Ewa Slominska

Unexpected Very Low Frequency (VLF) Radio Events Recorded by the Ionospheric Satellite DEMETER

DEMETER was a low Earth orbiting microsatellite in operation between July 2004 and December 2010. Its scientific objective was the study of ionospheric perturbations in relation to seismic activity and man-made activities. Its payload was designed to measure electromagnetic waves over a large frequency range as well as ionospheric plasma parameters (electron and ion densities, fluxes of energetic charged particles). This paper will show both expected and unusual events recorded by the satellite when it was in operation. These latter events have been selected from the DEMETER database because they are rare or even have never been observed before, because they have a very high intensity, or because they are related to abnormalities of the experiments under particular plasma conditions. Some events are related to man-made radio waves emitted by VLF ground-based transmitters or power line harmonic radiation. Natural waves, such as atypical quasi-periodic emissions or uncommon whistlers, are also shown.

Localization of RFI Sources for the SMOS Mission: A Means for Assessing SMOS Pointing Performances

Artificial sources emitting in the protected part of the L-band are contaminating the retrievals of the soil moisture and ocean salinity (SMOS) satellite launched by the European Space Agency (ESA) in November 2009. Detecting and pinpointing such sources is crucial for the improvement of SMOS science products as well as for the identification of the emitters. In this contribution, we present a method to obtain snapshot-wise information about sources of radio-frequency interference (RFI). The localization accuracy of this method is also assessed for observed RFI sources. We also show that RFI localizations constitute a useful data set for assessing the pointing performance of the satellite, and present how it is possible, using the results of this method, to identify and estimate two systematic errors in the geo-location of the satellite field of view. The potential causes and the approaches to mitigate both these errors are discussed.

Seasonal trends of nighttime plasma density enhancements in the topside ionosphere

In situ registrations of electron density from the Langmuir probe on board Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions satellite are used to study spatial and temporal evolution of nighttime plasma density enhancements (NPDEs). The study introduces the normalized density difference index INDD in order to provide global estimates of the phenomenon. In the validation test, in situ data are compared with synthetic data set generated with the International Reference Ionosphere model. We find signatures of two most common examples of NPDEs, the Weddell Sea Anomaly (WSA) and midlatitude nighttime summer anomaly (MSNA) with proposed index, in the topside ionosphere. The study provides evidence that the occurrence of the WSA and MSNA is not limited to the local summer conditions. Analyzed annual trend of INDD and in particular spatial pattern obtained during equinoxes suggest that mechanisms governing the behavior of the equatorial ionosphere cannot be neglected in the explanation of the development of NPDEs.

Monitoring of RFI localizations for the SMOS mission: Seasonal variations and systematic errors

Artificial sources emitting in the protected part of the L-band are polluting the retrievals of ESAs Soil Moisture and Ocean Salinity (SMOS) satellite. Detection and localization of such sources are of interest for the exploitation of science products as well as for the identification of the emitters. A simple and fast method that provides snapshot-wise information is presented. From a statistical analysis of the results, some systematic errors are reported along with their potential causes and an approach to mitigate them. In the case of sources at high geomagnetic latitudes a seasonal variation of the localization error is also noticed; the origin of such phenomenon is still under investigation.

Iceberg tracking - SMOS over Antarctica

As part of a natural cycle, ice shelves periodically calve icebergs. In March 2000, Antarcticas Ross Ice Shelf released a colossal berg, assigned as B-15. The B-15 was the world`s largest recorded iceberg with the area of over 11,000 km2. B15 started to break into smaller pieces in 2002 and 2003. One of the pieces from the “B-15 family” (more precisely B-15J) was spotted by the SMOS satellite. For nearly a year the iceberg was tracked on the SMOS data, what provided significant set of information for detailed studies of the object evolution. During the last two months of 2011, the iceberg had strayed far enough from Antarctica in the equatorial direction to begin breaking into smaller pieces. At the end of December the signatures of observed iceberg were barely apparent, making further tracking not feasible. Therefore, we can state that SMOS was also the witness of the final stage of evolution of B-15J. Here we report the last months of iceberg-drifting. The analysis is carried out with application of SMOS land and sea full polarisation browse products (L1c data) in order to obtain general representation of seasonal variability in the southern hemisphere. We monitor the direction of motion, speed, and investigate the temporal evolution of brightness temperature, as well as polarimetric characteristics.