Zenit (Poland)

The European Space Agency (ESA) has recently published the Soil Moisture and Ocean Salinity Mission (SMOS) third mission reprocessing data, which include the changes in calibration and image reconstruction that have been made to the Level 1 Operational Processor (L1OP) version v724 during the past few years. The new L1 processor incorporates several improvements to the calibration and image reconstruction algorithms. The present article proposes a new methodology used by the SMOS team to evaluate the quality and stability of the L1 data. This is done by comparison with an ocean forward model over a well-known, sea-surface salinity stable, region. The L1 reprocessed radiometry accuracy and stability are studied in detail. The results presented here confirm the improvement on data quality expected for the new baseline algorithm. Furthermore, the remaining biases and open points are described and analyzed, establishing the basis for their improvement in following reprocessing campaigns.

The quality of the Soil Moisture and Ocean Salinity (SMOS) sea surface salinity (SSS) measurements has been noticeably improved in the past years. However, for some applications, there are still some limitations in the use of the Level-2 ocean salinity product. First, the SSS measurements are still affected by a latitudinal and seasonal bias. Second, the high standard deviation of the SSS error could significantly degrade part of the SSS signal. Finally, the coverage of the Level-2 salinity measurements is significantly reduced after applying filtering criteria to discard the poor-quality retrievals. In this work, we apply nodal sampling to the SMOS brightness temperatures (TBs), which effectively reduces the standard deviation of the TB error; then, we use debiased non-Bayesian retrieval for the mitigation of systematic biases on SSS and the statistical filtering criteria of the degraded salinity retrievals; and finally, we comprehensively characterize the residual latitudinal and seasonal biases and derive a correction for the retrieved SSS. We generate three years of an enhanced SMOS Level-2 Ocean Salinity product and we compare its performances with the ones corresponding to the European Space Agency SMOS Level-2 Ocean Salinity product (v662).

A new technique to mitigate Radio Frequency Interference (RFI) contamination for SMOS images was recently proposed. The technique consists in extrapolating the measured brightness temperature (BT) frequencies in the u/v coverage map outside the star coverage of SMOS. This technique has been implemented, and the quality improvements have been assessed with means of a triple collocation technique using SMOS and SMAP data.

The main directions in improving the color rendering index of a high-pressure sodium discharge are analyzed theoretically. The spectral characteristics of the sodium-mercury column in the pulsed and ac modes are compared. The effect of an increase in the xenon pressure and the introduction of rubidium and cesium into the charge on the radiation characteristics of pulsed sodium lamps is studied.

A remote control system for tv receivers is described which employs ultrasound in the vicinity of 40 kc. Slowly decaying single-frequency signals are produced by striking aluminum rods with a hammer. The receiver employs limiting followed by frequency selection and integration to discriminate against acoustic interference.