Modeling visible and near-infrared snow surface reflectance-simulation and validation

2011 ◽  
Vol 9 (10) ◽  
pp. 102901-102903
Author(s):  
吴宏伊 Hongyi Wu ◽  
童玲 Ling Tong
Keyword(s):  
Near Infrared ◽  
Surface Reflectance ◽  
Snow Surface ◽  
Simulation And Validation

scholarly journals Spectral Complexity of Hyperspectral Images: A New Approach for Mangrove Classification

2021 ◽  
Vol 13 (13) ◽  
pp. 2604
Author(s):  
Patrick Osei Darko ◽  
Margaret Kalacska ◽  
J. Pablo Arroyo-Mora ◽  
Matthew E. Fagan
Keyword(s):  
Statistical Physics ◽  
Near Infrared ◽  
Information Gain ◽  
Hyperspectral Imagery ◽  
Full Range ◽  
Surface Reflectance ◽  
Mangrove Species ◽  
New Approach ◽  
Spatio Temporal ◽  
Shortwave Infrared

Hyperspectral remote sensing across multiple spatio-temporal scales allows for mapping and monitoring mangrove habitats to support urgent conservation efforts. The use of hyperspectral imagery for assessing mangroves is less common than for terrestrial forest ecosystems. In this study, two well-known measures in statistical physics, Mean Information Gain (MIG) and Marginal Entropy (ME), have been adapted to high spatial resolution (2.5 m) full range (Visible-Shortwave-Infrared) airborne hyperspectral imagery. These two spectral complexity metrics describe the spatial heterogeneity and the aspatial heterogeneity of the reflectance. In this study, we compare MIG and ME with surface reflectance for mapping mangrove extent and species composition in the Sierpe mangroves in Costa Rica. The highest accuracy for separating mangroves from forest was achieved with visible-near infrared (VNIR) reflectance (98.8% overall accuracy), following by shortwave infrared (SWIR) MIG and ME (98%). Our results also show that MIG and ME can discriminate dominant mangrove species with higher accuracy than surface reflectance alone (e.g., MIG–VNIR = 93.6% vs. VNIR Reflectance = 89.7%).

scholarly journals In situ continuous visible and near-infrared spectroscopy of an alpine snowpack

2017 ◽  
Vol 11 (3) ◽  
pp. 1091-1110 ◽  
Author(s):  
Marie Dumont ◽  
Laurent Arnaud ◽  
Ghislain Picard ◽  
Quentin Libois ◽  
Yves Lejeune ◽  
...  
Keyword(s):  
Liquid Water ◽  
Near Infrared ◽  
Winter Season ◽  
Impurity Content ◽  
Saharan Dust ◽  
Infrared Range ◽  
Snow Surface ◽  
Surface Slope ◽  
Near Infrared Range

Abstract. Snow spectral albedo in the visible/near-infrared range has been continuously measured during a winter season at Col de Porte alpine site (French Alps; 45.30° N, 5.77° E; 1325 m a.s.l.). The evolution of such alpine snowpack is complex due to intensive precipitation, rapid melt events and Saharan dust deposition outbreaks. This study highlights that the resulting intricate variations of spectral albedo can be successfully explained by variations of the following snow surface variables: specific surface area (SSA) of snow, effective light-absorbing impurities content, presence of liquid water and slope. The methodology developed in this study disentangles the effect of these variables on snow spectral albedo. The presence of liquid water at the snow surface results in a spectral shift of the albedo from which melt events can be identified with an occurrence of false detection rate lower than 3.5 %. Snow SSA mostly impacts spectral albedo in the near-infrared range. Impurity deposition mostly impacts the albedo in the visible range but this impact is very dependent on snow SSA and surface slope. Our work thus demonstrates that the SSA estimation from spectral albedo is affected by large uncertainties for a tilted snow surface and medium to high impurity contents and that the estimation of impurity content is also affected by large uncertainties, especially for low values below 50 ng g−1 black carbon equivalent. The proposed methodology opens routes for retrieval of SSA, impurity content, melt events and surface slope from spectral albedo. However, an exhaustive accuracy assessment of the snow black properties retrieval would require more independent in situ measurements and is beyond the scope of the present study. This time series of snow spectral albedo nevertheless already provides a new insight into our understanding of the evolution of snow surface properties.

scholarly journals Apparatus for dry deposition of aerosols on snow

2018 ◽  
Vol 11 (12) ◽  
pp. 6803-6813 ◽  
Author(s):  
Nicholas D. Beres ◽  
Hans Moosmüller
Keyword(s):  
Dry Deposition ◽  
Mineral Dust ◽  
Aerosol Deposition ◽  
Natural State ◽  
Surface Reflectance ◽  
Snow Surface ◽  
Potential Applications ◽  
Combustion Aerosols ◽  
Carbon Combustion ◽  
Absorbing Aerosols

Abstract. Deposition of light-absorbing aerosol on snow can drastically change the albedo of the snow surface and the energy balance of the snowpack. To study these important effects experimentally and to compare them with theory, it is desirable to have an apparatus for such deposition experiments. Here, we describe a simple apparatus to generate and evenly deposit light-absorbing aerosols onto a flat snow surface. Aerosols are produced (combustion aerosols) or entrained (mineral dust aerosols) and continuously transported into a deposition chamber placed on the snow surface where they deposit onto and into the snowpack, thereby modifying its surface reflectance and albedo. We demonstrate field operation of this apparatus by generating black and brown carbon combustion aerosols and entraining hematite mineral dust aerosol and depositing them on the snowpack. Changes in spectral snow reflectance are demonstrated qualitatively through pictures of snow surfaces after aerosol deposition and quantitatively by measuring hemispherical-conical reflectance spectra for the deposited areas and for adjacent snowpack in its natural state. Additional potential applications for this apparatus are mentioned and briefly discussed.

A Practical UAV Remote Sensing Methodology to Generate Multispectral Orthophotos for Vineyards

2015 ◽  
Vol 6 (4) ◽  
pp. 65-87 ◽  
Author(s):  
Adam J. Mathews
Keyword(s):  
Spectral Reflectance ◽  
Near Infrared ◽  
Aerial Imagery ◽  
Spectral Information ◽  
Surface Reflectance ◽  
Digital Cameras ◽  
Individual Bands ◽  
Aerial Vehicle ◽  
Best Fit

This paper explores the use of compact digital cameras to remotely estimate spectral reflectance based on unmanned aerial vehicle imagery. Two digital cameras, one unaltered and one altered, were used to collect four bands of spectral information (blue, green, red, and near-infrared [NIR]). The altered camera had its internal hot mirror removed to allow the sensor to be additionally sensitive to NIR. Through on-ground experimentation with spectral targets and a spectroradiometer, the sensitivity and abilities of the cameras were observed. This information along with on-site collected spectral data were used to aid in converting aerial imagery digital numbers to estimates of scaled surface reflectance using the empirical line method. The resulting images were used to create spectrally-consistent orthophotomosaics of a vineyard study site. Individual bands were subsequently validated with in situ spectroradiometer data. Results show that red and NIR bands exhibited the best fit (R2: 0.78 for red; 0.57 for NIR).

scholarly journals Description and validation of an AOT product over land at the 0.6 μm channel of the SEVIRI sensor onboard MSG

2011 ◽  
Vol 4 (11) ◽  
pp. 2543-2565 ◽  
Author(s):  
E. Bernard ◽  
C. Moulin ◽  
D. Ramon ◽  
D. Jolivet ◽  
J. Riedi ◽  
...  
Keyword(s):  
Near Infrared ◽  
Weather Prediction ◽  
Temporal Frequency ◽  
Reasonable Assumption ◽  
High Temporal Resolution ◽  
Surface Reflectance ◽  
Aerosol Model ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Level 2 ◽  
Good Agreement

Abstract. The Spinning Enhanced Visible and InfraRed Imager (SEVIRI) aboard Meteosat Second Generation (MSG) launched in 2003 by EUMETSAT is dedicated to the Nowcasting applications and Numerical Weather Prediction and to the provision of observations for climate monitoring and research. We use the data in visible and near infrared (NIR) channels to derive the aerosol optical thickness (AOT) over land. The algorithm is based on the assumption that the top of the atmosphere (TOA) reflectance increases with the aerosol load. This is a reasonable assumption except in case of absorbing aerosols above bright surfaces. We assume that the minimum in a 14-days time series of the TOA reflectance is, once corrected from gaseous scattering and absorption, representative of the surface reflectance. The AOT and the aerosol model (a set of 5 models is used), are retrieved by matching the simulated TOA reflectance with the TOA reflectances measured by SEVIRI in its visible and NIR spectral bands. The high temporal resolution of the data acquisition by SEVIRI allows to retrieve the AOT every 15 min with a spatial resolution of 3 km at sub-satellite point, over the entire SEVIRI disk covering Europe, Africa and part of South America. The resulting AOT, a level 2 product at the native temporal and spatial SEVIRI resolutions, is presented and evaluated in this paper. The AOT has been validated using ground based measurements from AErosol RObotic NETwork (AERONET), a sun-photometer network, focusing over Europe for 3 months in 2006. The SEVIRI estimates correlate well with the AERONET measurements, r = 0.64, with a slight overestimate, bias = −0.017. The sources of errors are mainly the cloud contamination and the bad estimation of the surface reflectance. The temporal evolutions exhibited by both datasets show very good agreement which allows to conclude that the AOT Level 2 product from SEVIRI can be used to quantify the aerosol content and to monitor its daily evolution with a high temporal frequency. The comparison with daily maps of Moderate Resolution Imaging Spectroradiometer (MODIS) AOT level 3 product shows qualitative good agreement in the retrieved geographic patterns of AOT. Given the high spatial and temporal resolutions obtained with this approach, our results have clear potential for applications ranging from air quality monitoring to climate studies. This paper presents a first evaluation and validation of the derived AOT over Europe in order to document the overall quality of a product that will be made publicly available to the users of the aforementioned research communities.

Near-Infrared Imaging of Mars from HST: Surface Reflectance, Photometric Properties, and Implications for MOLA Data

Icarus ◽  
1999 ◽  
Vol 138 (1) ◽  
pp. 25-35 ◽  
Author(s):  
James F. Bell ◽  
Michael J. Wolff ◽  
Thomas C. Daley ◽  
David Crisp ◽  
Philip B. James ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Surface Reflectance ◽  
Near Infrared Imaging

scholarly journals Scientific impact of MODIS C5 calibration degradation and C6+ improvements

2014 ◽  
Vol 7 (12) ◽  
pp. 4353-4365 ◽  
Author(s):  
A. Lyapustin ◽  
Y. Wang ◽  
X. Xiong ◽  
G. Meister ◽  
S. Platnick ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Near Infrared ◽  
Atmospheric Correction ◽  
Temporal Trends ◽  
Polarization Sensitivity ◽  
Data Sets ◽  
Surface Reflectance ◽  
Data Set ◽  
Cross Calibration ◽  
Calibration Approach

Abstract. The Collection 6 (C6) MODIS (Moderate Resolution Imaging Spectroradiometer) land and atmosphere data sets are scheduled for release in 2014. C6 contains significant revisions of the calibration approach to account for sensor aging. This analysis documents the presence of systematic temporal trends in the visible and near-infrared (500 m) bands of the Collection 5 (C5) MODIS Terra and, to lesser extent, in MODIS Aqua geophysical data sets. Sensor degradation is largest in the blue band (B3) of the MODIS sensor on Terra and decreases with wavelength. Calibration degradation causes negative global trends in multiple MODIS C5 products including the dark target algorithm's aerosol optical depth over land and Ångström exponent over the ocean, global liquid water and ice cloud optical thickness, as well as surface reflectance and vegetation indices, including the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). As the C5 production will be maintained for another year in parallel with C6, one objective of this paper is to raise awareness of the calibration-related trends for the broad MODIS user community. The new C6 calibration approach removes major calibrations trends in the Level 1B (L1B) data. This paper also introduces an enhanced C6+ calibration of the MODIS data set which includes an additional polarization correction (PC) to compensate for the increased polarization sensitivity of MODIS Terra since about 2007, as well as detrending and Terra–Aqua cross-calibration over quasi-stable desert calibration sites. The PC algorithm, developed by the MODIS ocean biology processing group (OBPG), removes residual scan angle, mirror side and seasonal biases from aerosol and surface reflectance (SR) records along with spectral distortions of SR. Using the multiangle implementation of atmospheric correction (MAIAC) algorithm over deserts, we have also developed a detrending and cross-calibration method which removes residual decadal trends on the order of several tenths of 1% of the top-of-atmosphere (TOA) reflectance in the visible and near-infrared MODIS bands B1–B4, and provides a good consistency between the two MODIS sensors. MAIAC analysis over the southern USA shows that the C6+ approach removed an additional negative decadal trend of Terra ΔNDVI ~ 0.01 as compared to Aqua data. This change is particularly important for analysis of vegetation dynamics and trends in the tropics, e.g., Amazon rainforest, where the morning orbit of Terra provides considerably more cloud-free observations compared to the afternoon Aqua measurements.

scholarly journals Flow Duration Curves from Surface Reflectance in the Near Infrared Band

2021 ◽  
Vol 11 (8) ◽  
pp. 3458
Author(s):  
Angelica Tarpanelli ◽  
Alessio Domeneghetti
Keyword(s):  
Mississippi River ◽  
Near Infrared ◽  
Hydrological Regime ◽  
Physical Parameters ◽  
Surface Reflectance ◽  
Infrared Band ◽  
Earth Observations ◽  
Flow Duration ◽  
Specific Discharge ◽  
Flow Duration Curves

Flow duration curve (FDC) is a cumulative frequency curve that shows the percent of time a specific discharge has been equaled or exceeded during a particular period of time at a given river location, providing a comprehensive description of the hydrological regime of a catchment. Thus, relying on historical streamflow records, FDCs are typically constrained to gauged and updated ground stations. Earth Observations can support our monitoring capability and be considered as a valuable and additional source for the observation of the Earth’s physical parameters. Here, we investigated the potential of the surface reflectance in the Near Infrared (NIR) band of the MODIS 500 m and eight-day product, in providing reliable FDCs along the Mississippi River. Results highlight the capability of NIR bands to estimate the FDCs, enabling a realistic reconstruction of the flow regimes at different locations. Apart from a few exceptions, the relative Root Mean Square Error, rRMSE, of the discharge value in validation period ranges from 27–58% with higher error experienced for extremely high flows (low duration), mainly due to the limit of the sensor to penetrate the clouds during the flood events. Due to the spatial resolution of the satellite product higher errors are found at the stations where the river is narrow. In general, good performances are obtained for medium flows, encouraging the use of the satellite for the water resources management at ungauged river sites.

scholarly journals ACCUMULATED REFLECTANCE TECHNIQUE FOR SAMPLING DELIMITATION IN THE RIACHO FUNDO CREEK, LAGO PARANOÁ-DF, FROM PLANETSCOPE IMAGES

2020 ◽  
Vol XLII-3/W12-2020 ◽  
pp. 389-393
Author(s):  
C. S. Marinho ◽  
V. Sacramento ◽  
M. R. Cangiano ◽  
R. E. Cicerelli ◽  
T. Almeida
Keyword(s):  
Near Infrared ◽  
Optically Active ◽  
Laboratory Analysis ◽  
Surface Reflectance ◽  
Active Components ◽  
Spectral Variability ◽  
Collection Process ◽  
Digital Number ◽  
Sampling Points ◽  
Water Collection

Abstract. The delimitation of sampling points is an important step to avoid unnecessary costs in water collection process and laboratory analysis. Based on the accumulated reflectance of PlanetScope imagens, it was possible to verify areas of greater spectral variability related to the presence of Optically Active Components (OAC). In order to do that, the accumulated reflectance method was used, based on multitemporal images. For that, three PlanetScope Ortho Scene Products were tested: Atmospheric Corrected for Surface Reflectance (SR), Digital Number (DN), and Top of Atmosphere Reflectance (TOA) images. SR and DN products had similar outcome, while DN product was not ideal for the purpose of this article. Even though SR and DN products were able to delimitate sampling points, they may have radiometric issues, mainly because of their near infrared values.

Sign in / Sign up

Export Citation Format

Share Document