Seismogenic Anomalies in Atmospheric Gravity Waves as Observed from SABER/TIMED Satellite during Large Earthquakes

Atmospheric disturbances caused by seismic activity are a complex phenomenon. The Lithosphere–Atmosphere–Ionosphere Coupling (LAIC) (LAIC) mechanism gives a detailed idea to understand these processes to study the possible impacts of a forthcoming earthquake. The atmospheric gravity wave (AGW) is one of the most accurate parameters for explaining such LAIC process, where seismogenic disturbances can be explained in terms of atmospheric waves caused by temperature changes. The key goal of this work is to study the perturbation in the potential energy associated with stratospheric AGW prior to many large earthquakes. We select seven large earthquakes having Richter scale magnitudes greater than seven ( M > 7.0 ) in Japan (Tohoku and Kumamoto), Mexico (Chiapas), Nepal, and the Indian Ocean region, to study the intensification of AGW using the atmospheric temperature profile as recorded from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite. We observe a significant enhancement in the potential energy of the AGW ranging from 2 to 22 days prior to different earthquakes. We examine the conditions of geomagnetic disturbances, typhoons, and thunderstorms during our study and eliminate the possible contamination due to these events.

Improved ozone monitoring by ground-based FTIR spectrometry

Accurate observations of atmospheric ozone (O3) are essential to monitor in detail the key role of O3 in the atmospheric chemistry. The present paper examines the performance of different O3 retrieval strategies from FTIR (Fourier Transform InfraRed) spectrometry by using the 20-year time series of the high-resolution solar spectra acquired from 1999 to 2018 at the subtropical Izaña Observatory (IZO, Spain) within NDACC (Network for the Detection of Atmospheric Composition Change). In particular, the effect of two of the most influential factors have been investigated: the spectral region used for O3 retrievals and inclusion of an atmospheric temperature profile fit. The theoretical and experimental quality assessments of the different FTIR O3 products (total column, TC, amounts and volume mixing ratio, VMR, profiles) provide consistent results. Combining an optimal selection of spectral O3 absorption lines and a simultaneous temperature retrieval results in superior FTIR O3 products, with a precision greater than 0.6–0.7 % for O3 TCs as compared to coincident NDACC Brewer observations used as reference. However, this improvement can be only achieved provided the FTIR spectrometer is properly characterised and stable over time. For unstable instruments, the temperature fit has been found to exhibit a strong negative influence on O3 retrievals by increasing the cross-interference between instrumental performance and temperature retrieval. This cross-interference becomes especially noticeable beyond the upper troposphere/lower stratosphere as documented theoretically, as well as experimentally by comparing FTIR O3 profiles to those measured using Electrochemical Concentration Cell (ECC) sondes within NDACC. Consequently, it should be taken into account for the reliable monitoring of O3 vertical distribution, especially on long-term timescales.

The role of updrafts in the scaling of extreme precipitation in mid-latitudes

<p>We investigate the hypothesis that invigoration of convective updrafts under warming conditions contributes to the stronger than Clausius-Clapeyron (CC) scaling. Focus is on a mid-latitude case of extreme precipitation, based on idealised forcing conditions derived for the Netherlands, with strong surface forcing as well as strong forcing from large-scale rising motion associated with the passage of a synoptic scale low pressure or frontal system. Various Large Eddy Simulations (LES) of this composite case have been performed on a 192x192 km domain. By systematically perturbing the atmospheric temperature profile, a large response of cloud dynamics to warming with larger and more vigorous cloud structures in the warmer runs has been found.<sup>*</sup></p><p>Here, we study these cloud dynamics further by investigating the vertical wind velocity in the cloud (cores). Updrafts play a key role in rain formation by transporting moisture upward in the clouds. We will demonstrate how the distributions of these vertical velocities near the surface and at different levels in the clouds respond to warming in this mid-latitude setting and how they relate to cloud properties as cell size and buoyancy.</p><p> </p><p><sup><em>*</em></sup><em>Lochbihler, K., Lenderink, G., and Siebesma, A. P. (2019). Response of extreme precipitating cellstructures to atmospheric warming. Journal of Geophysical Research: Atmospheres</em></p>

Effects of CO2 Changes on Hyperspectral Infrared Radiances and Its Implications on Atmospheric Temperature Profile Retrieval and Data Assimilation in NWP

Although atmospheric CO2 is a trace gas, it has seasonal variations and has increased over the last decade. Its seasonal variation and increase have substantial radiative effects on hyperspectral infrared (IR) radiance calculations in both longwave (LW) and shortwave (SW) CO2 absorption spectral regions that are widely used for weather and climate applications. The effects depend on the spectral coverage and spectral resolution. The radiative effect caused by the increase of CO2 has been calculated to be greater than 0.5 K within 5 years, whereas a radiative effect of 0.1–0.5 K is introduced by the seasonal variation in some CO2 absorption spectral regions. It is important to take into account the increasing trend and seasonal variation of CO2 in retrieving the atmospheric temperature profile from hyperspectral IR radiances and in the radiance assimilation in numerical weather prediction (NWP) models. The simulation further indicates that it is very difficult to separate atmospheric temperature and CO2 information from hyperspectral IR sounder radiances because the atmospheric temperature signal is much stronger than that of CO2 in the CO2 absorption IR spectral regions.

Space experiment "Convergence": retrieving of atmospheric water vapor profile using of artificial neural networks

The paper is carried out to the investigation of the possibility of retrieving absolute humidity profile of the atmosphere using an artificial neural network based on the modeling of radiometric data of the passive microwave complex MIRS, which is part of the scientific equipment of the space experiment "Convergence". The main approaches to the construction of artificial neural networks are considered. The process of modeling MIRSs radiometric data are described. Selection of optimal characteristics of the neural network is carried out. Necessity of the information about atmospheric temperature profile for the best accuracy in solving the inverse problem are shown. The advantages of using differential channels in the 22 GHz absorption band for the humidity profile retrieving are proved. The expected errors of the atmospheric humidity profile retrieving during the Convergence experiment at altitudes from 0 to 10 km are given.

A Turbulence-Oriented Approach to Retrieve Various Atmospheric Parameters Using Advanced Lidar Data Processing Techniques

The article is aimed at presenting a semi-empirical model coded and computed in the programming language Python, which utilizes data gathered with a standard biaxial elastic lidar platform in order to calculate the altitude profiles of the structure coefficients of the atmospheric refraction index C N 2 ( z ) and other associated turbulence parameters. Additionally, the model can be used to calculate the PBL (Planetary Boundary Layer) height, and other parameters typically employed in the field of astronomy. Solving the Fernard–Klett inversion by correlating sun-photometer data obtained through our AERONET site with lidar data, it can yield the atmospheric extinction and backscatter profiles α ( z ) and β ( z ) , and thus obtain the atmospheric optical depth. Finally, several theoretical notions of interest that utilize the solved parameters are presented, such as approximated relations between C N 2 ( z ) and the atmospheric temperature profile T ( z ) , and between the scintillation of backscattered lidar signal and the average wind speed profile U ( z ) . These obtained profiles and parameters also have several environmental applications that are connected directly and indirectly to human health and well-being, ranging from understanding the transport of aerosols in the atmosphere and minimizing the errors in measuring it, to predicting extreme, and potentially-damaging, meteorological events.

Na I and Hα absorption features in the atmosphere of MASCARA-2b/KELT-20b

We used the HARPS-North high resolution spectrograph (ℛ = 115 000) at Telescopio Nazionale Galileo (TNG) to observe one transit of the highly irradiated planet MASCARA-2b/KELT-20b. Using only one transit observation, we are able to clearly resolve the spectral features of the atomic sodium (Na I) doublet and the Hα line in its atmosphere, which are corroborated with the transmission calculated from their respective transmission light curves (TLC). In particular, we resolve two spectral features centered on the Na I doublet position with an averaged absorption depth of 0.17 ± 0.03% for a 0.75 Å bandwidth with line contrasts of 0.44 ± 0.11% (D2) and 0.37 ± 0.08% (D1). The Na I TLC have also been computed, showing a large Rossiter-McLaughlin (RM) effect, which has a 0.20 ± 0.05% Na I transit absorption for a 0.75 Å passband that is consistent with the absorption depth value measured from the final transmission spectrum. We observe a second feature centered on the Hα line with 0.6 ± 0.1% contrast and an absorption depth of 0.59 ± 0.08% for a 0.75 Å passband that has consistent absorptions in its TLC, which corresponds to an effective radius of Rλ/RP = 1.20 ± 0.04. While the signal-to-noise ratio (S/N) of the final transmission spectrum is not sufficient to adjust different temperature profiles to the lines, we find that higher temperatures than the equilibrium (Teq = 2260 ± 50 K) are needed to explain the lines contrast. Particularly, we find that the Na I lines core require a temperature of T = 4210 ± 180 K and that Hα requires a temperature of T = 4330 ± 520 K. MASCARA-2b, like other planets orbiting A-type stars, receives a large amount of UV energy from its host star. This energy excites the atomic hydrogen and produces Hα absorption, leading to the expansion and abrasion of the atmosphere. The study of other Balmer lines in the transmission spectrum would allow the determination of the atmospheric temperature profile and the calculation of the lifetime of the atmosphere with escape rate measurements. In the case of MASCARA-2b, residual features are observed in the Hβ and Hγ lines, but they are not statistically significant. More transit observations are needed to confirm our findings in Na I and Hα and to build up enough S/N to explore the presence of Hβ and Hγ planetary absorptions.

High spectral resolution lidar at the university of wisconsin-madison

This paper describes the modifications done on the University of Wisconsin-Madison High Spectral Resolution Lidar (HSRL) that improved the instrument’s performance. The University of Wisconsin HSRL lidars designed by our group at the Space Science and Engineering Center were deployed in numerous field campaigns in various locations around the world. Over the years the instruments have undergone multiple modifications that improved the performance and added new measurement capabilities such as atmospheric temperature profile and extinction cross-section measurements.

Advances in atmospheric temperature profile measurements using high spectral resolution lidar

This paper reports the atmospheric temperature profile measurements using a University of Wisconsin-Madison High Spectral Resolution Lidar (HSRL) and describes improvements in the instrument performance. HSRL discriminates between Mie and Rayleigh backscattering [1]. Thermal motion of molecules broadens the spectrum of the transmitted laser light due to Doppler effect. The HSRL exploits this property to allow the absolute calibration of the lidar and measurements of the aerosol volume backscatter coefficient. Two iodine absorption filters with different line widths are used to resolve temperature sensitive changes in Rayleigh backscattering for atmospheric temperature profile measurements.