Revisiting internal gravity waves analysis using GPS RO density profiles: comparison with temperature profiles and application for wave field stability study

We revise selected findings regarding the utilization of Global Positioning System radio occultation (GPS RO) density profiles for the analysis of internal gravity waves (IGW), introduced by Sacha et al. (2014). Using various GPS RO datasets, we show that the differences in the IGW spectra between the dry-temperature and dry-density profiles that were described in the previous study as a general issue are in fact present in one specific data version only. The differences between perturbations in the temperature and density GPS RO profiles do not have any physical origin, and there is not the information loss of IGW activity that was suggested in Sacha et al. (2014). We investigate the previously discussed question of the temperature perturbations character when utilizing GPS RO dry-temperature profiles, derived by integration of the hydrostatic balance. Using radiosonde profiles as a proxy for GPS RO, we provide strong evidence that the differences in IGW perturbations between the real and retrieved temperature profiles (which are based on the assumption of hydrostatic balance) include a significant nonhydrostatic component that is present sporadically and might be either positive or negative. The detected differences in related spectra of IGW temperature perturbations are found to be mostly about ±10 %. The paper also presents a detailed study on the utilization of GPS RO density profiles for the characterization of the wave field stability. We have analyzed selected stability parameters derived from the density profiles together with a study of the vertical rotation of the wind direction. Regarding the Northern Hemisphere the results point to the western border of the Aleutian high, where potential IGW breaking is detected. These findings are also supported by an analysis of temperature and wind velocity profiles. Our results confirm advantages of the utilization of the density profiles for IGW analysis.Grantová Agentura České Republiky | Ref. 16-01562JMinisterstvo Školství, Mládeže a Tělovýchovy | Ref. 7AMB16AT021OeAD-GmbH | Ref. CZ 06/2016Ministerio de Ciencia e Innovación | Ref. CGL2015-71575-

The power of vertical geolocation of atmospheric profiles from GNSS radio occultation

Abstract High‐resolution measurements from Global Navigation Satellite System (GNSS) radio occultation (RO) provide atmospheric profiles with independent information on altitude and pressure. This unique property is of crucial advantage when analyzing atmospheric characteristics that require joint knowledge of altitude and pressure or other thermodynamic atmospheric variables. Here we introduce and demonstrate the utility of this independent information from RO and discuss the computation, uncertainty, and use of RO atmospheric profiles on isohypsic coordinates—mean sea level altitude and geopotential height—as well as on thermodynamic coordinates (pressure and potential temperature). Using geopotential height as vertical grid, we give information on errors of RO‐derived temperature, pressure, and potential temperature profiles and provide an empirical error model which accounts for seasonal and latitudinal variations. The observational uncertainty of individual temperature/pressure/potential temperature profiles is about 0.7 K/0.15%/1.4 K in the tropopause region. It gradually increases into the stratosphere and decreases toward the lower troposphere. This decrease is due to the increasing influence of background information. The total climatological error of mean atmospheric fields is, in general, dominated by the systematic error component. We use sampling error‐corrected climatological fields to demonstrate the power of having different and accurate vertical coordinates available. As examples we analyze characteristics of the location of the tropopause for geopotential height, pressure, and potential temperature coordinates as well as seasonal variations of the midlatitude jet stream core. This highlights the broad applicability of RO and the utility of its versatile vertical geolocation for investigating the vertical structure of the troposphere and stratosphere

Tropical Temperature Variability in the UTLS: New Insights from GPS Radio Occultation Observations

AbstractGlobal positioning system (GPS) radio occultation (RO) observations, first made of Earth's atmosphere in 1995, have contributed in new ways to the understanding of the thermal structure and variability of the tropical upper troposphere–lower stratosphere (UTLS), an important component of the climate system. The UTLS plays an essential role in the global radiative balance, the exchange of water vapor, ozone, and other chemical constituents between the troposphere and stratosphere, and the transfer of energy from the troposphere to the stratosphere. With their high accuracy, precision, vertical resolution, and global coverage, RO observations are uniquely suited for studying the UTLS and a broad range of equatorial waves, including gravity waves, Kelvin waves, Rossby and mixed Rossby–gravity waves, and thermal tides. Because RO measurements are nearly unaffected by clouds, they also resolve the upper-level thermal structure of deep convection and tropical cyclones as well as volcanic clouds. Their low biases and stability from mission to mission make RO observations powerful tools for studying climate variability and trends, including the annual cycle and intraseasonal-to-interannual atmospheric modes of variability such as the quasi-biennial oscillation (QBO), Madden–Julian oscillation (MJO), and El Niño–Southern Oscillation (ENSO). These properties also make them useful for evaluating climate models and detection of small trends in the UTLS temperature, key indicators of climate change. This paper reviews the contributions of RO observations to the understanding of the three-dimensional structure of tropical UTLS phenomena and their variability over time scales ranging from hours to decades and longer

Vorstudie für das Klima- und Energiefondsprojekt NH3-PM-AQ für das Burgenland

https://vetdoc.vu-wien.ac.at/vetdoc/suche.publikationen_mug_autoren?sprache_in=de&menue_id_in=400&id_in=&publikation_id_in=9489

Vorstudie für das Klima- und Energiefondsprojekt NH3-PM-AQ für die Steiermark

https://vetdoc.vu-wien.ac.at/vetdoc/suche.publikationen_mug_autoren?sprache_in=de&menue_id_in=400&id_in=&publikation_id_in=9489

Vorstudie für das Klima- und Energiefondsprojekt NH3-PM-AQ für Niederösterreich

https://vetdoc.vu-wien.ac.at/vetdoc/suche.publikationen_mug_autoren?sprache_in=de&menue_id_in=400&id_in=&publikation_id_in=9489

Are Adaptation Measures Used to Alleviate Heat Stress Appropriate to Reduce Ammonia Emissions?

The emission of ammonia (NH3) is predominantly caused by agriculture, especially by livestock keeping. The health effects of NH3 and the related formation of particulate matter are the reasons for solid efforts to reduce their ambient concentrations. In addition, the impact of global warming on livestock is increasing due to heat stress, likely also increasing NH3 emissions. Therefore, adaptation measures are under discussion to reduce the heat stress of animals inside livestock units. Because of the relationship between temperature increase and NH3 release, the impact of the adaptation measures to cool the indoor air of livestock units (three different energy-saving air preparation systems, an inversion of the feeding and resting times by half a day, a reduction of the stocking density and doubling the maximum volume flow rate) was investigated. The NH3 release was calculated by the following predictors: indoor air temperature; ventilation rate describing the turbulence inside the livestock building; and the diurnal variation caused by the animal activity. These parameters were calculated by a simulation model for the indoor climate of livestock buildings. The monthly mean of the NH3 emission for several adaptation measures, which were applied to reduce heat stress, were compared with the emission of a reference building for 1800 fattening pigs, divided into nine sections with 200 animals each for an all-in-all-out production cycle to calculate the mitigation potential. The higher the cooling power of such adaptation measures, the higher the mitigation potential for NH3. In particular, those adaptation measures which cool the inlet air (e.g., cooling pads reduce the emission by −2%, earth-air heat exchangers by −3.1%) show the best performance to mitigate the NH3 emission of livestock buildings

Are Adaptation Measures Used to Alleviate Heat Stress Appropriate to Reduce Ammonia Emissions?

The emission of ammonia (NH3) is predominantly caused by agriculture, especially by livestock keeping. The health effects of NH3 and the related formation of particulate matter are the reasons for solid efforts to reduce their ambient concentrations. In addition, the impact of global warming on livestock is increasing due to heat stress, likely also increasing NH3 emissions. Therefore, adaptation measures are under discussion to reduce the heat stress of animals inside livestock units. Because of the relationship between temperature increase and NH3 release, the impact of the adaptation measures to cool the indoor air of livestock units (three different energy-saving air preparation systems, an inversion of the feeding and resting times by half a day, a reduction of the stocking density and doubling the maximum volume flow rate) was investigated. The NH3 release was calculated by the following predictors: indoor air temperature; ventilation rate describing the turbulence inside the livestock building; and the diurnal variation caused by the animal activity. These parameters were calculated by a simulation model for the indoor climate of livestock buildings. The monthly mean of the NH3 emission for several adaptation measures, which were applied to reduce heat stress, were compared with the emission of a reference building for 1800 fattening pigs, divided into nine sections with 200 animals each for an all-in-all-out production cycle to calculate the mitigation potential. The higher the cooling power of such adaptation measures, the higher the mitigation potential for NH3. In particular, those adaptation measures which cool the inlet air (e.g., cooling pads reduce the emission by −2%, earth-air heat exchangers by −3.1%) show the best performance to mitigate the NH3 emission of livestock buildings

Vorstudie für das Klima- und Energiefondsprojekt NH3-PM-AQ für die Steiermark

Die ZAMG hat im Jänner 2019 gemeinsam mit der Veterinärmedizinischen Universität Wien beim Klima- und Energiefonds einen Projektantrag zur Untersuchung der Auswirkungen des Klimawandels auf landwirtschaftliche Ammoniakemissionen, Feinstaubbildung und die damit in Verbindung stehende Luftqualität eingereicht. Da die Gutachter den Einfluss der mittleren Temperaturerhöhung um etwa 1 °C über 40 Jahre in Mitteleuropa als nicht relevant für die postulierte Zunahme der Ammoniakemissionen einschätzten, wurde das Projekt NH3-PM-AQ in dieser Ausschreibung als nicht förderungswürdig eingestuft. Es wurde jedoch die Durchführung einer Vorstudie empfohlen, um die Variabilität der entscheidenden meteorologischen Parameter sowie deren Trends in den meteorologischen Eingangsdaten (der neuesten Version der Reanalysen des europäischen Zentrums für mittelfristige Wettervorhersage, ERA5) besser abzuschätzen und um zu untersuchen, ob mit einer relevanten Änderung der Ammoniakemissionen und der Feinstaubbildung zu rechnen ist. Diese Vorstudie wurde durch das Amt der Steirischen Landesregierung finanziert. Dieser vorliegende Bericht fasst die Ergebnisse zusammen, aufgrund deren im Jänner 2020 ein neuerlicher Projektantrag beim Klima- und Energiefonds eingereicht werden wird

GNSS radio occultation in-filling of the African radiosonde data gaps reveals drivers of tropopause climate variability

Radiosonde data are important for understanding and monitoring the upper troposphere and lower stratosphere (UTLS) region. Over much of Africa, however, such data are lacking; consequently, the African UTLS is understudied, and potential proxies such as climate models and reanalysis products fail to fully capture the behavior of the UTLS. This study pioneers the use of Global Navigation Satellite System-Radio Occultation (GNSS-RO) data from 2001 to 2020 to address the radiosonde data gap over Africa and contributes to a better understanding of the tropopause (TP) characteristics under the influence of global and regional climate drivers over the continent. As a first step to using GNSS-RO for infilling the radiosonde data gap over Africa, we analyzed the performance of GNSS-RO (2001–2020) and reanalysis products (European Centre for Medium-Range Weather Forecasts Reanalysis 5 (ERA5) and Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2)) against radiosonde observations applying the Kling-Gupta Efficiency metric. The analyses show that GNSS-RO data from Challenging Mini-satellite Payload, Gravity Recovery and Climate Experiment, Meteorological Operational, Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), and COSMIC-2 are in good agreement with radiosonde measurements with differences being smaller than 1 K in the UTLS, thereby enabling infilling of missing radiosonde data in Africa during 2001–2020. By contrast, the smoothed vertical temperature profiles of reanalysis products lead to a warm bias of +0.8 K in ERA5 and +1.2 K in MERRA-2 and these biases alter some vertical and temporal structure details, with possible implications on climate change detection and attribution. Furthermore, the analysis of GNSS-RO data over Africa revealed: (a) the teleconnections of El Niño-Southern Oscillation (ENSO), Quasi-Biennial Oscillation (QBO), Indian Ocean Dipole (IOD), Madden-Julian Oscillation (MJO), North Atlantic Oscillation (NAO) and Southern Annular Mode (SAM) at the tropopause boundary; (b) multiple coupled global climate drivers such as ENSO-IOD, ENSO-MJO, ENSO-NAO, QBO-IOD, and ENSO-NAO-MJO; (c) coupled global and regional climate drivers that influence the TP variability, for example, ENSO-Inter Tropical Convergence Zone; and (d), the deep convection associated with the Asian Summer Monsoon and Tropical/African Easterly Jet also locally influence TP height. In conclusion, this study demonstrates the capability of GNSS-RO to fill the vast radiosonde data gap over Africa. This opens the opportunity for further detailed studies toward a better understanding of the tropopause characteristics including localization, quantification of trends, and influences of global, regional, and coupled climate drivers