Increase In Albedo Research Articles

Performance evaluation and optimization of albedo and tilt angle for solar photovoltaic system

This research focuses on the UN sustainable development goal (SDG)7 i.e., affordable and clean energy. As per goal 7, renewable energy sources are the cleanest sources and will help to reach net zero emissions. Performance of solar photovoltaic (PV) systems is analysed using PVsyst and Response Surface Methodology (RSM) for composite climatic conditions. Two critical parameters i.e., tilt angle and albedo are investigated. Specific production increases as albedo and tilt angle increase. Optimum tilt angle is 25⁰ at 0.54 albedo with a maximum specific production of 1643.3 kWh/kWp/year. Payback period is 5.8 years, the return of investment (ROI) is at 469.2% and the levelized cost of energy (LCOE) is 2.298 ₹/kWh. During its lifetime, the system reduces 3470.5 tCO2 carbon emission compared to the conventional plant. Therefore, installing such a system will dramatically reduce CO2 emissions, encourage environmental sustainability and enhance the number of claimed carbon credits.

Evaluation and Analysis of the Effectiveness of the Main Mitigation Measures against Surface Urban Heat Islands in Different Local Climate Zones through Remote Sensing

The significant transformation of land use as a consequence of current population growth, together with global warming (atmospheric emissions and extreme weather events), is generating increases in ambient temperatures. This circumstance is affecting people’s quality of life, especially those considered more vulnerable or with fewer economic resources. Currently, 30% of the world’s population suffers climatic conditions of extreme heat, and forecasts indicate that in the next 20 years, this number will reach 74%. The present study analyzes the effectiveness of the main mitigation strategies for the surface urban heat island (SUHI) effect between the years 2002 and 2022 in the different local climate zones of the city of Granada (Spain). Using Landsat 5 and 8 images, the evolution experienced by the land surface temperature and the surface urban heat island was determined and connected to the following variables: normalized difference vegetation index, vegetal proportion, normalized difference building index, and albedo. Our results indicate that compact and industrial areas have higher temperatures and lower vegetation and albedo in contrast to open areas, which have lower temperatures and higher vegetation and albedo. The mitigation measures analyzed presented similar efficiencies, but a greater minimization of the SUHI was reported when vegetation was increased in open areas as opposed to in closed areas, where the increase in albedo was more effective. Our study will allow the implementation of more efficient measures based on the types of LCZs in cities.

Bolometric Hemispherical Albedo Map of Pluto from New Horizons Observations

The New Horizons encounter with the Pluto system revealed Pluto to have an extremely spatially variable surface with expansive dark, bright, and intermediate terrains, refractory and volatile ices, and ongoing/recent endogenous and exogenous processes. Albedo is useful for understanding volatile transport because it quantifies absorbed solar energy; albedo may also provide insights into surface processes. Four filters of the New Horizons LORRI and MVIC imagers are used to approximate the bolometric (flux-weighted, wavelength-integrated) albedo. The bolometric hemispherical albedo (local energy balance albedo) as a function of the incidence angle of the solar illumination is measured for both Cthulhu and Sputnik Planitia, which are extensive, extreme dark and extreme bright terrains on Pluto. For both terrains, the bolometric hemispherical albedo increases by >30% from 0° to 90° incidence. The incidence-angle-average bolometric hemispherical albedo of Cthulhu is 0.12 ± 0.01, and that of Sputnik Planitia is 0.80 ± 0.06, where uncertainties are estimates based on scatter from different photometric functional approximations. The bolometric Bond albedo (global energy balance albedo) of Cthulhu is 0.12 ± 0.01, and that of Sputnik Planitia is 0.80 ± 0.07. A map of Pluto’s incidence-angle-average bolometric hemispherical albedo is produced. The incidence-angle-average bolometric hemispherical albedo, spatially averaged over areas north of ≈30° S, is ≈0.54. Pluto has three general albedo categories: (1) very low albedo southern equatorial terrains, including Cthulhu; (2) high-albedo terrains, which constitute most of Pluto’s surface; and (3) very high albedo terrains, including Sputnik Planitia. Pluto’s extraordinary albedo variability with location is also spatially sharp at some places.

A Functionalized Monte Carlo 3D Radiative Transfer Model: Radiative Effects of Clouds Over Reflecting Surfaces

AbstractIn the Earth Sciences, the 3D radiative transfer equation is often solved for by Monte Carlo (MC) methods. They can, however, be computationally taxing, and that can narrow their range of application and limit their use in explorations of model parameter spaces. A novel family of MC algorithms is investigated here in which single simulations provide estimates of both radiative quantities A for a set of parameters , as usual, as well as the overarching functional (x) that can be evaluated, extremely efficiently, at any x. One such algorithm is developed and demonstrated for horizontally averaged broadband solar radiative fluxes as functions of surface albedo for uniform Lambertian surfaces beneath inhomogeneous cloudy atmospheres. Simulations for a high‐resolution synthetic cloud field, at various solar zenith angles, illustrate the potential of the method to gain insights into the nature of 3D radiative effects for complicated atmosphere‐surface conditions using information specially derived from the MC simulation. For simulations performed with a single surface albedo it is found that as surface albedo increases, 3D radiative effects increase, too, with maxima occurring at middling to large values, and then decrease. By utilizing the derived coefficients that describe it was established that these 3D effects stem from differences in fractions of radiation entrapped at successive orders of internal multiple reflections for 1D and 3D transfer.

About the Assessment of Cover Crop Albedo Potential Cooling Effect: Risk of the Darkening Feedback Loop Effects

Today societies face an unprecedented challenge to limit global warming and restore agricultural soils. Recent studies show that the introduction of cover crops over Europe could result in a cooling impact due to an increase in soil organic carbon stocks, a decrease in the use of fertilizers, and an increase in surface albedo of the croplands. Based on the use of remote sensing data, land cover database, meteorological data, national agricultural statistics, and ground measurements, a generic model was developed to simulate the radiative forcing following the change in surface albedo. This article analyzes the impact of the introduction of cover crops in Europe during the fallow periods. Compared to previous studies, this work discusses: (i) The maximum greening potential in Europe and the associated indirect surface properties changes (ii) for snowfall episodes, and (iii) due to an increase in organic matter. This study shows that the mitigation potential of cover crops through albedo effects could reach 6.74 MtCO2-eq.yr−1 by extending the periods of the introduction of the cover crops to all possible fallow periods. This mitigation could be limited to 5.68 MtCO2-eq.yr−1 if the impact of snowfalls is considered. This would be equivalent to 9.12 gCO2.m−2.yr−1. Finally, this study investigates the feedback loop due to soil darkening with soil organic carbon content increase when cover crops are introduced, considering two scenarios. The first considers the soil organic carbon content increase following repeated incorporation of cover crop biomass into the soil, simulated with the DayCent model. The second, more conceptual and extreme scenario aims at alerting on the possible impact of a combination of carbon farming practices, such as biochar or organic amendments. Our results show that this effect could lead to a loss of 20% of the climate benefit (i.e., 5.39 MtCO2-eq.yr−1). In conclusion, this study shows that cover crops have a strong potential for climate mitigation through direct albedo effects (soil coverage). However, once introduced, cropland should be permanently covered by vegetation or straws in order to avoid this darkening feedback loop effect.

Urbanization Heat Flux Modeling Confirms It Is a Likely Cause of Significant Global Warming: Urbanization Mitigation Requirements

Recent ground-based measurements find the magnitude of the urbanization effect on the global average annual mean surface air temperature corresponds to an urbanization contribution of 12.7%. It is important to provide modeling to help understand these results as there are conflicting concerns. This study models the global warming contribution that urbanization heat fluxes (UHF) can make due to anthropogenic heat release (AHR), and solar heating of impermeable surface areas (ISAs), with additional secondary effects. Results help explain and support ground-based observations. Climate models typically omit anthropogenic heat release (AHR) as warming estimates are below 1%. In agreement, the baseline assessment in this paper has similar findings. However, in this study, the methods of climate amplification estimates (MCAE) with data-aided physics-based amplification models are used. When the MCAE are applied at the global and microclimate levels that consider greenhouse gases (GHGs), feedback, and other secondary effects; the results show that AHR fluxes can amplify, increasing to have an estimated global warming (GW) influence of 6.5% from 1950 to 2022 yielding a 0.9% decade−1 increase. This increasing rate due to energy consumption is found as anticipated to be reasonably correlated to the increasing population growth rate over this time. Furthermore, using the MCAEs, this paper studies heat fluxes assessment due to solar heating of unshaded impermeable surfaces including likely secondary amplification effects. Impermeable surface areas (ISAs) such as asphalt roads, roofs, and building sides have been reported with high land surface contact temperatures (LSCTs) relative to non-ISAs and significantly found to contribute to urbanization warming. Results indicate that high-temperature unshaded impermeable surfaces (including building sides) are estimated to average around 10–11 °C above the earth’s ambient temperature of 14.5 °C (showing albedo ISA estimates between 0.133 and 0.115 respectively); the ISA heat fluxes with secondary effects are estimated to have about a GW influence of 6.5%. This is broken down with average contributions of 4.0% from urban ISAs and 2.5% from rural ISA heat fluxes. Asphalt road ISA heat fluxes are estimated to have about a 1.1% global warming influence. Then the total UHF effect from ISAs and AHR with secondary effects is assessed in modeling to yield a combined average GW influence of 13% helping to confirm ground-based measurement results. Several key adjustment values were used for shading, cloud coverage, and rural-to-urban ISA ratios. Microclimate GHGs and related water vapor feedback (WVF) were assessed to increase urban warming by about 50%. As well an assessment of water vapor and radiation increases from UHF is provided. This study also shows the need to incorporate urbanization heat fluxes with secondary effects into climate models and indicates the necessity for Paris Agreement urban heat flux mitigation goals. Results also found that given average climate conditions, it is possible to mitigate much of the UHI effect with an albedo increase of 0.1 that is anticipated to lower the average impermeable surface temperatures by about 9 °C. Studies show this can be accomplished with cost-effective cool roads and roofs. Although roads are only estimated to occupy 14% of ISAs, changing roads from asphalt to concrete-type surfaces would improve reflectivity by about a factor of 5 and is estimated to mitigate about 5.5% of global warming. Unfortunately, the current overuse of black asphalt on pavements and roofs is highly dangerous to our environment causing UHI increases in heatwaves, excessive temperatures, and global warming issues and should be banned. Asphalt usage also reduces opportunities for solar geoengineering of urbanization.

Impact of growth of a medium-sized Indian coastal city on urban climate: A case study using data fusion and analytics

In India, unlike mega cities, little is known about how the growth of small and medium-sized cities (SMSC) impacts urban climate. Further, such impacts are amplified in coastal settings. We use data fusion and analytics to study how the growth of Thiruvananthapuram, a typical medium-sized coastal city in India, modifies the urban climate. The datasets used are National Aeronautics and Space Administration (NASA) Moderate Resolution Imaging Spectroradiometer (MODIS) land products, NASA Modern-Era Retrospective analysis for Research and Applications (MERRA-2) and Indian Meteorological Department surface observations contained within the National Oceanic and Atmospheric Administration (NOAA) global compilation of in-situ observations. The study found a ∼ 48% increase in urban and built-up land cover over the last two decades, causing an increase in albedo, surface roughness and a decrease in emissivity and moisture availability. Decreasing moisture availability most affected air temperature, with urban growth adding to large-scale climatic trends of increasing monthly mean daily maximum (+1 °C), minimum (+0.4 °C) and average temperatures (+0.22 °C). Sea-breeze circulation strengthened in response to increasing coastal urbanization and the inland propagation modified with increased convergence and (potentially) rainfall, near the coast.

Can a Symbolic Mega-Unit of Radiative Forcing (RF) Improve Understanding and Assessment of Global Warming and of Mitigation Methods Using Albedo Enhancement from Algae, Cloud, and Land (AEfACL)?

By expressing radiative forcing (RF) in a symbolic mega-unit we better communicate, to governing organizations and the public, the extent of global warming (GW) and the potency of mitigation methods while also ‘translating’ different GW measures to better explain their interrelationship. An easily visualized symbol that has been suggested is the net shading, or mega-unit, of RF of a “standard 1 km2 cumulus cloud over one day of −25 W/m2” (ScCd). As defined, ScCd is equal to 600,000 kWh and equivalent to Temporary heat radiation Equivalent Carbon (ThrEC) of 18,400 tons of carbon heat effect, or 67,300 tons of CO2 and an approximately 0.136 albedo increase, over 1 km2. Shading over the whole earth caused by clouds is estimated by NASA as −13 W/m2. The excess of solar radiation or Earth Energy Imbalance (EEI) striking the earth was + 1.12 W/m2 in mid-2019 and has been continually increasing. Offsetting this requires the creation of additional reflective surfaces equivalent to 22.848 million square kilometers of ScCd. Such an increase could be provided by albedo enhancement from algae on the ocean surface, marine cloud brightening (MCB) or new marine cloud creation, or land area use that rejuvenates salt flats and similar locations (AEfACL). These are potentially politically acceptable and eventually could be achieved at large enough scale to be effective globally.

The Impact of Different Atmospheric CO2 Concentrations on Large Scale Miocene Temperature Signatures

AbstractBased on inferences from proxy records the Miocene (23.03–5.33 Ma) was a time of amplified polar warmth compared to today. However, it remains a challenge to simulate a warm Miocene climate and pronounced polar warmth at reconstructed Miocene CO2 concentrations. Using a state‐of‐the‐art Earth‐System‐Model, we implement a high‐resolution paleobathymetry and simulate Miocene climate at different atmospheric CO2 concentrations. We estimate global mean surface warming of +3.1°C relative to the preindustrial at a CO2 level of 450 ppm. An increase of atmospheric CO2 from 280 to 450 ppm provides an individual warming of ∼1.4°C, which is as strong as all other Miocene forcing contributions combined. Substantial changes in surface albedo are vital to explain Miocene surface warming. Simulated surface temperatures fit well with proxy reconstructions at low‐ to mid‐latitudes. The high latitude cooling bias becomes less pronounced for higher atmospheric CO2 concentrations. At such CO2 levels simulated Miocene climate shows a reduced polar amplification, linked to a breakdown of seasonality in the Arctic Ocean. A pronounced warming in boreal fall is detected for a CO2 increase from 280 to 450 ppm, in comparison to weaker warming for CO2 changes from 450 to 720 ppm. Moreover, a pronounced warming in winter is detected for a CO2 increase from 450 to 720 ppm, in contrast to a moderate summer temperature increase, which is accompanied by a strong sea‐ice concentration decline that promotes cloud formation in summer via enhanced moisture availability. As a consequence planetary albedo increases and dampens the temperature response to CO2 forcing at a warmer Miocene background climate.

The Possible Influence of Cosmic Rays on the Planetary Albedo of the Earth

The monthly average values of the planetary albedo at the top-of-atmosphere (TOA) and the averagealbedo values of the hemispheres were obtained based on the results of measurements for the flux of shortwavereflected solar radiation, carried out onboard the Meteor-M No. 2 satellite in 2014–2019. The globallyaveraged albedo shows an increase over time, as evidenced by the presence of a statistically significant lineartrend. We show that this trend is not associated with a change in the average near-surface temperature of theplanet. It is possible that the increase in albedo is explained by an increase in cloudiness caused by an increasein the flux of galactic cosmic rays during the decline of the solar activity cycle

The impacts of land use and land cover change on biophysical processes in West Africa using a regional climate model experimental approach

AbstractUsing 2001 and 2016 land use (LU) data and three developed deforestation LU scenarios, namely Deforest I, II and III, the possible impacts of the ongoing land use land cover change (LULCC) over West Africa (WA) and the uncertainty regarding the impacts on regional climate were assessed. Twelve Weather Research and Forecasting (WRF) model simulations were configured with the default and integrated MODIS satellite dataset for two sets of 3 months (December–February DJF 2011–2012 and July–September JAS 2012) over WA. Between 2001 and 2016, changes that occurred in precipitation, temperature and dew point temperature due to LULCC are mostly not significant at the 95% level with a decrease of 0.8, 0.0 and 0.1%, respectively. Deforest I, II and III caused significant changes with an increase of 44.4, 44.7, 41.5%; 0.8, 0.9, 1.1%; and 0.3, 0.1, −0.2%, respectively, for precipitation, temperature and dew point temperature. Precipitation was lower in the simulation with 2016 LU than it was with 2001 LU, which may have also been influenced by the reforestation that occurred between the periods. However, Deforest III resulted in a widespread nonsignificant rise in precipitation, as the modified areas showed a significant decrease during JAS period. Areas where forests were converted into barren lands revealed severe increase in the surface albedo which is a strong factor that its alteration is capable of influencing precipitation and other variables over WA. LULCC also altered the atmospheric column by modifying the strength of the African Easterly Jet (AEJ), Tropical Easterly Jet (TEJ), wind speed, and monsoonal, vertical, meridional and zonal winds. Heat related fields, such as dew point and air temperature, and moisture fields such as relative humidity were also modified by LULCC. Therefore, as WA reacts strongly to LULCC, sustainable land management practices should be encouraged to control its adverse effects.

Mid-summer snow-free albedo across the Arctic tundra was mostly stable or increased over the past two decades

Arctic vegetation changes, such as increasing shrub-cover, are expected to accelerate climate warming through increased absorption of incoming radiation and corresponding decrease in summer shortwave albedo. Here we analyze mid-summer shortwave land-surface albedo and its change across the pan-Arctic region based on MODerate resolution Imaging Spectroradiometer satellite observations over the past two decades (2000–2021). In contrast to expectations, we show that terrestrial mid-summer shortwave albedo has not significantly changed in 82% of the pan-Arctic region, while 14% show an increase and 4% a decrease. The total median significant change was 0.014 over the past 22 years. By analyzing the visible and near-/shortwave-infrared range separately, we demonstrate that the slight increase arises from an albedo increase in the near-/shortwave infrared domain while being partly compensated by a decrease in visible albedo. A similar response was found across different tundra vegetation types. We argue that this increase in reflectance is typical with increasing biomass as a result of increased multiple reflection in the canopy. However, CMIP6 global land surface model albedo predictions showed the opposite sign and different spatial patterns of snow-free summer albedo change compared to satellite-derived results. We suggest that a more sophisticated vegetation parametrization might reduce this discrepancy, and provide albedo estimates per vegetation type.

Orbital and In Situ Investigation of the Bagnold Dunes and Sands of Forvie, Gale Crater, Mars

AbstractThe Bagnold linear dune field investigated by Curiosity at Mount Desert Island (MDI) is north of the ∼5.5 km high Aeolis Mons mound in Gale crater. False‐color images (RGB: 2.496, 1.802, and 1.237 μm, respectively) generated from Mars Reconnaissance Orbiter Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) data show the dune field has a reddish‐brown color. The Sands of Forvie (SoF), located ∼2.5 km to the southeast of MDI, is darker and lacks the reddish‐brown color. Single scattering albedo (SSA) spectra retrieved at 12 m/pixel using along‐track oversampled CRISM observation FRT00021C92 show a long wavelength (1.7–2.5 μm) increase in albedo for MDI dunes. For the same wavelength interval, SoF is characterized by a broad ∼2.2 μm absorption feature, consistent with color differences between the two deposits. Checkerboard un‐mixing of the SSA image cube was used to isolate spectral endmembers within the MDI and SoF deposits. Radiative modeling of these CRISM spectral endmembers using Hapke (2012, https://doi.org/10.1017/CBO9781139025683) theory implies finer grain sizes, more pigeonite, plagioclase, and olivine, and less basaltic glass and augite for MDI as compared to the SoF deposit. These results are consistent with Curiosity‐based observations that MDI contains smaller ripples with overall finer grains, whereas SoF has large ripples with coarser grains on the crests. Although these sand deposits are only located ∼2.5 km away from one another, wind and local topographic controls are interpreted to have modulated grain sizes and mineralogy.

A Novel Measurement-Based Method for Assessing Global Warming Mitigation via High-Albedo Solutions

Global warming mitigation via terrestrial albedo increase has been widely investigated in literature; the proposed methodologies relate CO2 compensation to albedo increase generally via the concept of Radiative Forcing (RF). However, literature methods calculate RF by averaged input data, without considering RF variation due to many local and temporal phenomena. For instance, an average value of compensated effect of albedo change (Δα = 0.01) is 3 kg CO2eq/m2, which has been introduced no matter the position and climatic condition of the site. In our study, we propose a novel procedure to measure RF continuous time history by means of ground measurements, astronomical equations, and satellite calibration. The procedure is called RF-meter. In this way, a more accurate assessment of compensated CO2 may be achieved. A test facility is also designed and proposed to double check the procedure, and preliminary results are reported in order to show and test the calibration procedure. It is expected that albedo-increased surfaces as well as cool roofs and/or other technical solutions will be eligible to obtain Emission Credits (EC). The proposed procedure will aid in the assignment of EC to High-Albedo Solutions (HAS), as it could represent an objective and accurate method to relate the albedo increase to a corresponding CO2 offset.

Artificial neural networks for power output forecasting from bifacial solar PV system with enhanced building roof surface Albedo

The main objective of this research study is to evaluate the performance of bifacial solar PV systems (bPV) installed on flat roof buildings with controlled surface albedo and to develop forecasting models to anticipate the power output from bifacial solar PV systems due to the enhancement of surface albedo. The originality of this study and the novelty include integrating innovative bifacial solar PV and cool roof technologies to increase solar PV panel power output and anticipate electricity generation in advance to balance supply and demand. For the methodology, modeling and simulation analysis was used to test the performance of bPV system installed on a building with a surface albedo of 0.2–0.8. An Artificial Neural Network was used as a machine learning approach for bifacial solar PV power and energy forecasting. The significant findings show that an increase in surface albedo from 0.2 to 0.5 and 0.2 to 0.8 will help to boost the annual bifacial solar PV power production by 7.75% and 14.96%, respectively. The predictive models are exceptionally accurate in anticipating the bifacial solar PV power. The monthly power from bPV rose from 10.87 to 21.54%, with a 0.3 (from 0.2 to 0.5) to 0.6 (from 0.2 to 0.8) albedo increase. The coefficient of correlation R values for all of the power data ranges from 0.99145 to 0.99382 for the roof surface albedo, ranging from 0.2 to 0.8. The ANN models illustrate how effectively the model mimics the modeling and simulation data. For the research implications, the developed forecast models will assist the industry in predicting ahead of the power production, building operations and maintenance, demand-side management, and advanced energy purchases.

On the mitigation potential of higher urban albedo in a temperate oceanic metropolis

The urban overheating calls for the implementation of mitigation actions. The article aims at demonstrating the advantages and the risks associated with the increase of the city albedo in Melbourne (Australia), through high resolution numerical analyses based on a detailed urban land use. The Weather Research and Forecasting model was used to calculate the spatial and temporal local climate change for three increased albedo scenarios and three different urban densities. In the scenario with highest albedo, the ambient temperature decreases of about 1.6°C in the middle and high density zones and 0.9°C in the low density zones. The sea breeze extends the thermal benefit due to the albedo increase to non-urban areas, despite it is slightly weakened by the diminished land-sea temperature contrast. The pollutant levels are expected to increase, due to a combination of slower winds (drops up to 0.19 ms−1) and decreased planetary boundary layer heights (drops from 175 m up to 291 m). High and low density classes have the highest and lowest risk of stagnation, respectively. Due to the contrasting results in terms of thermal mitigation and pollution risks, the study calls for the identification of comprehensive metrics to asses optimal values of urban albedo.

Impacts of urban canyon aspect ratio and roof albedo on heat fluxes and temperatures in four urban centers

The impacts of urban canyon aspect ratio (UCAR defined as the ratio of buildings height to street width) and roof albedo on the heat fluxes and temperatures in four North America urban centers are investigated using a high-resolution numerical model coupled with the Town Energy Balance scheme. Analytical results show that UCAR affects the sensible heat flux over urban centers in a nonlinear way. While the increase of UCAR leads to the reduction of sensible heat fluxes from roads and walls during the daytime, the nonlinearity can lead to the enhancement of sensible heat flux over urban centers under certain condition. The comparisons between benchmark and three scenario model simulation results show that the the increase/decrease of UCAR leads to the increase/decrease of heat fluxes and over urban centers at temperature at 1.5 m in the early morning and nighttime. During the daytime, only very large UCAR can cause the decrease of heat flux and temperature. The increase of UCAR leads to the increase of urban heat island intensity, but there is no obvious correlation between UCAR and the temperature at each grid cell. The comparison between the benchmark simulation and the simulation with a double roof albedo suggests that the increase of roof albedo in the four North America urban areas leads to 0.1 °C-0.2 °C decrease in temperature at 1.5 m.

Spatiotemporal Dynamics of Land Surface Albedo and Its Influencing Factors in the Qilian Mountains, Northeastern Tibetan Plateau

Land surface albedo directly determines the distribution of radiant energy between the surface and the atmosphere, and it is a key parameter affecting the energy balance on the land surface. However, the spatiotemporal dynamics of land surface albedo and associated influencing factors in the Qilian Mountains (QM) have been rarely reported. By using the long-time series data products of MODIS shortwave albedo, normalized difference vegetation index (NDVI), and snow cover with a spatial resolution of 0.05° from 2001 to 2020, this paper analyzes the temporal and spatial variations of land surface albedo in the QM over the past 20 years and its influencing factors. The analysis results show that the multi-year average surface albedo in the QM has obvious differences in spatial distribution: it increases with the altitude, and it is high in the west (at the west of 98° E) and low in the east. Meanwhile, the surface albedo has different distribution characteristics in different seasons: the spatial distribution of surface albedo is similar in spring and autumn; the areas with a high surface albedo in summer are significantly fewer than those in other seasons. Besides, in the past 20 years, the annual average surface albedo has shown a weak growth trend in the QM, with a change rate of 5 × 10−3/10a, and the minimum and maximum values were reached in 2001 and 2019, respectively. In addition, the annual variation of the surface albedo in the QM showed a “U” shape, with the largest variation in January and the smallest variation in August. The annual variation of surface albedo is significantly positively correlated with snow cover (r = 0.96) and significantly negatively correlated with NDVI (r = −0.91). Moreover, the interannual variation of the surface albedo in the QM is closely related to land surface cover and is greatly affected by snow cover. Spatially, the annual variation of surface albedo in most areas of the QM is dominated by the change of snow cover, and the increase of surface albedo in the middle area is consistent with the increase of snow cover, while the decrease of albedo in the edge area is related to the improvement of vegetation cover. The results of this study provide a scientific basis for studying the climate and environmental changes caused by changes in the surface of the QM and making ecological environment restoration strategies.

Quantifying the Albedo of the Montreal Island and its Potential for Increase

Urbanization has changed the Earth’s surface, resulting in the urban heat island effect. There has been a recent focus on increasing urban albedo as a strategy to mitigate this phenomenon. Studies on Montreal’s albedo have primarily looked at the impact of albedo manipulations upon the urban heat island effect. However, the current albedo of the island, broken down by land use type, has yet to be quantified. Therefore, previous studies often rely on generalized urban albedo and land use estimates that have not been proven to be generalizable to Montreal. This study attempted to quantify the current albedo of the Island of Montreal through urban land use categorization. The findings were then used to estimate albedo increase under different roof replacement scenarios. Data sets for building footprints, vegetation, and roadways were incomplete in Montreal, requiring the combination of several sources to obtain representative data for analysis. This study found the albedo of Montreal island to be 0.19 ± 0.057. Further, the hypothetical roof change scenarios then aligned with a 0.1 albedo increase, which is the albedo change used in current urban heat island effect mitigation literature. Using the albedo increase potential that resulted from the three scenarios tested here, future research should explore further estimation of the associated surface and air temperature decrease.

Neptune’s Moon Triton: Continuing Surface Seasonal Volatile Transport

Observations of Triton’s rotational light curve from Table Mountain Observatory in 2017 show that volatile transport is continuing on its surface. Changes in the light curve are consistent with sustained increases in albedo in two patches near the equator at longitudes of ∼120° and ∼280°, as first reported by Bauer et al. based on observations obtained with the Hubble Space Telescope. An early observation of Triton’s visual albedo shows a substantially lower albedo in the past, when the northern polar region was visible. This result confirms the hypothesis of Moore & Spencer and Spencer & Moore of a net flux of volatile material into the southern hemisphere of Triton over much of the satellite’s history and up to the present. The averaged V-band geometric albedo of Triton has been stable over the past three decades. The color of Triton has also been stable during the past decade.