Microwave proxies for sunspot blocking and total irradiance

1995 ◽  
Vol 100 (A10) ◽  
pp. 19851 ◽  
Author(s):  
E. J. Schmahl ◽  
M. R. Kundu
Keyword(s):  
Total Irradiance

scholarly journals Detailed Characterization and Monitoring of a Retrogressive Thaw Slump from Remotely Piloted Aircraft Systems and Identifying Associated Influence on Carbon and Nitrogen Export

2021 ◽  
Vol 13 (2) ◽  
pp. 171
Author(s):  
Kevin W. Turner ◽  
Michelle D. Pearce ◽  
Daniel D. Hughes
Keyword(s):  
Surface Model ◽  
Carbon And Nitrogen ◽  
Aircraft Systems ◽  
Detailed Classification ◽  
Fill Volume ◽  
Remotely Piloted Aircraft ◽  
Total Irradiance ◽  
Retrogressive Thaw Slump ◽  
Rain Events ◽  
Sediment Export

Ice-rich permafrost landscapes are sensitive to ongoing changes in climate. Permafrost retrogressive thaw slumps (RTSs) represent one of the more abrupt and prolonged disturbances, which occur along Arctic river and lake shorelines. These features impact local travel and infrastructure, and there are many questions regarding associated impacts on biogeochemical cycling. Predicting the duration and magnitude of impacts requires that we enhance our knowledge of RTS geomorphological drivers and rates of change. Here we demonstrate the utility of remotely piloted aircraft systems (RPAS) for documenting the volumetric change, associated drivers and potential impacts of the largest active RTS along the Old Crow River in Old Crow Flats, Yukon, Canada. RPAS surveys revealed that 29,174 m3 of sediment was exported during the initial evacuation in June 2016 and an additional 18,845 m3 continued to be exported until June 2019. More sediment export occurred during the warmer 2017 summer that experienced less cumulative rainfall than summer 2018. However, several rain events during 2017 were of higher intensity than during 2018. Overall mean soil organic carbon (SOC) and total nitrogen (TN) within sampled thaw slump sediment was 1.36% and 0.11%, respectively. A combination of multispectral, thermal and irradiance (derived from the RPAS digital surface model) data provided detailed classification of thaw slump floor terrain types including raised dry clay lobes, shaded and relatively stable, and low-lying evacuation-prone sediments. Notably, the path of evacuation-prone sediments extended to a series of ice wedges in the northern headwall, where total irradiance was highest. Using thaw slump floor mean SOC and TN values in conjunction with sediment bulk density and thaw slump fill volume, we estimated that 713 t SOC and 58 t TN were exported to the Old Crow River during the three-year study. Findings showcase the utility of high-resolution RPAS datasets for refining our knowledge of thaw slump geomorphology and associated impacts.

scholarly journals A Radiometric Technique for Monitoring the Desulfurization Process of Blister Copper

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 842
Author(s):  
Alejandro Vásquez ◽  
Francisco Pérez ◽  
Maximiliano Roa ◽  
Ignacio Sanhueza ◽  
Hugo Rojas ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spectral Emissivity ◽  
Optical Probe ◽  
Blister Copper ◽  
Optical Absorption Spectroscopy ◽  
Total Irradiance ◽  
Desulfurization Process ◽  
Radiometric Technique ◽  
Collimating Lens ◽  
Total Emissivity

In this paper, a novel optical technique for following the progress of the blister copper desulfurization process is presented. The technique is based on the changes observed in the continuous spectrum of the visible–near-infrared (VIS–NIR) radiation that the blister melt emits while the chemical reactions of the sulfur elimination process are taking place. Specifically, the proposed technique uses an optical probe composed of an optical fiber, a collimating lens, and a quartz tube, which is immersed in the melt. This optical probe provides a field of view of the blowing zone where the desulfurization reaction occurs. The experimental results show that the melt VIS–NIR total irradiance evolves inversely to the SO2 concentration reported by a gas analyzer based on differential optical absorption spectroscopy. Furthermore, the blister copper spectral emissivity as well as the total emissivity observed throughout the process show strong correlation with the sulfur content during desulfurization reaction.

GOES High cadence Operational Total Irradiance: planned data products

2021 ◽  
Author(s):  
Martin Snow ◽  
Stephane Beland ◽  
Odele Coddington ◽  
Steven Penton ◽  
Don Woodraska
Keyword(s):  
Extreme Ultraviolet ◽  
Solar Spectrum ◽  
Total Solar Irradiance ◽  
The Other ◽  
Spectral Irradiance ◽  
First Year ◽  
X Ray ◽  
Solar Spectral Irradiance ◽  
Total Irradiance ◽  
High Cadence

<p>The GOES-R series of satellites includes a redesigned instrument for solar spectral irradiance: the Extreme ultraviolet and X-ray Irradiance Sensor (EXIS).  Our team will be using a high-cadence broadband visible light diode to construct a proxy for Total Solar Irradiance (TSI).  This will have two advantages over the existing TSI measurements:  measurements are taken at 4 Hz, so the cadence of our TSI proxy is likely faster than any existing applications, and the observations are taken from geostationary orbit, so the time series of measurements is virtually uninterrupted.  Calibration of the diode measurements will still rely on the standard TSI composites.  </p><p>The other measurement from EXIS that will be used is the Magnesium II core-to-wing ratio.  The MgII index is a proxy for chromospheric activity, and is measured by EXIS every 3 seconds.  The combination of the two proxies can be used to generate a model of the full solar spectrum similar to the NRLSSI2 empirical model.</p><p>We are in the first year of a three-year grant to develop the TSI proxy and the SSI model, so only very preliminary findings will be discussed in this presentation.</p>

Measurements of Phytoplankton Absorption Other Than Per Unit of Chlorophyll a

Ocean Optics ◽  
1994 ◽  
Author(s):  
Mary Jane Perry
Keyword(s):  
Primary Production ◽  
Chlorophyll A ◽  
Photosynthetic Pigments ◽  
Critical Role ◽  
Specific Effect ◽  
Water Volume ◽  
Phytoplankton Abundance ◽  
Chlorophyll A Concentration ◽  
Total Irradiance ◽  
Phytoplankton Absorption

Phytoplankton plays a critical role in determining light fields of the world’s oceans, primarily through absorption of light by photosynthetic pigments (see Chapters 1 to 5). Consequently there has been considerable interest from optical researchers in determining phytoplankton absorption. Conversely, from the biological point of view, this absorption assumes paramount importance because it is the sole source of energy for photosynthesis and thus should be central to direct estimates of primary production. There are two logical parts in determining this effect of phytoplankton and in estimating primary production. One is the estimation of abundance, and the other is estimation of specific effect or specific production rate. The earliest estimates of phytoplankton abundance were based on cell counts. From the time of Francis A. Richards’ Ph.D. dissertation, however, measurement of chlorophyll a concentration per unit of water volume, because of its relative ease, has assumed a central role in abundance estimation. Physiological studies and technological advances in optical instrumentation over the last decade lead me to question whether the continued use of chlorophyll a concentration to estimate phytoplankton abundance was wise either from the viewpoint of narrowing confidence intervals on estimates of absorption and production or from the viewpoint of mechanistic understanding of the processes involved. The measurement of chlorophyll a has become such a routine tool of biological oceanography, however, that the reasons for my heresy require elaboration. Some of the reasons are not too subtle. Chlorophyll a exists with other photosynthetic pigments in organized arrays associated with photosynthetic membranes. The function of these arrays is to harvest photons and transfer their energy to the specialized reaction center complexes that mediate photochemistry (see Chapter 9). The size of the arrays or packages and the ratio of chlorophyll a molecules to other light-harvesting pigments within the packages vary with phytoplankton cell size, total irradiance and its spectral distribution, as well as with other environmental parameters. It is well known that dark-adapted (= light-limited) cells increase their complements of photopigments. This plasticity in pigment packaging is evidenced in the variability of chlorophyll a-specific absorption coefficients. Simple optical models based only on chlorophyll a concentrations cannot be accurate or precise unless the effects of pigment packaging are considered.

The relation of oceanic primary production to available photosynthetic irradiance

1976 ◽  
Vol 27 (3) ◽  
pp. 441 ◽  
Author(s):  
HR Jitts ◽  
A Morel ◽  
Y Saijo
Keyword(s):  
Primary Production ◽  
Surface Ocean ◽  
Surface Samples ◽  
In Situ Method ◽  
Wide Range ◽  
Total Irradiance ◽  
Highly Correlated ◽  
Bodies Of Water ◽  
High Degree

Primary production was measured at 14 stations covering a wide range of oceanic waters. Measurements were made by both the in situ method (Pi) and the simulated in situ method (Ps) Production v. constant irradiance (P v. I) was also measured. Available photosynthetic irradiance [Eq(350-700) in quanta m-2 s-1] was calculated from continuous records of total irradiance and measurements of the percentage submarine transmission of irradiance were made with a quantum meter. Using the P v. I curves and Eq(350-700), primary production at several depths at each station was calculated (P,). Pc was shown to be a precise estimate of Ps at all depths. Pc was also highly correlated with Pi, but both Pc and Pi overestimated Pi at the surface by 40 %. Some experiments at three stations showed that a 2-mm thickness of clear glass placed over surface samples in the measurement of Ps could increase Ps by about 50%. This suggested that U.V. irradiance in surface ocean waters decreased Pi and could explain the overestimates by Pc and Ps. The results showed the need for precise information of spectrai composition of irradiance in studies of primary production but demonstrated the kalidity of Eq(350-700) as an estimate of available photosynthetic irradiance. They also showed that Pc could estimate Pi with a high degree of precision, and that such a calculative method could provide a useful way of continuously monitoring the primary production of large bodies of water for extended periods.

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