In-situ and optical observations of sub-ion magnetic holes

AbstractMany physical parameters of asteroids can be inferred from remote measurements at optical wavelengths. These observations constitute the bulk of the information we have about these objects, and nicely complement the detailed physical studies which are made possible by in situ explorations of a few selected targets. The discovery of many binary systems for which mass determinations become possible, the identification of hydration features in asteroid spectra, including unexpectedly many M-types, the detection of space-weathering phenomena affecting S-type near-Earth objects, as well as improved estimates of sizes, albedos, and spin properties for many objects are among the major results obtained in recent years by means of remote-sensing techniques. These data can be used to infer important properties of the internal structures of the asteroids.

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Constraining the ocean's biological pump with in situ optical observations and supervised learning. Part 2: 2 Carbon Flux

10.1002/essoar.10509084.2 ◽

2021 ◽

Author(s):

Daniel J Clements ◽

Simon Yang ◽

Thomas Weber ◽

Andrew Mcdonnell ◽

Rainer Kiko ◽

...

Keyword(s):

Supervised Learning ◽

Carbon Flux ◽

Optical Observations ◽

Biological Pump ◽

In Situ Optical Observations

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Measuring snowfall properties with the Video In Situ Snowfall Sensor during MOSAiC

10.5194/egusphere-egu21-3306 ◽

2021 ◽

Author(s):

Maximilian Maahn ◽

Martin Radenz ◽

Christopher Cox ◽

Michael Gallagher ◽

Jennifer Hutchings ◽

...

Keyword(s):

Optical Observations ◽

Cloud Droplets ◽

Cloud Dynamics ◽

First Results ◽

High Resolution Images ◽

Large Measurement ◽

Microphysical Processes ◽

Moisture Conditions ◽

The Impact

<p>Snow is an essential component of the climate system impacting surface albedo, glaciers, sea ice, freshwater storage, and cloud lifetime. Even though we do not know the exact pathways through which ice, liquid, cloud dynamics, and aerosols are interacting in clouds while forming snowfall, the involved processes can be identified by their fingerprints on snow particles. The general shape of individual crystals (dendritic, columns, plates) depends on the temperature and moisture conditions during growth from water vapor deposition. Aggregation can be identified when multiple individual particles are combined into a snowflake. Riming describes the freezing of cloud droplets onto the snow particle and can eventually form graupel. In order to exploit these unique fingerprints of cloud microphysical processes, optical observations are required.</p><p>The Video In Situ Snowfall&#160;Sensor (VISSS) was specifically developed for the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign to determine particle shape and particle size distributions. Different to other sensors, the VISSS minimizes uncertainties by combining two-dimensional high-resolution images with a large measurement volume and a design limiting the impact of wind. Here, we show first results from the MOSAiC campaign and present examples for synergy effects that can be obtained by combining radar and VISSS measurements.</p>

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PFISR nightside observations of naturally enhanced ion acoustic lines, and their relation to boundary auroral features

Annales Geophysicae ◽

10.5194/angeo-26-3623-2008 ◽

2008 ◽

Vol 26 (11) ◽

pp. 3623-3639 ◽

Cited By ~ 12

Author(s):

R. G. Michell ◽

K. A. Lynch ◽

C. J. Heinselman ◽

H. C. Stenbaek-Nielsen

Keyword(s):

Broad Band ◽

Low Frequency ◽

Wave Activity ◽

Electron Precipitation ◽

Optical Observations ◽

Small Scale ◽

Spatial And Temporal Scales ◽

Ion Acoustic ◽

Magnetic Zenith

Abstract. We present results from a coordinated camera and radar study of the auroral ionosphere conducted during March of 2006 from Poker Flat, Alaska. The campaign was conducted to coincide with engineering tests of the first quarter installation of the Poker Flat Incoherent Scatter Radar (PFISR). On 31 March 2006, a moderately intense auroral arc, (~10 kR at 557.7 nm), was located in the local magnetic zenith at Poker Flat. During this event the radar observed 7 distinct periods of abnormally large backscattered power from the F-region. These were only observed in the field-aligned radar beam, and radar spectra from these seven times show naturally enhanced ion-acoustic lines (NEIALs), the first observed with PFISR. These times corresponded to (a) when the polar cap boundary of the auroral oval passed through the magnetic zenith, and (b) when small-scale filamentary dark structures were visible in the magnetic zenith. The presence of both (a) and (b) was necessary for their occurrence. Soft electron precipitation occurs near the magnetic zenith during these same times. The electron density in the vicinity where NEIALs have been observed by previous studies is roughly between 5 and 30×1010 m−3. Broad-band extremely low frequency (BBELF) wave activity is observed in situ by satellites and sounding rockets to occur with similar morphology, during active auroral conditions, associated with the poleward edge of the aurora and soft electron precipitation. The observations presented here suggest further investigation of the idea that NEIALs and BBELF wave activity are differently-observed aspects of the same wave phenomenon. If a connection between NEIALs and BBELF can be established with more data, this could provide a link between in situ measurements of downward current regions (DCRs) and dynamic aurora, and ground-based observations of dark auroral structures and NEIALs. Identification of in situ processes, namely wave activity, in ground-based signatures could have many implications. One specific example of interest is identifying and following the temporal and spatial evolution of regions of potential ion outflow over large spatial and temporal scales using ground-based optical observations.

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Classification of Australian Waterbodies across a Wide Range of Optical Water Types

Remote Sensing ◽

10.3390/rs12183018 ◽

2020 ◽

Vol 12 (18) ◽

pp. 3018

Author(s):

Elizabeth J. Botha ◽

Janet M. Anstee ◽

Stephen Sagar ◽

Eric Lehmann ◽

Thais A. G. Medeiros

Keyword(s):

Spectral Response ◽

Optical Observations ◽

Optical Data ◽

Water Types ◽

Continental Scale ◽

Inherent Optical Properties ◽

Eastern Australia ◽

Wide Range ◽

Development Goals

Baseline determination and operational continental scale monitoring of water quality are required for reporting on marine and inland water progress to Sustainable Development Goals (SDG). This study aims to improve our knowledge of the optical complexity of Australian waters. A workflow was developed to cluster the modelled spectral response of a range of in situ bio-optical observations collected in Australian coastal and continental waters into distinct optical water types (OWTs). Following clustering and merging, most of the modelled spectra and modelled specific inherent optical properties (SIOP) sets were clustered in 11 OWTs, ranging from clear blue coastal waters to very turbid inland lakes. The resulting OWTs were used to classify Sentinel-2 MSI surface reflectance observations extracted over relatively permanent water bodies in three drainage regions in Eastern Australia. The satellite data classification demonstrated clear limnological and seasonal differences in water types within and between the drainage divisions congruent with general limnological, topographical, and climatological factors. Locations of unclassified observations can be used to inform where in situ bio-optical data acquisition may be targeted to capture a more comprehensive characterization of all Australian waters. This can contribute to global initiatives like the SDGs and increases the diversity of natural water in global databases.

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