Performance of WVSS-II hygrometers on the FAAM research aircraft

Vance, A.; Abel, Steven J.; Cotton, Richard; Woolley, A. R.

doi:10.5194/amt-8-1617-2015

Cited by 27 publications

(25 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We also utilize carbon monoxide (CO) measurements from an AERO AL5002 instrument. 30 Vertical wind information is given by the aircraft turbulence probe, temperature from a loom sensor mounted in a non-deiced Rosemount housing and humidity from a WVSS2 hygrometer (Vance et al , 2015). A downward pointing Leosphere lidar is used to measure cloud top height when the aircraft was flying above the boundary layer, following the method of Kealy et al 4 https://doi.org /10.5194/acp-2019-738 Preprint.…”

Section: Aircraft Instrumentationmentioning

confidence: 99%

Open cells can decrease the mixing of free-tropospheric biomass burning aerosol into the south-east Atlantic boundary layer

Abel

Barrett

Zuidema

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

This work presents synergistic satellite, airborne and surface based observations of a Pocket of Open Cells (POC) in the remote south-east Atlantic. The observations were obtained over and upwind of Ascension Island during the CLouds and Aerosol Radiative Impacts and Forcing (CLARIFY) and the Layered Smoke Interacting with Clouds (LASIC) field experiments. A novel aspect of this case-study is that an extensive free-tropospheric biomass burning aerosol plume that had been transported from the African continent was observed to be in contact with the boundary layer inversion over the POC and the 5 surrounding closed cellular cloud regime. The in-situ measurements show marked contrasts in the boundary layer thermodynamic structure, cloud properties, precipitation and aerosol conditions between the open cells and surrounding overcast cloud field.The data demonstrate that the overlying biomass burning aerosol was mixing down into the boundary layer in the stratocumulus cloud downwind of the POC, with elevated carbon monoxide, black carbon mass loadings and accumulation mode 10 aerosol concentrations measured beneath the trade-wind inversion. The stratocumulus cloud in this region was moderately polluted and exhibited very little precipitation falling below cloud base. A rapid transition to actively precipitating cumulus clouds and detrained stratiform remnants in the form of thin quiescent veil clouds was observed across the boundary into and deep within the POC. The sub-cloud layer in the POC was much cleaner than that in the stratocumulus region. The clouds in the POC formed within an ultra-clean layer (accumulation mode aerosol concentrations ∼few cm −3 ) in the upper region of the 15 boundary layer, that was likely to have been formed via efficient collision-coalescence and sedimentation processes. Enhanced Aitken mode aerosol concentrations were also observed intermittently in this ultra-clean layer, suggesting that new particle formation was taking place. Across the boundary layer inversion and immediately above the ultra-clean layer, accumulation mode aerosol concentrations were ∼ 1000 cm −3 . Importantly, the airmass in the POC showed no evidence of elevated carbon monoxide over and above typical background conditions at this location and time of year. As carbon monoxide is a good tracer 20 for biomass burning aerosol that is not readily removed by cloud processing and precipitation, it demonstrates that the open cellular convection in the POC is not able to entrain large quantities of the free-tropospheric aerosol that was sitting directly on 1 https://doi.top of the boundary layer inversion. This suggests that the structure of the mesoscale cellular convection may play an important role in regulating the transport of aerosol from the free-troposphere down into the marine boundary layer. We then develop a climatology of open cellular cloud conditions in the south-east Atlantic from 19 years of September MODIS Terra imagery. This shows that the maxima in open cell frequency (> 0.25) occurs far offshore and in a...

show abstract

Section: Aircraft Instrumentationmentioning

confidence: 99%

Open cells can decrease the mixing of free-tropospheric biomass burning aerosol into the south-east Atlantic boundary layer

Abel

Barrett

Zuidema

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Two WVSS-II instruments were mounted on the BAe-146 aircraft, sampling the air through the standard flush inlet and a modified Rosemount inlet, respectively. The water vapor measurements provided by the two instruments can be different (Vance et al, 2015), but for the case presented here the differences are small, of the order of less than 2 % in ambient RH; thus what we used in our analysis is their average. The ambient RH calculation from the WVSS-II water vapor measurements is provided in Appendix C.…”

Section: Ambient Relative Humiditymentioning

confidence: 99%

Profiling aerosol optical, microphysical and hygroscopic properties in ambient conditions by combining in situ and remote sensing

et al. 2017

View full text Add to dashboard Cite

Abstract. We present the In situ/Remote sensing aerosol Retrieval Algorithm (IRRA) that combines airborne in situ and lidar remote sensing data to retrieve vertical profiles of ambient aerosol optical, microphysical and hygroscopic properties, employing the ISORROPIA II model for acquiring the particle hygroscopic growth. Here we apply the algorithm on data collected from the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft during the ACEMED campaign in the Eastern Mediterranean. Vertical profiles of aerosol microphysical properties have been derived successfully for an aged smoke plume near the city of Thessaloniki with aerosol optical depth of ∼ 0.4 at 532 nm, single scattering albedos of ∼ 0.9-0.95 at 550 nm and typical lidar ratios for smoke of ∼ 60-80 sr at 532 nm. IRRA retrieves highly hydrated particles above land, with 55 and 80 % water volume content for ambient relative humidity of 80 and 90 %, respectively. The proposed methodology is highly advantageous for aerosol characterization in humid conditions and can find valuable applications in aerosolcloud interaction schemes. Moreover, it can be used for the validation of active space-borne sensors, as is demonstrated here for the case of CALIPSO.

show abstract

“…To our knowledge, HAI is the first airborne instrument that can measure all water phases with the same detection principle, the same evaluation strategy, and with two channels, each spectroscopically and temporally linked by one single laser. When independent devices have been used previously to measure these water products, even with similar TDLAS instruments like in Vance et al (2015), this always led to the discussion on how many of the deviations are caused by atmospheric effects and how many are linked to discrepancies between the participating instruments caused by different characteristics, response times, or nonlinearities of the individual instruments. Indeed, the calibration or even validation of all other open-path hygrometers cited above is based on laboratory measurement or in-flight comparisons with other hygrometers with different properties, making it nearly impossible to justify more than statistical (averaged) statements.…”

Section: Tdlas-based Multi-phase H 2 O Measurementsmentioning

confidence: 99%

“…Compared to most airborne TDLAS instruments, HAI has a relatively low number of reflections and thus relatively short path lengths. Further categorizing distinguishes between wavelength-modulation schemes like single modulation frequency, called direct TDLAS or dTDLAS (Ebert and Wolfrum, 1994), or double modulation schemes like wavelength modulation spectroscopy (WMS) (Podolske and Loewenstein, 1993;Silver, 1992;Silver and Hovde, 1994a;Silver and Zondlo, 2006;Vance et al, 2011;Webster et al, 2004). WMS, often used for very compact sensors, provides on the first glance higher sensitivities by using lock-in technologies to efficiently filter noise.…”

Section: Direct Tunable Diode Laser Absorption Spectroscopymentioning

confidence: 99%

HAI, a new airborne, absolute, twin dual-channel, multi-phase TDLAS-hygrometer: background, design, setup, and first flight data

et al. 2017

View full text Add to dashboard Cite

Abstract. The novel Hygrometer for Atmospheric Investigation (HAI) realizes a unique concept for simultaneous gas-phase and total (gas-phase + evaporated cloud particles) water measurements. It has been developed and successfully deployed for the first time on the German HALO research aircraft. This new instrument combines direct tunable diode laser absorption spectroscopy (dTDLAS) with a firstprinciple evaluation method to allow absolute water vapor measurements without any initial or repetitive sensor calibration using a reference gas or a reference humidity generator. HAI contains two completely independent dual-channel (closed-path, open-path) spectrometers, one at 1.4 and one at 2.6 µm, which together allow us to cover the entire atmospheric H 2 O range from 1 to 40 000 ppmv with a single instrument. Both spectrometers each comprise a separate, wavelength-individual extractive, closed-path cell for total water (ice and gas-phase) measurements. Additionally, both spectrometers couple light into a common open-path cell outside of the aircraft fuselage for a direct, sampling-free, and contactless determination of the gas-phase water content. This novel twin dual-channel setup allows for the first time multiple self-validation functions, in particular a reliable, direct, in-flight validation of the open-path channels. During the first field campaigns, the in-flight deviations between the independent and calibration-free channels (i.e., closed-path to closed-path and open-path to closed-path) were on average in the 2 % range. Further, the fully autonomous HAI hygrometer allows measurements up to 240 Hz with a minimal integration time of 1.4 ms. The best precision is achieved by the 1.4 µm closed-path cell at 3.8 Hz (0.18 ppmv) and by the 2.6 µm closed-path cell at 13 Hz (0.055 ppmv). The requirements, design, operation principle, and first in-flight performance of the hygrometer are described and discussed in this work.

show abstract

Performance of WVSS-II hygrometers on the FAAM research aircraft

Cited by 27 publications

References 6 publications

Open cells can decrease the mixing of free-tropospheric biomass burning aerosol into the south-east Atlantic boundary layer

Open cells can decrease the mixing of free-tropospheric biomass burning aerosol into the south-east Atlantic boundary layer

Profiling aerosol optical, microphysical and hygroscopic properties in ambient conditions by combining in situ and remote sensing

HAI, a new airborne, absolute, twin dual-channel, multi-phase TDLAS-hygrometer: background, design, setup, and first flight data

Contact Info

Product

Resources

About