GRIPS-HI - a Novel Interferometer for Measuring Two-Dimensional Temperature Distributions at the Mesopause

The NDMC (Network for the Detection of Mesopause Change) is a global network of ground based observatories with the objective of monitoring key parameters of the mesopause region. For temperature monitoring GRound-based Infrared P-branch Spectrometers (GRIPS) are widely deployed. These spectrometers allow for the retrieval of the mesopause temperature from the OH* P-band emission lines around 1530 nm. A common technology for GRIPS instruments are spectrometers based on diffraction gratings. To overcome the limitations of conventional grating spectrometers, a new type of spectrometer is being developed within the project Metrology for Earth Observation and Climate - 3 (MetEOC-3) which is coordinated by the European Metrology Project for Innovation and Research (EMPIR). The new spectrometer shall improve the quality and traceability of the atmospheric data obtained by the NDMC. It is intended to serve as a reference instrument with significantly smaller measurement uncertainties. It is also designed to identify temperature trends of 1K/decade. A Spatial Heterodyne Interferometer (SHI) was chosen as the most promising technology, offering several advantages. Compared to conventional grating spectrometers, the throughput and resolution of the interferometer is one order of magnitude larger. The use of a two-dimensional detector array in combination with an imaging optics enables the detection of spatial temperature distributions in the mesopause region, as caused by dynamical processes like gravity waves. The talk gives an introduction to the technology of spatial heterodyne interferometry, and the new instrument design and calibration results are presented.

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GRIPS-HI, a novel spectral imager for ground based measurements of mesopause temperatures

tm - Technisches Messen ◽

10.1515/teme-2021-0043 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Johannes Stehr ◽

Peter Knieling ◽

Friedhelm Olschewski ◽

Klaus Mantel ◽

Martin Kaufmann ◽

...

Keyword(s):

Spectral Resolution ◽

Global Network ◽

Vibrationally Excited ◽

Mesopause Region ◽

Order Of Magnitude ◽

Climate Signals ◽

Mesopause Temperature ◽

Spectral Imager ◽

New Generation ◽

Key Parameter

Abstract The NDMC (Network for the Detection of Mesospheric Change) is a global network of measurement sites dedicated to the surveillance of the mesopause region. One main objective of the network is the early identification of climate signals. A key parameter is the mesopause temperature which can be derived from the emission spectrum of a layer of vibrationally excited hydroxyl (OH) at an altitude of approximately 87 km 87\hspace{0.1667em}\text{km} . Foremost, emission lines in the SWIR regime between 1520 nm 1520\hspace{0.1667em}\text{nm} and 1550 nm 1550\hspace{0.1667em}\text{nm} are of interest for remote temperature sensing. This report deals with the development of a new generation of GRIPS instruments, which are commonly employed for the observation of mesopause temperatures. The new prototype demonstrates how the application of so called Spatial Heterodyne Interferometers (SHI) can overcome the limitations of currently used grating spectrometers, in terms of spectral resolution and optical throughput. The presented prototype proposes improvements in optical throughput and spectral resolution of about one order of magnitude, significantly reducing the uncertainties of the measured mesopause temperatures. Furthermore, an SHI can be built in monolithic configurations which are aligned and characterized once during assembly without the need of realignment at the measurement site. This makes SHI based instruments ideal for mobile applications.

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A two-dimensional glacier–fjord coupled model applied to estimate submarine melt rates and front position changes of Hansbreen, Svalbard

Journal of Glaciology ◽

10.1017/jog.2018.61 ◽

2018 ◽

Vol 64 (247) ◽

pp. 745-758 ◽

Cited By ~ 2

Author(s):

E. DE ANDRÉS ◽

J. OTERO ◽

F. NAVARRO ◽

A. PROMIŃSKA ◽

J. LAPAZARAN ◽

...

Keyword(s):

Coupled Model ◽

Small Scale ◽

Two Dimensional ◽

Time Step ◽

Software Packages ◽

Front Position ◽

Circulation Patterns ◽

Glacier Front ◽

Order Of Magnitude ◽

Frontal Ablation

ABSTRACTWe have developed a two-dimensional coupled glacier–fjord model, which runs automatically using Elmer/Ice and MITgcm software packages, to investigate the magnitude of submarine melting along a vertical glacier front and its potential influence on glacier calving and front position changes. We apply this model to simulate the Hansbreen glacier–Hansbukta proglacial–fjord system, Southwestern Svalbard, during the summer of 2010. The limited size of this system allows us to resolve some of the small-scale processes occurring at the ice–ocean interface in the fjord model, using a 0.5 s time step and a 1 m grid resolution near the glacier front. We use a rich set of field data spanning the period April–August 2010 to constrain, calibrate and validate the model. We adjust circulation patterns in the fjord by tuning subglacial discharge inputs that best match observed temperature while maintaining a compromise with observed salinity, suggesting a convectively driven circulation in Hansbukta. The results of our model simulations suggest that both submarine melting and crevasse hydrofracturing exert important controls on seasonal frontal ablation, with submarine melting alone not being sufficient for reproducing the observed patterns of seasonal retreat. Both submarine melt and calving rates accumulated along the entire simulation period are of the same order of magnitude, ~100 m. The model results also indicate that changes in submarine melting lag meltwater production by 4–5 weeks, which suggests that it may take up to a month for meltwater to traverse the englacial and subglacial drainage network.

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The Effect of Bench Arrangements on the Natural Ventilation of a Multispan Greenhouse

Volume 8A: Heat Transfer and Thermal Engineering ◽

10.1115/imece2013-63304 ◽

2013 ◽

Author(s):

Sunita Kruger ◽

Leon Pretorius

Keyword(s):

Fluid Dynamics ◽

Natural Ventilation ◽

Three Dimensional ◽

Two Dimensional ◽

Low Velocity ◽

Lower Velocity ◽

Cfd Models ◽

Temperature Distributions ◽

Computational Fluid Dynamics Cfd ◽

Plant Level

In this paper, the influence of various bench arrangements on the microclimate inside a two-span greenhouse is numerically investigated using three-dimensional Computational Fluid Dynamics (CFD) models. Longitudinal and peninsular arrangements are investigated for both leeward and windward opened roof ventilators. The velocity and temperature distributions at plant level (1m) were of particular interest. The research in this paper is an extension of two-dimensional work conducted previously [1]. Results indicate that bench layouts inside the greenhouse have a significant effect on the microclimate at plant level. It was found that vent opening direction (leeward or windward) influences the velocity and temperature distributions at plant level noticeably. Results also indicated that in general, the leeward facing greenhouses containing either type of bench arrangement exhibit a lower velocity distribution at plant level compared to windward facing greenhouses. The latter type of greenhouses has regions with relatively high velocities at plant level which could cause some concern. The scalar plots indicate that more stagnant areas of low velocity appear for the leeward facing greenhouses. The windward facing greenhouses also display more heterogeneity at plant level as far as temperature is concerned.

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Ferroelectric Liquid Crystal Light Valve Using SiO2 / A-Si:H Photodiode

MRS Proceedings ◽

10.1557/proc-219-203 ◽

1991 ◽

Vol 219 ◽

Author(s):

T. Horikawa ◽

S. Tahata ◽

S. Kaho ◽

T. Masumi ◽

N. Mikami ◽

...

Keyword(s):

Liquid Crystal ◽

Dark Conductivity ◽

Ferroelectric Liquid Crystal ◽

Two Dimensional ◽

Metal Insulator ◽

Resolution Capability ◽

New Type ◽

Light Valve ◽

Mis Diode ◽

High Photosensitivity

ABSTRACTA new type of ferroelectric liquid crystal light valve (FLCLV) is presented. The design of the FLCLV is based upon the linear equivalent circuit analyses. A photosensor in the FLCLV consists of a metal-insulator-semiconductor (MIS) photodiode. A-Si:H doped with boron and nitrogen [a-Si:(:N:B)] is used in the MIS diode. The a-Si:H(:B:N) film has a dark-conductivity of less than 1×1012 S/cm and a high photosensitivity.Consequently, the writing characteristics of the FLCLV for a two dimensional (2D) image are evaluated. Using writing light of 630 nm and 1 mW/cm2, a high resolution capability of 120∼140 1p/mm is obtained.

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Two-dimensional material-based functional aerogels for treating hazards in environment: Synthesis, functional tailoring, applications, and sustainability analysis

Nanoscale Horizons ◽

10.1039/d1nh00633a ◽

2022 ◽

Author(s):

Hao Kong ◽

Yun Chen ◽

Guozheng Yang ◽

Bin Liu ◽

Lei Guo ◽

...

Keyword(s):

Environmental Pollution ◽

Human Health ◽

Two Dimensional ◽

Ecological Balance ◽

Global Problem ◽

Sustainability Analysis ◽

New Type

Environmental pollution is a global problem that endangers human health and ecological balance. As a new type of nanomaterial, two-dimensional material (2DM)-based aerogel is one of the most promising candidates...

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Half division two-dimensional method for simple sinusoidal quantities parameters accurate measurement

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2021-4-16-21 ◽

2021 ◽

pp. 16-21

Author(s):

Kirill Yu. Solomentsev ◽

Vyacheslav I. Lachin ◽

Aleksandr E. Pasenchuk

Keyword(s):

Measuring Instruments ◽

Measured Signal ◽

Two Dimensional ◽

Measuring Device ◽

New Approach ◽

Precision Measuring ◽

Useful Signal ◽

Midpoint Method ◽

Order Of Magnitude ◽

Current Measuring

Several variants of half division two-dimensional method are proposed, which is the basis of a fundamentally new approach for constructing measuring instruments for sinusoidal or periodic electrical quantities. These measuring instruments are used in the diagnosis of electric power facilities. The most general variant, called midpoint method, is considered. The proposed midpoint method allows you to measure much smaller than using widespread methods, alternating currents or voltages, especially when changing the amplitude of the measured signal in very wide ranges, by 1–2 orders of magnitude. It is shown that using the midpoint method it is possible to suppress sinusoidal or periodic interference in the measuring path, in particular, to measure small alternating current when sinusoidal or periodic interference is 1–2 orders of magnitude higher than the useful signal. Based on the results of comparative tests, it was found that the current measuring device implementing the midpoint method is an order of magnitude more sensitive than the currently used high-precision measuring instruments.

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Post-LIA glacier changes along a latitudinal transect in the Central Italian Alps

The Cryosphere ◽

10.5194/tc-8-2235-2014 ◽

2014 ◽

Vol 8 (6) ◽

pp. 2235-2252 ◽

Cited By ~ 19

Author(s):

R. Scotti ◽

F. Brardinoni ◽

G. B. Crosta

Keyword(s):

Atmospheric Temperature ◽

Winter Precipitation ◽

Ice Age ◽

Glacier Change ◽

Mass Balances ◽

Italian Alps ◽

Temperature Trends ◽

Continental Divide ◽

Latitudinal Transect ◽

Order Of Magnitude

Abstract. The variability of glacier response to atmospheric temperature rise in different topo-climatic settings is still a matter of debate. To address this question in the Central Italian Alps, we compile a post-LIA (Little Ice Age) multitemporal glacier inventory (1860–1954–1990–2003–2007) along a latitudinal transect that originates north of the continental divide in the Livigno Mountains and extends south through the Disgrazia and Orobie ranges, encompassing continental-to-maritime climatic settings. In these sub-regions, we examine the area change of 111 glaciers. Overall, the total glacierized area has declined from 34.1 to 10.1 km2, with a substantial increase in the number of small glaciers due to fragmentation. The average annual decrease (AAD) in glacier area has risen by about 1 order of magnitude from 1860–1990 (Livigno: 0.45; Orobie: 0.42; and Disgrazia: 0.39 % a−1) to 1990–2007 (Livigno: 3.08; Orobie: 2.44; and Disgrazia: 2.27 % a−1). This ranking changes when considering glaciers smaller than 0.5 km2 only (i.e., we remove the confounding caused by large glaciers in Disgrazia), so that post-1990 AAD follows the latitudinal gradient and Orobie glaciers stand out (Livigno: 4.07; Disgrazia: 3.57; and Orobie: 2.47 % a−1). More recent (2007–2013) field-based mass balances in three selected small glaciers confirm post-1990 trends showing the consistently highest retreat in continental Livigno and minimal area loss in maritime Orobie, with Disgrazia displaying transitional behavior. We argue that the recent resilience of glaciers in Orobie is a consequence of their decoupling from synoptic atmospheric temperature trends, a decoupling that arises from the combination of local topographic configuration (i.e., deep, north-facing cirques) and high winter precipitation, which ensures high snow-avalanche supply, as well as high summer shading and sheltering. Our hypothesis is further supported by the lack of correlations between glacier change and glacier attributes in Orobie, as well as by the higher variability in ELA,sub>0 positioning, post-LIA glacier change, and interannual mass balances, as we move southward along the transect.

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Three-dimensional disturbances to a mixing layer in the nonlinear critical-layer regime

Journal of Fluid Mechanics ◽

10.1017/s002211209500262x ◽

1995 ◽

Vol 291 ◽

pp. 57-81 ◽

Cited By ~ 2

Author(s):

S. M. Churilov ◽

I. G. Shukhman

Keyword(s):

Travelling Waves ◽

Mixing Layer ◽

Three Dimensional ◽

Critical Layer ◽

Dimensional Case ◽

Two Dimensional ◽

Weakly Nonlinear ◽

Weakly Nonlinear Theory ◽

New Type ◽

Two Stages

We consider the nonlinear spatial evolution in the streamwise direction of slightly three-dimensional disturbances in the form of oblique travelling waves (with spanwise wavenumber kz much less than the streamwise one kx) in a mixing layer vx = u(y) at large Reynolds numbers. A study is made of the transition (with the growth of amplitude) to the regime of a nonlinear critical layer (CL) from regimes of a viscous CL and an unsteady CL, which we have investigated earlier (Churilov & Shukhman 1994). We have found a new type of transition to the nonlinear CL regime that has no analogy in the two-dimensional case, namely the transition from a stage of ‘explosive’ development. A nonlinear evolution equation is obtained which describes the development of disturbances in a regime of a quasi-steady nonlinear CL. We show that unlike the two-dimensional case there are two stages of disturbance growth after transition. In the first stage (immediately after transition) the amplitude A increases as x. Later, at the second stage, the ‘classical’ law A ∼ x2/3 is reached, which is usual for two-dimensional disturbances. It is demonstrated that with the growth of kz the region of three-dimensional behaviour is expanded, in particular the amplitude threshold of transition to the nonlinear CL regime from a stage of ‘explosive’ development rises and therefore in the ‘strongly three-dimensional’ limit kz = O(kx) such a transition cannot be realized in the framework of weakly nonlinear theory.

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Synchrotron and Laboratory Studies Utilizing a New Powder Diffraction Technique

Advances in X-ray Analysis ◽

10.1154/s0376030800019315 ◽

1992 ◽

Vol 36 ◽

pp. 653-661 ◽

Cited By ~ 1

Author(s):

G. S. Knapp ◽

M. A. Beno ◽

G. Jennings ◽

M. Engbretson ◽

M. Ramanathan

Keyword(s):

Powder Diffraction ◽

Sample Surface ◽

X Rays ◽

High Count ◽

Synchrotron Source ◽

Bent Crystal ◽

Capillary Sample ◽

Order Of Magnitude ◽

New Type ◽

Large Improvement

AbstractWe have developed a new type of powder diffractometer. The diffractometer has the potential of both high count rates and very high resolution when used at a synchrotron source. The laboratory based instrument can achieve an order of magnitude improvement in count rate over existing methods with proper optics. The method uses a focusing diffracted beam monochromator in combination with a multichannel detector. The incident x-rays fall on a flat plate or capillary sample and are intercepted by a bent focusing monochromator which has the focus of the bend at the sample surface. The powder diffraction lines emerging from the bent crystal monochromator are detected by a linear or 2-dimensional detector. This allows us to eliminate the background from fluorescence or other scattering and to take data over a range of 3° to 4° instead of one angle at a time thereby providing a large improvement over conventional diffractometers.

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