Laboratory For Atmospheric And Space Physics Research Articles

A New Instrument for Balloon-Borne In Situ Aerosol Size Distribution Measurements, the Continuation of a 50Year Record of Stratospheric Aerosols Measurements.

Profiles of stratospheric aerosol size distributions have been measured using balloon-borne in situ optical particle counters, from Laramie, Wyoming (41°N) since 1971. In 2019, this measurement record transitioned to the Laboratory for Atmospheric and Space Physics (LASP) in Boulder, Colorado (40°N). The new LASP Optical Particle Counter (LOPC), the fourth generation of instruments used for this record, is smaller and lighter (2kg) than prior instruments, measures aerosols with diameters ≥0.3-30μm in up to 450 size bins, with a flow rate of 20Lmin-1. The improved size resolution enables the complete measurement of size distributions, and calculation of aerosol extinction without fitting a priori distribution shapes. The higher flow provides the sensitivity required to measure super-micron particles in the stratosphere. The LOPC has been validated against prior Wyoming OPCs, through joint flights, laboratory comparisons, and statistical comparisons with the Wyoming record. The agreement between instruments is generally within the measurement uncertainty of ±10%-20% in sizing and ±10% in concentration, and within ±40% for calculated aerosol moments. The record is being continued with balloon soundings every 2months from Colorado, coordinated with measurements of aerosol extinction from the SAGE III instrument on the International Space Station. Comparisons of aerosol extinction from the remote and in situ platforms have shown good agreement in the stratosphere, particularly for wavelengths <755nm and altitudes <25km. For extinction wavelengths ≥1,021nm and altitudes above 25km SAGE III/International Space Station extinction has a low bias relative to the in situ measurements, yet still within the ±40% uncertainty.

Decadal validation of the LASP TRF cryogenic radiometer by NIST, and establishment of a replacement room temperature standard* *Official contribution of the National Institute of Standards and Technology; not subject to copyright in the United States.

We present the results of a recent, extensive measurement campaign validating the traceability of the solar irradiance record and Earth radiation budget data. The campaign also established future traceability, thus ensuring confidence in the continuing climate-data record. The total solar irradiance radiometer facility (TRF) at the Laboratory for Atmospheric and Space Physics (LASP) Boulder, uses a liquid helium cooled cryogenic radiometer as the reference standard for the validation of spaceflight total solar irradiance (TSI) instrumentation. In 2008 the radiometer was directly compared to the National Institute of Standards and Technology (NIST) Primary Optical Watt Radiometer (POWR) at a wavelength of 532.12 nm. At TSI power levels, a correction factor of 1.000 306 with an associated standard uncertainty (u) of 0.000 098, was reported for the TRF radiometer scale when using external voltage measurement electronics, and not correcting for cavity heating non-equivalence or cavity absorptance. The TRF radiometer has recently been revalidated at LASP using a POWR calibrated silicon photodiode trap transfer standard named TT4. We report a correction factor of 0.999 787, u = 0.000 285 to align the TRF radiometer scale with the current NIST POWR scale. A new room temperature reference standard radiometer was established. It measured 133 parts per million (ppm) higher than POWR using the same silicon transfer standard as above, and in a separate direct measurement, 168 ppm lower than the TRF radiometer shuttered at 400 s full shutter cycle. The difference agrees within stated uncertainties. A correction of 0.999 867, u = 0.000 247 will align the new radiometer scale with the NIST radiant power scale of POWR.

The INSPIRESat-1: Mission, science, and engineering

INSPIRESat-1 (IS-1) is a small scientific satellite being developed jointly by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado at Boulder in the United States, the Indian Institute of Space Science and Technology (IIST) in India, the National Central University (NCU) in Taiwan and the Nanyang Technological University (NTU) in Singapore. This paper describes the science objectives of the IS-1 mission, the engineering and current development status. The IS-1 has completed all functional and performance tests as well as all environmental tests. The spacecraft is manifested on the Indian Space Research Organization’s (ISRO) Polar Satellite Launch Vehicle (PSLV) C-52 mission in 2021. The IS-1 carries two scientific instruments: the Compact Ionospheric Probe (CIP) developed at NCU for studying Earth’s dynamic ionosphere and the Dual-zone Aperture X-ray Solar Spectrometer (DAXSS) developed at LASP for studying the highly-variable solar X-ray radiation. It also carries a Command and Data Handling board developed by IIST. The primary science objectives of the INSPIRESat-1 are twofold. First, using CIP to characterize the temporal and spatial distributions of small-scale plasma irregularities like plasma bubbles in the ionosphere. Secondly, IS-1 aims to provide a greater understanding of why the Sun’s corona is orders of magnitude hotter than the photosphere, why there is an abundance of elements change during different solar events, and how these events (observed with greater soft x-ray fidelity) affect the earth’s ionosphere. The International Satellite Program in Research and Education (INSPIRE) is a consortium of universities with active space programs, formed to advance space science and engineering.

SI-traceable Spectral Irradiance Radiometric Characterization and Absolute Calibration of the TSIS-1 Spectral Irradiance Monitor (SIM)

The current implementation for continuous, long-term solar spectral irradiance (SSI) monitoring is the Total and Spectral Solar Irradiance Sensor (TSIS-1) Spectral Irradiance Monitor (SIM) that began operations from the International Space Station (ISS) in March 2018 and nominally provides an SSI spectrum every 12 h. Advances in both instrument design and spectral irradiance calibration techniques have resulted in the TSIS-1 SIM achieving higher absolute accuracy than its predecessor instrument in the wavelength range (200–2400 nm). A comprehensive detector-based Spectral Radiometer Facility (SRF) was developed in collaboration with the US National Institute for Standards and Technology (NIST) to ensure the ties to spectral SI standards in power and irradiance. Traceability is achieved via direct laser calibration of a focal plane electrical substitution radiometer (ESR) against a cryogenic radiometer in power and also irradiance responsivity via calibrated apertures. The SIM accuracy definition followed an absolute sensor approach based on a full radiometric measurement equation where component-level performance characterizations and calibrations were quantified with an associated uncertainty error budget and verified by independent measurements for each parameter. Unit-level characterizations were completed over the full operational envelope of external driving factors (e.g., pointing and temperature ranges) and were allowed for the independent parameterization of sub-assembly performance for expected operating conditions. Validation and final instrument end-to-end absolute calibration in the Laboratory for Atmospheric and Space Physics (LASP)-SRF achieved low combined standard uncertainty (uc &lt; 0.25%, k = 1) in spectral irradiance.

A Solar Irradiance Climate Data Record

Abstract We present a new climate data record for total solar irradiance and solar spectral irradiance between 1610 and the present day with associated wavelength and time-dependent uncertainties and quarterly updates. The data record, which is part of the National Oceanic and Atmospheric Administration’s (NOAA) Climate Data Record (CDR) program, provides a robust, sustainable, and scientifically defensible record of solar irradiance that is of sufficient length, consistency, and continuity for use in studies of climate variability and climate change on multiple time scales and for user groups spanning climate modeling, remote sensing, and natural resource and renewable energy industries. The data record, jointly developed by the University of Colorado’s Laboratory for Atmospheric and Space Physics (LASP) and the Naval Research Laboratory (NRL), is constructed from solar irradiance models that determine the changes with respect to quiet sun conditions when facular brightening and sunspot darkening features are present on the solar disk where the magnitude of the changes in irradiance are determined from the linear regression of a proxy magnesium (Mg) II index and sunspot area indices against the approximately decade-long solar irradiance measurements of the Solar Radiation and Climate Experiment (SORCE). To promote long-term data usage and sharing for a broad range of users, the source code, the dataset itself, and supporting documentation are archived at NOAA’s National Centers for Environmental Information (NCEI). In the future, the dataset will also be available through the LASP Interactive Solar Irradiance Data Center (LISIRD) for user-specified time periods and spectral ranges of interest.

Magnetospheric Multiscale Instrument Suite Operations and Data System

The four Magnetospheric Multiscale (MMS) spacecraft will collect a combined volume of approximately 100 gigabits per day of particle and field data. On average, only 4 gigabits of that volume can be transmitted to the ground. To maximize the scientific value of each transmitted data segment, MMS has developed the Science Operations Center (SOC) to manage science operations, instrument operations, and selection, downlink, distribution, and archiving of MMS science data sets. The SOC is managed by the Laboratory for Atmospheric and Space Physics (LASP) in Boulder, Colorado and serves as the primary point of contact for community participation in the mission. MMS instrument teams conduct their operations through the SOC, and utilize the SOC's Science Data Center (SOC) for data management and distribution. The SOC provides a single mission data archive for the housekeeping and science data, calibration data, ephemerides, attitude and other ancillary data needed to support the scientific use and interpretation. All levels of data products will reside at and be publicly disseminated from the SDC. Documentation and metadata describing data products, algorithms, instrument calibrations, validation, and data quality will be provided. Arguably, the most important innovation developed by the SOC is the MMS burst data management and selection system. With nested automation and 'Scientist-in-the-Loop' (SITL) processes, these systems are designed to maximize the value of the burst data by prioritizing the data segments selected for transmission to the ground. This paper describes the MMS science operations approach, processes and data systems, including the burst system and the SITL concept.

Fourth World Radiometric Reference to SI radiometric scale comparison and implications for on-orbit measurements of the total solar irradiance

We report the fourth World Radiometric Reference (WRR)-to-SI comparison. At the National Physical Laboratory we compared three transfer pyrheliometer instruments in power mode with the SI radiometric scale. Compared with the three previous comparisons, we improved the experiment by operating the transfer instruments in vacuum. At the Total solar irradiance Radiometer Facility (TRF) located at the Laboratory for Atmospheric and Space Physics (LASP) in Boulder, we repeated the power comparison of one of the transfer instruments. The TRF also allowed the comparison and characterization of this instrument in irradiance mode. Using the WRR comparisons performed in Davos, we find that the WRR is 0.34% higher than the SI scale. Comparing irradiance mode calibrations with power mode calibrations reveals that previous estimates of stray light of PMO6-type radiometers were very low. The instrument calibrated at TRF was integrated in the space experiment PREMOS on the French satellite PICARD and carries the first vacuum irradiance calibration to space.

The Solar Dynamics Observatory (SDO)

The Solar Dynamics Observatory (SDO) was launched on 11 February 2010 at 15:23 UT from Kennedy Space Center aboard an Atlas V 401 (AV-021) launch vehicle. A series of apogee-motor firings lifted SDO from an initial geosynchronous transfer orbit into a circular geosynchronous orbit inclined by 28° about the longitude of the SDO-dedicated ground station in New Mexico. SDO began returning science data on 1 May 2010. SDO is the first space-weather mission in NASA’s Living With a Star (LWS) Program. SDO’s main goal is to understand, driving toward a predictive capability, those solar variations that influence life on Earth and humanity’s technological systems. The SDO science investigations will determine how the Sun’s magnetic field is generated and structured, how this stored magnetic energy is released into the heliosphere and geospace as the solar wind, energetic particles, and variations in the solar irradiance. Insights gained from SDO investigations will also lead to an increased understanding of the role that solar variability plays in changes in Earth’s atmospheric chemistry and climate. The SDO mission includes three scientific investigations (the Atmospheric Imaging Assembly (AIA), Extreme Ultraviolet Variability Experiment (EVE), and Helioseismic and Magnetic Imager (HMI)), a spacecraft bus, and a dedicated ground station to handle the telemetry. The Goddard Space Flight Center built and will operate the spacecraft during its planned five-year mission life; this includes: commanding the spacecraft, receiving the science data, and forwarding that data to the science teams. The science investigations teams at Stanford University, Lockheed Martin Solar Astrophysics Laboratory (LMSAL), and University of Colorado Laboratory for Atmospheric and Space Physics (LASP) will process, analyze, distribute, and archive the science data. We will describe the building of SDO and the science that it will provide to NASA.

Small Space Weather Research Mission Designed Fully by Students

1 of 2 Copyright 2011 by the American Geophysical Union Students at the University of Colorado at Boulder are building a satellite to study the space weather generated by high-energy particles near the Earth. The Colorado Student Space Weather Experiment (CSSWE) is a CubeSat mission funded by the U.S. National Science Foundation, scheduled for launch into a low-Earth polar orbit in June 2012 as a secondary payload under NASA’s Educational Launch of Nanosatellites (ELaNa) program. CSSWE will observe energetic particles for a minimum of 3 months with two goals: to relate the location, magnitude, and frequency of solar flares to the timing, duration, and energy spectrum of solar energetic particles (SEP) reaching Earth and to determine the evolution of the energy spectrum of radiation belt electrons. To accomplish these objectives, CSSWE will measure energetic ions and electrons coming directly from the Sun while it traverses the polar regions, where Earth’s magnetic field lines are directly connected to the interplanetary magnetic field. CSSWE will also measure radiation belt particles at lower latitudes. These types of radiation can affect the operations and life spans of Earth-orbiting spacecraft. Solar particles incident over the polar caps also produce ionospheric disturbances that can affect radio frequency communications. CSSWE (see Figure 1) consists of three stacked CubeSat units, each 10 × 10 × 10 centimeters, that together will contain a single science payload, the Relativistic Electron and Proton Telescope integrated little experiment (REPTile). REPTile is a miniaturization of the Relativistic Electron and Proton Telescope (REPT) currently being built at University of Colorado’s Laboratory for Atmospheric and Space Physics (LASP) for the NASA Radiation Belt Storm Probes (RBSP) mission, which consists of two identical spacecraft scheduled to launch in May 2012 that will go through the heart of the radiation belts in a low-inclination orbit. REPTile is designed to measure the directional differential flux of protons ranging between 10 and 40 megaelectron volts and electrons ranging between 0.5 and 3 megaelectron volts. These energetic particle measurements will be used in conjunction with flare measurements from other spacecraft, such as the Extreme Ultraviolet Variability Experiment on NASA’s Solar Dynamics Observatory and the Solar X-Ray Imager on NOAA’s Geostationary Operational Environmental Satellite

The SORCE Spacecraft and Operations

The Solar Radiation and Climate Experiment, SORCE, is a satellite carrying four scientific instruments that measure the total solar irradiance and the spectral irradiance from the ultraviolet to the infrared. The instruments were all developed by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado, Boulder. The spacecraft carrying and accommodating the instruments was developed by Orbital Sciences Corporation in Dulles, Virginia. It is three-axis stabilized with a control system to point the instruments at the Sun, as well as the stars for calibration. SORCE was successfully launched from the Kennedy Space Center in Florida on 25 January 2003 aboard a Pegasus XL rocket. The anticipated lifetime is 5 years, with a goal of 6 years. SORCE is operated from the Mission Operations Center at LASP where all data are collected, processed, and distributed. This paper describes the SORCE spacecraft, integration and test, mission operations, and ground data system.

Emission cross section of O I (135.6 nm) at 100 eV resulting from electron‐impact dissociative excitation of O2

In this Letter, we report for the first time, the ratio of the O I (135.6 nm)/O I (130.4 nm) absolute emission cross sections from electron‐impact dissociative excitation of O2 at 100 eV using facilities located at the University of Colorado, Laboratory for Atmospheric and Space Physics (LASP). The O I (135.6 nm) emission glow produced in the laboratory from the long‐lived transition O I g³P ← 5S° was measured in a large collision chamber (1m diameter) with a long focal length (50 cm) electrostatic electron gun. The ratio of the absolute emission cross sections of the O I (135.6 nm) and O I (130.4 nm) features resulting from electron‐impact dissociative excitation of O2 at 100 eV was found to be 2.3±0.6. From this ratio, the absolute emission cross section for the O I (135.6 nm) feature at 100 eV electron‐impact energy was determined to be (6.4±2.2)×10−18 cm². The O I (135.6 nm) cross section reported here can be used to better understand the recent Hubble Space Telescope observations of the O I (130.4 nm) and O I (135.6 nm) emission intensities from Ganymede [Feldman et al., 2000] and Europa [Hall et al., 1995].

Improving science return using orbit navigation analysis based on non-imaging science data and the GGS visualization tool

Planetary spacecraft orbital position and instrument pointing knowledge can be incomplete and/or inaccurate due to many operational factors. The degree of error has at times resulted in many hours of re-analysis by the science teams. NASA's Geometry and Graphics Software (GGS), an analysis tool being developed at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado at Boulder, provides the scientist with a standardized method to adjust the look direction knowledge based on the best fit to the science instrument data. The GGS tool locates the instrument boresight based on telemetered spacecraft knowledge and then adjusts that pointing knowledge based on the science analysis of the data obtained from the observation. This technique is similar to the C-Smithing technique (Wang, et al. 1988) which adjusts pointing knowledge based on body placement within an imaging instrument frame. The corrected geometry knowledge, in the SPICE kernel format, is then available for distribution to all mission science teams and for archiving. An example based on the Galileo Ultraviolet Spectrometer (UVS) data from the Earth 1 encounter will be presented.

Optical design of the Ultraviolet Imaging Spectrograph for the Cassini mission to Saturn

When the Cassini spacecraft arrives at Saturn early in the next century it will carry an Ultraviolet Imaging Spectrograph (UVIS) designed and built by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado. Observations made with the UVIS will support a broad set of scientific investigations including spectroscopy, imaging, and occultations. The UVIS consists of two spectroscopic channels covering the wavelength ranges 56 to 118 and 110 to 190 nm. Each channel has an off-axis parabolic telescope followed by a toroidal grating spectrograph and an imaging microchannel plate-CODACON detector. Mirror coatings and detector photocathode materials optimize the sensitivity of each channel for its particular wavelength range. Spectrograph entrance slit mechanisms provide three independent spectral and spatial resolution modes for each of the three channels. A third optical train consisting of a parabolic telescope and solar blind photomultiplier tube with a CsI photocathode provides a high-sensitivity photometer mode within the UVIS. The UVIS configuration was selected as a balanced solution to a large number of engineering and scientific constraints. We describe these constraints, the optical design, and the anticipated performance of the instrument.