WB-57 - JSC

The PUTLS comprises three individual instruments for the measurement of aerosol number size distribution in the upper troposphere and lower stratosphere: a Nucleation Mode Aerosol Size Spectrometer (NMASS), an Ultra-High Sensitivity Aerosol Spectrometer (UHSAS), and a Portable Optical Particle Spectrometer (POPS). These instruments, along with a Passive, Near-Isokinetic Inlet for sampling atmospheric particles from a fast-moving aircraft, provide a measurement of the UT/LS particle size distribution from 4 to 3000 nm diameter. Aerosol microphysical measurements in the UT/LS are integral to understanding the chemical and radiative processes that control the Earth’s climate, and PUTLS provides data for investigation of topics ranging from new particle formation to long range transport of dust and fine volcanic ash.

Roscoe is a new, more compact version of the NASA GSFC Cloud Physics Lidar that has flown on multiple NASA high altitude aircraft over the past two decades. While utilizing the same proven measurement technique of coupling a high repetition rate laser with photon-counting detection, Roscoe differs from CPL in two significant ways.  First, it is designed to simultaneously observe both upwards and downwards from the aircraft, to enable studies of stratospheric aerosols above flight altitude as well as below.  It is, essentially, two small CPL instruments in one package, one pointing nadir and one pointing zenith.  Second, it operates at only 1064 and 355 nm (not 532 nm) to satisfy eye-safety considerations for airborne operation.  Roscoe measures depolarization at both wavelengths to characterize the phase of the cloud and aerosol particles detected.

The LIF-NO instrument uses single-photon laser induced fluorescence to achieve fast, precise and accurate measurements of nitric oxide down to sub-pptv mixing ratios. The instrument is designed as a two-channel instrument and the second channel can be used to detect other species that can be converted into NO, such as NO2 or NOy. Measurements of reactive nitrogen species provide important constraints on radical oxidation chemistry, ozone destroying chemistry, and are useful tracers of pollution.

The LIF-SO2 instrument detects sulfur dioxide at the single-part per trillion (ppt) level using red-shifted laser-induced fluorescence. It has operated on the WB-57 and Global Hawk aircraft in the UT/LS, as well as on the DC-8. Sulfur Dioxide is an important precursor for aerosols including nucleation of new particles globally and can be greatly enhanced in the stratosphere following explosive volcanic eruptions. An important implication of the Asian Monsoon is transport of aerosol precursors including SO2 into the lower stratosphere.

Chi-WIS is a mid-infrared tunable diode laser off-axis integrated cavity output absorption spectrometer (ICOS) instrument for measurement of H2O and HDO in the upper troposphere and lower stratosphere. The high precision of the measurement allows detection of small changes in the HDO/H2O ratio that can be used to study water transport pathways and characterize the extent to which convection-driven water vapor perturbations propagate through the UT/LS to contribute to the overall stratospheric water budget. Chi-WIS participated in the 2017 StratoClim campaign onboard the M-55 Geophysica high altitude research aircraft measuring the isotopic composition of water vapor between 12 and 20 kilometers inside the Asian Summer Monsoon anticyclone.

COLD2 is an automated, portable, mid-infrared quantum cascade laser spectrometer for in situ carbon monoxide mixing ratio measurements in the upper troposphere and lower stratosphere. The instrument was designed to be versatile, suitable for easy installation on different platforms and capable of operating completely unattended, without the presence of an operator. The spectrometer features a small size (80 × 25 × 41 cm 3 ), light weight (23 kg) and low power consumption (85 W typical), without being pressurized. After the measurement campaign of the EU StratoClim Project, carried out in Nepal in summer 2017, the instrument was deployed onboard WB-57 for the SABRE test campaign (Houston TX, february 2022) and for the ACCLIP main campaign (Houston TX and Seoul RSK, july-august 2022). The instrument was shipped back and forth Florence (I) - Houston TX, and was operated during 27 test and scientific flights, providing full data without any maintenance (alignment, consumables, troubleshooting, etc.)

Vacuum ultraviolet radiation produced in a low pressure plasma discharge lamp is used to induce resonance scattering in Cl and Br atoms within a flowing sample. ClO and BrO are converted to Cl and Br by the addition of NO such that the rapid bimolecular reaction ClO + NO → Cl + NO2 (BrO + NO → Br + NO2) yields one halogen atom for each halogen oxide radical present in the flowing sample. Three detection axes are used to diagnose the spatial (and thus temporal) dependence of the ClO (BrO) to Cl (Br) conversion and to detect any removal of Cl (Br) following its formation. A double duct system is used both to maintain laminar flow through the detection region and to step the flow velocity in the detection region down from free stream (200 m/sec) to 20 m/sec in order to optimize the kinetic diagnosis.