Surface Reflectance Change can Induce Reduction in the Surrounding Ambient Environment Warming

Global warming has emerged as a major issue of concern as the fallout would have a wide-spread impact on many climate processes in addition to posing a serious threat for human development, directly or in-directly. COP21 at the Paris agreement settled to limit global warming well below 2°C in the future. This goal can be attained by ensuring a drastic reduction in the emission of greenhouse gases or by cutting down the use of energy consumption, an obvious solution but difficult to implement. A more acceptable and easy approach would be to reduce the use of energy to cool buildings and surfaces by adopting simple scientific techniques. The present work explores the feasibility of one such approach, which can be applied in large cities and urban regions; knowing that by increasing the surface reflectance (albedo) for incoming solar short wave (SSW) radiation it is possible to decrease the temperature of the surface. If the appropriated surface area is large enough then it is possible to cause a decrease in the ambient air temperature. Three different types of heat-resistant Superseal Thermoflex P-111 coatings of different colours were applied on the roof surface to evaluate their respective reflectance properties towards the incoming SSW radiation incident on the roof with reference to the resulting surface temperature. The average reflectance in the spectral range 280-880 nm – for dark pink, light pink and white colour coats – were estimated as 0.44, 0.61 and 0.76, respectively; the obtained values were significantly larger than that observed for asphalt/cement coated surfaces. The higher reflectance of white coating leads to less heat absorption by the roof surface open to the SSW radiation and thus a significant drop in the surface temperature. Also, the heat transmitted underneath the surface space will be much reduced, even the emission (loss) of radiation (Infra-Red) from such a surface into the surrounding environment will be reduced.

Daily snow cover mapping based on Dynamic Wavelength Warping using geostationary satellite data

<p>Snow cover mapping is a form of precipitation that detects snow-covered pixels by observing snow accumulated on the ground. Snow is the largest single component of the cryosphere and has high reflectance compared to other index, so it plays an important role in maintaining heat balance between the Earth’s surface and the atmosphere, or in maintaining the balance of the Earth’s energy balance in terms of global or regional aspects. In case of snow cover mapping using satellite data, a wide range of data can be easily obtained and time series observations can be made periodically for the same area. Although the characteristics of snow appear in satellite data show differences in reflectance compared to snow-free, the reflectance change pattern depending on wavelength also has a unique pattern. We focused to the unique reflectance change pattern according to the wavelength of the snow, and used the Dynamic Wavelength Warping (DWW) method to perform the snow cover mapping using the unique pattern. The DWW is a method that determines the similarity of change patterns by using reflectance change pattern according to wavelength. in this study, daily composite snow cover mapping was calculated using snow cover data calculated using DWW method. In order to evaluate the accuracy of the synthetic snow cover data calculated from this study, we used the Global Multisensor Automated Snow/Ice Map (GMASI) data from the National Oceanic and Atmospheric Administration (NOAA) and conducted quantitative and qualitative evaluations. As a result, Probability of Detection (POD) was 97.14 % and False Alarm Ratio (FAR) was 1.96 %.</p>

DETECTING THE AFFECTED AREAS OF MOUNT SINABUNG ERUPTION USING LANDSAT 8 IMAGERIES BASED ON REFLECTANCE CHANGE

The position of Indonesia as part of a "ring of fire" bringing the consequence that the life of the nation and the state will also be influenced by volcanism. Therefore, it is necessary to map rapidly the affected areas of a volcano eruption. Objective of the research is to detect the affected areas of Mount Sinabung eruption recently in North Sumatera by using optical images Landsat 8 Operational Land Imager (OLI). A pair of Landsat 8 images in 2013 and 2014, period before and after eruption, was used to analysis the reflectance change from that period. Affected areas of eruption was separated based on threshold value of reflectance change. The research showed that the affected areas of Mount Sinabung eruption can be detected and separated by using Landsat 8 OLI images based on the change of reflectance value band 4, 5 and NDVI. Band 5 showed the highest values of decreasing and band 4 showed the highest values of increasing. Compared with another uses of single band, the combination of both bands (NDVI) give the best result for detecting the affected areas of volcanic eruption.

Analysis of the Interference Modulation Depth in the Fourier Transform Spectrometer

Based on the principle of the Michelson interferometer, the paper briefly describes the theoretical significance and calculates and deduces three expressions of the interference modulation depth. The influence of the surface shape error of plane mirror on modulation depth is analyzed, and the tolerance of error is also pointed out. Moreover, the dependence of modulation depth on the reflectance change of beam splitter interface is also analyzed, and the curve is given. It is concluded that this paper is of general significance for the Fourier transform spectrometer based on the principle of the Michelson two-beam interference.

Influence of the Probe Laser Wavelength in Transient Reflectance Measurement of Gold

Transient reflectance of gold is measured with ultrafast spectroscopy by tunable probe wavelength. The influence of the probe wavelength on the signal is analyzed. It is found that when probed around 490 nm the signal is most sensitive to electron excitation and there is a simple linear relation between the reflectance change and the electron temperature change after sufficiently weak excitation. The two-temperature model is applied to calculate the electron-phonon coupling factor by fitting the transient reflectance signal.

Neural control of tuneable skin iridescence in squid

Fast dynamic control of skin coloration is rare in the animal kingdom, whether it be pigmentary or structural. Iridescent structural coloration results when nanoscale structures disrupt incident light and selectively reflect specific colours. Unlike animals with fixed iridescent coloration (e.g. butterflies), squid iridophores (i.e. aggregations of iridescent cells in the skin) produce dynamically tuneable structural coloration , as exogenous application of acetylcholine (ACh) changes the colour and brightness output. Previous efforts to stimulate iridophores neurally or to identify the source of endogenous ACh were unsuccessful, leaving researchers to question the activation mechanism. We developed a novel neurophysiological preparation in the squid Doryteuthis pealeii and demonstrated that electrical stimulation of neurons in the skin shifts the spectral peak of the reflected light to shorter wavelengths (greater than 145 nm) and increases the peak reflectance (greater than 245%) of innervated iridophores. We show ACh is released within the iridophore layer and that extensive nerve branching is seen within the iridophore. The dynamic colour shift is significantly faster (17 s) than the peak reflectance increase (32 s), revealing two distinct mechanisms. Responses from a structurally altered preparation indicate that the reflectin protein condensation mechanism explains peak reflectance change, while an undiscovered mechanism causes the fast colour shift.