A Visible And Near-Infrared Scanning Photometer For Field Measurements Of Spectral Albedo And Irradiance Under Polar Conditions*

1983 ◽  
Author(s):  
Thomas C. Grenfell
Keyword(s):  
Near Infrared ◽  
Field Measurements ◽  
Infrared Scanning

scholarly journals A Visible and Near-Infrared Scanning Photometer for Field Measurements of Spectral Albedo and Irradiance under Polar Conditions

1981 ◽  
Vol 27 (97) ◽  
pp. 476-481 ◽  
Author(s):  
T. C. Grenfell
Keyword(s):  
Solar Radiation ◽  
Near Infrared ◽  
Field Measurements ◽  
Interference Filter ◽  
Arctic Sea Ice ◽  
Spectral Irradiance ◽  
Operating Characteristics ◽  
Infrared Scanning ◽  
Solar Radiation Incident ◽  
Arctic Sea

AbstractThe design and operating characteristics are presented for a visible and near-infrared scanning photometer which can measure incident and reflected spectral irradiance from 400 nm to 2 450 nm. The instrument is designed to record over 98% of the solar radiation incident upon and reflected from the Earth’s surface using a turret-type cosine collector and a circular variable interference filter. The apparatus has been tested successfully on Arctic sea ice at temperatures down to –20°C. It is self-contained and easily portable, and its mass is less than 16 kg. Some preliminary results are presented.

scholarly journals A Visible and Near-Infrared Scanning Photometer for Field Measurements of Spectral Albedo and Irradiance under Polar Conditions

1981 ◽  
Vol 27 (97) ◽  
pp. 476-481 ◽  
Author(s):  
T. C. Grenfell
Keyword(s):  
Solar Radiation ◽  
Near Infrared ◽  
Field Measurements ◽  
Interference Filter ◽  
Arctic Sea Ice ◽  
Spectral Irradiance ◽  
Operating Characteristics ◽  
Infrared Scanning ◽  
Solar Radiation Incident ◽  
Arctic Sea

AbstractThe design and operating characteristics are presented for a visible and near-infrared scanning photometer which can measure incident and reflected spectral irradiance from 400 nm to 2 450 nm. The instrument is designed to record over 98% of the solar radiation incident upon and reflected from the Earth’s surface using a turret-type cosine collector and a circular variable interference filter. The apparatus has been tested successfully on Arctic sea ice at temperatures down to –20°C. It is self-contained and easily portable, and its mass is less than 16 kg. Some preliminary results are presented.

scholarly journals Prediction of non-recoverable collapse in Eucalyptus globulus from near infrared scanning of radial wood samples

2013 ◽  
Vol 71 (6) ◽  
pp. 755-768 ◽  
Author(s):  
Maximilian Wentzel-Vietheer ◽  
Russell Washusen ◽  
Geoffrey M. Downes ◽  
Christopher Harwood ◽  
Nicholas Ebdon ◽  
...  
Keyword(s):  
Eucalyptus Globulus ◽  
Near Infrared ◽  
Infrared Scanning

scholarly journals Retrieval and Validation of Water Turbidity at Metre-Scale Using Pléiades Satellite Data: A Case Study in the Gironde Estuary

2020 ◽  
Vol 12 (6) ◽  
pp. 946 ◽  
Author(s):  
Yafei Luo ◽  
David Doxaran ◽  
Quinten Vanhellemont
Keyword(s):  
Spatial Variability ◽  
Satellite Data ◽  
Near Infrared ◽  
Atmospheric Correction ◽  
Field Measurements ◽  
Quality Parameters ◽  
Satellite Constellations ◽  
Water Turbidity ◽  
Gironde Estuary ◽  
The Difference

This study investigated the use of frequent metre-scale resolution Pléiades satellite imagery to monitor water quality parameters in the highly turbid Gironde Estuary (GE, SW France). Pléiades satellite data were processed and analyzed in two representative test sites of the GE: 1) the maximum turbidity zone and 2) the mouth of the estuary. The main objectives of this study were to: (i) validate the Dark Spectrum Fitting (DSF) atmospheric correction developed by Vanhellemont and Ruddick (2018) applied to Pléiades satellite data recorded over the GE; (ii) highlight the benefits of frequent metre-scale Pléiades observations in highly turbid estuaries by comparing them to previously validated satellite observations made at medium (250/300 m for MODIS, MERIS, OLCI data) and high (20/30 m for SPOT, OLI and MSI data) spatial resolutions. The results show that the DSF allows for an accurate retrieval of water turbidity by inversion of the water reflectance in the near-infrared (NIR) and red wavebands. The difference between Pléiades-derived turbidity and field measurements was proven to be in the order of 10%. To evaluate the spatial variability of water turbidity at metre scale, Pléiades data at 2 m resolution were resampled to 20 m and 250 m to simulate typical coarser resolution sensors. On average, the derived spatial variability in the GE is lower than or equal to 10% and 26%, respectively, in 20-m and 250-m aggregated pixels. Pléiades products not only show, in great detail, the turbidity features in the estuary and river plume, they also allow to map the turbidity inside ports and capture the complex spatial variations of turbidity along the shores of the estuary. Furthermore, the daily acquisition capabilities may provide additional advantages over other satellite constellations when monitoring highly dynamic estuarine systems.

scholarly journals Characterising the surface magnetic fields of T Tauri stars with high-resolution near-infrared spectroscopy

2019 ◽  
Vol 630 ◽  
pp. A99 ◽  
Author(s):  
A. Lavail ◽  
O. Kochukhov ◽  
G. A. J. Hussain
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Magnetic Fields ◽  
Large Scale ◽  
Near Infrared ◽  
Field Measurements ◽  
T Tauri Stars ◽  
Small Scale ◽  
Surface Magnetic Field ◽  
T Tauri

Aims. In this paper, we aim to characterise the surface magnetic fields of a sample of eight T Tauri stars from high-resolution near-infrared spectroscopy. Some stars in our sample are known to be magnetic from previous spectroscopic or spectropolarimetric studies. Our goals are firstly to apply Zeeman broadening modelling to T Tauri stars with high-resolution data, secondly to expand the sample of stars with measured surface magnetic field strengths, thirdly to investigate possible rotational or long-term magnetic variability by comparing spectral time series of given targets, and fourthly to compare the magnetic field modulus ⟨B⟩ tracing small-scale magnetic fields to those of large-scale magnetic fields derived by Stokes V Zeeman Doppler Imaging (ZDI) studies. Methods. We modelled the Zeeman broadening of magnetically sensitive spectral lines in the near-infrared K-band from high-resolution spectra by using magnetic spectrum synthesis based on realistic model atmospheres and by using different descriptions of the surface magnetic field. We developped a Bayesian framework that selects the complexity of the magnetic field prescription based on the information contained in the data. Results. We obtain individual magnetic field measurements for each star in our sample using four different models. We find that the Bayesian Model 4 performs best in the range of magnetic fields measured on the sample (from 1.5 kG to 4.4 kG). We do not detect a strong rotational variation of ⟨B⟩ with a mean peak-to-peak variation of 0.3 kG. Our confidence intervals are of the same order of magnitude, which suggests that the Zeeman broadening is produced by a small-scale magnetic field homogeneously distributed over stellar surfaces. A comparison of our results with mean large-scale magnetic field measurements from Stokes V ZDI show different fractions of mean field strength being recovered, from 25–42% for relatively simple poloidal axisymmetric field topologies to 2–11% for more complex fields.

Screening prostate cancer using a portable near infrared scanning imaging unit with an optical fiber-based rectal probe

2012 ◽  
Author(s):  
Yang Pu ◽  
Wubao Wang ◽  
Guichen Tang ◽  
Yury Budansky ◽  
Mikhail Sharonov ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Optical Fiber ◽  
Near Infrared ◽  
Infrared Scanning ◽  
Scanning Imaging

scholarly journals Atmospheric observations of the water vapour continuum in the near-infrared windows between 2500–6600 cm<sup>−1</sup>

2019 ◽  
Author(s):  
Jonathan Elsey ◽  
Marc D. Coleman ◽  
Tom D. Gardiner ◽  
Kaah P. Menang ◽  
Keith P. Shine
Keyword(s):  
Water Vapour ◽  
Near Infrared ◽  
Laboratory Data ◽  
Field Measurements ◽  
The Self ◽  
Atmospheric Conditions ◽  
Sensing Applications ◽  
Atmospheric Observations ◽  
Real Atmosphere ◽  
Remote Sensing Applications

Abstract. Water vapour continuum absorption is potentially important for both closure of the Earth’s energy budget and remote sensing applications. Currently, there are significant uncertainties in its characteristics in the near-infrared atmospheric windows at 2.1 and 1.6 μm. There have been several attempts to measure the continuum in the laboratory; not only are there significant differences amongst these measurements but there are also difficulties in extrapolating the laboratory data taken at room temperature or higher to atmospheric temperatures. Validation is therefore required using field observations of the real atmosphere. There are currently few published observations in atmospheric conditions with enough water vapour to detect a continuum signal within these windows, or where the self-continuum component is significant. We present observations of the near-infrared water vapour continuum from Camborne, UK at sea level using a sun-pointing, radiometrically-calibrated Fourier transform spectrometer in the window regions between 2000–10000 cm−1. Analysis of this data is challenging, particularly because of the need to remove aerosol extinction, and the large uncertainties associated with such field measurements. Nevertheless, we present data that is consistent with recent laboratory datasets in the 4 and 2.1 μm windows (when extrapolated to atmospheric temperatures). These results indicate that the most recent revision (3.2) of the MT_CKD foreign continuum, versions of which are widely used in atmospheric radiation models, requires strengthening by a factor of ~ 5 in the centre of the 2.1 µm window. In the higher-wavenumber window at 1.6 µm, our estimated self and foreign continua are significantly stronger than MT_CKD. The possible contribution of the self and foreign continua to our derived total continuum optical depth is estimated by using laboratory or MT_CKD values of one, to estimate the other. The obtained self-continuum shows some consistency with temperature-extrapolated laboratory data in the centres of the 4 and 2.1 µm windows. The 1.6 μm region is more sensitive to atmospheric aerosol and continuum retrievals and therefore more uncertain than the more robust results at 2.1 and 4 μm. We highlight the difficulties in observing the atmospheric continuum and make the case for additional measurements from both the laboratory and field, with discussion of the requirements for any new field campaign.

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