scholarly journals A Measurement of the Sky Brightness Temperature at 408 MHz

1969 ◽  
Vol 22 (5) ◽  
pp. 641 ◽  
Author(s):  
RM Price
Keyword(s):  
Brightness Temperature ◽  
Resistive Load ◽  
Absolute Value ◽  
Average Brightness ◽  
Northern Latitudes ◽  
Celestial Pole ◽  
Northern Regions ◽  
Average Brightness Temperature ◽  
Receiver Input ◽  
Background Brightness

The absolute value of the background brightness temperature has been measured at a radiofrequency of 408 MHz. Observations were made with a large pyramidal "standard gain" horn aerial and the aerial temperatures were compared direct with the temperature observed with the receiver input connected to a matched resistive load of known temperature. For the region within 240 of the south celestial pole an average brightness temperature of 23� 9�K was obtained. Observations of northern regions indicate that values from previous determinations at northern latitudes are 4-5 degK too high.

scholarly journals Formation and observational features of primary disks in collapsing protostellar clouds

2021 ◽  
Author(s):  
N. S. Kargaltseva ◽  
◽  
A. E. Dudorov ◽  
S. A. Khaibrahmanov ◽  
S. Yu. Parfenov ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Angular Momentum ◽  
Brightness Temperature ◽  
Hierarchical Structure ◽  
Initial Conditions ◽  
Protostellar Disks ◽  
Average Brightness ◽  
Mhd Simulations ◽  
Under Construction ◽  
Average Brightness Temperature

We perform numerical MHD simulations of the isothermal collapse of magnetic rotating protostellar clouds to investigate initial conditions for protostellar disks formation. The simulations show that a hierarchical structure of the cloud is formed during the isothermal collapse: a flattened cloud envelope with a primary magnetostatic disk inside. The first core forms inside the primary disk further. We investigate the dependence of the characteristics (size, mass, angular momentum) of the envelope and primary disk on the initial thermal, magnetic, and rotational energies. Based on the results of numerical simulation the average brightness temperature in the NH3 line (2,2) is under construction.

scholarly journals The multi-thermal chromosphere

2020 ◽  
Vol 634 ◽  
pp. A56 ◽  
Author(s):  
J. M. da Silva Santos ◽  
J. de la Cruz Rodríguez ◽  
J. Leenaarts ◽  
G. Chintzoglou ◽  
B. De Pontieu ◽  
...  
Keyword(s):  
Thermal Structure ◽  
Low Frequency ◽  
Solar Chromosphere ◽  
Quiet Sun ◽  
Average Brightness ◽  
Near Ultraviolet ◽  
Plage Region ◽  
Hydrogen Ionization ◽  
Two Parameters ◽  
Average Brightness Temperature

Context. Numerical simulations of the solar chromosphere predict a diverse thermal structure with both hot and cool regions. Observations of plage regions in particular typically feature broader and brighter chromospheric lines, which suggests that they are formed in hotter and denser conditions than in the quiet Sun, but also implies a nonthermal component whose source is unclear. Aims. We revisit the problem of the stratification of temperature and microturbulence in plage and the quiet Sun, now adding millimeter (mm) continuum observations provided by the Atacama Large Millimiter Array (ALMA) to inversions of near-ultraviolet Interface Region Imaging Spectrograph (IRIS) spectra as a powerful new diagnostic to disentangle the two parameters. We fit cool chromospheric holes and track the fast evolution of compact mm brightenings in the plage region. Methods. We use the STiC nonlocal thermodynamic equilibrium (NLTE) inversion code to simultaneously fit real ultraviolet and mm spectra in order to infer the thermodynamic parameters of the plasma. Results. We confirm the anticipated constraining potential of ALMA in NLTE inversions of the solar chromosphere. We find significant differences between the inversion results of IRIS data alone compared to the results of a combination with the mm data: the IRIS+ALMA inversions have increased contrast and temperature range, and tend to favor lower values of microturbulence (∼3−6 km s−1 in plage compared to ∼4−7 km s−1 from IRIS alone) in the chromosphere. The average brightness temperature of the plage region at 1.25 mm is 8500 K, but the ALMA maps also show much cooler (∼3000 K) and hotter (∼11 000 K) evolving features partially seen in other diagnostics. To explain the former, the inversions require the existence of localized low-temperature regions in the chromosphere where molecules such as CO could form. The hot features could sustain such high temperatures due to non-equilibrium hydrogen ionization effects in a shocked chromosphere – a scenario that is supported by low-frequency shock wave patterns found in the Mg II lines probed by IRIS.

scholarly journals Detection and characterization of drizzle cells within marine stratocumulus using AMSR-E 89 GHz passive microwave measurements

2012 ◽  
Vol 5 (4) ◽  
pp. 4571-4597
Author(s):  
M. A. Miller ◽  
S. E. Yuter
Keyword(s):  
Brightness Temperature ◽  
Liquid Water ◽  
Cell Number ◽  
Passive Microwave ◽  
Liquid Water Path ◽  
Marine Stratocumulus ◽  
Data Set ◽  
Local Maxima ◽  
Spatial Coverage ◽  
Background Brightness

Abstract. This empirical study demonstrates the feasibility of using 89 GHz Advanced Microwave Scanning Radiometer – Earth Observing System (AMSR-E) passive microwave brightness temperature data to detect heavily drizzling cells within marine stratocumulus. A binary heavy drizzle product is described that can be used to determine areal and feature statistics of drizzle cells within the major marine stratocumulus regions. Current satellite liquid water path (LWP) and cloud radar products capable of detecting drizzle are either lacking in resolution (AMSR-E LWP), diurnal coverage (MODIS LWP), or spatial coverage (CloudSat). The AMSR-E 89 GHz data set at 6 × 4 km spatial resolution is sufficient for resolving individual heavily drizzling cells. Radiant emission at 89 GHz by liquid-water cloud and precipitation particles from drizzling cells in marine stratocumulus regions yields local maxima in brightness temperature against an otherwise cloud-free background brightness temperature. The background brightness temperature is primarily constrained by column-integrated water vapor and sea surface temperature. Clouds containing ice are screened out. Once heavily drizzling pixels are identified, connected pixels are grouped into discrete drizzle cell features. The identified drizzle cells are used in turn to determine several spatial statistics for each satellite scene, including drizzle cell number and size distribution. The identification of heavily drizzling cells within marine stratocumulus regions with satellite data facilitates analysis of seasonal and regional drizzle cell occurrence and the interrelation between drizzle and changes in cloud fraction.

scholarly journals A multi-layered image format for the web with an adaptive layer selection algorithm

2017 ◽  
Vol 14 (2) ◽  
pp. 177-197
Author(s):  
Milan Tair ◽  
Aleksandar Mihajlovic ◽  
Nikola Savanovic ◽  
Marko Sarac
Keyword(s):  
Weighted Average ◽  
Threshold Values ◽  
Selection Algorithm ◽  
Multiple Image ◽  
Average Brightness ◽  
Activation Conditions ◽  
Image Format ◽  
Background Brightness ◽  
Font Color ◽  
The Web

In this paper we present a proposed multi-layered image format for use on the web. The format implements an algorithm for selecting adequate layer images depending on the image container's surroundings and size. The layer selection depends on the weighted average brightness of the underlying web page background within the bounds of the image. The proposed image format supports multiple image layers with adjoined thresholds and activation conditions. Depending on these conditions and the underlying background, a layer's visibility will be adequately set. The selection algorithm takes into account the background brightness, each layer's adjoined threshold values, and other newly introduced layer conditions. <br><br><font color="red"><b> This article has been corrected. Link to the correction <u><a href="http://dx.doi.org/10.2298/SJEE1803371E">10.2298/SJEE1803371E</a><u></b></font>

scholarly journals Main directions, specifics and prospects of architectural and construction design development in conditions of Northern latitudes

2020 ◽  
Vol 17 (4) ◽  
pp. 122-127
Author(s):  
V. S. Gusev ◽  
◽  
Yu. V. Pukharenko ◽  
Keyword(s):  
The Arctic ◽  
Design Development ◽  
Construction Design ◽  
Arctic Regions ◽  
Northern Latitudes ◽  
Northern Regions ◽  
Extreme North ◽  
Scientific Achievements

Northern regions of the country are of great economic, geopolitical, defense and strategic importance. The article considers the problems of construction in the Arctic regions highlighting the importance of using construction technologies and materials that meet the conditions of the Extreme North, as well as integrating the latest scientific achievements into the field of architecture and construction with the need to implement the experience of foreign and Russian developers and facilitating the development of Arctic tourism.

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