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Local empirical models of the F2 layer peak electron density (NmF2) are developed for 43 low‐ middle latitude ionosonde stations using auto‐scaled data from Lowell GIRO data center and manually scaled data from World Data Center for Ionosphere and Space Weather. Data coverage at these stations ranges from a few years to up to 6 decades. Flare Irradiance Spectral Model index version 2 (FISM2) and ap3 index are used to parametrize the solar extreme ultraviolet (EUV) flux and geomagnetic activity dependence of NmF2. Learning curves suggest that approximately 8 years of data coverage is required to constrain the solar activity dependence of NmF2. Output of local models altogether captures well known anomalies of the F2 ionospheric layer. Performance metrics demonstrate that the model parametrized using FISM2 has better accuracy than a similarly parametrized model with F10.7, as well as than the IRI‐2020 model. Skill score metrics indicate that the FISM2 based model outperforms F10.7 model at all solar activity levels. The improved accuracy of model with FISM2 over F10.7 is due to better representation of solar rotation by FISM2, and due to its performance at solar extremum. Application of singular spectrum analysis to model output reveals that solar rotation contributes to about 2%–3% of the variance in NmF2 data and FISM2 based model, while F10.7 based models overestimate the strength of solar rotation to be at 4%–7%. At solar extremum, both F10.7‐based model and IRI‐2020 tend to overestimate the NmF2 while FISM2 provides the most accurate prediction out of three. Plain Language Summary: We developed local empirical models of peak electron density (NmF2) that describe its variation with solar activity, geomagnetic activity, and season. The NmF2 data for this model comes from 43 ionosonde stations all over the world. Our local models capture well known global characteristics of the NmF2. Further, we show that the solar activity dependence of NmF2 is better explained using the FISM2 which is an empirical model of solar EUV variability. Data‐model comparison reveals that FISM2 based model of NmF2 is more accurate than a F10.7 based model and significantly more accurate than the IRI‐2020 model. Among the three models, FISM2 provides the most accurate representation of the solar rotation signal in NmF2 and a better prediction of NmF2 during periods of solar maximum and minimum. Key Points: Local models of peak electron density for 43 low‐mid latitude ionosondes are developed. Models capture known global ionospheric featuresApproximately 8 years of minimum data coverage is required to describe the solar activity dependence of peak electron densityModels driven by the Flare Irradiance Spectral Model are more accurate than models driven by F10.7 and the IRI‐2020 model [ABSTRACT FROM AUTHOR]

Underground pipelines during operation are affected by mechanical and corrosive factors. The susceptibility of cathodically protected pipe to hydrogen degradation increases, which contributes to stress-corrosion cracking. It is believed that the main factor in pipeline steels degradation is deformation aging, which increases strength and reduces plasticity. Volume microdamages also develop in long-time exploited steels. But in many cases, the base metal and welded joints of long-term operated pipelines retain satisfactory performance. Due to the high value of viscosity and plasticity of the metal in an as-received state, the metal state of long-term operated gas pipelines can be considered satisfactory. [ABSTRACT FROM AUTHOR]

Using observations from the Global‐scale Observations of the Limb and Disk (GOLD) mission, we investigate post‐sunset ionospheric responses to the September 2019 Antarctic sudden stratospheric warming –first ever from a synoptic perspective. Observations reveal a prevalent quasi‐6‐day periodicity in the equatorial ionization anomaly region over South America and the Atlantic, coincident with enhanced quasi‐6‐day wave (Q6DW) activity in the mesosphere (Liu et al., 2021, https://doi.org/10.1029/2020JA028909). The atmosphere‐ionosphere coupling via large‐scale waves is rarely studied over the ocean due to the lack of observations. More importantly, further analyses suggest that multiple pathways are involved in transmitting the quasi‐6‐day periodicity from the middle atmosphere into the post‐sunset F‐region ionosphere, including modulation of F‐region field aligned winds and pre‐reversal enhancements by the tides and or Q6DW. A remarkable depletion in electron density, attributable to the overall change in thermosphere composition driven by the dissipative tides and or Q6DWs, is also seen during the period of enhanced Q6DW activity. Plain Language Summary: The equatorial ionization anomaly (EIA) owes an appreciable amount of variability to the lower/middle atmosphere wave forcing of various scales. The 2019 September Antarctic sudden stratospheric warming (SSW)—rarely occurs in the southern hemisphere—provides a great opportunity to explore the effects atmospheric waves have on the EIA, as a bunch of waves gets significantly reinforced following the polar vortex disruption. Combining the observations made by the NASA GOLD and TIMED missions reveals a coincident quasi‐6‐day modulation of the post‐sunset EIA crests and mesospheric temperatures during the course of this SSW event, demonstrating a solid case that the ionosphere couples with the atmosphere via planetary‐scale waves. Key Points: A prominent quasi‐6‐day periodicity in the post‐sunset equatorial ionization anomaly (EIA) is observed during the 2019 Antarctic sudden stratospheric warming, coincident with mesospheric quasi‐6‐day waves (Q6DWs)The EIA displays an overall depletion over South America and the Atlantic when the Q6DWs are quite activeMultiple mechanisms play roles in coupling of the Q6DW with the post‐sunset EIA [ABSTRACT FROM AUTHOR]

A new Cloud Imaging and Particle Size (CIPS) gravity wave (GW) variance data set is available that facilitates automated analysis of GWs entering the mesosphere. This work examines several years of CIPS GW variances from 50 to 55 km in the context of the Arctic and Antarctic polar vortices. CIPS observes highest GW activity in the vortex edge region where horizontal wind speeds are largest, consistent with previously published GW climatologies in the stratosphere and mesosphere. CIPS observes the well‐documented planetary wave (PW)‐1 patterns in GW activity in both hemispheres. In the Northern Hemisphere, maximum GW activity occurs over the North Atlantic and western Europe. In the Southern Hemisphere, maximum GW activity stretches from the Andes over the South Atlantic and Indian Oceans, as expected. In the NH, CIPS GW spatial patterns are highly correlated with horizontal wind speed. In the SH, CIPS GW patterns are less positively correlated with the winds due to increased zonal symmetry and orographic forcing. The Andes Mountains and Antarctic Peninsula, South Georgia Island, Kerguelen/Heard Islands, New Zealand, and Tasmania are persistent sources of orographic GWs. Atmospheric Infrared sounder observations of stratospheric GWs are analyzed alongside CIPS to explore vertical GW coherence and to infer GW propagation and sources. NH midlatitude GW activity is reduced during the January 2021 SSW, as expected. This reduction in GWs leads to a simultaneous reduction in traveling ionospheric disturbances (TIDs), providing more evidence that weak polar vortex events with weak GW activity leads to reduced daytime TID activity. Plain Language Summary: A new satellite gravity wave (GW) variance data set is available that facilitates automated analysis of GWs entering the mesosphere. This work examines several years of GW variances from 50 to 55 km in the context of the Arctic and Antarctic polar vortices. Highest GW activity is observed in the vortex edge region where horizontal wind speeds are largest, consistent with previous work. Known planetary wave‐1 patterns are confirmed in the new data set. In the Northern Hemisphere, maximum GW activity occurs over the North Atlantic and western Europe. In the Southern Hemisphere, maximum GW activity stretches from the Andes over the South Atlantic and Indian Oceans. In the Arctic winter, GW spatial patterns are highly correlated with horizontal wind speed. In the Antarctic winter, GW patterns are less positively correlated with the winds due to smaller variations around a latitude circle and larger orographic forcing. We show that Arctic midlatitude GW activity is reduced during the January 2021 SSW, as expected. This reduction in GWs leads to a simultaneous reduction in traveling ionospheric disturbances (TIDs), providing more evidence that weak polar vortex events with weak GW activity leads to reduced daytime TID activity. Key Points: This is the first work to present gravity waves (GWs) from 50 to 55 km observed by AIM CIPS with a focus on the winter polar vorticesDuring the 2020–2021 Arctic winter the longitude of maximum GW activity, maximum horizontal wind speed, and the polar vortex are co‐locatedReduced GW activity during the January 2021 SSW leads to simultaneous reductions in daytime traveling ionospheric disturbances [ABSTRACT FROM AUTHOR]

In the work on the examples of failure of four pipelines, the authors considered and analyzed the causes of failure of circumferential welded butt joints of main gas and oil pipelines with a long-term service life of 530-1420 mm diameter from low-alloy ferritic-perlitic steels of grades 17G1s, 17GS and 15GSTYu, constructed back at the end of the twentieth century. technical experts assume that, as a rule, accidents are associated with the failure of circumferential butt welded joints produced in field conditions. Literature sources give quite limited reliable information about the causes of defect formation that lead to the failure of field welded joints. The authors show that even having provided satisfactory mechanical properties of steels and at the absence of deviations in the chemical composition of welded joints, depressurization of pipelines occurred due to weakening of the weld as a result of defect formation during operation or during construction and assembly works. The defects include pores, lacks of fusion, lacks of penetration, edge displacement, use of embedded elements, etc. That were not detected by non-destructive testing methods. The obtained results made it possible to adjust a set of technological recommendations on the requirements and rules for performing assembly and welding works during the construction and repair of main pipelines in ukraine over the last 20 years. [ABSTRACT FROM AUTHOR]