scholarly journals Observation of tropospheric δ D by IASI over the Western Siberia: comparison with a GCM

2013 ◽  
Vol 6 (6) ◽  
pp. 11055-11092 ◽  
Author(s):  
M. Pommier ◽  
J.-L. Lacour ◽  
C. Risi ◽  
F.-M. Bréon ◽  
C. Clerbaux ◽  
...  
Keyword(s):  
Western Siberia ◽  
Signal To Noise Ratio ◽  
Specific Humidity ◽  
Remote Region ◽  
Satellite Measurements ◽  
Signal To Noise ◽  
Atmospheric Sounding ◽  
Global Coverage ◽  
Observational Errors ◽  
Good Signal

Abstract. This study presents the joint H216O and HDO retrieval from Infrared Atmospheric Sounding Interferometer (IASI) spectra over the Western Siberia. IASI is an instrument on board the MetOp-A European satellite. The global coverage of the instrument and the good signal-to-noise ratio allow us to provide information on δ D over this remote region. We show that IASI measurements may be used to estimate integrated δ D between the surface and 3 km altitude or from 1 to 5 km depending on the thermal contrast, with observational errors lower than 4% and 8%, respectively. The retrieved data are compared to simulations from an isotopic GCM, LMDZ-iso over 2011. The satellite measurements reproduce well the seasonal and day-to-day variations for δ D, showing for the latter a good correlation with the model (r up to 0.8 with the smoothed data in summer). The IASI-based retrievals also show the seasonal variation of the specific humidity in both altitude ranges.

scholarly journals Observation of tropospheric δD by IASI over western Siberia: comparison with a general circulation model

2014 ◽  
Vol 7 (6) ◽  
pp. 1581-1595 ◽  
Author(s):  
M. Pommier ◽  
J.-L. Lacour ◽  
C. Risi ◽  
F. M. Bréon ◽  
C. Clerbaux ◽  
...  
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Western Siberia ◽  
Signal To Noise Ratio ◽  
Circulation Model ◽  
Specific Humidity ◽  
Satellite Measurements ◽  
Global Coverage ◽  
Observational Errors ◽  
Good Signal

Abstract. This study presents the joint H216O and HDO retrieval from Infrared Atmospheric Sounding Interferometer (IASI) spectra over western Siberia. IASI is an instrument on board the MetOp-A European satellite. The global coverage of the instrument and the good signal-to-noise ratio allow us to provide information on δD over this remote region. We show that IASI measurements may be used to estimate integrated δD between the surface and 3 km altitude or from 1 to 5 km depending on the thermal contrast, with observational errors lower than 4% and 7%, respectively. The retrieved data are compared to simulations from an isotopic general circulation model, LMDZ-iso for 2011. The satellite measurements and the model agree well and they reproduce well the seasonal and day-to-day variations for δD, presenting a good correlation (r up to 0.8 with the smoothed data in summer). The IASI-based retrievals also show the seasonal variation of the specific humidity in both altitude ranges.

Retrieval of chlorine dioxide columns from Sentinel-5p observations

2020 ◽  
Author(s):  
Andreas Carlos Meier ◽  
Andreas Richter ◽  
Gaia Pinardi ◽  
Michel Van Roozendael ◽  
John Philip Burrows
Keyword(s):  
Chlorine Dioxide ◽  
Signal To Noise Ratio ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Current Status ◽  
Innovation Activity ◽  
Signal To Noise ◽  
Fine Spatial Resolution ◽  
Global Coverage ◽  
Good Signal

<p>The Sentinel-5-precursor (S5p) satellite with the TROPOMI payload was launched on 13 October 2017. It is part of the European Copernicus program and provides a set of operational products of atmospheric constituents related to air quality and climate change with almost daily global coverage. The good signal to noise ratio of the instrument enables precise measurements despite the fine spatial resolution of 3.5 x 5.5 km2. </p><p><br>The ESA S5p+ Innovation activity aims at extending the list of S5p products with scientific products, which are not yet part of the operational processor, to exploit the potential of the Sentinel-5p mission’s capabilities beyond its primary objectives. The retrieval of chlorine dioxide (OClO) from S5p is among the seven funded sub projects. Chlorine dioxide is an indicator for chlorine activation in the stratosphere and thus of importance for the understanding of stratospheric ozone chemistry, in particular in the polar vortex. Chlorine dioxide was retrieved from heritage instruments (GOME, SCIAMACHY, GOME2, OMI) and the S5p OClO product will act as a continuation of these time-series.</p><p><br>Here we present the current status of the IUP-Bremen S5p OClO product developed within the ESA S5p+ Innovation framework. The new S5p product will be put into context with products from previous and current (e.g. GOME-2c) satellite missions as well as ground-based measurements used for validation.</p>

Estimating Optimum Filter Length in Linear Prediction

1997 ◽  
Vol 51 (5) ◽  
pp. 718-720 ◽  
Author(s):  
O.-P. Sievänen
Keyword(s):  
Raman Spectra ◽  
Prediction Error ◽  
Linear Prediction ◽  
Signal To Noise Ratio ◽  
New Method ◽  
Signal To Noise ◽  
Filter Length ◽  
Optimum Filter ◽  
Good Signal ◽  
Prediction Filter

In this article a new method to estimate optimum filter length in linear prediction is described. Linear prediction was used to enhance resolution of a spectrum. In particular, the dependence of prediction error on filter length has been studied. With calculations of simulated spectra it is shown that the prediction error falls rapidly when the filter length attains its optimum value. This effect is quite pronounced when the spectrum has a good signal-to-noise ratio and the modified covariance method is used to calculate prediction filter coefficients. The method is illustrated with applications to real Raman spectra.

scholarly journals Direct Observations of the Heterogeneity of Supergiant Disks

1977 ◽  
Vol 4 (2) ◽  
pp. 405-405
Author(s):  
J. W. Harvey ◽  
C. R. Lynds ◽  
S. P. Worden
Keyword(s):  
Signal To Noise Ratio ◽  
Atmospheric Dispersion ◽  
Stellar Atmosphere ◽  
High Magnification ◽  
Specific Technique ◽  
Signal To Noise ◽  
Speckle Imaging ◽  
Direct Observations ◽  
Good Signal ◽  
Limb Darkening

Resolved images of the disks of the largest stars observed with the largest telescopes can be constructed using the class of techniques called speckle imaging. The observations must be made with narrow passbands (~ 10 nm), short exposures (~ 20 ms) compensation for atmospheric dispersion, high magnification and good signal-to-noise ratio. One specific technique applied to a Ori (Lynds et al., 1976) shows slight but apparently real differences in the images of the disk corresponding to low and high opacity in the stellar atmosphere which we interpret as due to temperature differences. There are also significant differences in the star’s diameter and/or limb darkening at the two different opacity wavelengths.

Spectroscopy with Nonimaging Optics: Application to the Infrared Spectroscopy of Langmuir Monolayers

1992 ◽  
Vol 46 (5) ◽  
pp. 725-731 ◽  
Author(s):  
Joseph T. Buontempo ◽  
Stuart A. Rice
Keyword(s):  
Infrared Spectroscopy ◽  
Crystalline Phase ◽  
Signal To Noise Ratio ◽  
Langmuir Monolayers ◽  
Infrared Light ◽  
Signal To Noise ◽  
Low Intensity ◽  
Nonimaging Optics ◽  
Infrared Reflection ◽  
Good Signal

We discuss the principles of nonimaging optics and demonstrate how nonimaging concentrators can be used to maximize the collection of low-intensity infrared light. Specifically, we show that infrared reflection-absorption spectra can be obtained from a Langmuir monolayer of heneicosanol with a reasonable number of scans. Preliminary results indicate that at 24 Å2/molecule and 6 dyne/cm a heneicosanol monolayer is in a crystalline phase with highly ordered, mostly all- trans molecules, and at 42 Å2/molecule and 0 dyne/cm the monolayer consists of islands of the crystalline phase in coexistence with disordered molecules in a liquid phase. The good signal-to-noise ratio of the spectra obtained demonstrates the important role that nonimaging optics has in spectroscopy, by maximizing light throughput, and we make several suggestions for its implementation in other spectroscopic applications.

Practicalities of Data Collection

2017 ◽  
pp. 77-88
Author(s):  
Riitta Hari ◽  
Aina Puce
Keyword(s):  
Data Collection ◽  
Infection Control ◽  
Signal To Noise Ratio ◽  
Impedance Measurement ◽  
Electrical Safety ◽  
High Signal ◽  
Electrode Impedance ◽  
Signal To Noise ◽  
Skin Preparation ◽  
Good Signal

This chapter provides a number of suggestions about optimization of MEG/EEG recording sessions to guarantee as good signal quality and as high signal-to-noise ratio as possible. It also advices for performing replicability checks on the data. The practical aspects of preparing and performing an EEG recording (skin preparation, electrode-impedance measurement) and postrecording infection control are presented. Similarly, practicalities of performing MEG recordings are discussed. Measurement of MEG sensor-array location with respect to landmarks on the scalp and different methods for the measurement of EEG electrode positions are presented. The chapter ends with a discussion on electrical safety in the MEG/EEG laboratory.

The Silicon Pixel Sensors in ATLAS

2001 ◽  
Vol 16 (supp01c) ◽  
pp. 1100-1102 ◽  
Author(s):  
◽  
IGOR GOLELOV
Keyword(s):  
Collection Efficiency ◽  
Signal To Noise Ratio ◽  
Small Cell ◽  
Pixel Detector ◽  
Signal To Noise ◽  
Charge Collection Efficiency ◽  
Atlas Experiment ◽  
Pixel Sensors ◽  
Small Cell Size ◽  
Good Signal

The ATLAS experiment is now in the process of finalizing the development of the design of silicon pixel sensors for use in the pixel detector. The sensors will be operated in a severe LHC radiation enviroment with bias voltages at the end of lifetime up to 600 V while maintaining a good signal-to-noise ratio and charge collection efficiency, small cell size and minimal multiple scattering. The radiation hardness issues and quality assurance procedures are discussed.

scholarly journals Two-color modulation transfer spectroscopy

2009 ◽  
Vol 87 (1) ◽  
pp. 95-100 ◽  
Author(s):  
A Pérez Galván ◽  
D Sheng ◽  
L A Orozco ◽  
Y Zhao
Keyword(s):  
Velocity Distribution ◽  
Excited States ◽  
Signal To Noise Ratio ◽  
Modulation Transfer ◽  
Signal To Noise ◽  
Atomic Properties ◽  
Laser Frequencies ◽  
Step Transition ◽  
Good Signal

We present two-color modulation transfer spectroscopy as a tool for precision studies of atomic properties of excited states. The bi-colored technique addresses a narrow set of velocity groups of a thermal atomic vapour using a two-step transition to “burn a hole” in the velocity distribution. The resulting spectrum presents sub-Doppler linewidths, good signal-to-noise ratio and the trademark sidebands that work as an {in situ} ruler for the energy spacing between atomic resonances. The spectra obtained can be used for different applications such as measurements of energy splittings or stabilization of laser frequencies to excited atomic transitions.PACS Nos.: 32.10.Fn, 32.30.–r, 42.50.Gy, 42.60.Fc

scholarly journals Advantages of a soft protective layer for good signal-to-noise ratio proton radiographs in high debris environments

2011 ◽  
Vol 7 (4) ◽  
pp. 247-251
Author(s):  
Nathalie Renard-Le Galloudec ◽  
J. Cobble ◽  
S.L. Nelson ◽  
A. Merwin ◽  
Y. Paudel ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Protective Layer ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Good Signal
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