Spectroscopic database for TROPOMI/Sentinel-5P: CO and H2O at 2.3μm

The TROPOspheric Monitoring Instrument (TROPOMI) aboard the European Space Agency's Copernicus Sentinel-5 Precursor satellite, to be launched this year, mandates high-accuracy spectral reference data for CO and H2O in the 2.3μm region [1]. We present measurements of absorption line parameters for H2O and for the 2-0 rovibrational band of CO to be used in TROPOMI atmospheric retrievals. The experiments were carried out on a Bruker IFS 125HR Fourier transform spectrometer and a multispectrum fitting software developed at DLR was used for parameter retrieval [2] using the Hartmann-Tran-Profile [3,4]. In the case of carbon monoxide, we report line intensities, air-broadening and -shift parameters for lines of the 2-0 rovibrational band, which serve as a useful validation of the HITRAN2012 spectral database [5] while our analysis of Dicke narrowing, speed dependence and Rosenkranz line mixing emphasizes the importance of modern line shape functions. Comparisons with previous studies of these non-Voigt parameters (e.g. [6]) show good agreement. As for H2O, spectral parameters were measured in the 4190cm-1-4340cm-1 spectral range. Comparisons of measured line intensities of the ν3 band show remarkable agreement (<1.5% deviation on average) with ab initio values [7,8] and we will present air-broadening, -narrowing and -shift parameters together with their temperature dependences. References [1] J.P. Veefkind et al, Remote Sensing of Environment 120, 70 (2012) [2] J. Loos et al, 13th HITRAN database conference, 2014 (doi: 10.5281/zenodo.11156) [3] N.H. Ngo et al, JQSRT 129, 89 (2013) [4] N.H. Ngo et al, JQSRT 134, 105 (2014) [5] L.S. Rothman et al, JQSRT 130, 4 (2013) [6] V.M. Devi et al, JQSRT 113, 1013 (2012) [7] L. Lodi et al, J Chem Phys 135, 034113 (2011) [8] J. Tennyson, University College London, Private communicatio

Level 1b error budget for MIPAS on ENVISAT

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a Fourier transform spectrometer measuring the radiance emitted from the atmosphere in limb geometry in the thermal infrared spectral region. It was operated onboard the ENVISAT satellite from 2002 to 2012. Calibrated and geolocated spectra, the so-called level 1b data, are the basis for the retrieval of atmospheric parameters. In this paper we present the error budget for the level 1b data of the most recent data version 8 in terms of radiometric, spectral, and line of sight accuracy. The major changes of version 8 compared to older versions are also described. The impact of the different error sources on the spectra is characterized in terms of spectral, vertical, and temporal correlation because these correlations have an impact on the quality of the retrieved quantities. The radiometric error is in the order of 1% to 2.4%, the spectral accuracy is better than 0.3ppm, and the line of sight accuracy at the tangent point is around 400m. All errors are well within the requirements, and the achieved accuracy allows atmospheric parameters to be retrieved from the measurements with high quality

Fourier-transform intensity measurements with 0.1% accuracy

Remote sensing of atmospheric trace gases with climate relevance requires spectroscopic data with better than 0.1% absolute intensity accuracy. This requirement poses a big challenge, especially to Fourier-transform spectroscopy (FTS). The alternative CRDS method has the advantage of a higher sensitivity compared to FTS. CRDS is also independent from cavity length and there is no instrumental line shape. In contrast, the FTS technique has the major advantages of a broadband coverage and the entire spectral range is measured simultaneously. Both techniques are thus complementary. The demanding metrological requirements for multireflection cell absorption path determination as well as for pressure and temperature measurement to achieve 0.1% absolute intensity accuracies will be addressed. Furthermore, the instrumental line shape characterization, the treatment of offset errors, and multipassing will be discussed. For this high accuracy application, a sophisticated multispectrum fitting software is essential. Finally, highly accurate results require several measurements under different conditions to validate the overall uncertainties. As examples CO 3-0 and CO2 1.6 µm intensity measurements will be presented

Measurement of positions, intensities and self-broadening line shape parameters of H2O lines in the spectral ranges 1850-2280 cm-1 and 2390-4000 cm-1

A Bruker IFS 125 HR Fourier transform spectrometer was used to measure several pure water transmittance spectra in the spectral range 1850-4000cm-1. A total of 15 measurements with Absorption path lengths between 24.9 cm and 174.6 m and sample gas pressures from 0.1 to 20 mbar were performed at 296 K. The transmittance spectra were corrected for various error sources and were analyzed in the spectral ranges 1850-2280 cm-1 and 2390-4000 cm-1 for the majority of intensities between 3x10-26 and 3x10-19 cm molecule-1. A multispectrum fitting Approach was used applying a quadratic speed-dependent Voigt model Extended to account for line mixing in the Rosenkranz first order perturbation approximation. Line positions, intensities,self-broadening widths, their speed-dependence and in some cases line mixing had to be adjusted for fitting the measurements to noise level. An extensive error estimation calculation was performed propagating several instrumental and measurement errors into individual parameter inaccuracies. The determined Parameters are compared to HITRAN12 and Independent experimental values while intensities are compared to recent ab initio calculations performed at UCL. The Overall agreement between ab initio calculations and experimental values is remarkable and below 1% in most cases. The determined line Parameters are provided as a Supplement to this publication

Remote Sensing of Stratospheric Trace Gases by TELIS

TELIS (TErahertz and submillimeter LImb Sounder) is a balloon-borne cryogenic heterodyne spectrometer with two far infrared and submillimeter channels (1.8 THz and 480--650 GHz developed by DLR and SRON, respectively). The instrument was designed to investigate atmospheric chemistry and dynamics with a focus on the stratosphere. TELIS participated in three scientific campaigns in Kiruna, Sweden between 2009 and 2011. The recent campaign took place in 2014 over Ontario, Canada. During previous campaigns, TELIS shared a balloon gondola with MIPAS-B and mini-DOAS. The primary scientific goal of these campaigns has been to monitor the time-dependent chemistry of chlorine and bromine, and to achieve the closure of chemical families inside the polar vortex. In this work, we present retrieved profiles of ozone (O3), hydrogen chlorine (HCl), carbon monoxide (CO), and hydroxyl radical (OH) obtained by the 1.8 THz channel from the polar winter flights during 2009--2011. Furthermore, the corresponding retrieval algorithm is described. The quality of the retrieval products is analyzed in a quantitative manner including: error characterization, internal comparisons of the two different channels, and external comparisons with coincident spaceborne observations. The errors due to the instrument parameters and pressure dominate in the upper troposphere and lower stratosphere, while the errors at higher altitudes are mainly due to the spectroscopic parameters and the radiometric calibration. The comparisons with other limb sounders help us to assess the measurement capabilities of TELIS, thereby establishing the instrument as a valuable tool to study the chemical interactions in the stratosphere

FT spectroscopy in support of atmospheric spectroscopic databases: Recent advances at DLR

High resolution Fourier Transform spectroscopy of atmospheric trace gas has been carried out at DLR since 1990. The primary focus is on supplying well characterized uncertainties. The core instrument is the commercial high-resolution Bruker IFS 125 HR Fourier-transform spectrometer operating from 10 to 40000 cm-1. The laboratory infrastructure has been continuously improved over the last 30 years, especially the absorption cells. A 22 cm absorption path 200-350 K cell features two windows pairs allowing quasi-simultaneous measurement from FIR to UV. A 200 m absorption path multireflection cell operates in the temperature range 200-350 K with high temperature homogeneity. Line fitting software was steadily improved, resulting in a multispectrum fitting tool with several line shape models including the Hartmann-Tran profile. The instrumental line shape of the Fourier-transform spectrometer is adopted from the LINEFIT software by Frank Hase, IMK, which is also used by the TCCON community. Recent results are a spectroscopic database of the O3 fundamentals and temperature dependent UV absorption cross sections for O3, together solving the 4% discrepancy between UV and MIR atmospheric O3 columns, a comprehensive H2O spectroscopic database in the range 1850-4300 cm-1, a new method to obtain H2O continua, H2O foreign- and self-continua in the 3 µm region, and a CO2 database in the range 6000-7000 cm-1 with absolute intensity uncertainties <0.15%. Most of these results have become part of the HITRAN20 database

Pressure-Dependent Line Intensity and Continuum Absorption for Pure Co2: Experimental Results

Fourier-transform measurements of pure CO2 in the 1.6 µm region covering bands from ground state to 30011, 30012, 30013, and 30014 states at ambient temperature and 212 K with pressures up to 1 bar have been recorded. Line parameters have been retrieved by multispectrum fitting. An intensity depletion parameter quantifying linear intensity dependence on pressure was introduced and fitted. From the fitted baseline polynomials the self continuum was determined for the 30012 and 30013 bands. The depleted intensity was found to be transferred to the continuum for both temperatures, thus the band intensity is conserved. The intensity in the continuum at 1 atm was about 1% of the total band intensities for ambient temperature and about 3% at 212 K. For both temperatures the depleted intensity/continuum area was found in excellent agreement with values calculated from the second virial coefficient. The experimental work is accompanied by rCMDS calculations. The results presented here have significant impact on CO2 retrieval from atmospheric measurements. For OCO/CO2M-type observations it was calculated that in case of the 2 µm band retrieved CO2 columns are too large by about 3% when omitting depletion and continuum. A new spectroscopic database was produced. Systematic line intensity uncertainties are well below 0.1%

Virtue and the Health Professions

Presented to the WMU Center for the Study of Ethics in Society, February 8, 1991

Efficient Processing of Geospatial mHealth Data Using a Scalable Crowdsensing Platform

Smart sensors and smartphones are becoming increasingly prevalent. Both can be used to gather environmental data (e.g., noise). Importantly, these devices can be connected to each other as well as to the Internet to collect large amounts of sensor data, which leads to many new opportunities. In particular, mobile crowdsensing techniques can be used to capture phenomena of common interest. Especially valuable insights can be gained if the collected data are additionally related to the time and place of the measurements. However, many technical solutions still use monolithic backends that are not capable of processing crowdsensing data in a flexible, efficient, and scalable manner. In this work, an architectural design was conceived with the goal to manage geospatial data in challenging crowdsensing healthcare scenarios. It will be shown how the proposed approach can be used to provide users with an interactive map of environmental noise, allowing tinnitus patients and other health-conscious people to avoid locations with harmful sound levels. Technically, the shown approach combines cloud-native applications with Big Data and stream processing concepts. In general, the presented architectural design shall serve as a foundation to implement practical and scalable crowdsensing platforms for various healthcare scenarios beyond the addressed use case

Design and Implementation of a Scalable Crowdsensing Platform for Geospatial Data of Tinnitus Patients

Smart devices and low-powered sensors are becoming increasingly ubiquitous and nowadays almost all of these devices are connected, which is a promising foundation for crowdsensing of data related to various environmental phenomena. Resulting data is especially meaningful when it is related to time and location. Interestingly, many existing approaches built their solution on monolithic backends that process data on a per-request basis. However, for many scenarios, such technical setting is not suitable for managing data requests of a large crowd. For example, when dealing with millions of data points, still many challenges arise for modern smartphones if calculations or advanced visualization features must be accomplished directly on the smartphone. Therefore, the work at hand proposes an architectural design for managing geospatial data of tinnitus patients, which combines a cloudnative approach with Big Data concepts used in the Internet of Things. The presented architectural design shall serve as a generic foundation to implement (1) a scalable backend for a platform that covers the aforementioned crowdsensing requirements as well as to provide (2) a sophisticated stream processing concept to calculate and pre-aggregate incoming measurement data of tinnitus patients. Following this, this paper presents a visualization feature to provide users with a comprehensive overview of noise levels in their environment based on noise measurements. This shall help tinnitus or hearing-impaired patients to avoid locations with a burdensome sound level