Assessment of Ground-Based Microwave Radiometer Calibration to Enable Investigation of Gas Absorption Models

Ground-based microwave radiometers are becoming more and more common for remotely sensing the atmospheric temperature and humidity profile, as well as path integrated cloud liquid water content. Several studies have been published, which compare radiosonde profiles with temperature profiles derived from microwave radiometer measurements and find biases of up to 1 K. The retrieved temperature profile is based on radiometric measurements and radiative transfer calculations. Once the accuracy of radiometer measurements is known, these can be used to validate existing gas absorption models. As the absolute accuracy of microwave radiometer measurements is determined by the quality of the calibration, this work investigates the uncertainty of two calibration techniques, which are commonly used with microwave radiometers. Namely, these are the liquid nitrogen calibration and the tipping curve calibration (Han and Westwater, 2000). Both methods are known to have open issues concerning systematic offsets and calibration repeatability. In this regard, this work focuses on the error assessment for the absolute calibration of the network suitable microwave radiometer HATPRO-G2 (Humidity And Temperature PROfiler - Generation 2), which makes up a significant part of the worldwide available systems (Rose et al., 2005). In order to capture dry high altitude conditions on the one side and mid-latitude, close to sea level conditions on the other side, the analysis is based on two deployments. Between August and October 2009, HATPRO-G2 was part of the Radiative Heating of Underexplored Bands Campaign - Part 2 (RHUBC-II) in Northern Chile (5320 m above mean sea level) conducted within the Atmospheric Radiation Measurement (ARM) program. Since 2010, it is part of the JOYCE (Jülich ObservatorY for Cloud Evolution) site located in Germany 92 m above mean sea level. For each of the deployments, a detailed error propagation for both techniques is performed. The uncertainty range of brightness temperature Tb measurements based on a single liquid nitrogen calibration is mainly caused by a reflective component from the liquid nitrogen surface of the cold calibration target. The overall calibration uncertainty is assessed for typical Tb values measured at each deployment. For RHUBC-II, the maximum uncertainty of $T_b$ has been determined to +-1.6 K in the K-band and to +-1.0 K in the V-band. For JOYCE, the maximum uncertainty is assessed to be +-1.5 K in the K-band and +-0.6 K in the V-band. When a standing wave phenomena at the cold calibration point is eliminated by averaging several calibrations, the uncertainty in the K-band can be reduced to +-0.8 K for both deployments. In the V-band, the uncertainties are reduced to values less or equal +-0.7 K for both deployments. Furthermore, the analyses of the liquid nitrogen calibration has revealed, that the pressure dependent boiling point correction for liquid nitrogen, originally used by HATPRO-G2, is only exact for standard pressure conditions. Therefore, the boiling point correction has been modified and is now valid for all altitudes. At the low pressure conditions of RHUBC-II (530 hPa), the improved boiling point correction shifts the cold target temperature compared to the previously used formulation by more than 1 K. HATPRO-G2 has seven channels in the K-band and seven channels in the V-band. At standard pressure conditions, only the K-band channels are transparent enough to be calibrated by the tipping curve calibration. However, at 530 hPa, the technique can be applied to two low opacity channels in the V-band as well. This offers the unique opportunity of an independent validation of the liquid nitrogen calibration in the V-band. The analysis shows, that the uncertainty in the tipping curve calibration is mainly due to atmospheric inhomogeneities. For RHUBC-II, the total uncertainty is assessed to be +-0.1 K to +-0.2 K in the K-band and +-0.6 K and +-0.7 K for the two V-band channels at 51 GHZ and 52 GHz. For the low altitude deployment at JOYCE, the total uncertainties for K-band channels are +-0.2 K to +-0.6 K. Finally, the well-characterized radiometer measurements are used to investigate current absorption models. The profiles of temperature, humidity, and pressure from 62 clear sky radiosondes are used for Tb simulations at zenith and compared to HATPRO-G2 measurements. Biases, outside the uncertainty range of the calibration can be ascribed to errors within the gas absorption coefficients. It is found that the results of the Atmospheric Model (AM)(Paine, 2012), which uses the most recent oxygen absorption parameters (Tretyakov et al., 2005, Makarov et al., 2011), are closest to RHUBC-II measurements

ACRF Instrumentation Status: New, Current, and Future - September – October 2007

The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) instrumentation status. The report is divided into the following four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) SBIR instrument development

The atmosphere above Mauna Kea at mid-infrared wavelengths

xii, 143 leaves : ill. ; 28 cm.The performance of astronomical interferometer arrays operating at (sub) millimeter wave-lengths is seriously compromised by rapid variations of atmospheric water vapour content that distort the phase coherence of incoming celestial signals. Unless corrected, these phase distortions, which vary rapidly with time and from antenna to antenna, seriously compromise the sensitivity and image quality of these arrays. Building on the success of a prototype infrared radiometer for millimeter astronomy (IRMA I), which was ued to measure atmospheric water vapour column abundance, this thesis presents results from a second generation radiometer (IRMA II) operating at the James Clerk Maxwell Telescope (JCMT) on Mauna Kea, Hawaii from December, 2000 to March, 2001. These results include comparisons with other measures of water vapour abundance available on the summit of Mauna Kea and a comparison with a theorteical curve-of-growth calculated from a new radiative transfer model, ULTRAM, developed specifically for the purpose. Plans for a third generation radiometer (IRMA III) are also be discussed

The telecommunications and data acquisition report

Deep Space Network operations, engineering, and implementation are reported. Developments in Earth-based radiotechnology as applied to other research programs in the fields of Geodynamics, Astrophysics, and programs related to radio searchers (instrumentation and methods) in extraterrestrial areas in the microwave region of the electromagnetic spectrum are also presented

Space programs summary no. 37-58, volume 3 for the period 1 June - 31 July 1969. Supporting research and advanced development

Review of developments in current engineering and scientific work at JP

The Fifteenth Marcel Grossmann Meeting

The three volumes of the proceedings of MG15 give a broad view of all aspects of gravitational physics and astrophysics, from mathematical issues to recent observations and experiments. The scientific program of the meeting included 40 morning plenary talks over 6 days, 5 evening popular talks and nearly 100 parallel sessions on 71 topics spread over 4 afternoons. These proceedings are a representative sample of the very many oral and poster presentations made at the meeting.Part A contains plenary and review articles and the contributions from some parallel sessions, while Parts B and C consist of those from the remaining parallel sessions. The contents range from the mathematical foundations of classical and quantum gravitational theories including recent developments in string theory, to precision tests of general relativity including progress towards the detection of gravitational waves, and from supernova cosmology to relativistic astrophysics, including topics such as gamma ray bursts, black hole physics both in our galaxy and in active galactic nuclei in other galaxies, and neutron star, pulsar and white dwarf astrophysics. Parallel sessions touch on dark matter, neutrinos, X-ray sources, astrophysical black holes, neutron stars, white dwarfs, binary systems, radiative transfer, accretion disks, quasars, gamma ray bursts, supernovas, alternative gravitational theories, perturbations of collapsed objects, analog models, black hole thermodynamics, numerical relativity, gravitational lensing, large scale structure, observational cosmology, early universe models and cosmic microwave background anisotropies, inhomogeneous cosmology, inflation, global structure, singularities, chaos, Einstein-Maxwell systems, wormholes, exact solutions of Einstein's equations, gravitational waves, gravitational wave detectors and data analysis, precision gravitational measurements, quantum gravity and loop quantum gravity, quantum cosmology, strings and branes, self-gravitating systems, gamma ray astronomy, cosmic rays and the history of general relativity

The Fifteenth Marcel Grossmann Meeting

The three volumes of the proceedings of MG15 give a broad view of all aspects of gravitational physics and astrophysics, from mathematical issues to recent observations and experiments. The scientific program of the meeting included 40 morning plenary talks over 6 days, 5 evening popular talks and nearly 100 parallel sessions on 71 topics spread over 4 afternoons. These proceedings are a representative sample of the very many oral and poster presentations made at the meeting.Part A contains plenary and review articles and the contributions from some parallel sessions, while Parts B and C consist of those from the remaining parallel sessions. The contents range from the mathematical foundations of classical and quantum gravitational theories including recent developments in string theory, to precision tests of general relativity including progress towards the detection of gravitational waves, and from supernova cosmology to relativistic astrophysics, including topics such as gamma ray bursts, black hole physics both in our galaxy and in active galactic nuclei in other galaxies, and neutron star, pulsar and white dwarf astrophysics. Parallel sessions touch on dark matter, neutrinos, X-ray sources, astrophysical black holes, neutron stars, white dwarfs, binary systems, radiative transfer, accretion disks, quasars, gamma ray bursts, supernovas, alternative gravitational theories, perturbations of collapsed objects, analog models, black hole thermodynamics, numerical relativity, gravitational lensing, large scale structure, observational cosmology, early universe models and cosmic microwave background anisotropies, inhomogeneous cosmology, inflation, global structure, singularities, chaos, Einstein-Maxwell systems, wormholes, exact solutions of Einstein's equations, gravitational waves, gravitational wave detectors and data analysis, precision gravitational measurements, quantum gravity and loop quantum gravity, quantum cosmology, strings and branes, self-gravitating systems, gamma ray astronomy, cosmic rays and the history of general relativity

Preclinical MRI of the Kidney

This Open Access volume provides readers with an open access protocol collection and wide-ranging recommendations for preclinical renal MRI used in translational research. The chapters in this book are interdisciplinary in nature and bridge the gaps between physics, physiology, and medicine. They are designed to enhance training in renal MRI sciences and improve the reproducibility of renal imaging research. Chapters provide guidance for exploring, using and developing small animal renal MRI in your laboratory as a unique tool for advanced in vivo phenotyping, diagnostic imaging, and research into potential new therapies. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Cutting-edge and thorough, Preclinical MRI of the Kidney: Methods and Protocols is a valuable resource and will be of importance to anyone interested in the preclinical aspect of renal and cardiorenal diseases in the fields of physiology, nephrology, radiology, and cardiology. This publication is based upon work from COST Action PARENCHIMA, supported by European Cooperation in Science and Technology (COST). COST (www.cost.eu) is a funding agency for research and innovation networks. COST Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation. PARENCHIMA (renalmri.org) is a community-driven Action in the COST program of the European Union, which unites more than 200 experts in renal MRI from 30 countries with the aim to improve the reproducibility and standardization of renal MRI biomarkers

Preclinical MRI of the kidney : methods and protocols

This Open Access volume provides readers with an open access protocol collection and wide-ranging recommendations for preclinical renal MRI used in translational research. The chapters in this book are interdisciplinary in nature and bridge the gaps between physics, physiology, and medicine. They are designed to enhance training in renal MRI sciences and improve the reproducibility of renal imaging research. Chapters provide guidance for exploring, using and developing small animal renal MRI in your laboratory as a unique tool for advanced in vivo phenotyping, diagnostic imaging, and research into potential new therapies. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Cutting-edge and thorough, Preclinical MRI of the Kidney: Methods and Protocols is a valuable resource and will be of importance to anyone interested in the preclinical aspect of renal and cardiorenal diseases in the fields of physiology, nephrology, radiology, and cardiology. This publication is based upon work from COST Action PARENCHIMA, supported by European Cooperation in Science and Technology (COST). COST (www.cost.eu) is a funding agency for research and innovation networks. COST Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation. PARENCHIMA (renalmri.org) is a community-driven Action in the COST program of the European Union, which unites more than 200 experts in renal MRI from 30 countries with the aim to improve the reproducibility and standardization of renal MRI biomarkers