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ACT-America: Instruments

ACT-America will deploy high-quality, field-tested (TRL-8 (Technology Readiness Level) or higher) trace gas and meteorological instruments. The mix of remote and in situ sensors enables extensive spatial coverage of key variables. The C-130 instruments includes the Multi-Functional Fiber Laser Lidar for CO2 columns, range to ground and surface reflectance; the Cloud Physics Lidar for ABL (Atmospheric boundary layer) depths and atmospheric aerosols; Picarro cavity ring-down spectrometers for in situ CO2, CH4, water vapor, and carbon monoxide (CO); 2B Technologies for in situ ozone; Flasks for CO2, CH4, CO, carbonyl sulfide, and 14CO2; and an environmental suite for in situ pressure, temperature and winds. The UC-12 has the same in situ sensors save for winds. Towers utilize Picarros for in situ CO2 and CH4.

ACT-America science instruments.




Data Latency

Purpose of

MFLL (C-130)

Column CO2 number density,
altimetry, surface reflectance

10 Hz

1 day (≤6 months)

Core GHG CO2 measurement
& ranging capability

CPL (C-130)

ABL height, aerosol distribution

2 Hz, 30m vertical resolution

1 day (≤4 months)

Transport model constraint, OCO-2

Picarro Air (C-130 & B-200)

CO2, CH4, CO, H2O
mole fraction

1 Hz

1 day (≤4 months)

Core GHG measurements, combustion
& airmass tracer

2-B Tech. (C-130 & B-200)

O3 mole fraction

1 Hz

1 day (≤4months)

Airmass tracer

Atm. state and nav. (C-130)

GPS Lat.-Lon, Wind speed, direction,
Pressure, Temp.

1 Hz or higher

1 day (≤6 months)

Evaluate atmospheric transport models

Atm. State and nav. (B-200)

GPS Lat. and Lon., Pressure,

1 Hz or higher

1 day (≤6 months)

Evaluate atmospheric transport models

Flasks (C-130 & B-200)

Multiple trace gases. See table 3-2

12 flasks / aircraft / flight

1 month

(≤6 months)

Core GHG measurements, GHG source

Picarro Ground

CO2, CH4, H2O
mole fraction

1 Hz

1 day (≤6 months)

Core GHG measurements.

Science Instrumentation

The C-130 payload includes two remote sensing instruments: the Multi-Functional Fiber Laser Lidar (MFLL, Dobler et al. 2013), a Laser Absorption Spectrometer (LAS) for measuring CO2 column number density weighted to the near surface atmosphere as well as range to the surface and surface reflectance, and the Cloud Physics Lidar (CPL, McGill et al. 2002), an aerosol backscatter lidar for measuring ABL depth and aerosol distributions. The C-130 also carries a comprehensive suite of in situ sensors measuring CO2, CH4, carbon monoxide (CO), ozone (O3), and H2O (water), and flasks that measure CO2 and CH4 as well as GHG tracers, particularly CO, COS, and 14CO2. The B-200 has an identical suite of in situ sensors and flask sampling capability. In situ sensor redundancy for CO2, CH4 and CO on each aircraft provides the opportunity to evaluate in flight performance of the measurements. Both aircraft are also equipped to provide high accuracy and precision meteorological measurements. All instruments meet or exceed the precision and accuracy levels required by the STM over the requisite averaging scale. Most instruments exceed the STM requirements at their native resolutions, which are higher than those required by the STM.

Remote Sensing Instruments
MFLL: The MFLL is a suite of Continuous-Wave (CW) lidar instruments consisting of: 1) an intensity modulated multi-frequency single-beam synchronous-detection Laser Absorption Spectrometer (LAS) operating at 1571 nm for measuring the column amount of CO2 number density and range between the aircraft and the surface or to cloud tops, and surface reflectance; and 2) a Pseudo-random Noise (PN) altimeter at 1596 nm for measuring the path length from the aircraft to the scattering surface and/or cloud tops..

The LAS instrument, developed by Exelis, Inc. (now part of Harris Corp.) in 2004 (Dobler, et al., 2013, Lin, et al., 2013, Dobbs et al., 2007, 2008a), has been extensively evaluated in 1000+ hours of ground testing and in 13 multi-day flight campaigns conducted over a variety of meteorological conditions and surface types during both days and nights (Browell et al., 2008, 2009, 2012). The LAS CO2 column measurements have a precision of 0.08% for a 10-s horizontal average (~1.5 km on C-130) over land and 0.18% over water. These precision values are equivalent to relative CO2 mole fraction precisions of about 0.30 ppm and 0.72 ppm, respectively. Absolute comparisons of CO2 remote and in situ measurements showed an absolute accuracy of 0.65 ppm of CO2 (Dobler, et al., 2013, Browell et al., 2012), meeting the 1 ppm CO2 accuracy requirement. Based on this extensive flight testing, the LAS instrument meets the CO2 column measurement requirements of the mission and is considered to be at TRL-8.

CPL: The CPL is an airborne lidar system designed specifically for studying clouds and aerosols (McGill, et al., 2002), and has participated in nearly 30 science measurement campaigns (e.g. McGill et al., 2003, and McGill et al., 2004). It also has been used extensively for satellite validation (e.g., McGill et al., 2007 and Vaughan et al., 2010). The Cloud Physics Lidar provides a complete battery of cloud physics information, greatly surpassing the measurement requirements for ACT-America, especially for ABL height measurements. Data products include:

  • Cloud profiling with 30 m vertical and 200 m horizontal resolution at 1064 nm, 532 nm, and 355 nm, providing cloud location and internal backscatter structure.
  • Aerosol, boundary layer, and smoke plume profiling at all three wavelengths.
  • Depolarization ratio to determine the phase (e.g., ice or water) of clouds using the 1064 nm output.
  • Cloud particle size determined from a multiple field-of-view measurement using the 532 nm output (off-nadir multiple scattering detection).
  • Direct determination of the optical depth of cirrus clouds (up to ~OD 3) using the 355 nm output.

The CPL uses photon-counting detectors with a high repetition rate laser to maintain a large signal dynamic range. This dramatically reduces the time required to produce reliable and complete data sets. The goal of the CPL analysis is to provide data within 24 hours of a flight including the cloud and aerosol quick-look pictures, cloud boundaries, ABL height, and depolarization information. The final data release shall be within 4 months for the mission.

Airborne In Situ Instruments
Picarro continuous CO2/CH4/H2O/CO: The C-130 and B-200 both have Picarro instruments. The Picarro instruments have been extensively tested on aircraft flights (Karion et al., 2013a, b; Mays et al., 2009; Turnbull et al., 2011). Picarro analyzers are based on Wavelength-Scanned Cavity Ring Down Spectroscopy (WS-CRDS), a time-based measurement utilizing a near-infrared laser to measure a spectral signature of molecular absorption. Gas flows through a 35-cc optical cavity with an effective path length of up to 20 km and pressure of 140 Torr. Extremely stable and high-precision measurements are achieved through cavity temperature, pressure, and laser frequency control to better than 0.002 °C, 0.00003 atm and 1 MHz, respectively. Aircraft instruments are similar to surface-based sensors, but use faster flow rates, solid-state data storage, and additional vibration isolation. These instruments exceed the precision requirements of the STM for all four gases (Table 2, Karion et al., 2013a). Accuracies of 0.2 ppm for CO2 and 2 ppb for CH4 (Karion et al., 2013a) also exceed mission accuracy requirements of 1 ppm for CO2 and 4 ppb for CH4.

2B Technologies Continuous O3: The Model 205 O3 monitor uses two ultraviolet beams in two cells to simultaneously measure O3-scrubbed air and unscrubbed air. This model has been approved by the Environmental Protection Agency as a Federal Equivalent Method (FEM) and is the fastest UV-based O3 monitor available. The O3 monitor has been previously flown on tropospheric chemistry field missions and meets the accuracy and precision requirements laid out in the STM (Bertschi et al. 2004).

Flask Measurement System: The NOAA Earth System Research Laboratory (ESRL) carbon cycle group has developed programmable flask packages (PFP) used in their aircraft network since 2003 and the tall tower measurement network since 2006. The PFPs hold twelve 0.7-L silicate glass flasks that can be triggered manually or automatically at specific altitudes, times or locations. Measurements of CO2, CH4, CO and other trace gases are made on one of two nearly identical automated analytical systems; the same systems are used in the ESRL ground, tall tower, and aircraft networks (Conway et al., 1994; Dlugokencky et al., 1994; Novelli et al., 1998). COS (and hydrocarbons and halocarbons) will be measured via Gas Chromatography/Mass Spectrometry measurements. PFP flask sample responses are calibrated against whole air working reference gases, which, in turn, are calibrated with respect to gravimetric primary standards. At selected times, duplicate flasks will be collected and analyzed for 14CO2. Accuracy and precision for these measurements are 0.2 ppm for CO2, 2 ppb for CH4 (Karion et al., 2013a), 2 ppb for CO (Novelli et al., 1998), 2 ppt for COS (Montzka et al., 2007), and 2 per mil for 14CO2, matching or exceeding the STM accuracy and precision requirements.

Environmental Parameters Suite: Water vapor, pressure, and ambient temperature are measured on both aircraft. Wind direction and speed will be measured on the C-130 only. Water vapor will be measured using a 3-stage chilled mirror hygrometer to make dew/frost point measurements with an accuracy of 0.2 °C. Ambient temperature will be derived using a Rosemount non-deiced model 102 total air temperature probe with a precision of 0.2 °C. Horizontal and vertical winds on board the C-130 are calculated from high precision pressure transducers and aircraft position and attitude data generated by Honeywell inertial navigation positioning systems. Wind speed direction will be measured to within 5 degrees while horizontal winds will have an accuracy of ±1 m/s. Both measurements are made at 10-Hz intervals.

Surface Measurements
ACT-America will install five Picarro CO2/CH4/H2O instruments on existing communications towers, filling gaps that exist in or near our three study regions in the existing tower network. Specific sites will be selected in science-critical locations based on tall tower and local Ethernet or cell phone data connection availability. Data will be collected at 100 m above ground level (AGL) or higher. Daily, automated data transfer to the Langley Atmospheric Science Data Center will allow remote monitoring of instrument status and investigation planning. The tower-based investigators continuously operated five similar tower installations in the Midwest from 2007-2009 (Richardson et al., 2012b; Miles et al., 2012) and are currently operating 12 such installations around the city of Indianapolis (Miles et al., 2013). Additional measurements that will be used in this study include NOAA moorings along the East and Gulf coasts, the Total Carbon Column Observing Network (TCCON) sites at Park Falls, Wisconsin (WLEF) and the Department of Energy-Atmospheric Radiation Measurement (DOE-ARM) Central Facility, OK sites, and the NOAA Aircraft (biweekly vertical profiles) and Tall Tower networks. These data are all accessible to the public. ACT-America investigators have extensive background working with these networks and the responsible investigators and programs.

January 24, 2022

Four joint flights were conducted this past Tuesday and Wednesday (Jan 18-19) to capitalize on another cold air outbreak event, similar to the previous week. We observed significant temperature variations in the various vertical profiles conducted by the low-flying Falcon, with evidence of significant precipitation near the transition from overcast to open-cell cloud conditions. A significant decreasing gradient in cloud drop number concentrations was observed with distance offshore especially during the January 18 flights.

June 20, 2022

ACTIVATE’s final flight deployment ended this past week with Research Flight 179 (Saturday June 18) transiting back from Bermuda to Virginia. A number of flights in the past week continued to build on the dataset for aerosol-cloud-meteorology interactions surrounding the Bermuda area, including on Tuesday June 14 a “process study flight” where the coordinated aircraft characterized a building cumulus cloud system. The Falcon conducted its traditional “wall” pattern used during process study flights with ~20 stacked legs going from below to above the cloud. Meanwhile the UC-12 flew overhead conducting remote sensing measurements of the same system while launching numerous dropsondes. A day earlier (June 13), the joint research flight conducted was synchronized with a CALIPSO overpass in conditions that are ideal for intercomparison of data including cloud-free air with significant aerosol concentrations and a diversity of aerosol types including in particular African dust. Now the ACTIVATE team focuses on processing and data archival of the 2022 flight deployments.

January 24, 2022

Four joint flights were conducted this past Tuesday and Wednesday (Jan 18-19) to capitalize on another cold air outbreak event, similar to the previous week. We observed significant temperature variations in the various vertical profiles conducted by the low-flying Falcon, with evidence of significant precipitation near the transition from overcast to open-cell cloud conditions. A significant decreasing gradient in cloud drop number concentrations was observed with distance offshore especially during the January 18 flights.

June 14, 2021

This past week included two double-flight days on Monday-Tuesday (June 7-8). June 7 was notable in that the second flight (RF 80) was a “process study” flight, which accounts for approximately 10% of ACTIVATE flights. We targeted an area with a cluster of clouds and conducted a total of 10 Falcon legs in cloud at different altitudes ranging from ~2 to ~13 kft. These legs and a subsequent downward spiral resulted in 10 cloud water samples for a single cloud system. Simultaneously, the King Air conducted a ‘wheel and spoke” pattern far above to allow the remote sensors to characterize the environment and cloud that the Falcon was directly sampling. A total of 14 dropsondes were launched by the King Air in the ~3 hr flight. This flight and the other “process study” flight in this summer campaign (RF77 on June 2) will provide a remarkable dataset to investigate aerosol-cloud-meteorology interactions with very detailed measurements for single evolving cloud systems.

March 15, 2021

ACTIVATE conducted four more successful joint flights (Research Flights 51-54) this past week. We characterized a variety of cloud conditions including post-frontal clouds associated with another cold air outbreak on Monday (March 8) in contrast to the following day (Tuesday March 9) where there was a sharp inversion with uniform cloud top heights and generally thin clouds. Flights this past week were marked by influence from local and regional burning emissions. The second of two flights on Friday (March 12) was coordinated with a CALIPSO overpass.

Febraury 5, 2021

ACTIVATE’s had its first joint flight of the winter 2021 campaign on February 3. We were successful to sample a transition from overcast stratocumulus clouds to broken cumulus clouds near our farthest southeast point of the flight track. There was extensive mixed-phase precipitation in areas closer to shore but pure liquid clouds farther offshore coinciding with the open cell cloud field. Although at low optical depth, an interesting aerosol layer was observed above 6 km that most likely was dust due to its depolarizing nature.

January 30, 2020

This past week ACTIVATE took to the skies again to begin our 2021 winter campaign. In contrast to last year, we started a bit earlier in the month of January to capitalize on a higher frequency of cold air outbreak events. Friday’s flights (January 29) were particularly ideal with both aircraft sampling along cloud streets aligned with the predominant wind direction coming from the north/northwest. We observed a transition from supercooled droplets to mixed phase precipitation with distance away from shore.

June 13, 2022

The past week coincided with a string of excellent weather conditions leading to eight joint flights between June 7-11 (RF166-173). There was evidence of African dust in the region that the aircraft sampled, in addition to coordinated efforts with glider platforms operated by the Bermuda Institute of Ocean Sciences to study the upper parts of the ocean surface that may affect the ACTIVATE measurements via sea-air interactive processes. Research flight 166 on 7 June was somewhat unique in that we sampled distinct cloud streets that we more commonly flew in during the winter season associated with cold air outbreaks. The ACTIVATE team also hosted a successful outreach event at the Longtail Aviation hangar featuring 40 students from three local grade schools.

June 6, 2022

On 31 May, the ACTIVATE team conducted a joint plane transit flight from Langley Research Center to Bermuda to base operations there until June 18. A series of flights (Research Flights 161-165) up through Sunday 5 June helped obtain statistics of atmospheric conditions around Bermuda. Many of the local Bermuda flights ended with a spiral sounding just offshore the Tudor Hill facility to obtain important vertical data for trace gases, aerosol, and weather parameters that will complement extensive surface monitoring work going on in coordination with the NSF-funded BLEACH project going on focused on halogen chemistry. Flights have already gathered important statistics associated with shallow “popcorn” cumulus cloud fields.

May 23, 2022

Four graduate students from the University of Arizona visited Langley Research Center to learn about and participate in the operational side of ACTIVATE. They took part in a very active flight week, with a total of eight joint flights deployed (Flights 153 - 160). Flights 156 and 157 on Wednesday, May 18th were special because these were the first flights to and from Bermuda that included a CALIPSO underflight. The CALIPSO track was clear of clouds and various aerosol layers such as smoke and dust were present. Another set of joint flights to and from Bermuda was conducted on Saturday, marking a successful end to the May flights. The next update will be in a couple weeks as the coming week will be used to prepare to fly out to Bermuda to base operations there from 1-18 June.

May 16, 2022

The previous week was marked by a persistent low pressure system positioned off the mid-Atlantic coast that impacted flight operations. Only one joint flight was conducted as a result on Tuesday (10 May; Research Flight 152), which featured strong northeasterly winds and warm air advection over the coastal cold waters created stratiform clouds near the surface. During parts of the flight there were several layers of decoupled stratiform cloud in the lower (free) troposphere.  There was evidence of strong sea salt influence on this day with a high volume of cloud water samples collected that will be helpful for continued characterization of the cloud chemistry in the study region. This week was marked by some visitors to Langley Research Center from the science team including Hailong Wang (PNNL) and Minnie Park (BNL), along with Simon Kirschler who is visiting from DLR in Germany.

May 09, 2022

ACTIVATE’s sixth and final deployment began this past week with three successful joint flights (Flights 149-151). In contrast to the winter deployment, aerosol optical depths increased this past week with dust and smoke signatures, with the latter possibly stemming from plumes advected from the western United States. These data will be helpful to learn more about the impacts of these aerosol types on clouds even if they reside above cloud tops. On Thursday (5 May 2022) we conducted a successful refueling trip to Providence, Rhode Island marked by extensive cloud characterization and upwards of 20 cloud water samples helpful for cloud composition studies.

March 30, 2022

We wrapped up Deployment 5 on Tuesday after finishing a couple joint flights (Research Flights 146-148). Monday’s flight was intriguing owing to the diversity of aerosol types sampled ranging from the usual marine aerosol types such as sea salt to also smoke, dust, and pollen. Tuesday’s flights were excellent for cold air outbreak characterization including upwind clear air sampling and then also the transition from overcast cloud conditions to an open cloud field. We will begin Deployment 6 in the first week of May and conduct flights through the end of June.

March 28, 2022

After considerable effort and patience due to pandemic-related barriers, ACTIVATE was able to successfully execute its first flight to Bermuda this past week. Research flights 142-143 on Tuesday March 22nd involved out-and-back flights from Hampton, Virginia to Bermuda. Flights to Bermuda are important for a number of reasons including the ability to extend the spatial range of data off the U.S. East Coast to be farther removed from continental and Gulf Stream influence and closer to more “background marine” conditions. Flights 144-145 on Saturday March 26th were special in that a wide range of aerosol types were sampled including dust, smoke, sea salt, and biological particles especially in the form of pollen near the coast.

March 21, 2022

ACTIVATE had a golden flight day on 13 March 2022 (Sunday) with a cold air outbreak and two joint flights in morning and afternoon. In the morning flight we sampled an overcast cloud field that began to transition into a more broken field. We conducted 3 “walls” with the low flyer (Falcon) involving level legs below and in cloud stacked vertically on top of each other for better vertical characterization of the ‘aerosol-cloud system’. We launched 11 dropsondes with the high flyer (King Air). Data suggest significant new particle formation above cloud tops offshore during the cold air outbreak event. The two flights that day provide excellent data for model intercomparison to understand boundary layer cloud evolution. Later in the week (Monday March 14) was marked by smoke conditions offshore that the Falcon was able to characterize with its suite of instruments. Two graduate students and a research scientist from the University of Arizona visited NASA Langley Research Center this past week to learn about and participate in the operational side of ACTIVATE.

March 14, 2022

This week was dominated by a stalled cold front over the ACTIVATE flight domain, which prevented the team from executing flights most of the week owing to complex conditions that would affect data quality (e.g., mid and high level clouds impacting remote sensors on the King Air) and sampling of well-defined boundary layer clouds. We were successful though with flights at the beginning of the week (Research flights 135-136) on Monday March 7th, including both clear air and cloud characterization to the southern part of our usual sampling domain. The following week appears to be very promising with cold air outbreak conditions setting up as soon as this Sunday March 13th.

March 7, 2022

The past week of ACTIVATE flights (research flights 130-134) including more clear air characterization than past weeks, with both dust and smoke influence over the northwest Atlantic. Two of the flights consisted of a vertical spiral sounding in cloud-free and polluted conditions with the HU-25 Falcon with the King Air flying overhead, which will be helpful for a number of types of analyses, including intercomparison between aerosol remote sensing products from the HSRL-2/RSP (on the King Air) and in situ aerosol observations from the Falcon. The two flights on Friday March 4th in particular were excellent as there was high cloud fraction across most of our sampling region which afforded a chance to sample clouds impacted by potential dust and smoke plumes.

March 1, 2022

After standing down for a week to swap the B200 with the UC-12 King Air, flights resumed this past week (research flights 120-125) with three days of double-flights (Feb. 15, 16, 19). The statistical database representative of typical wintertime conditions continued to expand with these flights that all included cloud sampling and similar characteristics as recent weeks. For instance, gradients of decreasing cloud drop concentration with distance east of the shore continued to be observed, along with both warm and mixed-phase precipitation, and situations where cumulus clouds connected to overlying stratiform clouds.

February 22, 2022

After standing down for a week to swap the B200 with the UC-12 King Air, flights resumed this past week (research flights 120-125) with three days of double-flights (Feb. 15, 16, 19). The statistical database representative of typical wintertime conditions continued to expand with these flights that all included cloud sampling and similar characteristics as recent weeks. For instance, gradients of decreasing cloud drop concentration with distance east of the shore continued to be observed, along with both warm and mixed-phase precipitation, and situations where cumulus clouds connected to overlying stratiform clouds.

February 7, 2022

Research flights 115-119 in the past week continued the extensive characterization of the northwest Atlantic in during typical wintertime conditions. Notable features this week included gradients offshore such as how in flight 115 (Tuesday, Feb 1) clouds were initially scattered by the coast and then rapidly started to deepen and fill in forming an overcast deck on the outbound leg. Towards the northeast part of the flight path, clouds took on a distinctly decoupled appearance with cumulus clouds feeding an upper stratiform deck. Aerosol gradients were evident too with regard to number concentration and composition. These distinct differences in the study region on individual flights present a critical opportunity for data analysis to better understand the aerosol-cloud-meteorology system.

January 31, 2022

Six joint flights were conducted this past week, including three double-flight days between January 24 and 27. The two flights on January 24th included more sampling towards the southern part of our operation domain to get more diversity in conditions with regard to weather and aerosol conditions. The two flights on Thursday (Jan 27) included a refueling stop at Providence, Rhode Island to allow us to extend our spatial range of sampling. That day included complex cloud structure with wave characteristics (i.e., variable base and top heights) and decoupling of cloud layers. There was an abundance of ice nuclei during the two flights on this day.

January 18, 2022

ACTIVATE returned with flights this past week by executing Research Flights 100-104, including consecutive double-flight days on Tuesday and Wednesday (January 11-12, 2022). The two flights on January 11th were used to sampled upwind and into a region of clouds during a cold air outbreak event; the second flight was used to keep tracking the evolution of the cold air outbreak farther downwind to the southeast of where the first flight left off. Intriguing features were observed on the two flights on Tuesday including steam fog, funnel clouds, and waterspouts. Both warm and mixed-phase precipitation were observed, along with new particle formation above cloud tops.

December 13, 2021

Four joint flights were conducted this past week in ACTIVATE’s final week of science flights for December before resuming flights in January 2022. Notable was the back-to-back flight day on Thursday (9 Dec 2021) when the two aircraft flew north for a refueling stop at Quonset State Airport (Rhode Island). This marks the first refueling stop at a secondary base in the ACTIVATE project. Extending our typical spatial range was helpful for a more extensive characterization of the complex cloud scene  including solid and broken boundary layer cloud structure with distinctly different cloud types including both warm and mixed-phase precipitation. ACTIVATE measurements during these two flights will be very helpful to understand gradients in the aerosol-cloud system during the transitions between cloud types (e.g., stratocumulus, fair weather cumulus) and the solid versus broken cloud fields.

The ACTIVATE team hosted an open data workshop with 70+ participants over two days on October 20-21, 2021. Discussion centered around how to access and use the data, in addition to walking through two detailed case study flights. Participants from the international audience presented some slides of their own to stimulate ideas and brainstorming around research into aerosol-cloud-meteorology interactions. Material from the workshop, including recordings of the two days can be found at:

December 6, 2021

The 5th ACTIVATE deployment started this past week with two joint flights having similar headings going southeast from the base of operations at NASA Langley Research Center. These flights allowed for unique sampling of trace gases, aerosols, and marine boundary layer clouds in the month of December, which has yet to be done during ACTIVATE’s first 93 flights leading up to these two flights. More flights are planned in the coming week before a break and then resumption of flights in January.

July 1, 2021

We finished our summer campaign this past week with four more ACTIVATE flights (Research Flights 90-93) between June 28 and 30. These flights focused on extensive data collection in typical summertime shallow cumulus clouds. A notable feature in these flights was sampling behind ship vessels near the coast that yielded especially large enhancements in particle concentration parameters.

June 28, 2021

Four flights were conducted last week, with two single flight days on June 22 and 24, and a double flight day on June 26. Saturday’s conditions (June 26) were in particular very good for ACTIVATE with a scattered shallow cumulus cloud scene throughout the day that both planes were able to jointly characterize. The past week also was linked to high variability in aerosol conditions with the northward advancement of African dust into our study region.

June 21, 2021

This past week included three single-flight days on Tuesday-Thursday (June 15-17). The first flight of this week (June 15) was a statistical cloud survey but proved to be a challenging flight to execute as the King Air encountered pervasive cirrus along the track and the Falcon dealt with low clouds at varying altitude ranges. The June 16 flight targeted mostly clear skies with observations of moderate aerosol loading. This flight also included an overflight of Langley Research Center at the end to intercompare with the AERONET site and the High Altitude Lidar Observatory (HALO) HSRL/water vapor lidar that was conducting upward looking ground tests. The last flight of the week (June 17) included a coordinated run along the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite overpass and then two reverse headings to capture in cloud data in vicinity of the ASTER overpass for additional contextual data. The flights on June 16-17 both saw non-spherical particles near the coast and drizzle over the ocean was observed on June 17.

June 7, 2021

Four successful joint flights occurred last week. The double flight day on Wednesday June 2 was particularly noteworthy. Our morning flight conducted our typical statistical survey flight plan to an area south of the Virginia coast where there was a cumulus cloud field, with some regions evolving into deeper, more organized, convection. Based on that flight and satellite imagery, we set up the second flight to execute a “process study” pattern where the Falcon conducted a series of transects through a selected cloud cluster to characterize the vertical microphysical properties of the developing cluster immediately followed by an environmental profile in the surrounding cloud-free region. Simultaneously, the King Air conducted a “wheel and spoke” pattern centered around the cloud system, with multiple dropsondes launched above, and on the periphery of the cloud cluster alongside remote sensing transects to characterize the cloud and aerosol system underneath. Data from both planes will be used to characterize the range of cloud types observed on that day, with a focus on understanding the processes that drive shallow cumulus organization.

June 1, 2021

The last two weeks were busy with 9 joint flights, including three separate double-sortie days. The May 21 morning flight in particular was intriguing with a mixture of different conditions offshore with the two aircraft flying mostly straight to the east and then returning on the same track to NASA LaRC. Closer to shore, the aircraft observed a stratus deck with a prominent aerosol layer just above cloud as observed by the HSRL-2. These clouds then transitioned progressively into a more scattered cumulus cloud field to the east. At the far eastern end of the track there was a cold pool that we sampled within and just outside. Throughout this and the other flights this past week, there was evidence both either (or both) smoke and dust in the free troposphere. Measurement data will help unravel how these various aerosol types interact with the different types of clouds such as in the May 21 flights. On May 19, we also coordinated the flight along the CALIPSO satellite track where both aircraft and the satellite had successful made measurements.

May 17, 2021

After a short break after the Winter 2021 campaign, ACTIVATE took back to the skies this past week to start the Summer 2021 campaign. We conducted 4 successful joint flights between May 13-15 with interesting cloud conditions in each flight. The lower-flying Falcon characterized multiple layers of clouds and observed both warm and mixed-phase precipitation. Remote sensing observations on the higher-flying King Air detected aerosol layers aloft in the free troposphere potentially from dust and smoke on separate flights.

April 5, 2021

ACTIVATE wrapped up its winter 2021 flight campaign with five joint research flights this past week (RF 57-61) capped off by a double-flight day on Friday (4/2) to capitalize on another cold air outbreak event. Those two flights included an increased number of dropsondes (~10 per flight) to get extensive temporal and spatial characterization of the vertical atmospheric structure as the cold air outbreak cloud field evolved during the day. Notable in the other flights last week was successful coordination with ASTER and CALIPSO overpasses in our flight region.

March 29, 2021

We executed a joint flight (RF 56) on Tuesday March 23rd on a day marked by fairly ‘clean’ conditions in terms of very low aerosol and cloud drop number concentrations in the marine boundary layer. Cloud fraction on this day was markedly lower than a typical cold air outbreak type of day, which is helpful for ACTIVATE which is aiming to generate statistics in a wide range of conditions associated with aerosols, clouds, and meteorology.

March 22, 2021

The previous week posed significant weather challenges but Saturday (March 20, 2020) did finally provide low clouds evolving in a cold air outbreak. Interesting features in that joint flight (Research Flight 55) were Asian dust residing aloft above the boundary layer clouds, in addition to an interesting layer of depolarizing aerosol right above clouds near the end of flight as observed by the HSRL-2; it is unclear what the source of that layer was, but data analysis with the Falcon data will help unravel those details.

March 8, 2021

ACTIVATE executed three successful joint flights (Research Flights 48-50) this past week. On Thursday March 4th we coordinated our flight with a NASA A-Train overpass over an area with some scattered marine boundary layer clouds. The back-to-back flights on Friday March 5th served two objectives to capitalize on an excellent cold air outbreak event: (i) characterize the aerosol and meteorological characteristics upwind of the cloud field farther downwind; and (ii) characterize the evolution of the cloud field with the desire to capture the transition from overcast cloudy conditions to open cell structure. Noteworthy features in these flights were dust layers from long-range transport and significant new particle formation.