Radiometric flight results from the HyperSpectral Imager for Climate Science (HySICS)

Abstract. Long-term monitoring of the Earth-reflected solar-spectrum is necessary for discerning and attributing changes in climate. High radiometric-accuracy enables such monitoring over decadal timescales with non-overlapping instruments, and high precision enables trend detection on shorter timescales. The Hyperspectral Imager for Climate Science (HySICS) is a visible and near-infrared spatial/spectral imaging-spectrometer intended to ultimately achieve ~ 0.2 % radiometric accuracies of Earth scenes from space, providing an order-of-magnitude improvement over existing space-based imagers. On-orbit calibrations from measurements of spectral solar irradiances acquired by direct views of the Sun enable radiometric calibrations with superior long-term stability than currently possible with any manmade spaceflight light-source or detector. Solar- and lunar-observations enable in-flight focal-plane-array flat-fielding and other instrument calibrations. The HySICS has demonstrated this solar cross-calibration technique for future spaceflight instrumentation via two high-altitude balloon flights. The second of these two flights acquired high radiometric-accuracy measurements of the ground, clouds, the Earth's limb, and the Moon. Those results and the details of the uncertainty analyses of those flight data are described.

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Instrument Development: Chinese Radiometric Benchmark of Reflected Solar Band Based on Space Cryogenic Absolute Radiometer

Remote Sensing ◽

10.3390/rs12172856 ◽

2020 ◽

Vol 12 (17) ◽

pp. 2856

Author(s):

Xin Ye ◽

Xiaolong Yi ◽

Chao Lin ◽

Wei Fang ◽

Kai Wang ◽

...

Keyword(s):

Remote Sensing ◽

Measurement Accuracy ◽

Signal To Noise Ratio ◽

Imaging Spectrometer ◽

Term Stability ◽

Long Term Stability ◽

Remote Sensors ◽

Cross Calibration ◽

Transfer Chain

Low uncertainty and long-term stability remote data are urgently needed for researching climate and meteorology variability and trends. Meeting these requirements is difficult with in-orbit calibration accuracy due to the lack of radiometric satellite benchmark. The radiometric benchmark on the reflected solar band has been under development since 2015 to overcome the on-board traceability problem of hyperspectral remote sensing satellites. This paper introduces the development progress of the Chinese radiometric benchmark of the reflected solar band based on the Space Cryogenic Absolute Radiometer (SCAR). The goal of the SCAR is to calibrate the Earth–Moon Imaging Spectrometer (EMIS) on-satellite using the benchmark transfer chain (BTC) and to transfer the traceable radiometric scale to other remote sensors via cross-calibration. The SCAR, which is an electrical substitution absolute radiometer and works at 20 K, is used to realize highly accurate radiometry with an uncertainty level that is lower than 0.03%. The EMIS, which is used to measure the spectrum radiance on the reflected solar band, is designed to optimize the signal-to-noise ratio and polarization. The radiometric scale of the SCAR is converted and transferred to the EMIS by the BTC to improve the measurement accuracy and long-term stability. The payload of the radiometric benchmark on the reflected solar band has been under development since 2018. The investigation results provide the theoretical and experimental basis for the development of the reflected solar band benchmark payload. It is important to improve the measurement accuracy and long-term stability of space remote sensing and provide key data for climate change and earth radiation studies.

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Validation of nine years of MOPITT V5 NIR using MOZAIC/IAGOS measurements: biases and long-term stability

Atmospheric Measurement Techniques ◽

10.5194/amt-7-3783-2014 ◽

2014 ◽

Vol 7 (11) ◽

pp. 3783-3799 ◽

Cited By ~ 8

Author(s):

A. T. J. de Laat ◽

I. Aben ◽

M. Deeter ◽

P. Nédélec ◽

H. Eskes ◽

...

Keyword(s):

Near Infrared ◽

Transport Model ◽

A Priori ◽

Validation Data ◽

Chemistry Transport Model ◽

Large Variability ◽

Long Term Stability ◽

Spatio Temporal ◽

Good Agreement

Abstract. Validation results from a comparison between Measurement Of Pollution In The Troposphere (MOPITT) V5 Near InfraRed (NIR) carbon monoxide (CO) total column measurements and Measurement of Ozone and Water Vapour on Airbus in-service Aircraft (MOZAIC)/In-Service Aircraft for a Global Observing System (IAGOS) aircraft measurements are presented. A good agreement is found between MOPITT and MOZAIC/IAGOS measurements, consistent with results from earlier studies using different validation data and despite large variability in MOPITT CO total columns along the spatial footprint of the MOZAIC/IAGOS measurements. Validation results improve when taking the large spatial footprint of the MOZAIC/IAGOS data into account. No statistically significant drift was detected in the validation results over the period 2002–2010 at global, continental and local (airport) scales. Furthermore, for those situations where MOZAIC/IAGOS measurements differed from the MOPITT a priori, the MOPITT measurements clearly outperformed the MOPITT a priori data, indicating that MOPITT NIR retrievals add value to the MOPITT a priori. Results from a high spatial resolution simulation of the chemistry-transport model MOCAGE (MOdèle de Chimie Atmosphérique à Grande Echelle) showed that the most likely explanation for the large MOPITT variability along the MOZAIC-IAGOS profile flight path is related to spatio-temporal CO variability, which should be kept in mind when using MOZAIC/IAGOS profile measurements for validating satellite nadir observations.

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Irradiance Observations from the UARS/SUSIM and ATLAS/SUSIM Experiments

International Astronomical Union Colloquium ◽

10.1017/s0252921100024568 ◽

1994 ◽

Vol 143 ◽

pp. 72-72 ◽

Cited By ~ 1

Author(s):

Guenter Brueckner ◽

Linton E. Floyd ◽

Paul A. Lund ◽

Dianne K. Prinz ◽

Michael E. Vanhoosier

Keyword(s):

Solar Spectrum ◽

Daily Basis ◽

Spectral Irradiance ◽

Reference Channel ◽

Term Stability ◽

Long Term Stability ◽

Solar Uv ◽

Solar Ultraviolet ◽

Better Than

The SUSIM (Solar Ultraviolet Spectral Irradiance Monitor) on board the UARS (Upper Atmosphere Research Satellite) has measured the solar UV output from 120 nm to 400 nm on a daily basis since October 1991. A reference channel records a solar spectrum semi-annually only to reduce the instrument degradation of this channel and to provide long-term stability marks. Four deuterium lamps are used at monthly, semi-annual and annual intervals to provide long term calibration of the instrument. A preliminary analysis of the long term stability of SUSIM-UARS indicates that the precision of the instrument should be better than a few percent. The repeatability of two scans is better than 0.2%. A simplified SUSIM instrument is flying on NASA’s ATLAS Spacelab missions anually to provide calibration points for the SUSIM-UARS.

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Sensing with Chirality Pure near Infrared Fluorescent Carbon Nanotubes

10.26434/chemrxiv.13005320 ◽

2020 ◽

Author(s):

Robert Nißler ◽

Larissa Kurth, ◽

Han Li ◽

Alexander Spreinat ◽

Ilyas Kuhlemann ◽

...

Keyword(s):

Carbon Nanotubes ◽

Dna Sequences ◽

Near Infrared ◽

Single Wall Carbon Nanotubes ◽

Term Stability ◽

Long Term Stability ◽

Sensing Applications ◽

Main Challenge ◽

The Impact

Semiconducting single wall carbon nanotubes (SWCNTs) fluoresce in the near infrared (NIR) and the emission wavelength depends on their chirality (n,m). Interactions with the environment affect the fluorescence and can be tailored by functionalizing SWCNTs with biopolymers such as DNA, which is the basis for fluorescent biosensors. So far, such biosensors were mainly assembled from mixtures of SWCNT chiralities with large spectral overlap, which affects sensitivity as well as selectivity and prevents multiplexed sensing. The main challenge to gain chirality pure sensors has been to combine approaches to isolate specific SWCNTs and generic (bio)functionalization approaches. Here, we created chirality pure SWCNT-based NIR biosensors for important analytes such as neurotransmitters and investigated the impact of SWCNT chirality/handedness as well as long-term stability and sensitivity. For this purpose, we used aqueous two-phase extraction (ATPE) to gain chirality pure (6,5)-, (7,5)-, (9,4)- and (7,6)- SWCNTs (emission at ~ 990, 1040, 1115 and 1130 nm). Exchange of the surfactant sodium deoxycholate (DOC) to specific singlestranded (ss)DNA sequences yielded monochiral sensors for small analytes (dopamine, riboflavin, ascorbic acid, pH). DOC used in the separation process was completely removed because residues impaired sensing. The assembled monochiral sensors were up to 10 times brighter than their non-purified counterparts and the ssDNA sequence affected absolute fluorescence intensity as well as colloidal (long-term) stability and selectivity for the analytes. (GT)40-(6,5)-SWCNTs displayed the maximum fluorescence response to the neurotransmitter dopamine (+140 %, Kd = 1.9 x10-7 M) and a long-term stability > 14 days. Furthermore, the specific ssDNA sequences imparted selectivity to the analytes independent of SWCNT chirality and handedness of (+/-) (6,5)-SWCNTs. These monochiral/single-color SWCNTs enabled ratiometric/multiplexed sensing of dopamine, riboflavin, H2O2 and pH. In summary, we demonstrated the assembly, characteristics and potential of monochiral (single-color) SWCNTs for multiple NIR fluorescent sensing applications.

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

10.5194/amt-2017-438 ◽

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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Sensing with Chirality Pure near Infrared Fluorescent Carbon Nanotubes

10.26434/chemrxiv.13005320.v1 ◽

2020 ◽

Author(s):

Robert Nißler ◽

Larissa Kurth, ◽

Han Li ◽

Alexander Spreinat ◽

Ilyas Kuhlemann ◽

...

Keyword(s):

Carbon Nanotubes ◽

Dna Sequences ◽

Near Infrared ◽

Single Wall Carbon Nanotubes ◽

Term Stability ◽

Long Term Stability ◽

Sensing Applications ◽

Main Challenge ◽

The Impact

Semiconducting single wall carbon nanotubes (SWCNTs) fluoresce in the near infrared (NIR) and the emission wavelength depends on their chirality (n,m). Interactions with the environment affect the fluorescence and can be tailored by functionalizing SWCNTs with biopolymers such as DNA, which is the basis for fluorescent biosensors. So far, such biosensors were mainly assembled from mixtures of SWCNT chiralities with large spectral overlap, which affects sensitivity as well as selectivity and prevents multiplexed sensing. The main challenge to gain chirality pure sensors has been to combine approaches to isolate specific SWCNTs and generic (bio)functionalization approaches. Here, we created chirality pure SWCNT-based NIR biosensors for important analytes such as neurotransmitters and investigated the impact of SWCNT chirality/handedness as well as long-term stability and sensitivity. For this purpose, we used aqueous two-phase extraction (ATPE) to gain chirality pure (6,5)-, (7,5)-, (9,4)- and (7,6)- SWCNTs (emission at ~ 990, 1040, 1115 and 1130 nm). Exchange of the surfactant sodium deoxycholate (DOC) to specific singlestranded (ss)DNA sequences yielded monochiral sensors for small analytes (dopamine, riboflavin, ascorbic acid, pH). DOC used in the separation process was completely removed because residues impaired sensing. The assembled monochiral sensors were up to 10 times brighter than their non-purified counterparts and the ssDNA sequence affected absolute fluorescence intensity as well as colloidal (long-term) stability and selectivity for the analytes. (GT)40-(6,5)-SWCNTs displayed the maximum fluorescence response to the neurotransmitter dopamine (+140 %, Kd = 1.9 x10-7 M) and a long-term stability > 14 days. Furthermore, the specific ssDNA sequences imparted selectivity to the analytes independent of SWCNT chirality and handedness of (+/-) (6,5)-SWCNTs. These monochiral/single-color SWCNTs enabled ratiometric/multiplexed sensing of dopamine, riboflavin, H2O2 and pH. In summary, we demonstrated the assembly, characteristics and potential of monochiral (single-color) SWCNTs for multiple NIR fluorescent sensing applications.

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Quality assessment of ozone total column amounts as monitored by ground-based solar absorption spectrometry in the near infrared (> 3000 cm<sup>−1</sup>)

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-7-2071-2014 ◽

2014 ◽

Vol 7 (3) ◽

pp. 2071-2106

Author(s):

O. E. García ◽

M. Schneider ◽

F. Hase ◽

T. Blumenstock ◽

E. Sepúlveda ◽

...

Keyword(s):

Near Infrared ◽

Absorption Spectrometry ◽

Systematic Difference ◽

Total Carbon ◽

Atmospheric Composition ◽

Solar Absorption ◽

Annual Cycles ◽

Long Term Stability ◽

Total Column

Abstract. This study examines the possibility of ground-based remote sensing ozone total column amounts (OTC) from spectral signatures at 3040 and 4030 cm−1. These spectral regions are routinely measured by the NDACC (Network for the Detection of Atmospheric Composition Change) ground-based FTIR (Fourier Transform InfraRed) experiments. In addition, they are potentially detectable by the TCCON (Total Carbon Column Observing Network) FTIR instruments. The ozone retrieval strategy presented here estimates the OTC from NDACC FTIR high resolution spectra with a theoretical precision of about 2% and 5% in the 3040 cm−1 and 4030 cm−1 regions, respectively. Empirically, these OTC products are validated by inter-comparison to FTIR OTC reference retrievals in the 1000 cm−1 spectral region (standard reference for NDACC ozone products), using a 8 year FTIR time series (2005–2012) taken at the subtropical ozone super-site of the Izaña Observatory (Tenerife, Spain). Associated with the weaker ozone signatures at the higher wavenumber regions, the 3040 cm−1 and 4030 cm−1 retrievals show lower vertical sensitivity than the 1000 cm−1 retrievals. Nevertheless, we observe that the rather consistent variations are detected: the variances of the 3040 cm−1 and the 4030 cm−1 retrievals agree within 90% and 75%, respectively, with the variance of the 1000 cm−1 standard retrieval. Furthermore, all three retrievals show very similar annual cycles. However, we observe a large systematic difference of about 7% between the OTC obtained at 1000 cm−1 and 3040 cm−1, indicating a significant inconsistency between the spectroscopic ozone parameters (HITRAN 2012) of both regions. Between the 1000 cm−1 and the 4030 cm−1 retrieval the systematic difference is only 2–3%. Finally, the long-term stability of the OTC retrievals has also been examined, observing that both near infrared retrievals can monitor the long-term OTC evolution in consistency to the 1000 cm−1reference data.

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Determination of the TROPOMI-SWIR instrument spectral response function

Atmospheric Measurement Techniques ◽

10.5194/amt-11-3917-2018 ◽

2018 ◽

Vol 11 (7) ◽

pp. 3917-3933 ◽

Cited By ~ 5

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 ◽

Monochromatic Light ◽

Imaging Spectrometer ◽

Swir Band ◽

Shortwave Infrared ◽

Single Instrument

Abstract. The Tropospheric Monitoring Instrument (TROPOMI) is the single instrument on board 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 shortwave 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. In this paper, we report on the determination of the TROPOMI-SWIR ISRF during an extensive on-ground calibration campaign. Measurements are taken with a monochromatic light source scanning the whole detector, using the spectrometer itself to determine the light intensity and wavelength. The accuracy of the resulting ISRF calibration key data is well within the requirement for trace-gas retrievals. Long-term in-flight monitoring of SWIR ISRF is achieved using five on-board diode lasers.

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New spectral functions of the near-ground albedo derived from aircraft diffraction spectrometer observations

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-6953-2014 ◽

2014 ◽

Vol 14 (13) ◽

pp. 6953-6965 ◽

Cited By ~ 19

Author(s):

C. A. Varotsos ◽

I. N. Melnikova ◽

A. P. Cracknell ◽

C. Tzanis ◽

A. V. Vasilyev

Keyword(s):

Near Infrared ◽

Solar Spectrum ◽

Quadratic Function ◽

Ultraviolet Region ◽

Snow Albedo ◽

Near Infrared Spectra ◽

Ultraviolet Wavelength ◽

Research Aircraft ◽

Order Of Magnitude ◽

Term Basis

Abstract. The airborne spectral observations of the upward and downward irradiances are revisited to investigate the dependence of the near-ground albedo as a function of wavelength in the entire solar spectrum for different surfaces (sand, water, snow) and under different conditions (clear or cloudy sky). The radiative upward and downward fluxes were determined by a diffraction spectrometer flown on a research aircraft that was performing multiple flight paths near the ground. The results obtained show that the near-ground albedo does not generally increase with increasing wavelengths for all kinds of surfaces as is widely believed today. Particularly, in the case of water surfaces it was found that the albedo in the ultraviolet region is more or less independent of the wavelength on a long-term basis. Interestingly, in the visible and near-infrared spectra the water albedo obeys an almost constant power-law relationship with wavelength. In the case of sand surfaces it was found that the sand albedo is a quadratic function of wavelength, which becomes more accurate if the ultraviolet wavelengths are neglected. Finally, it was found that the spectral dependence of snow albedo behaves similarly to that of water, i.e. both decrease from the ultraviolet to the near-infrared wavelengths by 20–50%, despite the fact that their values differ by one order of magnitude (water albedo being lower). In addition, the snow albedo vs. ultraviolet wavelength is almost constant, while in the visible near-infrared spectrum the best simulation is achieved by a second-order polynomial, as in the case of sand, but with opposite slopes.

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