is evaluated. Results show this model performs well for the SPP pyranometer but underestimates the absolute value of thermal offset for the CMP11 and SR20 pyranometers.

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Cloudiness and Earth's hemispheric albedo symmetry

10.5194/egusphere-egu21-153 ◽

2021 ◽

Author(s):

George Datseris ◽

Bjorn Stevens

Keyword(s):

Surface Albedo ◽

Shortwave Radiation ◽

Cloud Albedo ◽

Radiation Data ◽

Cloud Properties ◽

Open Questions ◽

Long Time ◽

Planetary Albedo ◽

Hemispheric Communication ◽

Radiation Measurements

<p>Radiation measurements at the top of the atmosphere show that the two hemispheres of Earth reflect the same amount of shortwave radiation in the long time average (so-called hemispheric albedo symmetry). Here we try to find the origin of this symmetry by analyzing radiation data directly, as well as cloud properties. The radiation data, while being mostly noise, hint that a hemispheric communication mechanism is likely but do not provide enough information to identify it. Cloud properties allow us to define an effective cloud albedo field, much more useful than the commonly used cloud area fraction. Based on that we first show that extra cloud albedo of the SH exactly compensates the extra surface albedo of the NH. We then identify that this this compensation comes almost exclusively from the storm tracks of the extratropics. We close discussing the importance of approaching planetary albedo as a whole and open questions that remain.</p>

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Comparison of Pyranometric and Pyrheliometric Methods for the Determination of Sunshine Duration

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech2013.1 ◽

2007 ◽

Vol 24 (5) ◽

pp. 835-846 ◽

Cited By ~ 12

Author(s):

Yvonne B. L. Hinssen ◽

Wouter H. Knap

Keyword(s):

Solar Irradiance ◽

Extreme Values ◽

Sunshine Duration ◽

Global Radiation ◽

Surface Radiation ◽

Global Irradiance ◽

Correlation Algorithm ◽

Mean Differences ◽

Radiation Measurements

Abstract Two pyranometric methods for the determination of sunshine duration (SD) from global irradiance measurements are evaluated by means of summated sunshine seconds derived from pyrheliometric measurements in combination with the WMO threshold of 120 W m−2 for the direct solar irradiance. The evaluation is performed using direct and global radiation measurements made at the Cabauw Baseline Surface Radiation Network (BSRN) site in the Netherlands for the period March 2005–February 2006. The “Slob algorithm” uses 10-min mean and extreme values of the measured global irradiance and parameterized estimates of the direct and diffuse irradiance. The “correlation algorithm” directly relates SD to 10-min mean measurements of global irradiance. The cumulative pyrheliometric SD for the mentioned period is 1429 h. Relative to this value, the Slob algorithm and correlation algorithm give −72 h (−5%) and +8 h (+0.6%). On a daily mean basis, the values are −0.22 ± 0.05 h day−1 and 0.03 ± 0.03 h day−1, respectively. By means of tuning the irradiance parameterizations of the Slob algorithm, the yearly cumulative and daily mean differences can be reduced to +7 h (+0.5%) and 0.02 ± 0.04 h day−1, respectively. It is concluded that, by use of either algorithm, it is possible to estimate daily sums of SD from 10-min mean measurements of global irradiance with a typical uncertainty of 0.5–0.7 h day−1. For yearly sums, the uncertainty typically amounts to 0.5%.

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Radiation Data Portal: Integration of Radiation Measurements at the Aviation Altitudes and Solar‐Terrestrial Environment Observations

Space Weather ◽

10.1029/2020sw002653 ◽

2020 ◽

Author(s):

V.M. Sadykov ◽

I.N. Kitiashvili ◽

W. K. Tobiska ◽

M. Guhathakurta

Keyword(s):

Terrestrial Environment ◽

Radiation Data ◽

Data Portal ◽

Radiation Measurements

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Analysis of solar radiation measurements at EI-Kharga (250 N, 300E), Egypt

MAUSAM ◽

10.54302/mausam.v44i1.3772 ◽

2021 ◽

Vol 44 (1) ◽

pp. 39-44

Author(s):

A. I. SALEM ◽

M. GABR ◽

S. SALEEM ◽

A. H. BASSYOUNI

Keyword(s):

Solar Radiation ◽

Diurnal Variation ◽

Frequency Distribution ◽

Process Design ◽

Global Solar Radiation ◽

Correlation Equations ◽

Radiation Data ◽

Sequence Variations ◽

Radiation Measurements ◽

Daily Total

Daily global solar. radiation data of EI-Kharga for five year (1984-88) have been processed, analysed and classified into eight radiation levels spaced at an interval of 4.19 MJ m-2 day-l. Mean annual monthly and daily total the diurnal variation, and the frequency distribution of daily totals of global solar radiation are computed and discussed. A correlation between the hourly values of the clearness and diffuse indices were obtained and the recommended correlation ,equations were also given. The, results presented in this analysis are encouraging since they Indicate that periods of several days of low radiation of less than 8.38 MJm , day are rare. This In turn means that the weather sequence variations are not expected, to be of great Importance when considering the storage problems Involved In solar process design.

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Simulation and design of collector array units within large systems

10.18777/ieashc-task55-2019-0004 ◽

2019 ◽

Author(s):

Jianhua Fan ◽

Zhiyong Tian ◽

Simon Furbo ◽

Weiqiang Kong ◽

Daniel Tschopp

Keyword(s):

Solar Radiation ◽

Thermal Performance ◽

Global Radiation ◽

Diffuse Radiation ◽

Solar Heating ◽

Heating Systems ◽

Global Irradiance ◽

Radiation Data ◽

Large Systems ◽

Beam Component

Solar radiation data is necessary for the design of solar heating systems and used to estimate the thermal performance of solar heating plants. Compared to global irradiance, the direct beam component shows much more variability in space and time. The global radiation split into beam and diffuse radiation on collector plane is important for the evaluation of the performance of different collector types and collector field designs.

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Evaluation of a New Photodiode Sensor for Measuring Global and Diffuse Irradiance, and Sunshine Duration

Journal of Solar Energy Engineering ◽

10.1115/1.1531149 ◽

2003 ◽

Vol 125 (1) ◽

pp. 43-48 ◽

Cited By ~ 27

Author(s):

John Wood ◽

Tariq Muneer ◽

J. Kubie

Keyword(s):

Standard Error ◽

Sunshine Duration ◽

New Device ◽

Global Irradiance ◽

Diffuse Irradiance ◽

Reference Measure ◽

Irradiance Data ◽

Stable Performance ◽

Integrated Device ◽

Story Building

A new integrated device (called the BF3) has been developed, which enables the simultaneous measurement of horizontal global and diffuse irradiance as well as sunshine presence at any time. The sensor needs no specific polar alignment or routine adjustment, and works at any latitude. To evaluate the performance of this new device, a BF3 sensor was installed on the roof of a six-story building in the Merchiston Campus of Napier University, Edinburgh from February 22–July 3, 2001. Horizontal global and diffuse irradiance data were collected from the BF3. To enable a cross check, two Kipp and Zonen CM11 sensors, one with a shade ring, have also been installed beside the BF3 sensor on the same roof. These were used to give a reference measure of the horizontal global and diffuse irradiance. To evaluate the BF3 sunshine duration performance, the direct beam normal irradiance was calculated from the CM11 global and diffuse readings, and compared with a threshold of 120W.m−2 to give sunshine presence according to the WMO definition. This was compared against the BF3 output, and also with data from two Campbell-Stokes sunshine recorders on the same site. The results show a stable performance on the part of the BF3 sensor for the measurement of horizontal global and diffuse irradiance. The global irradiance measured by the BF3 showed values 4.7% high, with a standard error of 16.5W.m−2 compared to the Kipp and Zonen sensors. Diffuse values were 1.4% high with a standard error of 13.4W.m−2. The BF3 sunshine duration was within 2% of that calculated from the WMO definition over the study period, with a typical daily error of less than 20 min. This is well within the WMO requirements for a sunshine recorder. In comparison, the Campbell-Stokes recorders gave readings up to 7% different from the WMO values, with a typical daily error of almost an hour.

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