Development of a substorms catalog including the MPB observed at Panagjurishte station, Bulgaria

In this work the first results of the creation of a substorms catalog including the mid-latitude positive bays (MPB) registered at the Bulgarian station Panagjurishte (∼37° GMLat, ∼97° GMLon) are presented. MPB index characterizes the mid-latitude effect of substorm, which developed at auroral latitudes, and it is associated with the substorm current wedge. The work went in several lines. First, the catalog design and content were taken. Second, tools of data processing have been developed. Third, substorms during two months, namely January and February 2013 were identified. And finally, data processing was implemented and the characteristics of the positive bays were determined. The obtained data and their visualizations were put in a convenient folder and file structure, ftp positioned.

Processes responsible for variations in the isotopic composition (ΔD and Δ18O) of thermal waters of the Kuril islands arc

Many active volcanoes of the Kuril Islands host hydrothermal systems. Their surface manifestations are represented by numerous thermal springs showing diverse chemical composition and physical-chemical parameters. Four main isotopic shifts relative to the local meteoric water line can be observed in the corresponding δD vs. δ18O diagrams. For the acid Cl-SO4 waters there is a clear mixing trend between meteoric water and volcanic vapor. The acid SO4waters demonstrate trends indicating kinetic fractionation at temperatures close to the boiling-point. Isotopic composition of the coastal springs tend to march the mixing line between meteoric and seawater. The δ18O-shift for deep thermal water is accounted to of isotopic exchange with host rock. The latitude effect revealed for meteoric waters also observed in the isotopic composition of the thermal waters.

Mesospheric anomalous diffusion during noctilucent cloud scenarios

The Andenes specular meteor radar shows meteor trail diffusion rates increasing on average by about 10 % at times and locations where a lidar observes noctilucent clouds (NLCs). This high-latitude effect has been attributed to the presence of charged NLC after exploring possible contributions from thermal tides. To make this claim, the current study evaluates data from three stations at high, middle, and low latitudes for the years 2012 to 2016 to show that NLC influence on the meteor trail diffusion is independent of thermal tides. The observations also show that the meteor trail diffusion enhancement during NLC cover exists only at high latitudes and near the peaks of NLC layers. This paper discusses a number of possible explanations for changes in the regions with NLCs and leans towards the hypothesis that the relative abundance of background electron density plays the leading role. A more accurate model of the meteor trail diffusion around NLC particles would help researchers determine mesospheric temperature and neutral density profiles from meteor radars at high latitudes.

Processes Responsible of Variations in the δ18O – δD values of Thermal Waters from the Kuril Islands (Russia)

Many active and dormant volcanoes of the Kuril Islands host hydrothermal systems which discharge acid to ultra-acid SO4-Cl (Cl-SO4) and SO4 waters. On some island, hot near-neutral Na-Cl waters can be found discharging in coastal hot springs. Four main different isotopic shifts relative to the local meteoric water line can be observed in the corresponding δD vs. δ18O diagram. For the acid Cl-SO4 waters discharging within thermal fields on volcano slopes, there is a clear mixing trend between meteoric water and volcanic vapor. Steam-heated SO4 waters demonstrate trends indicating kinetic fractionation at temperatures close to the boiling-point. For the coastal springs, the trend is apparently a mixing line between meteoric and seawater. The δ18O-shift for deep thermal waters is related to isotopic exchange with host rock but there is also a clear latitude effect in the isotopic composition of the meteoric endmember.

Mesospheric Anomalous Diffusion During Noctilucent Clouds

The Andenes specular meteor radar shows meteor-trail diffusion rates increasing on average by ~ 20 % at times and locations where a lidar observes noctilucent clouds (NLCs). This high-latitude effect has been attributed to the presence of charged NLC but this study shows that such behaviors result predominantly from thermal tides. To make this claim, the current study evaluates data from three stations, at high-, mid-, and low-latitudes, for the years 2012 to 2016, comparing diffusion to show that thermal tides correlate strongly with the presence of NLCs. This data also shows that the connection between meteor-trail diffusion and thermal tide occurs at all altitudes in the mesosphere, while the NLC influence exists only at high-latitudes and at around peak of NLC layer. This paper discusses a number of possible explanations for changes in the regions with NLCs and leans towards the hypothesis that relative abundance of background electron density plays the leading role. A more accurate model of the meteor trail diffusion around NLC particles would help researchers determine mesospheric temperature and neutral density profiles from meteor radars.

Global scale remote sensing of water isotopologues in the troposphere: representation of first-order isotope effects

Over the last-decade, global scale datasets of atmospheric water vapor isotopologues (HDO) have become available from different remote-sensing instruments. Due to the observational geometry and the spectral ranges that are used, only few satellites sample water isotopologues in the lower troposphere, where the bulk of hydrological processes within the atmosphere take place. Here, we compare three satellite HDO datasets, two from the Tropospheric Emission Spectrometer (TES retrieval version 4 and 5) and one from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY), with results from the atmospheric global circulation model ECHAM4 (European Center HAMburg 4). We examine a list of known isotopologue effects to qualitatively benchmark the various observational datasets. TES version 5 (TESV5), TES version 4 (TESV4), SCIAMACHY, ECHAM, and ECHAM convoluted with averaging kernel of TES version 5 (ECHAMAK5) successfully reproduced a number of established isotopologue effects such as the latitude effect, the amount effect, and the continental effect, but to different extent. The improvement of TES version 5 over version 4 was confirmed by the steeper latitudinal gradient at higher latitudes in agreement with SCIAMACHY. Other features of the water isotopologue cycle such as the seasonally varying signal in the tropics due to the movement of the Inter Tropical Convergence Zone (ICTZ) are captured in TESV5 and SCIAMACHY. We suggest that the qualitative and quantitative tests carried out in this study could become benchmark tests for evaluation of future satellite isotopologue datasets.