scholarly journals СOAL-INERT DUST MIXTURE SURFACE REFLECTIVITY- BASED ANALYZING METHOD

2017 ◽  
pp. 116-123
Author(s):  
M.Yu. Nedostup ◽  
A.P. Pashnin ◽  
A.O. Rebiatnikov ◽  
V.I. Sokolchuk
Keyword(s):  
Inert Dust ◽  
Surface Reflectivity

scholarly journals СOAL-INERT DUST MIXTURE SURFACE REFLECTIVITY- BASED ANALYZING METHOD

2017 ◽  
pp. 116-123
Author(s):  
M.Yu. Nedostup ◽  
A.P. Pashnin ◽  
A.O. Rebiatnikov ◽  
V.I. Sokolchuk
Keyword(s):  
Inert Dust ◽  
Surface Reflectivity

RESEARCH INTO MIRRORS SURFACE REFLECTIVITY FOR MEMS OPTICAL SWITCHES

2012 ◽  
Vol 71 (16) ◽  
pp. 1495-1502
Author(s):  
A. I. Filipenko ◽  
E.L. Dyachenko ◽  
V.N. Kazimirova
Keyword(s):  
Optical Switches ◽  
Surface Reflectivity

scholarly journals Diurnal variations in the UV albedo of arctic snow

2008 ◽  
Vol 8 (21) ◽  
pp. 6551-6563 ◽  
Author(s):  
O. Meinander ◽  
A. Kontu ◽  
K. Lakkala ◽  
A. Heikkilä ◽  
L. Ylianttila ◽  
...  
Keyword(s):  
High Surface ◽  
Measured Temperature ◽  
Snow Melt ◽  
Clear Sky ◽  
Different Types ◽  
Essential Parameter ◽  
Surface Reflectivity ◽  
Climate Studies ◽  
Radiative Transfer Modeling ◽  
Surface Layer Thickness

Abstract. The relevance of snow for climate studies is based on its physical properties, such as high surface reflectivity. Surface ultraviolet (UV) albedo is an essential parameter for various applications based on radiative transfer modeling. Here, new continuous measurements of the local UV albedo of natural Arctic snow were made at Sodankylä (67°22'N, 26°39'E, 179 m a.s.l.) during the spring of 2007. The data were logged at 1-min intervals. The accumulation of snow was up to 68 cm. The surface layer thickness varied from 0.5 to 35 cm with the snow grain size between 0.2 and 2.5 mm. The midday erythemally weighted UV albedo ranged from 0.6 to 0.8 in the accumulation period, and from 0.5 to 0.7 during melting. During the snow melt period, under cases of an almost clear sky and variable cloudiness, an unexpected diurnal decrease of 0.05 in albedo soon after midday, and recovery thereafter, was detected. This diurnal decrease in albedo was found to be asymmetric with respect to solar midday, thus indicating a change in the properties of the snow. Independent UV albedo results with two different types of instruments confirm these findings. The measured temperature of the snow surface was below 0°C on the following mornings. Hence, the reversible diurnal change, evident for ~1–2 h, could be explained by the daily metamorphosis of the surface of the snowpack, in which the temperature of the surface increases, melting some of the snow to liquid water, after which the surface freezes again.

Feedback control law of solar sail with variable surface reflectivity at Sun-Earth collinear equilibrium points

2020 ◽  
Vol 106 ◽  
pp. 106144 ◽  
Author(s):  
Lorenzo Niccolai ◽  
Giovanni Mengali ◽  
Alessandro A. Quarta ◽  
Andrea Caruso
Keyword(s):  
Feedback Control ◽  
Equilibrium Points ◽  
Solar Sail ◽  
Control Law ◽  
Variable Surface ◽  
Surface Reflectivity

Dependence of the spectral surface irradiance on aerosol properties and surface reflectivity

Solar Energy ◽  
1980 ◽  
Vol 24 (3) ◽  
pp. 279-286 ◽  
Author(s):  
J. Otterman ◽  
Y. Kaufman ◽  
M. Podolak ◽  
S. Ungar
Keyword(s):  
Surface Irradiance ◽  
Surface Reflectivity ◽  
Aerosol Properties

Spaceborne GNSS Reflectometry for soil moisture using data from CYGNSS mission: results in the Contiguous United States

2021 ◽  
Author(s):  
Paulo de Tarso Setti Junior ◽  
Tonie van Dam
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Optical Depth ◽  
Roughness Coefficient ◽  
Navigation Satellite ◽  
Gnss Reflectometry ◽  
Surface Reflectivity ◽  
Global Navigation ◽  
Global Navigation Satellite

<p>Soil moisture is an essential climate variable, influencing geophysical and hydrological processes such as vegetation and agriculture, land-atmosphere circulation, and drought development. It is possible to remotely sense soil moisture based on the dielectric constant of soil at microwave frequencies. Low earth orbit (LEO) satellites are capable of receiving Global Navigation Satellite Systems (GNSS) signals reflected off the surface of the Earth to infer properties of the reflecting surface itself, in a technique known as GNSS-Reflectometry (GNSS-R). However, converting surface reflectivity derived from GNSS-R into soil moisture is not straightforward. Reflectivity is influenced by other factors such as the vegetation optical depth and the soil roughness around the specular reflection. The Cyclone Global Navigation Satellite System (CYGNSS) is a mission from the National Aeronautics and Space Administration (NASA) consisting of eight small GNSS-R satellites with the primary objective of measuring wind speed in hurricanes and tropical cyclones. The satellites were launched in December 2016 in a 35° inclination orbit, and the measurements are made of reflected Global Positioning System (GPS) L1 (1.575 GHz) navigation signals. Reflections over land can be used to estimate soil moisture in the upper 5 cm of soil surface if they are correctly treated and modelled. In this work, we use three years of observations from CYGNSS mission (March 2017 - March 2020) to compute surface reflectivity over land assuming coherent reflections. Using linear regression models and ancillary information from Soil Moisture Active Passive (SMAP) mission (soil moisture, vegetation optical depth, and roughness coefficient), these reflectivity observations are then used to estimate soil moisture. Retrievals are compared with observations from 44 in-situ soil moisture stations from the International Soil Moisture Network (ISMN) in the Contiguous United States (CONUS), presenting in most of the cases a good agreement. Results are also correlated with vegetation optical depth, surface roughness, and topographic relief around the in-situ stations. In addition, some challenges regarding soil moisture estimation using spaceborne GNSS-R data are presented and discussed.</p>

Sign in / Sign up

Export Citation Format

Share Document