This paper for the first time reports conjugate observations of a group of evolving equatorial plasma bubbles (EPBs) generated in the longitudinal sector of China on 4/5 November 2013 using ...simultaneous airglow and Communication/Navigation Outage Forecasting System (C/NOFS) observations. The airglow depletion structures seen by two all‐sky airglow imagers had the same zonal wavelength as that of the longitudinally periodic electron density depletions observed by the C/NOFS satellite which occurred at almost the same time but at magnetically conjugate latitudes. Data from a VHF radar and a Digisonde were combined to investigate the evolution of the EPB group, including their generation, development, and dissipation. Results indicate that the EPB group developed from the bottomside large‐scale wave‐like structure (LSWS) at about 195–210 km height with a characteristic zonal wavelength and longitudinal extension of about 450 km and 2250 km, respectively. The EPB group also caused periodic bottomside type spread F associated with the LSWS. We found that the development of the EPB group and their associated spread F could be limited by the equatorward motion of equatorial ionization anomaly (EIA) and the southwestward motion of an extremely bright airglow region (SMEBAR). The SMEBAR is a newly discovered structure of plasma density increase but not a plasma blob reported before. Both EIA and SMEBAR could feed high plasma density into an EPB airglow depletion structure that was eventually seen as a bright airglow structure or disappeared. Meanwhile, spread F associated with the EPBs did not evolve from the bottomside type into the strong range type.
Key Points
First report of a southwestward moving extremely bright airglow region (SMEBAR)
Evolution processes of a group of EPBs simultaneously measured by ground‐based and satellite instruments in China
Equatorial ionization anomaly (EIA) and SMEBAR could restrict the development of the EPB group
The 2019/2020 Australian New Year's wildfires injected record amounts of smoke and biomass burning products into the lower stratosphere. The Aura Microwave Limb Sounder (MLS) tracked the evolution of ...distinct plumes of fire–influenced air as they rapidly spiraled up to the mid–stratosphere. In the months following the fires, smoke spread throughout the Southern Hemisphere (SH) stratosphere. We contrast the evolution of the SH midlatitude lower stratosphere in 2020 with the 17–year MLS record. Long after the coherent plumes dispersed, data from MLS and other satellite instruments show unprecedented persistent and pervasive depletion in HCl (50%–60% below climatology) and enhancements in ClO and ClONO2 that were not transport related; peak anomalies occurred in mid–2020. We conclude that the observed perturbations likely arose from heterogeneous chlorine activation on widespread smoke particles. The sustained chlorine activation was far weaker than in typical winter polar vortices, inducing at most minor changes in ozone.
Plain Language Summary
In late December 2019/early January 2020, during the Black Summer fire season in Australia, an intense outbreak of a number of fire–induced and smoke–infused thunderstorms occurred, collectively known as the Australian New Year's event. Multiple plumes of polluted air were rapidly lofted from the surface and deposited in the lower stratosphere (above 14 km altitude). The largest of the plumes of biomass burning pollutants were tracked by the Microwave Limb Sounder (MLS) on NASA's Aura satellite for several months as they circled the globe. In addition to those distinct confined plumes, smoke from the fires permeated the Southern Hemisphere (SH) lower stratosphere. Well after the discrete plumes dispersed, MLS and other satellite instruments observed widespread and long–lasting perturbations in the composition of the SH midlatitude lower stratosphere. In particular, unprecedented depletion in the main stratospheric chlorine reservoir species (HCl) was accompanied by enhancements in another chlorine reservoir (ClONO2) as well as the ozone–destroying form of chlorine (ClO), with maximum departures from average measured in mid–2020. These anomalous signatures likely arose from chemical processing on smoke particles. The enhancement in the ozone–destroying form of chlorine, far weaker than that in winter polar regions, had only minor effects on ozone.
Key Points
Satellite data show strongly depleted HCl and enhanced ClO and ClONO2 in the southern midlatitude lower stratosphere through much of 2020
The unprecedented midlatitude chlorine repartitioning likely arose from heterogeneous activation on widespread Australian wildfire smoke
The sustained midlatitude chlorine activation was far weaker than in typical winter polar vortices, inducing at most minor changes in ozone
The main objective of this work was to evaluate the nearshore wind resources in the Black Sea area by using a high resolution wind database (ERA-Interim). A subsequent objective was to estimate what ...type of wind turbines and wind farm configurations would be more suitable for this coastal environment. A more comprehensive picture of these resources was provided by including some satellite measurements, which were also used to assess the wind conditions in the vicinity of some already operating European wind projects. Based on the results of the present work, it seems that the Crimea Peninsula has the best wind resources. However, considering the current geopolitical situation, it seems that the sites on the western part of this basin (Romania and Bulgaria) would represent more viable locations for developing offshore wind projects. Since there are currently no operational wind projects in this marine area, some possible configurations for the future wind farms are proposed.
Estimating the thermal information in the subsurface and deeper ocean from satellite measurements over large basin-wide scale is important but also challenging. This paper proposes a support vector ...machine (SVM) method to estimate subsurface temperature anomaly (STA) in the Indian Ocean from a suite of satellite remote sensing measurements including sea surface temperature anomaly (SSTA), sea surface height anomaly (SSHA), and sea surface salinity anomaly (SSSA). The SVM estimation of STA features the inclusion of in-situ Argo STA data for training and testing. SVM, one of the most popular machine learning methods, can well estimate the STA in the upper 1000m of the Indian Ocean from satellite measurements of sea surface parameters (SSTA, SSHA and SSSA as input attributes for SVM). The results, based on the common SVM application of Support Vector Regression (SVR), were validated for accuracy and reliability using the Argo STA data. Both MSE and r2 for performance measures are improved after including SSSA for SVR (MSE decreased by 12% and r2 increased by 11% on average). The results showed that SSSA, in addition to SSTA and SSHA, is a useful parameter that can help detect and describe the deeper ocean thermal structure, as well as improve the STA estimation accuracy. Moreover, our method can provide a useful technique for studying subsurface and deeper ocean thermal variability which has played an important role in recent global surface warming hiatus since 1998, from satellite measurements in large basin-wide scale.
•A new approach to estimate subsurface temperature anomaly from remote sensing•SVM can estimate STA upper 1000m in the Indian Ocean from sea surface features.•A helpful technique for studying subsurface and deeper ocean thermal variability•The intensity of STA was negatively related to the depth.
While multiple data sources have confirmed that Antarctica is losing ice at an accelerating rate, different measurement techniques estimate the details of its geographically highly variable mass ...balance with different levels of accuracy, spatio-temporal resolution, and coverage. Some scope remains for methodological improvements using a single data type. In this study we report our progress in increasing the accuracy and spatial resolution of time-variable gravimetry from the Gravity Recovery and Climate Experiment (GRACE). We determine the geographic pattern of ice mass change in Antarctica between January 2003 and June 2014, accounting for glacio-isostatic adjustment (GIA) using the IJ05_R2 model. Expressing the unknown signal in a sparse Slepian basis constructed by optimization to prevent leakage out of the regions of interest, we use robust signal processing and statistical estimation methods. Applying those to the latest time series of monthly GRACE solutions we map Antarctica's mass loss in space and time as well as can be recovered from satellite gravity alone. Ignoring GIA model uncertainty, over the period 2003–2014, West Antarctica has been losing ice mass at a rate of −121±8 Gt/yr and has experienced large acceleration of ice mass losses along the Amundsen Sea coast of −18±5 Gt/yr2, doubling the mass loss rate in the past six years. The Antarctic Peninsula shows slightly accelerating ice mass loss, with larger accelerated losses in the southern half of the Peninsula. Ice mass gains due to snowfall in Dronning Maud Land have continued to add about half the amount of West Antarctica's loss back onto the continent over the last decade. We estimate the overall mass losses from Antarctica since January 2003 at −92±10 Gt/yr.
•A decade of time-variable gravity observations details Antarctic ice melting.•Slepian-function analysis reduces footprint of satellite-gravity based approaches.•Localized estimation approach dramatically reduces number of degrees of freedom.•We robustly resolve detailed patterns of ice melting using GRACE data products.•Glacio-isostatic adjustment models affect trends, not patterns or accelerations.
•MODIS and Landsat data is used to study cyanobacteria blooms (CB) in the Black Sea in 1985-2019•Modis-based algorithm of CB identification in marine environment is proposed•The main areas of CB are ...located near the Dnieper-Bug estuary and the Danube•Evolution, propagation, and seasonal variability of CB in these areas are different•CB weakens after 2011 due to rise of wind intensity in the summer period
Long-term high and medium resolution satellite data are used to study spatial, seasonal and interannual variability of the cyanobacteria blooms (CB) in the North-Western Shelf (NWS) of the Black Sea. High-resolution Landsat data demonstrate that CB were regularly observed in the study area on satellite images in 1985-2020. Comparison of quasi-synchronous Landsat and MODIS images was used to study the characteristic features of CB spectra, which are: a “step” formed by MODIS 3 (469) and 4 (488) channel, probably related to the absorption by photoprotective carotenoids; increased reflectance in near-infrared; maximum at 547-555 nm. On the base of these features, we develop the automated algorithm of CB identification and reconstruct the daily dataset of CB over 2003-2019. The main advantage of the developed algorithm is its ability to filter out non-bloom areas in all seasons and meteorological conditions and during blooms of other algae in the deep part of the sea. Analysis of this dataset, complemented by Landsat data, allows to identify two primary sources of the CB in the NWS: the Dnieper-Bug estuary and the Danube mouth, and study the evolution of CB in these areas in detail. CB can penetrate on more than 150 km from the sources reaching in rare cases the Crimean coast. Such offshore propagation is mainly wind-driven and was often related to the upwelling frontal currents. The climatic seasonal peak of CB near the Danube is observed in May-June following the peak of river discharge in April-May. It precedes the peak of CB near the Dnieper-Bug estuary observed during maximum surface heating in August. At the same time, the case study of bloom evolution in 2009 shows that CB can be observed in these areas several times in a season, triggered mainly by periods of low winds. The strongest bloom of CB in 2003-2019 was observed in 2004-2006 and 2008-2010 following by the sharp decrease after 2011. This decrease is related to the observed reduction of the river discharge and, more important, the rise of the wind intensity in summers of the recent period.
In this work, we have studied the recently discovered hectometric continuum radiation in near-Earth plasma. We have carried out a detailed statistical analysis of the occurrence of a hectometric ...continuum near Earth at distances 1.1–2 Re, where Re is the Earth radius, for a two-year period, using data from the ERG (Arase) satellite. We have established that the generation of the hectometric radiation depends on the local magnetic time. The continuum radiation of this type is shown to occur mainly at night and in the morning. We have also studied the dependence of the occurrence of hectometric radiation on geomagnetic activity and have demonstrated that there is no direct dependence of the occurrence of hectometric radiation on geomagnetic disturbances. Moreover, the statistical analysis made it possible to localize sources of radio emission of this type in near-Earth space and to show that the source(s) of generation of the hectometric continuum radiation is located at low latitudes.
•Underground coal mines as point sources of methane emission.•Causes of methane emission from underground coal mines.•Well prepared strategy for atmospheric GHG observation capabilities.•An ...integrated CH4 monitoring system so that the point sources of CH4 emission can be identified clearly.
The Upper Silesian Coal Basin in Poland is one of the major European hotspots of CH4 release. Until now, no data concerning short-term CH4 emissions from coal mines have been accessible worldwide. They are available only on a yearly timescale. No values are provided on a higher temporal scale, that’s why the measurements presented here are of great importance. This paper discusses short-term CH4 emissions from ventilation shafts of three mining fronts (Mf) divided into two periods. The concentrations of CH4 in shafts varied from 0.05 to 0.4 %. The highest levels occurred in Shaft IV (Mf I) and Shaft VI (Mf II): from 0.15 to 0.38 % (Period 1). These values correspond to emission levels ranging from 27 to 75 m3/min (Shaft IV) and from 18 to 40 m3/min (Shaft VI). In Period 2, the highest concentrations of CH4 occurred in Shaft VI (Mf II and III): from 0.2 to 0.4 %. The most significant CH4 emissions were recorded for Shaft VI (Mf II) and ranged from 29 to 54 m3/min. Presented data have been used to validate the measurements obtained in the CoMet campaign, which aimed at verifying the sensitivity of the test equipment operating from aircraft. During the test flights of HALO in 2015, the CoMet team achieved a remarkable consistency of measurements conducted with airborne equipment (26 ± 3m3/min) and the emission data (24.34 m3/min), for Shaft VI (Mf II). The analysed short-term data for individual shafts are more reliable and can improve CH4 flux estimates during the CoMet campaign in 2018.
Recent years have witnessed a growing interest in techniques and systems for rainfall surveillance on regional scale, with increasingly stringent requirements in terms of the following: (i) accuracy ...of rainfall rate measurements, (ii) adequate density of sensors over the territory, (iii) space-time continuity and completeness of data and (iv) capability to elaborate rainfall maps in near real time. The devices deployed to monitor the precipitation fields are traditionally networks of rain gauges distributed throughout the territory, along with weather radars and satellite remote sensors operating in the optical or infrared band, none of which, however, are suitable for full compliance to all of the requirements cited above. More recently, a different approach to rain rate estimation techniques has been proposed and investigated, based on the measurement of the attenuation induced by rain on signals of pre-existing radio networks either in terrestrial links, e.g., the backhaul connections in cellular networks, or in satellite-to-earth links and, among the latter, notably those between geostationary broadcast satellites and domestic subscriber terminals in the Ku and Ka bands. Knowledge of the above rain-induced attenuation permits the retrieval of the corresponding rain intensity provided that a number of meteorological and geometric parameters are known and ultimately permits estimating the rain rate locally at the receiver site. In this survey paper, we specifically focus on such a type of “opportunistic” systems for rain field monitoring, which appear very promising in view of the wide diffusion over the territory of low-cost domestic terminals for the reception of satellite signals, prospectively allowing for a considerable geographical capillarity in the distribution of sensors, at least in more densely populated areas. The purpose of the paper is to present a broad albeit synthetic overview of the numerous issues inherent in the above rain monitoring approach, along with a number of solutions and algorithms proposed in the literature in recent years, and ultimately to provide an exhaustive account of the current state of the art. Initially, the main relevant aspects of the satellite link are reviewed, including those related to satellite dynamics, frequency bands, signal formats, propagation channel and radio link geometry, all of which have a role in rainfall rate estimation algorithms. We discuss the impact of all these factors on rain estimation accuracy while also highlighting the substantial differences inherent in this approach in comparison with traditional rain monitoring techniques. We also review the basic formulas relating rain rate intensity to a variation of the received signal level or of the signal-to-noise ratio. Furthermore, we present a comprehensive literature survey of the main research issues for the aforementioned scenario and provide a brief outline of the algorithms proposed for their solution, highlighting their points of strength and weakness. The paper includes an extensive list of bibliographic references from which the material presented herein was taken.
We use 1277 tide gauge records since 1807 to provide an improved global sea level reconstruction and analyse the evolution of sea level trend and acceleration. In particular we use new data from the ...polar regions and remote islands to improve data coverage and extend the reconstruction to 2009. There is a good agreement between the rate of sea level rise (3.2±0.4mm·yr−1) calculated from satellite altimetry and the rate of 3.1±0.6mm·yr−1 from tide gauge based reconstruction for the overlapping time period (1993–2009). The new reconstruction suggests a linear trend of 1.9±0.3mm·yr−1 during the 20th century, with 1.8±0.5mm·yr−1 since 1970. Regional linear trends for 14 ocean basins since 1970 show the fastest sea level rise for the Antarctica (4.1±0.8mm·yr−1) and Arctic (3.6±0.3mm·yr−1). Choice of GIA correction is critical in the trends for the local and regional sea levels, introducing up to 8mm·yr−1 uncertainties for individual tide gauge records, up to 2mm·yr−1 for regional curves and up to 0.3–0.6mm·yr−1 in global sea level reconstruction. We calculate an acceleration of 0.02±0.01mm·yr−2 in global sea level (1807–2009). In comparison the steric component of sea level shows an acceleration of 0.006mm·yr−2 and mass loss of glaciers accelerates at 0.003mm·yr−2 over 200year long time series.
•Updated global and regional sea level rise since 1807•Fastest sea level rise in Arctic (3.6mm·yr−1) and Antarctica (4.1mm·yr−1) since 1970.•Acceleration of 0.02mm·yr−2 in global sea level (1807–2010)•Uncertainties in GSL reconstruction due to GIA corrections are up to 0.3mm·yr−1.
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