ULEIS

ULEIS
Name	ULEIS
Type	airborne mass spectrometer
Operator	NASA; European Space Agency
Manufacturer	Jet Propulsion Laboratory; University of Colorado Boulder
Introduced	2000s
Primary user	Atmospheric Chemistry Instrument teams; Goddard Space Flight Center
Mission	Stratospheric Observatory for Infrared Astronomy deployments; DISCOVER-AQ; ATTREX

ULEIS

ULEIS is an ultralight elemental and isotopic mass spectrometer system designed for in situ detection of low-abundance particulate and gas-phase species in the upper troposphere and lower stratosphere. Developed through collaborations involving NASA, the Jet Propulsion Laboratory, and university laboratories such as University of Colorado Boulder and University of Manchester, ULEIS has been fielded on aircraft, high-altitude balloons, and suborbital platforms to measure composition relevant to ozone layer chemistry, aerosol radiative forcing, and trace gas transport. The instrument’s small size, high sensitivity, and rapid time response enable coordinated campaigns with platforms like ER-2 and observatories including Goddard Space Flight Center assets.

Overview

ULEIS (Ultralight Elemental and Isotopic Spectrometer) targets elemental and isotopic composition of aerosols, meteoric smoke, and refractory trace species. Its development involved teams and institutions such as National Center for Atmospheric Research, California Institute of Technology, Imperial College London, and instrumentation groups at Massachusetts Institute of Technology. ULEIS complements sensors aboard missions like Aura (satellite), CALIPSO, and ground-based networks including AERONET by providing direct, size-resolved chemical information. Field deployments have coordinated with campaigns such as ARCTAS, HIPPO, and INTEX-B to probe continental outflow, biomass burning plumes, and polar stratospheric events.

Instrument Design and Operation

ULEIS combines an aerodynamic inlet, size-selective sampling stages, and a compact time-of-flight mass spectrometer coupled to an electron-impact/laser ablation source. Mechanical and electronics engineering drew on expertise from Jet Propulsion Laboratory, Rutherford Appleton Laboratory, and the European Organization for Nuclear Research. The inlet design is influenced by heritage from instruments flown on ER-2 and WB-57 aircraft, with flow control systems tested against standards from National Institute of Standards and Technology. Operation modes include continuous aerosol sampling for campaigns like MILAGRO and episodic high-altitude collection during NOAA flights. Data acquisition hardware and firmware incorporate processors similar to those used in Hubble Space Telescope guidance electronics for low-noise timing.

Scientific Objectives and Measurements

Primary objectives encompass quantifying elemental abundances (e.g., Fe, Mg, Si, Na), isotopic ratios (e.g., 54Fe/56Fe), and refractory fractions in stratospheric and mesospheric particulates. Measurements address questions tied to processes studied by Mount Pinatubo aerosol research, El Chichón eruption follow-ups, and long-term trends observed by Mauna Loa Observatory. ULEIS provides constraints on meteoric ablation inputs to models used by groups at Max Planck Institute for Chemistry and Centre National de la Recherche Scientifique for stratospheric chemistry simulations. It also measures composition within wildfire plumes studied by Black Saturday bushfires and urban outflow examined during MILAGRO and DISCOVER-AQ. Data inform assessments relevant to policy forums like Intergovernmental Panel on Climate Change when combined with radiative datasets from CERES and aerosol profiling from MODIS.

Calibration and Data Processing

Calibration protocols reference isotopic standards maintained by International Atomic Energy Agency and traceable particulate standards from National Institute of Standards and Technology. Onboard calibration routines use internal reference gases and metal foil standards developed in laboratories at Scripps Institution of Oceanography and University of Cambridge. Data processing pipelines adapt algorithms from time-of-flight mass spectrometry heritage in experiments at Lawrence Berkeley National Laboratory and Brookhaven National Laboratory, including peak deconvolution methods refined for Cassini and Rosetta mass spectrometers. Quality assurance includes intercomparisons with chemical ionization mass spectrometers used by teams at University of Washington and filter-based speciation from Environmental Protection Agency-coordinated networks.

Mission Deployments and Flights

ULEIS has flown on high-altitude platforms including NASA ER-2, NASA WB-57, and research aircraft operated by National Oceanic and Atmospheric Administration. Campaigns include deployments to study Asian outflow during INTEX-B, Arctic measurements during STEP expeditions, and stratospheric aerosol sampling after volcanic eruptions coordinated with Global Atmosphere Watch. Balloon campaigns launched from stations like Kiruna and Esrange complemented satellite overpasses from Aqua (satellite) and Aura (satellite), while suborbital flights aligned with sounding rocket campaigns conducted by Andøya Space Center.

Key Results and Impact

ULEIS measurements have refined estimates of meteoric input functions used in models at University of Leeds and ETH Zurich, clarified iron and silicon partitioning in volcanic plumes studied after Eyjafjallajökull, and provided isotopic fingerprints distinguishing dust sources traced to regions like Sahara and Gobi Desert. Results have influenced assessments by NASA teams on aerosol radiative effects and supported studies from IPCC authors on stratospheric aerosol forcing. Intercomparison studies with instruments from NOAA and ESA validated ULEIS sensitivity for sub-micron refractory species, leading to publications co-authored with researchers at Columbia University and Princeton University.

Future Developments and Upgrades

Planned upgrades target increased mass resolution, integration of a compact resonance-ionization laser developed with Lawrence Livermore National Laboratory, and autonomy improvements inspired by designs from the European Space Agency's small-satellite programs. Prospective deployments include cubesat validation alongside missions from SpaceX-launched platforms and collaborative campaigns with NOAA and JAXA to extend coverage over the Pacific and polar regions. Instrument teams at California Institute of Technology and University of Colorado Boulder aim to enhance onboard processing using machine-learning classifiers trained on datasets from Harvard University and MIT.

Category:Mass spectrometers Category:Atmospheric instrumentation