Stratospheric Aerosol processes, Budget, and Radiative Effects

The Laser Induced Fluorescence-Nitrogen Oxide (LIF-NO) is an airborne optical sensor operated by NOAA that detects nitric oxide (NO) in the upper troposphere and lower stratosphere. It utilizes single-photon laser-induced fluorescence and employs a tunable laser at 1074-1076 nm to generate the fifth harmonic, near 215 nm, for NO detection. It has a sampling rate of 1 Hz, a detection limit of 1 pptv, and an accuracy of 9%.

The Airborne Carbonic Oxides and Sulfide Spectrometer (ACOS) is an in situ airborne spectrometer operated by NOAA. It is a modified Los Gatos Research (LGR) Off-Axis Integrated Cavity Output Spectrometer (OA-ICOS) used to measure carbonyl sulfide (OCS), carbon dioxide (CO2), carbon monoxide (CO), and atmospheric water vapor. ACOS provides these measurements simultaneously at a typical measurement rate of 1 Hz.

Generic-Radiometers refer to non-specific radiometers on a platform. These are typically passive microwave radiometers that measure brightness temperature. Radiometers can be used to retrieve temperature and water vapor profiles, soil moisture content, ocean salinity, precipitation and cloud properties, and vegetation.

The Cloud Aerosol and Precipitation Spectrometer (CAPS) is an in situ airborne spectrometer manufactured by Droplet Measurement Technologies. It combines the Cloud Imaging Probe (CIP), the Cloud and Aerosol Spectrometer (CAS), and the Hotwire Liquid Water Content (LWC) Sensor into a single instrument. CAPS measures the size distribution of aerosol, cloud, and liquid droplets for particles between 50-1600 μm in size, with a time resolution of 1 Hz. It can also capture images of cloud particles and provide measurements of temperature, pressure, and LWC.

The Microorifice Uniform Deposit Impactor (MOUDI) is an in situ airborne or ground-based sampler developed by the MSP Corporation. It is an eight-stage impactor used for high-accuracy aerosol sampling for gravimetric or chemical analysis. MOUDI has a sample flow rate of 30 liters per minute and can sample particles in the size range of 0.056-18 µm. It is used for applications such as air pollution research, engine emission testing, and aerosol analysis.

The Particle Analysis by Laser Mass Spectrometry (PALMS) is a laser ionization mass spectrometer operated by NOAA. PALMS provides in situ measurements of aerosol particles and their chemical composition by using a UV laser pulse (193 nm) to generate ions. These ions are then analyzed with a time-of-flight mass spectrometer to produce the mass spectrum of each particle, which can be used to classify individual aerosol particles. PALMS has an aerosol size range of 0.2 to 3 microns and typically collects data at about 1 to 10 Hz. It can be used for either airborne or laboratory aerosol measurements.

The Single Particle Soot Photometer (SP2) is an in situ laser-induced photometer developed by Droplet Measurement Technologies. SP2 measures the black carbon (BC) mass in individual aerosol particles, along with their optical and physical properties that contain BC. The device detects aerosol particles with diameters of 200-400 nm and can analyze up to 25,000 particles per second. It operates at a sampling rate of 1 Hz and uses a wavelength of 1.06 μm. It can be used on airborne or ground-based platforms and paired with a Humidified-Dual SP2 (HD-SP2).

The NOAA Dual-Beam UV-Absorption Ozone Photometer (NOAA-O3) is an in situ optical balloon-borne and airborne instrument that measures ozone concentrations in the troposphere and lower stratosphere. It operates at a wavelength of 254 nm, enabling it to calculate ozone number density due to the precise ozone absorption cross section at that wavelength. It has a sampling rate of 2 Hz and a horizontal resolution of 100 to 200 meters during typical research flights.

The Spectrometers for Optical Aerosol Properties (SOAP) is an in situ airborne spectrometer operated by NOAA. It measures aerosol extinction and absorption at 532 nm. It uses cavity ringdown spectroscopy to measure extinction and photoacoustic spectroscopy to measure absorption. SOAP has a temporal resolution of 1 second.

The High Altitude Chemical Ionization Mass Spectrometer (Strat-CIMS) is an in situ airborne mass spectrometer operated by NOAA. It is designed to measure gas-phase inorganic and organic species in the upper troposphere and lower stratosphere. The instrument's ion source uses a photoionization krypton lamp operating in the vacuum ultraviolet (VUV) range (124 and 117 nm) to produce iodide ions. These ions react with the target species through an adduct formation process and are then detected with a high-resolution mass spectrometer. Strat-CIMS was designed to operate in harsh environments like low ambient pressure (60 mbar) and temperatures (190K). It has a response time of less than 1 second and an accuracy of approximately 15 to 30%, depending on the species.

The Diode Laser Hygrometer (DLH) is an in situ airborne hygrometer developed by NASA’s Langley Research Center (LaRC). It uses tunable diode laser absorption to detect water vapor in the atmosphere. DLH operates in the near-infrared range at about 1.4 μm and has a measurement frequency of 100 Hz. It can deliver precise measurements of water vapor even when flying through clouds.

The Meteorological Measurement System (MMS) is an in situ airborne instrument used to measure atmospheric state parameters. MMS provides high-resolution, accurate measurements of atmospheric pressure, temperature, and wind direction and speed immediately around the plane. Additional parameters that can be derived include potential temperature, true airspeed, turbulence dissipation rate, and Reynolds number. Measurements of all parameters are typically collected at a rate of 20 Hz.

The Uncrewed Aircraft Systems (UAS) Chromatograph for Atmospheric Trace Species (UCATS) is an in situ airborne instrument suite that measures trace gases in the atmosphere. It includes three separate instruments: a three-channel gas chromatograph (GC), a dual-beam ozone photometer (OZ), and a tunable diode laser (TDL) spectrometer. The GC measures nitrous oxide (N2O) and sulfur hexafluoride (SF6) every 70 seconds and detects hydrogen (H2), methane (CH4), and carbon monoxide (CO) every 140 seconds. The OZ sensor operates at 254 nm and provides ozone measurements every 10 seconds. The TDL spectrometer operates at 1370 nm and offers water vapor measurements every 1 second. UCATS was designed for operation on UAS, but it has also been deployed on piloted aircraft.

The Aerosol Microphysical Properties (AMP) is an in situ airborne instrument suite operated by NOAA. It includes instruments such as the Nucleation-Mode Aerosol Size Spectrometer (NMASS), Ultra-High Sensitivity Aerosol Spectrometer (UHSAS), Laser Aerosol Spectrometer (LAS), and Coarse-Mode Aerosol Size Spectrometer (CMASS). AMP provides measurements of aerosol particle size distribution, as well as particle number, size, and volume concentration. It can measure aerosols within a size range of 3 to 40,000 nm and offers measurements at 1 Hz resolution.

The Laser Induced Fluorescence-Sulfur Dioxide (LIF-SO2) is an airborne optical sensor operated by NOAA to measure SO2 in the upper troposphere and lower stratosphere. It is based on the single-photon laser-induced fluorescence technique and uses a tunable diode laser at 1084.5 nm to excite SO2 at 216.9 nm. It detects SO2 at a sampling rate of 1 Hz, with a detection limit of 5 pptv and an accuracy of 10%.