Electron Heating by Debye-Scale Turbulence in Guide-Field Reconnection.

We report electrostatic Debye-scale turbulence developing within the diffusion region of asymmetric magnetopause reconnection with a moderate guide field using observations by the Magnetospheric Multiscale mission. We show that Buneman waves and beam modes cause efficient and fast thermalization of the reconnection electron jet by irreversible phase mixing, during which the jet kinetic energy is transferred into thermal energy. Our results show that the reconnection diffusion region in the presence of a moderate guide field is highly turbulent, and that electrostatic turbulence plays an important role in electron heating.

Simulation of sea surface wave influence on small target detection with airborne laser depth sounding.

A theoretical model for simulation of airborne depth-sounding lidar is presented with the purpose of analyzing the influence from water surface waves on the ability to detect 1-m3 targets placed on the sea bottom. Although water clarity is the main limitation, sea surface waves can significantly affect the detectability. The detection probability for a target at a 9-m depth can be above 90% at 1-m/s wind and below 80% at 6-m/s wind for the same water clarity. The simulation model contains both numerical and analytical components. Simulated data are compared with measured data and give realistic results for bottom depths between 3 and 10 m.

Analytical waveform generation from small objects in lidar bathymetry.

We present a model to simulate receiver waveforms from an airborne sea-depth-sounding lidar to compare the influence that is due to different shapes of objects placed on the sea bottom. The objects are of size 1 m(3), and the bottom depths are 5-12 m. We use an existing analytical beam-propagation model and divide the bottom into squares. For each element on the bottom grid we create a transmitted and a reflected waveform. The waveforms are summed, yielding a total contribution from all bottom elements. We compare two object types, cylinder and cube, and find that the difference in the receiver waveform is small between these objects. Simulated waveforms are compared with experimental data from the Swedish Hawk Eye system and show good agreement.