scholarly journals Spectral solar irradiance and its entropic effect on Earth's climate

2011 ◽  
Vol 2 (1) ◽  
pp. 45-70 ◽  
Author(s):  
W. Wu ◽  
Y. Liu ◽  
G. Wen
Keyword(s):  
Solar Radiation ◽  
Solar Irradiance ◽  
Conventional Approach ◽  
Incident Solar Radiation ◽  
Earth’S Atmosphere ◽  
Radiation Entropy ◽  
Entropy Flux ◽  
The Difference ◽  
Earth’S Climate ◽  
Spectral Solar Irradiance

Abstract. The high-resolution measurements of the spectral solar irradiance at the top of the Earth's atmosphere by the Solar Radiation and Climate Experiment (SORCE) satellite suggest significant deviation of solar radiation from the commonly assumed blackbody radiation. Here, we use these spectral irradiance measurements to estimate the Earth's incident solar radiation entropy flux, and examine the importance of a proper estimation approach. The Earth's incident solar radiation entropy flux estimated by directly applying the observed spectral solar irradiance into the most accurate Planck expression is compared with that estimated with a conventional approach that uses the Sun's brightness temperature under the assumption of a blackbody Sun. The globally averaged non-blackbody incident solar radiation entropy flux at the top of the Earth's atmosphere equals 0.31 W m−2 K−1. This value is about 4 times larger than that estimated from the conventional blackbody approach, with the difference comparable to the typical value of the entropy production rate associated with atmospheric latent heat process. Further analysis reveals that the decrease of spectral solar radiation entropy flux with radiation traveling distance, unlike the decrease of spectral solar radiation energy flux with radiation traveling distance, is wavelength dependent, and that the difference between the two estimates can be attributed to the fact that the conventional approach ignores the influence of radiation traveling distance on the spectral solar radiation entropy flux. Moreover, sensitivity study further shows that the distribution of top-of-atmosphere spectral solar irradiance could significantly impact the magnitude of the estimated Earth's incident solar radiation entropy flux. These results together suggest that the spectral distribution of incident solar radiation is critical for determining the Earth's incident solar radiation entropy flux, and thus the Earth's climate.

scholarly journals Recent variability of the solar spectral irradiance and its impact on climate modelling

2013 ◽  
Vol 13 (8) ◽  
pp. 3945-3977 ◽  
Author(s):  
I. Ermolli ◽  
K. Matthes ◽  
T. Dudok de Wit ◽  
N. A. Krivova ◽  
K. Tourpali ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Solar Radiation ◽  
Spectral Range ◽  
Solar Irradiance ◽  
Spectral Irradiance ◽  
Climate Modelling ◽  
Earth’S Atmosphere ◽  
Solar Spectral Irradiance ◽  
Earth's Atmosphere ◽  
Earth’S Climate

Abstract. The lack of long and reliable time series of solar spectral irradiance (SSI) measurements makes an accurate quantification of solar contributions to recent climate change difficult. Whereas earlier SSI observations and models provided a qualitatively consistent picture of the SSI variability, recent measurements by the SORCE (SOlar Radiation and Climate Experiment) satellite suggest a significantly stronger variability in the ultraviolet (UV) spectral range and changes in the visible and near-infrared (NIR) bands in anti-phase with the solar cycle. A number of recent chemistry-climate model (CCM) simulations have shown that this might have significant implications on the Earth's atmosphere. Motivated by these results, we summarize here our current knowledge of SSI variability and its impact on Earth's climate. We present a detailed overview of existing SSI measurements and provide thorough comparison of models available to date. SSI changes influence the Earth's atmosphere, both directly, through changes in shortwave (SW) heating and therefore, temperature and ozone distributions in the stratosphere, and indirectly, through dynamical feedbacks. We investigate these direct and indirect effects using several state-of-the art CCM simulations forced with measured and modelled SSI changes. A unique asset of this study is the use of a common comprehensive approach for an issue that is usually addressed separately by different communities. We show that the SORCE measurements are difficult to reconcile with earlier observations and with SSI models. Of the five SSI models discussed here, specifically NRLSSI (Naval Research Laboratory Solar Spectral Irradiance), SATIRE-S (Spectral And Total Irradiance REconstructions for the Satellite era), COSI (COde for Solar Irradiance), SRPM (Solar Radiation Physical Modelling), and OAR (Osservatorio Astronomico di Roma), only one shows a behaviour of the UV and visible irradiance qualitatively resembling that of the recent SORCE measurements. However, the integral of the SSI computed with this model over the entire spectral range does not reproduce the measured cyclical changes of the total solar irradiance, which is an essential requisite for realistic evaluations of solar effects on the Earth's climate in CCMs. We show that within the range provided by the recent SSI observations and semi-empirical models discussed here, the NRLSSI model and SORCE observations represent the lower and upper limits in the magnitude of the SSI solar cycle variation. The results of the CCM simulations, forced with the SSI solar cycle variations estimated from the NRLSSI model and from SORCE measurements, show that the direct solar response in the stratosphere is larger for the SORCE than for the NRLSSI data. Correspondingly, larger UV forcing also leads to a larger surface response. Finally, we discuss the reliability of the available data and we propose additional coordinated work, first to build composite SSI data sets out of scattered observations and to refine current SSI models, and second, to run coordinated CCM experiments.

Is ‘Reflectance’ Basking Real?

1990 ◽  
Vol 154 (1) ◽  
pp. 31-43
Author(s):  
BERND HEINRICH
Keyword(s):  
Solar Radiation ◽  
Opposite Direction ◽  
Acute Angle ◽  
Direct Sunlight ◽  
Convective Cooling ◽  
Incident Solar Radiation ◽  
Solar Reflectance ◽  
Thoracic Temperature ◽  
Air Stream ◽  
The Difference

Various kinds of butterflies raise both (or sometimes one) of their pairs of wings while basking with their body at approximately right angles to the incident solar radiation and with their wings held at an acute angle to the incident sunlight. I here test the effects of wing posture on thoracic temperature in so-called ‘reflectance’ basking. 1. Butterflies with pale yellow or white dorsal wing surfaces held with their wings at 45, 90 or 180° with respect to each other (or 22–23, 45 and 90°with respect to the solar radiation) heated to mean thoracic temperatures (Tth) of 38.2, 39.5 and 39.9°C, respectively, in direct sunlight. These closely similar values of T^ are significantly different (P < 0.02) from each other, but the difference is in the opposite direction to that predicted by the solar reflectance hypothesis. 2. The Tth of butterflies tested under a sun lamp in the laboratory showed the same trend of Tth with wing angle. Reflectance from the wings thus makes little or no practical contribution to the animal's heating response. 3. Butterflies with wings at 45° that were heated from above with a sun lamp showed an immediate increase in Tth when turned at right angles to a gentle air stream. Thoracic temperature immediately declined when they were again turned to face the air stream. 4. Those butterflies that were at right angles to the air stream showed an immediate increase in Tth when the wings were raised from 180 to 45°, and their Tth again declined to previous values when the wings were again lowered. However, little or no effect of wing angle on Tth was observed when the wing angle of butterflies parallel to the air stream was altered. These results indicate that wing elevation in basking butterflies does not increase Tth by way of solar reflection from the wings. Instead, the raised wings increase Tth by reducing convective cooling. ‘Reflectance’ basking is a form of dorsal basking used by species of butterflies that perch above vegetation rather than above a heated substratum.

scholarly journals Modelling of Solar Spectral Radiation in Penang Island on a Digital Elevation Model

2019 ◽  
Vol 7 (4.14) ◽  
pp. 461
Author(s):  
Eng Choon Yeap ◽  
Hwee San Lim ◽  
Zubir Mat Jafri
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Digital Elevation Model ◽  
Solar Irradiance ◽  
Satellite Image ◽  
Atmospheric Effects ◽  
Spectral Radiation ◽  
Digital Elevation ◽  
Elevation Model ◽  
Spectral Solar Irradiance

Interest has been increasingly focused on the studies of solar radiation across the globe ever since people are more concern about energy conservation. Due to the increment of terrestrial application of solar energy, the scientific interest on solar distribution has expanded from broadband solar energy to its spectral distribution. Measurement of solar radiation with its spectral profile provides knowledge for making important decisions involving resources and energy, agriculture and climate. In remote sensing, the measurement of spectral solar radiation is important for sensor calibration and image enhancement to extract the most information out of a satellite image. The spectral radiation can be measured using spectral radiometer specifically design for measuring solar radiation; however such instruments are expensive and only provide point data which is very limited in most studies. This study aims to provide a rigorous spectral radiation model that predict the spectral solar irradiance in temporal resolution of every minute with spectral range from 350nm to 2200nm under cloudless condition. The parameters used in this model include the distance between sun and earth, time, coordinate, atmospheric interference and terrain effect. Atmospheric sounding data was used in this study to provide the necessary atmospheric parameter in the simulation of solar propagation through the atmosphere. The atmospheric effects considered in this study include Rayleigh scattering, aerosol attenuation and the absorption of water vapor, ozone and uniformly mixed gas. The simulation results were projected onto a digital elevation model to further calculate the effect introduced by the topographic variation and to get a three dimensional solar spectral radiation. The result obtained from this study is compared with spectral solar irradiance data collected during the month of June and July, 2018 with root mean square deviation of 9 watt per meter square at the wavelength of 350nm to 2200nm.  

scholarly journals Readdressing the UV solar variability with SATIRE-S: non-LTE effects

2019 ◽  
Vol 631 ◽  
pp. A178 ◽  
Author(s):  
R. V. Tagirov ◽  
A. I. Shapiro ◽  
N. A. Krivova ◽  
Y. C. Unruh ◽  
K. L. Yeo ◽  
...  
Keyword(s):  
Solar Irradiance ◽  
Spectral Synthesis ◽  
Solar Variability ◽  
Spectral Irradiance ◽  
Solar Dynamics Observatory ◽  
Quiet Sun ◽  
Total Irradiance ◽  
Solar Dynamics ◽  
Earth’S Climate ◽  
Spectral Solar Irradiance

Context. Solar spectral irradiance (SSI) variability is one of the key inputs to models of the Earth’s climate. Understanding solar irradiance fluctuations also helps to place the Sun among other stars in terms of their brightness variability patterns and to set detectability limits for terrestrial exoplanets. Aims. One of the most successful and widely used models of solar irradiance variability is Spectral And Total Irradiance REconstruction model (SATIRE-S). It uses spectra of the magnetic features and surrounding quiet Sun that are computed with the ATLAS9 spectral synthesis code under the assumption of local thermodynamic equilibrium (LTE). SATIRE-S has been at the forefront of solar variability modelling, but due to the limitations of the LTE approximation its output SSI has to be empirically corrected below 300 nm, which reduces the physical consistency of its results. This shortcoming is addressed in the present paper. Methods. We replaced the ATLAS9 spectra of all atmospheric components in SATIRE-S with spectra that were calculated using the Non-LTE Spectral SYnthesis (NESSY) code. To compute the spectrum of the quiet Sun and faculae, we used the temperature and density stratification models of the FAL set. Results. We computed non-LTE contrasts of spots and faculae and combined them with the corresponding fractional disc coverages, or filling factors, to calculate the total and spectral irradiance variability during solar cycle 24. The filling factors have been derived from solar full-disc magnetograms and continuum images recorded by the Helioseismic and Magnetic Imager on Solar Dynamics Observatory (SDO/HMI). Conclusions. The non-LTE contrasts yield total and spectral solar irradiance variations that are in good agreement with empirically corrected LTE irradiance calculations. This shows that the empirical correction applied to the SATIRE-S total and spectral solar irradiance is consistent with results from non-LTE computations.

The Controversial One

2021 ◽  
pp. 196-227
Author(s):  
Eelco J. Rohling
Keyword(s):  
Global Warming ◽  
Solar Radiation ◽  
Solar Energy ◽  
Solar Radiation Management ◽  
The Sun ◽  
Earth’S Atmosphere ◽  
Solar Geoengineering ◽  
Earth's Atmosphere ◽  
Earth’S Climate ◽  
Radiation Management

This chapter considers solar radiation management, also known as solar geoengineering, which seeks to manipulate Earth’s climate energy balance by reducing the absorption of incoming solar energy. As the chapter explains, this approach spans a class of proposed measures that has been polarizing the community, with some advocating it as an essential means of keeping global warming within acceptable limits, while others see only grave drawbacks and dangers. The chapter describes the two approaches to limiting the absorption of solar energy: measures taken in space, between Earth and the Sun, to reflect or disperse solar radiation before it even hits Earth’s atmosphere; and measures taken in Earth’s atmosphere or at the Earth’s surface to reflect incoming solar radiation. It goes on to discuss the various proposed methods, their potential, and their drawbacks.

scholarly journals Solar Radiation on a Parabolic Concave Surface

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2245
Author(s):  
Avi Aronescu ◽  
Joseph Appelbaum
Keyword(s):  
Solar Radiation ◽  
Concave Surface ◽  
The South ◽  
Oriented Surface ◽  
Incident Solar Radiation ◽  
Photovoltaic Modules ◽  
Curved Structures ◽  
Global Irradiation ◽  
The Difference ◽  
Analytical Expressions

Curved structures are used in buildings and may be integrated with photovoltaic modules. Self-shading occurs on non-flat (curved) surface collectors resulting in a non-uniform distribution of the direct beam and the diffuse incident solar radiation along the curvature the surface. The present study uses analytical expressions for calculating and analyzing the incident solar radiation on a general parabolic concave surface. Concave surfaces facing north, south and east/west are considered, and numerical values for the annual incident irradiations (in kWh) are demonstrated for two locations: 32° N (Tel Aviv, Israel) and 52.2° N (Lindenberg, Germany). The numerical results show that the difference in the incident global irradiation for the different surface orientations is not very wide. At 32° N, the irradiation difference between the south and north-oriented surface is about 15 percent, and between the south and east surface orientation it is about 9.6 percent. For latitude 52.2° N, the global irradiation difference between the south and north-oriented surface is about 16 percent, and between the south and east orientation it is about 3 percent.

scholarly journals Utilising Open Geospatial Data to Refine Weather Variables for Building Energy Performance Evaluation—Incident Solar Radiation and Wind-Driven Infiltration Modelling

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 802
Author(s):  
Kristian Skeie ◽  
Arild Gustavsen
Keyword(s):  
Solar Radiation ◽  
Web Service ◽  
Meteorological Data ◽  
Surface Wind ◽  
Building Energy ◽  
Energy Performance ◽  
Geospatial Data ◽  
Weather Data ◽  
Building Site ◽  
Incident Solar Radiation

In building thermal energy characterisation, the relevance of proper modelling of the effects caused by solar radiation, temperature and wind is seen as a critical factor. Open geospatial datasets are growing in diversity, easing access to meteorological data and other relevant information that can be used for building energy modelling. However, the application of geospatial techniques combining multiple open datasets is not yet common in the often scripted workflows of data-driven building thermal performance characterisation. We present a method for processing time-series from climate reanalysis and satellite-derived solar irradiance services, by implementing land-use, and elevation raster maps served in an elevation profile web-service. The article describes a methodology to: (1) adapt gridded weather data to four case-building sites in Europe; (2) calculate the incident solar radiation on the building facades; (3) estimate wind and temperature-dependent infiltration using a single-zone infiltration model and (4) including separating and evaluating the sheltering effect of buildings and trees in the vicinity, based on building footprints. Calculations of solar radiation, surface wind and air infiltration potential are done using validated models published in the scientific literature. We found that using scripting tools to automate geoprocessing tasks is widespread, and implementing such techniques in conjunction with an elevation profile web service made it possible to utilise information from open geospatial data surrounding a building site effectively. We expect that the modelling approach could be further improved, including diffuse-shading methods and evaluating other wind shelter methods for urban settings.

scholarly journals Thermal comfort in winter incorporating solar radiation effects at high altitudes and performance of improved passive solar design—Case of Lhasa

2020 ◽  
Author(s):  
Lingjiang Huang ◽  
Jian Kang
Keyword(s):  
Solar Radiation ◽  
Thermal Comfort ◽  
Energy Saving ◽  
Solar Irradiance ◽  
Indoor Environment ◽  
Thermal Mass ◽  
High Altitudes ◽  
Energy Saving Potential ◽  
Environment Control ◽  
Passive Solar

AbstractThe solar incidence on an indoor environment and its occupants has significant impacts on indoor thermal comfort. It can bring favorable passive solar heating and can result in undesired overheating (even in winter). This problem becomes more critical for high altitudes with high intensity of solar irradiance, while received limited attention. In this study, we explored the specific overheating and rising thermal discomfort in winter in Lhasa as a typical location of a cold climate at high altitudes. First, we evaluated the thermal comfort incorporating solar radiation effect in winter by field measurements. Subsequently, we investigated local occupant adaptive responses (considering the impact of direct solar irradiance). This was followed by a simulation study of assessment of annual based thermal comfort and the effect on energy-saving potential by current solar adjustment. Finally, we discussed winter shading design for high altitudes for both solar shading and passive solar use at high altitudes, and evaluated thermal mass shading with solar louvers in terms of indoor environment control. The results reveal that considerable indoor overheating occurs during the whole winter season instead of summer in Lhasa, with over two-thirds of daytime beyond the comfort range. Further, various adaptive behaviors are adopted by occupants in response to overheating due to the solar radiation. Moreover, it is found that the energy-saving potential might be overestimated by 1.9 times with current window to wall ratio requirements in local design standards and building codes due to the thermal adaption by drawing curtains. The developed thermal mass shading is efficient in achieving an improved indoor thermal environment by reducing overheating time to an average of 62.2% during the winter and a corresponding increase of comfort time.

scholarly journals The role of L/W in the solar radiation for Saharian cities

2019 ◽  
Vol 91 ◽  
pp. 05006
Author(s):  
Rami Qaoud ◽  
Alkama Djamal
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Energy Levels ◽  
Direct Solar Radiation ◽  
Test Field ◽  
Natural Lighting ◽  
The Difference ◽  
The Impact ◽  
The Relationship

The urban fabric of the desert cities is based on the principle of reducing the impact of urban canyons on direct solar radiation. Here comes this research, which is based on a comparative study of the periods of direct solarisation and values of the solar energy of urban canyons via two urban fabrics that have different building densities, where the ratio between L/W is different. In order to obtain the real values of the solar energy (thermal, lighting), the test field was examined every two hours, each three consecutive days. The measurement stations are positioned by the three types of the relationship between L/W, (L≥2w, L=w, L≤0.5w). According to the results, we noticed and recorded the difference in the periods of direct solarization between the types of urban engineering canyons, reaching 6 hours a day, the difference in thermal values of air, reaching 4 °C, and the difference in periods of direct natural lighting, reaching 6 hours. It should be noted that the role of the relationship between L/W is to protect the urban canyons by reducing the impact of direct solar radiation on urban canyons, providing longer hours of shading, and reducing solar energy levels (thermal, lighting) at the urban canyons. This research is classified under the research axis (the studies of external spaces in the urban environment according to the bioclimatic approach and geographic approach). But this research aims to focus on the tracking and studying the distribution of the solar radiation - thermal radiation and lighting radiation - in different types of street canyons by comparing the study of the direct solarization periods of each type and the quantity of solar energy collected during the solarization periods.

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