ARTICLE AND FIGURES PROVIDED BY: KENNETH VIERRA (SCIENCE TECHNOLOGY CORPORATION/UXS RESEARCH TRANSITION OFFICE) AND PATRICIA QUINN (NOAA/PMEL)
The scattering and absorption of solar radiation by atmospheric aerosol particles affects the Earth’s radiation budget, including cooling at the Earth’s surface (Intergovernmental Panel on Climate Change (IPCC) 2014 ; NOAA Science Council Fact Sheet). Aerosols, weather and climate). Cooling can also occur when aerosol particles absorb water and form cloud droplets which can increase cloud brightness. The extent to which direct aerosol forcing and aerosol-cloud interactions cool the planet and offset warming by greenhouse gases is highly uncertain. According to the IPCC, climate forcing associated with aerosol-cloud interactions contributes to the greater uncertainty in total radiative forcing estimates. Vertical profiles of aerosol and cloud properties are needed to improve models and reduce uncertainties, especially over oceans due to the sensitivity of sea clouds to small changes in aerosol concentrations. (Rosenfeld et al., 2019).
Between August 8 and August 18, 2022, the NOAA Pacific Marine Environmental Laboratory (PMEL) and the University of Washington Cooperative Institute for Climate, Ocean, and Ecosystem Studies (CICOES) operated the Wing Vertical Takeoff and Landing Rotator fixed L3Harris (FVR-55) unmanned aerial system (UAS) for measuring vertical aerosol and cloud profiles with the NOAA Clear Sky and Cloudy Sky science payloads (descriptions provided below). Payload sensors measure aerosol properties related to direct aerosol radiative forcing and aerosol-cloud interactions. The mission was supported, in part, by NOAA’s Earth Radiation Budget (ERB) program which was launched to investigate natural and human activities that may alter cloud reflectivity at marine boundaries. The UAS measurements reported here will provide essential information on the processes that lead to the brightening of marine clouds with potential cooling of the Earth’s surface.
Participants included staff from the Pacific Marine Environmental Laboratory (PMEL) of NOAA Oceanic and Atmospheric Research (OAR), University of Washington Cooperative Institute for Climate, Ocean, and Ecosystem Studies (CICOES), NOAA Uncrewed Systems Research Transition Office (UxSRTO), Office of Marine and Aviation Operation (OMAO) UxS Operation Center, L3Harris and the Tillamook UAS Test Range operated by Near Space Corporation (NSC) (Figure 1).
The FVR-55 was developed by Latitude Engineering, LLC (later acquired by L3Harris Technologies) with NOAA Phase I and II Small Business Innovation Research (SBIR) awards. Ongoing development and operations were funded and logistically supported by the OMAO UxS Operations Center (UxSOC) and the OAR Unmanned Systems Research Transition Office (UxSRTO).
In March 2022, NOAA and L3Harris completed fully autonomous onboard operation of FVR-55 with Clear Sky and Cloudy Sky payloads on board. A total of 11 flights and 14.9 flight hours were completed, demonstrating the UAS’s ability to repeatedly land in a small confined space on a moving vessel. Operations were conducted in line-of-sight conditions with an altitude ceiling of 1200 feet due to Certificate of Clearance (COA) restrictions in place.
The August 2022 measurements took place at the NSC Tillamook UAS Test Range (TUTR). With flight plans developed by NOAA and TUTR to meet test requirements, including the use of NSC COA and follower aircraft, operations beyond visual line of sight (BVLOS) were conducted over Tillamook Airport and in offshore warning areas beyond 12 NM. the Oregon coast. The follower aircraft escorted the UAS through uncontrolled airspace to warning areas and deconfined with other air traffic. NSC personnel communicated flights to local FAA ATC (Seattle Center) and managed airspace deconfliction. The UAS UxSOC division developed the concept of operations and acted as mission commander during flight operations. Mission control was based from the NSC operations tower (Figure 2). For line-of-sight flights over the airport up to 4500 feet, L3Harris and UxSRTO personnel operated as visual observers. The science team instructed the pilot flying (PIC) to modify flight paths based on real-time incoming data from the payloads.
A total of 14 flights (38.5 hours) were successfully completed, nine with the Cloudy Sky and five with the Clear Sky payload (Table 1). BVLOS vertical profiles were flown from the surface to 10,000 feet on a non-interference basis in Tillamook Class G airspace or offshore warning areas after aircraft escort of hunting. Seven flights were flown over the airport and 7 were flown in offshore warning areas. During two of the flights, a pilot-in-command (PIC) and a mission commander were stationed both in the NSC operations tower and on a beach (Netarts Bay or Bayocean beach). The science team was located on the beach to direct flight paths based on incoming payload data (Figure 3). The PIC was transferred from the NSC operations tower to the beach location once the beach PIC detected the aircraft. All flights were continuously monitored and ultimately controlled by Mission Control based at the NSC Operations Tower. The PIC at the range ensured optimum line of sight to the test area and allowed the aircraft to descend to 400 feet for measurements under cloud. Flight times ranged from 2 to 4.5 hours. Flight details are listed in Table 1.
NOAA PMEL has developed two payloads to measure the properties of aerosols and clouds necessary for observing the direct radiative effects of aerosols (Clear Sky payload) and the impacts of aerosols on clouds (Cloudy Sky Payload) (Figure 4).
PMEL Clear Sky payload
The Clear Sky payload (Figure 5) consists of four instruments: a Mixing Condensation Nucleus Counter (MCPC) to measure the concentration of total particle count, a 3-length Particle Soot Absorption Photometer wave (PSAP) to measure absorption, which is a proxy for soot; a portable optical particle spectrometer (POPS) to measure the number of particles according to their size; and a Miniature Sun Scanning Aerosol Photometer (mSASP) for aerosol optical depth measurement. There’s also a temperature and relative humidity probe that extends into the airflow and a filter carousel to collect samples for post-flight chemical analysis. The payload weight is 5.45 kg (12 lb).
PMEL cloudy sky payloadThe Cloudy Sky payload (Figure 6) contains a Miniature Scanning Electric Mobility Spectrometer (mSEMS) to measure particle number size distribution and a Cloud Droplet Probe (CDP) to measure particle number concentration and size. cloud droplets. In addition, there are ambient temperature and relative humidity sensors. The payload weighs 5.9 kg (13 lb).
Depending on assets and funding, PMEL plans to use its Clear Sky and Cloudy Sky payloads on L3Harris UAS to participate in the AEROMMA (Atmospheric Emissions and Reactions Observed from Megacities to Marine Areas) experiment in 2023. AEROMMA is a study investigation conducted by NOAA. Chemical Sciences Laboratory to meet emerging research needs on urban air quality, marine emissions, climate feedbacks and atmospheric interactions. AEROMMA will bring together airborne, ground-based and satellite-based observation systems, as well as state-of-the-art air quality and climate models, to study these research topics.
|Date||Flight||Playload||Launch time||Landing time||Maximum Altitude (ft)||Duration (minutes)||Location|
|08/09/22||#1||Cloudy sky||9:40 a.m.||11:39||1,500||120||Local|
|08/09/22||#2||Cloudy sky||1:47 p.m.||3:40 p.m.||1,750||113||Local|
|08/10/22||#3||Cloudy sky||9:15 a.m.||11:14 a.m.||3,000||119||Local|
|08/10/22||#4||Cloudy sky||2:18 p.m.||4:25 p.m.||3,500||127||Local|
|08/11/22||#5||Clear sky||12:30 p.m.||4:04 p.m.||9,700||225||Offshore|
|08/12/22||#6||Cloudy sky||8:35 am||11:26||6,500||171||Offshore|
|08/12/22||#seven||Cloudy sky||1:04 p.m.||3:37 p.m.||4,000||153||Local|
|08/13/22||#8||Cloudy sky||2:57 p.m.||4:15 p.m.||4,500||78||Local|
|08/14/22||#ten||Cloudy sky||2:41 p.m.||4:34 p.m.||6,500||113||Offshore|
|08/15/22||#11||Cloudy sky||09:44||1:27 p.m.||6,500||223||Offshore|
|08/16/22||#13||Clear sky||2:43 p.m.||4:23 p.m.||10,000||100||Offshore|
|08/17/22||#14||Clear sky||9:35 a.m.||2:00 p.m.||10,000||265||Local|
Table 1: Summary table of Clear and cloudy sky flights with links to videos of the launch and landing for flights 5 and 11.
Intergovernmental Panel on Climate Change (IPCC), Climate Change 2014: Synthesis Report Contribution of Working Groups I, II and III to the Fifth Assessment Report of the
Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp.
Rosenfeld, D., Y. Zhu, M. Wang, Y. Zheng, T. Goren and S. Yu (2019), Aerosol-induced droplet concentrations dominate low cloud cover and water, Science ,363, DOI: 10.1126/science.aav0566.