Aviation and Jet Contrails: Impact on Astronomy

Symposium - International Astronomical Union ◽

10.1017/s007418090016406x ◽

2001 ◽

Vol 196 ◽

pp. 173-178

Author(s):

H. Pedersen

Keyword(s):

Fuel Consumption ◽

Northern Hemisphere ◽

Detrimental Effect ◽

Thermal Emission ◽

Science Data ◽

Time Resolved ◽

Astronomical Observations ◽

Linear Shape

Attention is drawn to aspects of aviation that have a detrimental effect on ground-based astronomy. Depending on observing methods, science data can be influenced by an aircraft's emission of light, its thermal emission, exhaust products and condensation trail. Although these effects are mostly short-lasting for a given observing direction, they can be highly significant, and influence time-resolved astronomical observations. While the very young contrails can easily be recognized by ground-based or spaceborne observations, concern should also be given to older (hours, days) contrails, which have lost their characteristic linear shape. Contrails may grow to widths of tens of kilometers, and become almost indistinguishable from natural cirrus. As aviation increases, this may imply fewer photometric nights, in particular in the northern hemisphere, where by far the largest fuel consumption takes place.

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The Electronic Structure of a-Si,Ge:H Alloys

MRS Proceedings ◽

10.1557/proc-336-493 ◽

1994 ◽

Vol 336 ◽

Cited By ~ 4

Author(s):

F. Zhong ◽

J.D. Cohen ◽

J. Yang ◽

S. Guha

Keyword(s):

Thermal Emission ◽

Drive Level ◽

Optical Methods ◽

Defect States ◽

Thermal Transitions ◽

Defect Band ◽

Time Resolved ◽

Photocurrent Spectroscopy ◽

First Time ◽

Negative Signal

ABSTRACTWe have carried out a detailed study of the energy distribution of deep defects for high quality glow discharge a-Si,Ge:H alloys using both thermal emission and optical Methods: drive-level capacitance profiling, transient photocapacitance and photocurrent plus modulation photocurrent spectroscopy. Four distinct bands of transitions involving defect states have been identified: two associated with thermal transitions, and the other two related to optical transitions. We have, for the first time, observed a negative signal in the photocapacitance spectra at photon energies near 1.2eV. This striking aspect verifies the presence of a distinct defect band above Ep from which electron thermal emission is greatly suppressed. Our Measurements also disclose a fairly narrow defect band below the Fermi level which contrasts with the defect properties observed in a-Si:H. Time resolved photocapacitance spectra indicate that this defect band exhibits configuration relaxation.

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Deep Defect Relaxation in Hydrogenated Amorphous Silicon: New Experimental Evidence and Implications

MRS Proceedings ◽

10.1557/proc-507-781 ◽

1998 ◽

Vol 507 ◽

Author(s):

J. David Cohen ◽

Fan Zhong ◽

Daewon Kwon ◽

C.-C. Chen

Keyword(s):

Fermi Level ◽

Emission Rate ◽

Thermal Emission ◽

Hydrogenated Amorphous Silicon ◽

Depletion Region ◽

Time Resolved ◽

Apparent Shift ◽

Hydrogenated Amorphous ◽

Defect Relaxation ◽

Thermal Emission Rate

ABSTRACTWe review modulated photocurrent experiments which indicate that thermal emission rate for Do defects in intrinsic samples varies in response to changes in the Fermi-level or quasi-Fermi position. This apparent shift in energy threshold is confirmed using time resolved sub-band-gap spectroscopy. We also demonstrate that such a variation of emission rate with changes in the Fermi-level position, if present within the depletion region near a barrier junction, is consistent with the details of the temperature dependence of the junction capacitance in intrinsic samples.

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Northern Hemisphere Surface Freeze/Thaw Product from Aquarius L-band Radiometers

10.5194/essd-2018-25 ◽

2018 ◽

Author(s):

Michael Prince ◽

Alexandre Roy ◽

Ludovic Brucker ◽

Alain Royer ◽

Youngwook Kim ◽

...

Keyword(s):

Northern Hemisphere ◽

Earth Science ◽

Surface Air Temperature ◽

Freezing And Thawing ◽

Science Data ◽

Freeze Thaw ◽

Open Land ◽

Hemisphere Surface ◽

L Band ◽

Earth Science Data

Abstract. In the Northern Hemisphere, seasonal changes in surface freeze/thaw (FT) cycle are an important component of surface energy, hydrological and eco-biogeochemical processes that must be accurately monitored. This paper presents the weekly polar-gridded Aquarius passive L-Band surface freeze/thaw product (FT-AP) distributed on the Equal-Area Scalable Earth Grid version 2.0, above the parallel 50° N, with a spatial resolution of 36 km x 36 km. The FT-AP classification algorithm is based on a seasonal threshold approach using the normalized polarization ration, references for frozen and thawed conditions and optimized thresholds. To evaluate the uncertainties of the product, we compared it with another satellite FT product also derived from passive microwave observations but at higher frequency: the resampled 37 GHz FT Earth Science Data Record (FT-ESDR). The assessment was carried out during the overlapping period between 2011 and 2014. Results show that 77.1 % of their common grid cells have an agreement better than 80 %. Their differences vary with land cover type (tundra, forest and open land) and freezing and thawing periods. The best agreement is obtained during the thawing transition and over forest areas, with differences between product mean freeze or thaw onsets of under 0.4 weeks. Over tundra, FT-AP tends to detect freeze onset 2–5 weeks earlier than FT-ESDR, likely due to FT sensitivity to the different frequencies used. Analysis with mean surface air temperature time series from six in situ meteorological stations shows that the main discrepancies between FT-AP and FT-ESDR are related to false frozen retrievals in summer for some regions with FT-AP. The Aquarius product is distributed by the U.S. National Snow and Ice Data Center (NSIDC) at https://nsidc.org/data/nsidc-0736/versions/1 with the doi:10.5067/OV4R18NL3BQR.

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Balloon-borne radiometer measurement of Northern Hemisphere mid-latitude stratospheric HNO<sub>3</sub> profiles spanning 12 years

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-11561-2007 ◽

2007 ◽

Vol 7 (4) ◽

pp. 11561-11586 ◽

Cited By ~ 1

Author(s):

M. Toohey ◽

B. M. Quine ◽

K. Strong ◽

P. F. Bernath ◽

C. D. Boone ◽

...

Keyword(s):

Northern Hemisphere ◽

Atmospheric Chemistry ◽

Thermal Emission ◽

Emission Spectra ◽

Late Summer ◽

Radiative Properties ◽

Mixing Ratios ◽

Retrieval Technique ◽

Chemistry Experiment ◽

Radiometer Measurement

Abstract. Low-resolution atmospheric thermal emission spectra collected by balloon-borne radiometers over the time span of 1990–2002 are used to retrieve vertical profiles of HNO3, CFC-11 and CFC-12 volume mixing ratios between approximately 10 and 35 km altitude. All of the data analyzed have been collected from launches from a Northern Hemisphere mid-latitude site, during late summer, when stratospheric dynamic variability is at a minimum. The retrieval technique incorporates detailed forward modeling of the instrument and the radiative properties of the atmosphere, and obtains a best fit between modeled and measured spectra through a combination of onion-peeling and global optimization steps. The retrieved HNO3 profiles are consistent over the 12-year period, and are consistent with recent measurements by the Atmospheric Chemistry Experiment-Fourier transform spectrometer satellite instrument. This suggests that, to within the errors of the 1990 measurements, there has been no significant change in the HNO3 summer mid-latitude profile.

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Baroclinic waves in the northern hemisphere of Mars as observed by the MRO Mars Climate Sounder and the MGS Thermal Emission Spectrometer

Icarus ◽

10.1016/j.icarus.2020.114152 ◽

2020 ◽

pp. 114152

Author(s):

David P. Hinson ◽

R. John Wilson

Keyword(s):

Northern Hemisphere ◽

Thermal Emission ◽

Baroclinic Waves

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Non-Contact Photo-Assisted Charge-Based Characterization of Dielectric Interfaces in SiC: Evidence of Slow States

Materials Science Forum ◽

10.4028/www.scientific.net/msf.897.139 ◽

2017 ◽

Vol 897 ◽

pp. 139-142 ◽

Cited By ~ 1

Author(s):

Alexander Savtchouk ◽

Marshall Wilson ◽

Jacek Lagowski

Keyword(s):

Thermal Emission ◽

Interface State ◽

Interface States ◽

Time Resolved ◽

Uv Illumination ◽

Dielectric Interfaces ◽

Charging Current ◽

The Cost ◽

Minority Carriers

In this work we present novel photo-assisted characterization of dielectric interfaces in SiC using a modified non-contact corona-Kelvin technique. This technique eliminates the cost and time associated with fabrication of electrical test structures. UV illumination in deep depletion is used to generate minority carriers that empty deep interface states too slow to be emptied by thermal emission. After illumination, the interface state charging current is measured with time resolved voltage decay. This enables novel non-contact corona-Kelvin characterization of hole emission and electron capture processes involving slow interface states. This novel application complements standard corona-Kelvin measurement of dielectric, interface and semiconductor parameters.

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Transient eddy kinetic energetics on Mars in three reanalysis datasets

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-21-0038.1 ◽

2021 ◽

Author(s):

J. Michael Battalio

Keyword(s):

Kinetic Energy ◽

Energy Conversion ◽

Northern Hemisphere ◽

Thermal Emission ◽

Ensemble Member ◽

Eddy Kinetic Energy ◽

Mean Flow ◽

Short Period ◽

Barotropic Energy Conversion ◽

Baroclinic Energy Conversion

AbstractThe ability of Martian reanalysis datasets to represent the growth and decay of short-period (1.5 < P < 8 sol) transient eddies is compared across the Mars Analysis Correction Data Assimilation (MACDA), Open access to Mars Assimilated Remote Soundings (OpenMARS), and Ensemble Mars Reanalysis System (EMARS). Short-period eddies are predominantly surface-based, have the largest amplitudes in the northern hemisphere, and are found, in order of decreasing eddy kinetic energy amplitude, in Utopia, Acidalia, and Arcadia Planitae in the northern hemisphere, and south of the Tharsis Plateau and between Argyre and Hellas Basins in the southern hemisphere. Short-period eddies grow on the upstream (western) sides of basins via baroclinic energy conversion and by extracting energy from the mean flow and long-period (P > 8 sol) eddies when interacting with high relief. Overall, the combined impact of barotropic energy conversion is a net loss of eddy kinetic energy, which rectifies previous conflicting results. When Thermal Emission Spectrometer observations are assimilated (Mars years 24–27), all three reanalyses agree on eddy amplitude and timing, but during the Mars Climate Sounder (MCS) observational era (Mars years 28–33), eddies are less constrained. The EMARS ensemble member has considerably higher eddy generation than the ensemble mean, and bulk eddy amplitudes in the deterministic OpenMARS reanalysis agree with the EMARS ensemble rather than the EMARS member. Thus, analysis of individual eddies during the MCS era should only be performed when eddy amplitudes are large and when there is agreement across reanalyses.

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Balloon-borne radiometer measurements of Northern Hemisphere mid-latitude stratospheric HNO<sub>3</sub> profiles spanning 12 years

Atmospheric Chemistry and Physics ◽

10.5194/acp-7-6075-2007 ◽

2007 ◽

Vol 7 (23) ◽

pp. 6075-6084 ◽

Cited By ~ 2

Author(s):

M. Toohey ◽

B. M. Quine ◽

K. Strong ◽

P. F. Bernath ◽

C. D. Boone ◽

...

Keyword(s):

Northern Hemisphere ◽

Atmospheric Chemistry ◽

Thermal Emission ◽

Emission Spectra ◽

Late Summer ◽

Radiative Properties ◽

Mixing Ratios ◽

Retrieval Technique ◽

Chemistry Experiment

Abstract. Low-resolution atmospheric thermal emission spectra collected by balloon-borne radiometers over the time span of 1990–2002 are used to retrieve vertical profiles of HNO3, CFC-11 and CFC-12 volume mixing ratios between approximately 10 and 35 km altitude. All of the data analyzed have been collected from launches from a Northern Hemisphere mid-latitude site, during late summer, when stratospheric dynamic variability is at a minimum. The retrieval technique incorporates detailed forward modeling of the instrument and the radiative properties of the atmosphere, and obtains a best fit between modeled and measured spectra through a combination of onion-peeling and optimization steps. The retrieved HNO3 profiles are consistent over the 12-year period, and are consistent with recent measurements by the Atmospheric Chemistry Experiment-Fourier transform spectrometer satellite instrument. We therefore find no evidence of long-term changes in the HNO3 summer mid-latitude profile, although the uncertainty of our measurements precludes a conclusive trend analysis.

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