scholarly journals Solar Contamination on HIRAS Cold Calibration View and the Corrected Radiance Assessment

2021 ◽  
Vol 13 (19) ◽  
pp. 3869
Author(s):  
Lu Lee ◽  
Chunqiang Wu ◽  
Chengli Qi ◽  
Xiuqing Hu ◽  
Mingge Yuan ◽  
...  
Keyword(s):  
Brightness Temperature ◽  
Moving Average ◽  
Correction Method ◽  
Short Wave ◽  
Stray Light ◽  
Anomalous Data ◽  
Swir Band ◽  
Calibration Accuracy ◽  
Cross Track ◽  
Radiance Data

The deep-space (DS) view spectra are used as a cold reference to calibrate the Hyperspectral Infrared Atmospheric Sounder (HIRAS) Earth scene (ES) observations. The DS spectra stability in the moving average window is crucial to the calibration accuracy of ES radiances. While in the winter and spring seasons, the HIRAS detector-3 DS view is susceptible to solar stray light intrusion when the satellite flies towards the tail of every descending orbit, and as a result, the measured DS spectra are contaminated by the stray light pseudo spectra, especially in the short-wave infrared (SWIR) band. The solar light intrusion issue was addressed on 13 December 2019 when the DS view angle of the scene selection mirror (SSM) was adjusted from −77.4° to −87°. As for the historic contaminated data, a correction method is applied to detect the anomalous data by checking the continuity of the DS spectra and then replace them with the proximate normal ones. The historic ES observations are recalibrated after the contaminated DS spectra correction. The effect of the correction is assessed by comparing the recalibrated HIRAS radiances with those measured by the Cross-track Infrared Sounder onboard the Suomi National Polar-orbiting Partnership Satellite (SNPP/CrIS) via the extended simultaneous nadir overpasses (SNOx) technique and by checking the consistency among the radiance data from different HIRAS detectors. The results show that the large biases of the radiance brightness temperature (BT) caused by the contamination are ameliorated greatly to the levels observed in the normal conditions.

scholarly journals Road Feature Extraction from LANDSAT-8 and ResourceSat-2 Images

2021 ◽  
Vol 21 (3) ◽  
pp. 1-9
Author(s):  
Sama Lenin Kumar Reddy ◽  
◽  
C. V. Rao ◽  
P. Rajesh Kumar ◽  
◽  
...  
Keyword(s):  
Feature Extraction ◽  
Random Fields ◽  
Markov Random Fields ◽  
Short Wave ◽  
Landsat 8 ◽  
Road Extraction ◽  
Remote Sensing Images ◽  
The Road ◽  
Markov Random ◽  
Swir Band

This paper presents a methodology of road feature extraction from the different resolutions of Remote Sensing images of Landsat-8 Operational Lander Image (OLI) and ResourceSat-2 of Linear Imaging Self Sensor-3 (LISS-3) and LISS-4 sensors with the spatial resolutions of 15 m, 24 m, and 5 m. In the methodology of road extraction, an index is proposed based on the spectral profile of Roads, also involving Morphological transform (Top-Hat or Bot-Hat) and Markov Random Fields (MRF). In the proposed index, Short Wave Infrared (SWIR) band has a significant role in the detection of roads from sensors, and it is named Normalized Difference Road Index (NDRI). To enhancement of features from the index, Bot-Hat transforms used. To segment the road features from this image, MRF used. The methodology is performed on the OLI, LISS-3 and LISS-4 images, and presented with results.

scholarly journals Single flat lens enabling imaging in the short-wave infra-red (SWIR) band

OSA Continuum ◽  
2019 ◽  
Vol 2 (10) ◽  
pp. 2968 ◽  
Author(s):  
Sourangsu Banerji ◽  
Monjurul Meem ◽  
Apratim Majumder ◽  
Curt Dvonch ◽  
Berardi Sensale-Rodriguez ◽  
...  
Keyword(s):  
Short Wave ◽  
Swir Band ◽  
Infra Red ◽  
Flat Lens

scholarly journals Establishment of AIRS Climate-Level Radiometric Stability using Radiance Anomaly Retrievals of Minor Gases and SST

2020 ◽  
Author(s):  
L. Larrabee Strow ◽  
Sergio DeSouza-Machado
Keyword(s):  
Surface Temperature ◽  
Brightness Temperature ◽  
Optimal Estimation ◽  
Detailed Examination ◽  
Short Wave ◽  
Climate Trend ◽  
Temperature Anomalies ◽  
Temperature Trends ◽  
Multiplicative Shift ◽  
Geophysical Anomalies

Abstract. Temperature, H2O, and O3 profiles, as well as CO2, N2O, CH4, CFC12, and SST scalar anomalies are computed using a clear subset of AIRS observations over ocean for the first 16-years of NASA's EOS-AQUA AIRS operation. The AIRS Level 1c radiances are averaged over 16 days and 40 equal-area zonal bins and then converted to brightness temperature anomalies. Geophysical anomalies are retrieved from the brightness temperature anomalies using a relatively standard optimal estimation approach. The CO2, N2O, CH4, and CFC12 anomalies are derived by applying a vertically uniform multiplicative shift to each gas in order to obtain an estimate for the ngas mixing ratio. The minor gas anomalies are compared to the NOAA ESRL in-situ values and used to estimate the radiometric stability of the AIRS radiances. Similarly the retrieved SST anomalies are compared to the SST values used in the ERA-Interim reanalysis and to NOAA's OISST SST product. These inter-comparisons strongly suggest that many AIRS channels are stable to better than 0.02 to 0.03 K/Decade, well below climate trend levels, indicating that the AIRS blackbody is not drifting. However, detailed examination of the anomaly retrieval residuals (observed minus computed) show various small unphysical shifts that correspond to AIRS hardware events (shutdowns, etc.). Some examples are given highlighting how the AIRS radiances stability could be improved, especially for channels sensitive to N2O and CH4. The AIRS short wave channels exhibit larger drifts that make them unsuitable for climate trending, and they are avoided in this work. The AIRS Level 2 surface temperature retrievals only use short wave channels. We summarize how these short wave drifts impacts recently published comparisons of AIRS surface temperature trends to other surface climatologies.

scholarly journals Atmospheric Correction of OLCI Imagery over Extremely Turbid Waters Based on the Red, NIR and 1016 nm Bands and a New Baseline Residual Technique

2019 ◽  
Vol 11 (3) ◽  
pp. 220 ◽  
Author(s):  
Juan Gossn ◽  
Kevin Ruddick ◽  
Ana Dogliotti
Keyword(s):  
Atmospheric Correction ◽  
Short Wave ◽  
Considerable Improvement ◽  
Atmospheric Conditions ◽  
Black Water ◽  
Baseline Subtraction ◽  
Spectral Bands ◽  
Turbid Waters ◽  
Swir Band ◽  
Infra Red

A common approach to the pixel-by-pixel atmospheric correction of satellite water colour imagery is to calculate aerosol and water reflectance at two spectral bands, typically in the near infra-red (NIR, 700–1000 nm) or the short-wave-infra-red (SWIR, 1000–3000 nm), and then extrapolate aerosol reflectance to shorter wavelengths. For clear waters, this can be achieved simply for NIR bands, where the water reflectance can be assumed negligible i.e., the “black water” assumption. For moderately turbid waters, either the NIR water reflectance, which is non-negligible, must be modelled or longer wavelength SWIR bands, with negligible water reflectance, must be used. For extremely turbid waters, modelling of non-zero NIR water reflectance becomes uncertain because the spectral slopes of water and aerosol reflectance in the NIR become similar, making it difficult to distinguish between them. In such waters the use of SWIR bands is definitely preferred and the use of the MODIS bands at 1240 nm and 2130 nm is clearly established although, on many sensors such as the Ocean and Land Colour Instrument (OLCI), such SWIR bands are not included. Instead, a new, cheaper SWIR band at 1016 nm is available on OLCI with potential for much better atmospheric correction over extremely turbid waters. That potential is tested here. In this work, we demonstrate that for spectrally-close band triplets (such as OLCI bands at 779–865–1016 nm), the Rayleigh-corrected reflectance of the triplet’s “middle” band after baseline subtraction (or baseline residual, BLR) is essentially independent of the atmospheric conditions. We use the three BLRs defined by three consecutive band triplets of the group of bands 620–709–779–865–1016 nm to calculate water reflectance and hence aerosol reflectance at these wavelengths. Comparison with standard atmospheric correction algorithms shows similar performance in moderately turbid and clear waters and a considerable improvement in extremely turbid waters.

A high-performance short-wave infrared phototransistor based on a 2D tellurium/MoS2 van der Waals heterojunction

2021 ◽  
Vol 9 (38) ◽  
pp. 13123-13131
Author(s):  
Jinrong Yao ◽  
Fangfang Chen ◽  
Juanjuan Li ◽  
Junli Du ◽  
Di Wu ◽  
...  
Keyword(s):  
High Performance ◽  
Response Spectrum ◽  
Van Der Waals ◽  
Short Wave ◽  
Swir Band ◽  
Vdw Heterostructure ◽  
Short Wave Infrared

A gate-tunable Te/MoS2 vdW heterostructure is fabricated, exhibiting favourable photodetection properties with a response spectrum covering the whole SWIR band.

Research on Correction Method of Stray Light in Directional Polarization Camera

2017 ◽  
Vol 37 (11) ◽  
pp. 1112003
Author(s):  
张苗苗 Zhang Miaomiao ◽  
孟炳寰 Meng Binghuan ◽  
钱鸿鹄 Qian Honghu ◽  
韩 琳 Han Lin ◽  
陈怀军 Chen Huaijun ◽  
...  
Keyword(s):  
Correction Method ◽  
Stray Light ◽  
Polarization Camera

scholarly journals Comparison of AIRS and IASI Radiances Using GOES Imagers as Transfer Radiometers toward Climate Data Records

2010 ◽  
Vol 49 (3) ◽  
pp. 478-492 ◽  
Author(s):  
Likun Wang ◽  
Xiangqian Wu ◽  
Mitch Goldberg ◽  
Changyong Cao ◽  
Yaping Li ◽  
...  
Keyword(s):  
Brightness Temperature ◽  
Climate Data ◽  
Atmospheric Infrared Sounder ◽  
Mean Values ◽  
Tropical Regions ◽  
Time Period ◽  
Double Differences ◽  
Cross Track ◽  
Spectral Channels

Abstract The Atmospheric Infrared Sounder (AIRS) and the Infrared Atmospheric Sounding Interferometer (IASI), together with the future Cross-track Infrared Sounder, will provide long-term hyperspectral measurements of the earth and its atmosphere at ∼10 km spatial resolution. Quantifying the radiometric difference between AIRS and IASI is crucial for creating fundamental climate data records and establishing the space-based infrared calibration standard. Since AIRS and IASI have different local equator crossing times, a direct comparison of these two instruments over the tropical regions is not feasible. Using the Geostationary Operational Environmental Satellite (GOES) imagers as transfer radiometers, this study compares AIRS and IASI over warm scenes in the tropical regions for a time period of 16 months. The double differences between AIRS and IASI radiance biases relative to the GOES-11 and -12 imagers are used to quantify the radiance differences between AIRS and IASI within the GOES imager spectral channels. The results indicate that, at the 95% confidence level, the mean values of the IASI − AIRS brightness temperature differences for warm scenes are very small, that is, −0.0641 ± 0.0074 K, −0.0432 ± 0.0114 K, and −0.0095 ± 0.0151 K for the GOES-11 6.7-, 10.7-, and 12.0-μm channels, respectively, and −0.0490 ± 0.0100 K, −0.0419 ± 0.0224 K, and −0.0884 ± 0.0160 K for the GOES-12 6.5-, 10.7-, and 13.3-μm channels, respectively. The brightness temperature biases between AIRS and IASI within the GOES imager spectral range are less than 0.1 K although the AIRS measurements are slightly warmer than those of IASI.

The impact of artifact correction methods of RR series on heart rate variability parameters

2018 ◽  
Vol 124 (3) ◽  
pp. 646-652 ◽  
Author(s):  
Anderson Ivan Rincon Soler ◽  
Luiz Eduardo Virgilio Silva ◽  
Rubens Fazan ◽  
Luiz Otavio Murta
Keyword(s):  
Heart Rate ◽  
Time Series ◽  
Heart Rate Variability ◽  
Linear Time ◽  
Spline Interpolation ◽  
Moving Average ◽  
Linear Interpolation ◽  
Correction Method ◽  
Artifact Correction ◽  
The Impact

Heart rate variability (HRV) analysis is widely used to investigate the autonomic regulation of the cardiovascular system. HRV is often analyzed using RR time series, which can be affected by different types of artifacts. Although there are several artifact correction methods, there is no study that compares their performances in actual experimental contexts. This work aimed to evaluate the impact of different artifact correction methods on several HRV parameters. Initially, 36 ECG recordings of control rats or rats with heart failure or hypertension were analyzed to characterize artifact occurrence rates and distributions, to be mimicked in simulations. After a rigorous analysis, only 16 recordings ( n = 16) with artifact-free segments of at least 10,000 beats were selected. RR interval losses were then simulated in the artifact-free (reference) time series according to real observations. Correction methods applied to simulated series were deletion, linear interpolation, cubic spline interpolation, modified moving average window, and nonlinear predictive interpolation. Linear (time- and frequency-domain) and nonlinear HRV parameters were calculated from corrupted-corrected time series, as well as for reference series to evaluate the accuracy of each correction method. Results show that NPI provides the overall best performance. However, several correction approaches, for example the simple deletion procedure, can provide good performance in some situations, depending on the HRV parameters under consideration. NEW & NOTEWORTHY This work analyzes the performance of some correction techniques commonly applied to the missing beats problem in RR time series. From artifact-free RR series, spurious values were inserted based on actual data of experimental settings. We intend our work to be a guide to show how artifacts should be corrected to preserve as much as possible the original heart rate variability properties.

scholarly journals New method to determine the instrument spectral response function, applied to TROPOMI-SWIR

2017 ◽  
Author(s):  
Richard M. van Hees ◽  
Paul J. J. Tol ◽  
Sidney Cadot ◽  
Matthijs Krijger ◽  
Stefan T. Persijn ◽  
...  
Keyword(s):  
Response Function ◽  
Near Infrared ◽  
Spectral Response ◽  
Short Wave ◽  
Trace Gas ◽  
Imaging Spectrometer ◽  
Swir Band ◽  
Novel Method ◽  
Single Instrument

Abstract. The Tropospheric Monitoring Instrument (TROPOMI) is the single instrument on board of the ESA Copernicus Sentinel-5 Precursor satellite. TROPOMI is a nadir-viewing imaging spectrometer with bands in the ultraviolet and visible, the near infrared and the short-wave infrared (SWIR). An accurate instrument spectral response function (ISRF) is required in the SWIR band where absorption lines of CO, methane and water vapor overlap. Therefore a novel method for ISRF determination for an imaging spectrometer was developed and applied to the TROPOMI-SWIR band. The ISRF of all detector pixels of the SWIR spectrometer has been measured during an on-ground calibration campaign. The accuracy of the derived ISRF is well within the requirement for accurate trace-gas retrievals. Long-term in-flight monitoring of the ISRF is guaranteed by the presence of five SWIR diode lasers.

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