scholarly journals A Blackbody Design for SI-Traceable Radiometry for Earth Observation

2008 ◽  
Vol 25 (11) ◽  
pp. 2046-2054 ◽  
Author(s):  
P. Jonathan Gero ◽  
John A. Dykema ◽  
James G. Anderson
Keyword(s):  
Phase Transitions ◽  
Temperature Scale ◽  
International System ◽  
Thermal Infrared ◽  
Earth Observation ◽  
International Standards ◽  
Future Climate Change ◽  
Single Temperature ◽  
System Of Units ◽  
Infrared Measurements

Abstract Spaceborne measurements pinned to international standards are needed to monitor the earth’s climate, quantify human influence thereon, and test forecasts of future climate change. The International System of Units (SI, from the French for Système International d’Unités) provides ideal measurement standards for radiometry as they can be realized anywhere, at any time in the future. The challenge is to credibly prove on-orbit accuracy at a claimed level against these international standards. The most accurate measurements of thermal infrared spectra are achieved with blackbody-based calibration. Thus, SI-traceability is obtained through the kelvin scale, making thermometry the foundation for on-orbit SI-traceable spectral infrared measurements. Thermodynamic phase transitions are well established as reproducible temperature standards and form the basis of the international practical temperature scale (International Temperature Scale of 1990, ITS-90). Appropriate phase transitions are known in the temperature range relevant to thermal infrared earth observation (190–330 K) that can be packaged such that they are chemically stable over the lifetime of a space mission, providing robust and traceable temperature calibrations. A prototype blackbody is presented that is compact, highly emissive, thermally stable and homogeneous, and incorporates a small gallium melting point cell. Precision thermal control of the blackbody allows the phase transition to be identified to within 5 mK. Based on these results, the viability of end-to-end thermometric calibration of both single-temperature and variable-temperature blackbodies on orbit by employing multiple-phase-change cells was demonstrated.

scholarly journals A Quantum Cascade Laser–Based Reflectometer for On-Orbit Blackbody Cavity Monitoring

2009 ◽  
Vol 26 (8) ◽  
pp. 1596-1604 ◽  
Author(s):  
P. Jonathan Gero ◽  
John A. Dykema ◽  
James G. Anderson
Keyword(s):  
Quantum Cascade Laser ◽  
Single Mode ◽  
Thermal Infrared ◽  
Low Earth Orbit ◽  
International Standards ◽  
Optical Systems ◽  
Future Climate Change ◽  
Cavity Surface ◽  
Quantum Cascade ◽  
Blackbody Cavity

Abstract Satellite measurements pinned to international standards are needed to monitor the earth’s climate, quantify human influence thereon, and test forecasts of future climate change. Credible observations require that measurement uncertainties be evaluated on orbit during a mission’s operational lifetime. The most accurate spaceborne measurements of thermal infrared radiance are achieved with blackbody calibration. The physical properties of blackbody cavity surface coatings are known to change upon extended exposure to the low earth orbit environment. Any such drift must be quantified to continue correctly calibrating observed radiance on orbit. A method is presented to diagnose the effective emissivity of a blackbody cavity in situ using a quantum cascade laser (QCL)-based reflectometer. QCLs provide high-power single-mode output in the thermal infrared and have small mechanical footprints that facilitate integration into existing optical systems. The laser reflectivity in a test blackbody cavity was measured to be 9.22 × 10−4 with an uncertainty of 8.9 × 10−5, which is equivalent to a detection limit of 3 mK in the error in radiance temperature for a calibration blackbody (at 330 K and 1000 cm−1) resulting from cavity emissivity drift. These results provide the experimental foundation for this technology to be implemented on satellite instruments and thus eliminate a key time-dependent systematic error from future measurements on orbit.

Metrication and SI Units

PEDIATRICS ◽  
1980 ◽  
Vol 65 (3) ◽  
pp. 659-664
Author(s):  
Arno R. Hohn ◽  
Alfred B. Amler ◽  
Paul S. Bergeson ◽  
Harvey R. Gold ◽  
Stewart L. Griggs ◽  
...  
Keyword(s):  
United States ◽  
International System ◽  
The United States ◽  
International Standards ◽  
Reference Laboratory ◽  
Royal Decree ◽  
Weights And Measures ◽  
International System Of Units ◽  
System Of Units ◽  
Metre Convention

Because of the increasing international use of the SI system (International System of Units) in medicine, the Committee on Hospital Care has written this statement to familiarize pediatricians with this concept. The current state of the system, its derivation, purported advantages, and controversial aspects are described; and the Committee has made specific recommendations for consideration regarding its future use and development. BACKGROUND The British Imperial System of Weights used in the United States today derives from a variety of ancient cultures. A Roman contribution is the use of the awkward number 12 as a base. Royal decree established the yard as the distance from the tip of the nose to the end of the thumb of King Henry I. The inch was based on the size of three grains of barley "dry and round." Equally illogically derived units evolved to eventually form the irrational English "system."1 The metric system with its "base-10" or "decimal" system derived its units of mass and volume from its units of length, thus correlating its basic units to each other. The need for further refinement of metrics and a single worldwide and interdisciplinary system of measurements led to the development of the International System of Units (le Systeme International d'Unités) with the international abbreviation "SI." This is sometimes referred to as "the modern metric system" and is said to complete the process of metrication.2 Seventeen countries, including the United States, signed the Metre Convention in 1870. This led to the establishment of the International Bureau of Weights and Measures at Sèvres, France, which acts as an international standards reference laboratory and as the permanent secretariat for the Metre Convention.

Performance criteria for reference measurement procedures and reference materials

2015 ◽  
Vol 53 (6) ◽  
Author(s):  
Heinz Schimmel ◽  
Ingrid Zegers
Keyword(s):  
Reference Materials ◽  
International System ◽  
Metrological Traceability ◽  
International Standards ◽  
Performance Criteria ◽  
Systematic Bias ◽  
End User ◽  
Reference Measurement ◽  
System Of Units ◽  
Measurement Results

AbstractThe concept of metrological traceability of measurement results to property values assigned to measurement standards of higher metrological order or to the International System of Units (SI) through sequential calibrations, using reference materials and reference measurement procedures, plays a key role in ensuring that end user measurement procedures perform at an acceptable level in the clinical context. The aim is that measurement results produced over time or by different end users or with different end user measurement procedures for the same measurand will be equivalent within their corresponding uncertainties. These goals can only be reached under certain conditions and if requirements laid down in international standards on calibration concepts, reference measurement procedures and reference materials are fulfilled. Calibration hierarchies have to be implemented correctly and parameters contributing to measurement uncertainty and systematic bias need to be controlled and eliminated, respectively, by technically improving methods and reference materials and intermediate calibrators used for effectively achieving equivalence of measurement results and for meeting analytical performance requirements for in vitro diagnostic devices.

scholarly journals Salinity and relative humidity: climatological relevance and metrological needs

ACTA IMEKO ◽  
2015 ◽  
Vol 4 (4) ◽  
pp. 57 ◽  
Author(s):  
Rainer Feistel
Keyword(s):  
Relative Humidity ◽  
State Of The Art ◽  
Numerical Models ◽  
International System ◽  
Metrological Traceability ◽  
Ocean Surface ◽  
International Standards ◽  
Surface Salinity ◽  
Climatic Trends ◽  
System Of Units

Water plays the leading thermodynamic role in Earth's 'steam engine' climate. Followed by clouds and CO<sub>2</sub>, water vapour in the atmosphere is dominating the greenhouse effect. Evaporation from the ocean surface is the main route of energy export from the ocean, the rate of which is known with poor 20 % uncertainty only. Regional climatic trends in evaporation and precipitation are reflected in small changes of ocean surface salinity.<br /> Observational data of salinity and relative humidity need to be globally comparable within requisite uncertainties over decades and centuries, but both quantities rely on century-old provisional standards of unclear stability, and on ambiguous definitions. This increasingly urgent and long-pending problem can only be solved by proper metrological traceability to the International System of Units (SI). Consistent with such SI-based definitions, state-of-the-art correlation equations for thermophysical properties of water, seawater, ice and humid air such as those available from the recent oceanographic standard TEOS-10 need to be developed and adopted as joint international standards for all branches of climate research, in oceanography, meteorology and glaciology for data analysis and numerical models.<br /> The IAPSO/SCOR/IAPWS Joint Committee on Seawater JCS is targeting at these aims in cooperation with BIPM, WMO and other international bodies.

The NPU format for clinical laboratory science reports regarding properties, units, and symbols (IUPAC Technical Report)

2014 ◽  
Vol 86 (12) ◽  
pp. 1923-1930
Author(s):  
Georges Férard ◽  
René Dybkaer
Keyword(s):  
Clinical Laboratory ◽  
Clinical Chemistry ◽  
International System ◽  
Epidemiological Studies ◽  
International Standards ◽  
Clinical Laboratory Science ◽  
Laboratory Science ◽  
Technical Report ◽  
System Of Units ◽  
Clinical Laboratory Sciences

Abstract The terminology of NPU (nomenclature for properties and units) aims at describing properties examined in clinical laboratories for a patient. It was originally jointly approved in 1966 by IUPAC and by the International Federation of Clinical Chemistry (IFCC) and covers multiple disciplines in the field of clinical laboratory sciences, including clinical allergology, clinical chemistry, clinical haematology, clinical immunology and blood banking, clinical microbiology, clinical pharmacology, molecular biology and genetics, reproduction and fertility, thrombosis and haemostasis, and toxicology. The NPU terminology adheres to international standards of metrology and of terminology, in particular the International System of Quantities (ISQ) and International System of Units (SI), the International Vocabulary of Metrology (VIM), and also to ‘An outline for a vocabulary of nominal properties and examinations – basic and general concepts and associated terms,’ recently prepared on behalf of the IFCC-IUPAC Committee-Subcommittee on Nomenclature for Properties and Units. The present document recalls the definitions of the concepts used to express a property of a patient, regarded as a system. The aim is to promote by this comprehensive summary the proper NPU terminology for reliable exchange of patient examination data. The use of this syntax and of SI units enables the translation of these descriptions into other languages without loss of meaning or accuracy. The NPU format is also well adapted for comparative and epidemiological studies. More information will be found in the upcoming 2nd edition of the Compendium of Terminology and Nomenclature of Properties in Clinical Laboratory Sciences, the IUPAC and IFCC ‘Silver Book’, and in the recently published ‘Properties and units in the clinical laboratory sciences. Part XXIII. The NPU terminology, principles, and implementation: A user’s guide (IUPAC Technical Report)’ (DOI:10.1351/PAC-REP-11-05-03).

Dimensions of plane and solid angles and their units in the International System of Units (SI)

2020 ◽  
pp. 26-32
Author(s):  
M. I. Kalinin ◽  
L. K. Isaev ◽  
F. V. Bulygin
Keyword(s):  
Solid Angle ◽  
International System ◽  
International Committee ◽  
Plane Angle ◽  
Arc Length ◽  
Weights And Measures ◽  
International System Of Units ◽  
System Of Units ◽  
In Series ◽  
Solid Angles

The situation that has developed in the International System of Units (SI) as a result of adopting the recommendation of the International Committee of Weights and Measures (CIPM) in 1980, which proposed to consider plane and solid angles as dimensionless derived quantities, is analyzed. It is shown that the basis for such a solution was a misunderstanding of the mathematical formula relating the arc length of a circle with its radius and corresponding central angle, as well as of the expansions of trigonometric functions in series. From the analysis presented in the article, it follows that a plane angle does not depend on any of the SI quantities and should be assigned to the base quantities, and its unit, the radian, should be added to the base SI units. A solid angle, in this case, turns out to be a derived quantity of a plane angle. Its unit, the steradian, is a coherent derived unit equal to the square radian.

scholarly journals A quantum ampere

2020 ◽  
Vol 87 (4) ◽  
pp. 258-265
Author(s):  
Luca Callegaro
Keyword(s):  
Electric Current ◽  
International System ◽  
International System Of Units ◽  
System Of Units ◽  
Elementary Charge ◽  
User Friendly

AbstractThe revision of the International System of Units (SI), implemented since 20 May 2019, has redefined the unit of electric current, the ampere ( A), linking it to a fixed value of the elementary charge. This paper discusses the new definition and the realisation of the electrical units by quantum electrical metrology standards, which every year become more and more accessible, reliable and user friendly.

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