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• Vertical column density and column averaged dry air concentrations of GHGs were retrieved from FTIR using GFIT model. • Seasonal and interannual variations of GHGs were studied. • FTIR retrieved X CO 2 and X CO data were compared with satellite data. Solar absorption spectra collected using a ground-based Fourier Transform Infrared (FTIR) Spectrometer were used to retrieve the column-averaged concentrations (X) of CO 2 , CH 4 , CO, and N 2 O during the years 2016–2019 in the Suburban region of Shadnagar, Telangana, India. For the research period, the diurnal mean amplitudes of X CO 2 , X CH 4 , X CO, and X N 2 O are ∼ 13 ppmv, ∼50 ppbv, ∼13 ppbv, and ∼ 19 ppbv respectively. Strong seasonality at the study site is indicated by the seasonal variations of X CO 2 and X CO of 18.3 ppmv and 39.2 ppbv, respectively. Additionally, we compared FTIR data to X CO 2 detected by Orbiting Carbon Observatory-2 (OCO-2) and CO columns from Measurements of Pollution in the Troposphere (MOPITT). For the X CO 2 and CO columns, the comparison research shows a mean relative bias between FTIR data and satellite data of 0.92 % and 0.71 %, respectively. The FTIR and satellite data show a Pearson correlation coefficient (r) of 0.71 (X CO 2 , N = 26 co-located) and 0.60 (CO columns, N = 44), respectively. The findings demonstrate a good agreement between our data and satellite data. [ABSTRACT FROM AUTHOR]

The proper radiometric calibration of the INSAT-3D and --3DR IMAGER is of utmost importance for effective weather forecasting and monitoring. Accurate and reliable images are crucial for predicting weather patterns, tracking storms, and assessing the impact of natural disasters. This research paper presents an evaluation of the radiometric calibration of the INSAT-3D and --3DR IMAGER using a reflectance-based method referenced to in-situ ground site measurements. Calibration campaigns were conducted at the Great Rann of Kutch (GROK) in Gujarat, India during February 2022 to ensure synchronous measurements of surface reflectance and atmospheric variables. In this study, the radiative transfer model called 6 SV (Second Simulation of a Satellite Signal in the Solar Spectrum Vector) was employed to simulate the Top-Of-Atmospheric (TOA) radiance. The calibration coef- ficients for the Visible (VIS) and Short Wave Infrared (SWIR) bands of the IMAGER were determined by comparing the TOA radiance obtained from the radiative transfer model with the Level 1B product of satellite data. The results convincingly demonstrate that the reflectance-based calibration method yields highly accurate and reliable radiometric calibration for both the VIS and SWIR bands of the INSAT-3D and --3DR IMAGER, with an uncertainty significantly smaller than the expected sensor degradation. Specifically, it was found that the VIS band of INSAT-3D underestimates the radiance value by 9.05%, while the VIS band of INSAT-3DR underestimates it by 4.88%. The study also discusses various sources of uncertainty and emphasizes the need for comprehensive uncertainty quantification to ensure the radiometric accuracy of the IMAGER data. Overall, the calibration results indicate that the absolute radiometric accuracy for the VIS and SWIR bands of the IMAGER on-board INSAT-3D and INSAT-3DR satellites is better than 4%. This research contributes to enhancing the reliability and usability of the INSAT-3D and --3DR IMAGER data for weather forecasting and monitoring applications. [ABSTRACT FROM AUTHOR]

• Prism shaped solar still (PSS) has better heat retaining capacity than conventional solar stills (CSS). • With Lauric acid, PSS yields 2530 ml/m2 compared to CSS yield of 2360 ml/m2 with exergy efficiency of 1.01 % and 0.87 % respectively. • Black phosphorus doped Pyrex glass Quantum dot (QD) material able to absorb the large spectrum of solar radiation. • With QD and PCM, PSS yields up to 3685 ml/m2 compared to CSS yield 3040 ml/m2. • Cost analysis shows per liter of distilled water incurred INR 1.6 and 1.9 with payback period of 2.8 years and 3.2 years. The present article takes the challenge to improve solar still performance by surface coating for better energy conversion. An experimental investigation has been conducted on two solar still (SS), namely conventional solar still (CSS) facing the south direction and prism-shaped solar still (PSS) facing the east–west direction in the metrological condition of Varanasi (25.31° N), India. SS's surface solar absorptance and heat storage capacity has been modified by black phosphorus quantum dot material (BPQD) and Lauric acid. The experiments were conducted in three phases, namely SS without BPQD and PCM; SS with PCM only; and SS with BPQD and PCM on different days in nearly the same climatic conditions that showed prism-shaped solar still coated with BPQD material performed better due to its good heat retention capacity than CSS. The results showed that CSS and PSS without PCM and BPQD yield up to 1660 ml/m2 and 1830 ml/m2 with a heating efficiency of 19.72 % and 0.36 % and exergy efficiency of 25.59 %, and 1.08 %, respectively. While using PCM only, CSS and PSS yield up to 2360 ml/m2 and 2530 ml/m2 with heating efficiency of 27.84 % and 0.87 % and exergy efficiency of 35.12 % and 1.01 %, respectively. Whereas, with PCM and BPQD, SSs can produce 3040 ml/m2 and 3685 ml/m2 with exergy and heating of 1.79 % and 37.23 % for CSS, 2.20 %, and 49.30 % for PSS. Moreover, the economic analysis showed that the monetary and energy cost of distilled water incurs only INR 1.9, and INR 1.6 for each liter and INR 2.84 and 2.48 for each kWh with a payback period of 3.2 yr. and 2.8 yr. for CSS and PSS respectively. [ABSTRACT FROM AUTHOR]

This study describes On-Orbit absolute radiometric calibration for the Ocean Colour Monitor2 (OCM2) onboard Oceansat-2 satellite through a vicarious calibration experiment performed at the Great Rann of Kutch calibration site in Gujarat, India, in February 2022. To achieve accurate and consistent calibration for the OCM2 channels, a reflectance-based calibration method was used which relies on synchronous in-situ measurements of surface reflectance and atmospheric parameters at the time of satellite overpass. In this exercise, the 6 SV (Second Simulation of a Satellite Signal in the Solar Spectrum Vector) radiative transfer (RT) model was used to simulate the Top Of Atmosphere (TOA) spectral radiance for the OCM2 channels. The on-orbit radiometric performance/changes were derived by comparing the 6 SV simulated TOA radiance with those of the OCM2 Level 1B (L1B) data product. The results indicate that the average gain for band 1 to band 8 was found in the range from 0.88 to 1.23 and the relative error from 1.58% to 18.79% for the OCM2 sensor. However, the Root-Mean-Square-Error (RMSE) between the OCM2 measured and the 6 SV simulated TOA radiance data range from 0.17 (µW cm−2 sr−1 nm−1) at 443 nm to 2.04 (µW cm−2 sr−1 nm−1) at 620 nm. Furthermore, we analysed in detail the various uncertainties in this approach emanating from surface reflectance, atmospheric conditions (ozone, water vapour and aerosol optical depth), aerosol-type assumption in the RT model, BRDF, and inherent accuracy of the 6 SV RT model. The overall uncertainty was within 6% estimated using the reflectance-based calibration method. [ABSTRACT FROM AUTHOR]

The Solar X-ray Monitor (abbreviated as XSM) on board India's Chandrayaan-2 mission is designed to carry out broadband spectroscopy of the Sun from lunar orbit. It observes the Sun as a star and measures the spectrum every second in the soft X-ray band of 1 – 15 keV with an energy resolution better than 180 eV at 5.9 keV. The primary objective of the XSM is to provide the incident solar spectrum for the X-ray fluorescence spectroscopy experiment on the Chandrayaan-2 orbiter, which aims to generate elemental abundance maps of the lunar surface. However, observations with the XSM can independently be used to study the Sun as well. The Chandrayaan-2 mission was launched on 22 July 2019, and the XSM began nominal operations, in lunar orbit, from September 2019. The in-flight observations, so far, have shown that its spectral performance has been identical to that on the ground. Measurements of the effective area from ground calibration were found to require some refinement, which has been carried out using solar observations at different incident angles. It also has been shown that the XSM is sensitive enough to detect solar activity well below A class. This makes the investigations of microflares and the quiet solar corona feasible in addition to the study of the evolution of physical parameters during intense flares. This article presents the in-flight performance and calibration of the XSM instrument and discusses some specific science cases that can be addressed using observations with the XSM. [ABSTRACT FROM AUTHOR]

During the last decade, energy demand has increased manifold in India. To cope up with the rising energy demand, the Indian government has announced the National Solar Mission to generate 100 GW solar power by 2022. Large-scale solar power developers have been allotted around 60% of the National Solar Mission target. Therefore, it becomes pivotal to find the ground reality of solar power developers. To fulfill this objective, we selected the solar sources of the country and adopted a hybrid research methodology. The solar irradiation data were collected for one year in the four big cities of India, Mumbai, New Delhi, Chennai, and Bangalore during 2019 to evaluate the efficiency of photovoltaics (PVs). MATLAB and RETScreen were employed for data analysis and evaluating the efficiency of photovoltaics. We take this a step further by performing the Life Cycle Assessment analysis to scrutinize the different features of solar energy, including fuel consumption, price, average lifetime, maintenance and operation expenses, land requirements, and greenhouse gas emissions. The results reveal that all these cities have an enormous solar power potential, as they are located in an area where solar irradiations are consistently available all over the year (except for monsoon season). Moreover, solar energy is more durable, cost-saving, and easy to maintain. Furthermore, we identified the significant barriers over the whole solar energy spectrum by conducting semi-structured interviews with industry experts. These barriers are broadly classified into technological, policy, regulatory, financial, transparency, accountability, infrastructural, and trade policy categories. Finally, essential policy recommendations have been suggested for all stakeholders in order to fulfill the country's energy demand on its way to a future of sustainable development. [ABSTRACT FROM AUTHOR]

The present work seeks to assess the sustainability of different solar photovoltaic (SPV) electricity-generating systems based upon energy, environment and economics. The sustainability indicators evaluated for energy, environment and economics are electrical output, life-cycle greenhouse gas (GHG) emissions and life-cycle cost of electricity generated per kilowatt hour. The selected SPV-based electricity generation technologies for sustainability evaluation are amorphous, monocrystalline and polycrystalline at different locations and tilt angles across India. For SPV systems, most of the emissions are the result of electricity use during manufacturing. In these cases, an average grid mix for the region of manufacture is typically used to calculate energy use and emissions. Based upon these three indicators, a figure of merit (FM) has been proposed. The results proposed that polycrystalline gives the maximum electrical output, minimum GHG emission, minimum cost and maximum FM at a radiation level of 6 kWh/m2/day with latitude and tilt angle of 34° and 35°, respectively. This work will be helpful to users of solar energy, academicians, researchers and other concerned persons, in understanding the importance, severity and benefits obtained by the application and implementation of the SPV electricity-generating systems. [ABSTRACT FROM AUTHOR]

In the long future, dependency on conventional air conditioning systems for thermal comfort certainly needs to be reduced, with alternate strategies like passive photonic radiative cooling. Recent metamaterial development with highly reflective in the solar spectrum pushes the radiative cooling technique toward application assessment. In this paper, the photonic radiative cooler performance is analyzed for year 2019 at various Indian locations considering the diversity of climate and forecasted for year 2030. The effect of three types of climate change is considered: geographical, seasonal and year-wise. Some photonic coolers with different emissive profiles are also compared. As the radiative cooling depends upon air temperature, humidity, wind speed and solar flux intensity, the effects of influencing climatic or weather parameters during summer months are studied extensively and major performance influencing factors are identified. Photonic radiative cooler performance in energy-saving as rooftop envelope assisted to conventional air conditioning system is assessed and observed cooling energy saving of 25–32 kWh th /month for selected locations. Study reveals that the windshield is the necessary condition to get net cooling flux through the rooftop. The reduction of cooling load on active systems of 34% is observed for low humidity locations with the integration of radiative cooler as a roof envelope. Image 1 • Potential of photonic radiative cooler in Indian cities is assessed and forecasted for 2030. • Effects of weather parameters on the cooler performance are studied for summer months. • Wind velocity and humidity are found major performance influencing weather parameters. • Selective cooler is found better for low humidity and broadband one is for high humidity. • In situ maximum cooling load reduction of 36% is observed for low humidity location. [ABSTRACT FROM AUTHOR]