Airborne Platforms to Advance NASA Earth System Science Priorities Assessing the Future Need for a Large Aircraft (2021) / Chapter Skim
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4 The Role of Airborne Platforms in Addressing Emerging Science
4 The Role of Airborne Platforms in Addressing Emerging Science
Pages 57-126
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ecosystem change -- land and ocean; (e) sea level rise in a changing climate and coastal impacts; and (f)
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. This list included mega wildland fires and a record-setting hurricane season with the most landfalling tropical cyclones ever recorded in the United States since the 1860s.
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They are also responsible for the highest number of deaths: 6,502 since 1980.a Flooding from extreme rainfall and storm surge associated with landfalling tropical cyclones accounts for more than 75 percent of death tolls and most of the economic losses. Coastal and inland flooding due to landfalling tropical cyclones is expected to get much worse in a warming climate and rising sea levels.
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Four ESAS questions focus on the coupled water and energy cycles and consider the movement, distribution, and availability of water and how these are changing over time (NASEM, 2018a)
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was a winter 2002 and spring 2003 field and airborne science campaign that required the heavy-lift capacity of the DC-8 to carry the Airborne Synthetic Aperture Radar (AIRSAR) P-, L-, and C-band radar (predecessor to the smaller Uninhabited Aerial Vehicle Synthetic Aperture Radar [UAVSAR]
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storage interact and modify the water • Surface deformation due to H-2c (MI) and energy cycles locally, regionally, groundwater depletion and C-2e (I)
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Thus, looking to future missions, opportunities for a DC-8like large aircraft are envisioned for coupled water and energy cycles applications.
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As such, the SBG DO is synergistically linked to the ACCP DO for the planet's coupled water and energy cycles. Cal-Val of SBG measurements will likely benefit from a prolonged-duration aircraft, especially Cal-Val activities in remote polar regions.
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SnowEx. The multiyear SnowEx campaign exemplifies how airborne science enables understanding of coupled water and energy cycles across a range of snow climates including prairie, maritime, tundra, taiga, and alpine.
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Future missions for ACCP and SBG DOs will benefit from using a large aircraft and will better address some science questions that require suborbital measurements. Smaller airborne platforms will continue to be valuable for coupled water and energy cycles observations across multiple spatial and temporal scales.
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Airborne science observations are fundamental to advancing our understanding of coupled water and energy cycles through developing trusted algorithms and datasets with known uncertainties, as a step toward a satellite mission, to build a community of data producers and expert data users prior to a satellite mission, and to create validation datasets for use with planned satellite missions. 4.1b Physics and Dynamics for Improving Weather Forecasts Earth's weather and climate systems are strongly influenced by the interactions between the atmosphere and land, ocean, and sea ice surfaces, the radiation from the sun, and by the release and redistribution of latent and radiative heating.
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are among the processes with the strongest impact on weather and climate. Being able to predict the formation of convective storms and their evolution into severe weather such as thunderstorms and tropical cyclones is critical for improving weather forecasts.
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. Questions Best Addressed with Large Aircraft and Variables to Be Measured To advance understanding of physical and dynamical processes outlined in the ESAS priority areas, throughout the depth of the troposphere, comprehensive airborne observations are needed of atmospheric dynamic and thermodynamic processes,
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ocean, and sea ice) exchanges of kinematic and thermodynamics C-4c (I)
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radio occultation for PBL temperature and humidity and heights, differential absorption lidar for water vapor profiling, and backscatter lidars for PBL height. Airborne atmospheric measurements of the PBL, in addition to in situ measurements, rely on active remote sensors (wind and backscatter lidars, radars, and scatterometers)
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For tropical studies, this might go well beyond 14-15 km above sea level (ASL)
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Conclusion 4.4. To obtain comprehensive sets of measurements covering a wide range of temporal and spatial scales needed for advancement of science questions in the weather area, a large aircraft is necessary to meet the requirements for flight duration (about 10 hours or longer)
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. Long-range aircraft that can stay in the air for long periods with room for multiple sensors could still be valuable in multiple aircraft deployments as the wide complement of remote sensors and radiative flux measurements could be important for getting the three-dimensional structure inside the cloud, provided they are used in coordination with other aircraft flying at different altitudes.
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Measurements from long-duration UAS or stratospheric balloons could now have the capability of tracking the evolution of weather phenomena that have long lifetimes, such as the evolution of tropical cyclones, where it is important to observe the process of rapid intensification; the complete life cycle of cyclones as they traverse the United States; and collection of routine statistics on various meteorological phenomena. Finally, measurements of cloud particles, winds, temperature, and humidity in convective cores are almost nonexistent because current airborne platforms, both piloted and uncrewed, are not able to safely penetrate convective cores with large updraft speeds.
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The atmosphere is also rapidly moving with respect to Earth's surface while emissions are being added and chemical transformations are occurring, which adds some additional measurement challenges compared to the study of many land-, ocean-, and cryosphere-based surface processes discussed in other sections that largely focus on remote sensing of the surface from airborne and spaceborne instrumentation. These measurement challenges in the study of atmospheric chemistry coupled with atmospheric dynamics have been met most successfully in the troposphere and parts of the lower stratosphere using the long-duration, heavy-lift DC-8 aircraft to make detailed in situ observations throughout the atmosphere (e.g., Barth et al., 2015; Crawford et al., 2021; Fishman et al., 1996; Hoell et al., 1996, 1997, 1999; Jacob et al., 2003, 2010; Raper et al., 2001; Singh et al., 2006, 2009; Toon et al., 2016)
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Table 4.3 highlights four major questions in atmospheric chemistry and maps them onto a number of specific ESAS questions and objectives that are deemed "Most Important" for three science and applications areas: Extending and Improving Weather and Air Quality Forecasts, Ecosystem Change, and Reducing Climate Uncertainty and Informing Societal Response. Table 4.3 also indicates the types of measurements needed to answer these questions; for clarity, they are given in a grouped format in Table 4.3, while a much more detailed view of individual species measured as well as their spatial and temporal resolutions are given in Table E.1 (Appendix E)
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The detailed list of variables in Table E.1 also includes additional information on the historical progression in the number and quality of variables that have been measured. The large number of variables and the payload size this dictates, and, as will be discussed later, the maturation in capability to measure atmospheric composition more completely, are some of the many factors that drive the need for continued heavy-lift, long-range capability for airborne science to answer ESAS questions involving atmospheric chemistry coupled with dynamics.
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W-5a (MI) meteorological variables, carbon cycle and W-6a (I)
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80 Airborne Platforms to Advance NASA Earth System Science Priorities Figure 4.4 An integrated research strategy for atmospheric chemistry, showing the strengths and limitations of each perspective and their collective contributions to advancing understanding and predictive capabilities. In the satellite remote sensing portion, T represents temperature and q represents water vapor.
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Airborne science has also played and will continue to play a critical role in improving atmospheric and Earth system models. Earth system models and chemical transport models are the tools for predicting future impacts of atmospheric composition changes and feedbacks between the atmosphere and other components of the Earth system.
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. Looking forward, the continued maturation of the integrated research strategy for atmospheric chemistry in Figure 4.4 will be needed to achieve the ESAS science priorities for which atmospheric chemistry plays a role.
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, six different air quality modeling teams participated in the campaign, which enabled detailed intercomparison of the models against each other in the context of detailed observations. As these parallel advances in airborne, satellite, and models progress, the integrated strategy in Figure 4.4 will continue to dictate airborne science demands into the future and the types of measurements and measurement platforms needed to continue to make progress in answering the ESAS questions.
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Also relevant for addressing relevant ESAS questions is the recent World Meteorological Organization initiative, Global Air Quality Forecasting Information System, which will bring engagement from the international modeling community to identify where air quality forecasts are most challenged and in need of study. In this framework, a robust airborne capability that can conduct detailed assessments of atmospheric chemistry across the globe will be needed, such as the DC-8 payload has demonstrated in the ATom mission.
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. The essential role that an aircraft with characteristics similar to those of the DC-8 in terms of large payload capacity, long duration, and broad altitude range will play in the integrated strategy for answering the ESAS questions involving atmospheric chemistry coupled with dynamics over the next decade and beyond has been highlighted in this section.
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In addition, since the DC-8's first NASA atmospheric chemistry research flights in 1987, the space afforded by the downsizing of more established instruments has been filled by new instruments to expand the capacity to measure atmospheric composition more completely and thus advance in addressing the ESAS questions. Large capacity has also enabled the DC-8 to have both remote sensing and in situ measurements together on the same platform.
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enables vertical profiles of numerous constituents that are essential for both satellite observation intercomparisons and an understanding of processes that comes from the combination of satellite and airborne observations and chemical transport models. This is emphasized in Figure 4.4, which shows that atmospheric chemistry campaigns are intended to provide more than direct validation.
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Overall, in the framework of answering ESAS questions in this science area using the integrated strategy depicted in Figure 4.4, and considering specific characteristics of the DC-8 aircraft that have led to significant advances in atmospheric chemistry over the past three decades, advancing the science of atmospheric chemistry in the next decade and beyond calls for airborne capabilities that enable the following: 1. Comprehensive measurements of atmospheric composition (both gas and aerosol phases)
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The notion that combinations of smaller aircraft could fill the heavy-lift, altitude, and long-range requirements to answer ESAS questions in atmospheric chemistry is not viable. That said, smaller aircraft have played critical roles in atmospheric chemistry research and will continue to be needed.
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Thus, in addition to collaborations with the DC-8, smaller aircraft can be used to meet the airborne needs for some tightly focused atmospheric chemistry questions that do not require the full suite of measurements generally needed to solve atmospheric chemistry questions. Role of Other Airborne Platforms Current use of UAS platforms for atmospheric chemistry is limited, in part due to their typically small payload capacity.
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Conclusion 4.10. Current and near-future UAS and small balloon capabilities contribute to ESAS atmospheric chemistry questions, but improvements in the combination of payload capacity and altitude range are still needed for these platforms to have a wider use in atmospheric chemistry research.
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With new satellite capabilities coming online in the next decade associated with the constellation of satellites combining information from LEO and GEO perspectives, a strong airborne science capability that includes a DC-8-like large airborne platform will be needed to address ESAS atmospheric chemistry questions and to bring three decades of NASA investment to fruition. 4.1d Ecosystem Change -- Land and Ocean Disciplines within the broad topic of ecosystem science extend from the study of onecelled organisms to the organizational structures and governing mechanisms that regulate the entire biosphere.
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NASA and ISRO conducted a series of airborne science campaigns (Phase-1, winter 2015-2016) that collected data over 57 10 See https://www.nasa.gov/content/earth-expeditions-naames/.
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Flights in fall 2021 include the GIII and GIV aircraft flying AVIRIS-NG and PRISM to measure biogeochemical traits and estimate carbon, water, and nitrogen fluxes. Hyperspectral Thermal Emissions Spectrometer is measuring temperatures of the plants and surface at high spatial resolution, to estimate physiological processes such as ET, photosynthesis, and respiration, and LVIS lidar is collecting data to provide detailed three-dimensional measurements of topography, canopy structure, and ecosystem structure.
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• Low-altitude airborne measurements of greenhouse gases (GHGs) such as CO2, CO, CH4, H2O, NO2 • In situ measurements of CO2, CH4, H2O E-3: What are the fluxes • Optical measurements of leaf area, leaf type E-3a (MI)
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AVIRIS-NG-like imaging spectrometer. Data collection from multiple instruments, particularly including radar, requires a large aircraft and heavy-lift capabilities like the DC-8, in addition to co-flights on other aircraft, and in situ measurements on the ground and from towers.
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. Recent powerful wildland fires have created internal weather conditions that caused hot and fast-moving fires, and others that injected dense smoke clouds into the lower stratosphere.
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Such information would revolutionize fire science and greatly enhance public safety and reduce wildland fire cost and risks. See also Section 4.2b for expanded discussion of an interdisciplinary approach to wildland fires.
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, which aligns with ESAS questions E-1, E-2, and E-3, and is now ready to expand to regional, continental, and global scales. Successful use of large aircraft to fly multiple instruments is needed to address the E-1 ecosystem research question but has not been demonstrated in the DC-8; however, the NASA ER-2, potentially capable of collecting data from four instrument pods, has been used.
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explicitly identify weather impacts on the health of ecosystems and interacting processes that affect spatiotemporal structures of air pollutants. Geological hazards, atmospheric chemistry, sea level rise, and other priority areas of ESAS interact as well but are outside the scope of ESAS.
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Satellite overpasses may be too infrequent or at the wrong time of day, while aircraft can be deployed to meet specific monitoring needs. Wildland fires typically have a diurnal pattern for peak rates of spread; thus, airborne monitoring at these times provides essential information for management.
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These requirements might make coordination of individual small aircraft better suited for some missions rather than using one large aircraft. The newer emerging imaging technologies for addressing cutting-edge science (including the ESAS questions for ecosystems)
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mass input to the ocean, largely as a result of ice sheet melting from Antarctica and Greenland, as illustrated in Figure 4.6. For the ice sheets, Figure 4.6 Processes contributing to sea level rise include mass additions from melting glaciers and ice sheets, thermal expansion of the ocean as a result of ocean heat content increases, groundwater releases, isostatic adjustment changing relative sea level, and alterations of the hydrological cycle.
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Within the ESAS report, two science priorities, C-1 and S-3, focus specifically on sea level rise, including the impacts of ice sheet mass loss (Table 4.5)
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, which has evaluated sea level rise by surveying key variables over Greenland and Antarctica. The key parameters and instruments required to estimate them include ice sheet topography from laser and radar altimeters, snow depth from snow radars, ice velocity from SAR interferometry and optical imagery, gravity from gravimeters to evaluate changes in ice mass and to infer the underlying bathymetry, surface melt from optical and microwave sensors, and bare-Earth topography from penetrating radars.
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Conclusion 4.18. A long-range aircraft is essential for understanding ice sheet dynamics and projecting future contributions of Antarctic and Greenland ice sheet melt to sea level rise.
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. Since water is impermeable to electromagnetic radiation, these in situ systems are critical for measuring the ocean interior, and they have the potential to be used more extensively in the future to understand both global and regional sea level rise and related questions, potentially with minimal reliance on aircraft.
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Piloted aircraft, however, allow greater spontaneity to adapt flight plans in response to unexpected observations. Additional Benefits to Earth System Science and Applications Activities for Airborne Platforms Airborne platforms have broad capabilities that span a range of science questions that extend beyond the priority "most important" sea level rise questions identified in ESAS.
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While a heavy-lift, long-range aircraft is not currently required to investigate sea level rise, it has been invaluable in the past and could be invaluable for future multi-sensor measurement programs. 4.1f Surface Dynamics, Geological Hazards, and Disasters Surface dynamics, geological hazards, and disasters are responses of Earth's surface to tectonic, hydrological, ecological, and climatic processes and anthropogenic activities (NASEM, 2018a)
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Airborne platforms can support investigation of the ESAS priority questions on Earth's terrestrial surface dynamics, geological hazards, and disasters (Table 4.6)
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volcanic products following an eruption S-3: How will local sea level • Land surface deformation S-3b (MI) change along coastlines around the world in the next decade to century?
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Landslide studies need monitoring of landslide movements, especially those near population centers at varying timescales. The required datasets are high-resolution bare-Earth topography at spatial resolution of about 10 m and accuracy of about 10 cm from lidar, and land surface deformation at spatial resolution of meters and accuracy of 10 mm (per measurement)
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Questions Best Addressed with Large Aircraft and Variables to Be Measured Large aircraft that are capable of stable and precise positioning and altitude, long range and duration, and accommodation of multiple sensors can be useful to understand geological processes. Although nearly all of the ESAS priority questions on surface dynamics, geological hazards, and disasters can be optimally addressed by smaller aircraft, the long-range capacity of a large aircraft that can host multiple sensors (e.g., SARs at several bands, lidar, and hyperspectral optical instruments)
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For surface dynamics and geological hazards research, the long-range capacity of a large aircraft that could host multiple sensors (e.g., SARs of several bands, and/or lidar and optical instruments) could enhance data collection over a long distance and duration, improving efficiency and temporal sampling for interdisciplinary sciences, including this science area, over a large geographic scale.
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Role of Other Airborne Platforms Addressing future Earth system science questions requires multisensor observations at high spatial resolution, high temporal sampling, and improved measurement accuracy. In addition, rapid deployment of airborne sensors for urgent responses is essential for geohazard characterization and forecast.
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4.2 PROVIDING CAPACITY FOR EXPANDING FUTURE EARTH SYSTEM RESEARCH NEEDS 4.2a Integrating Themes in Earth System Science For the science areas discussed in sections 4.1a-f, linkages emerged that point to successful campaigns and studies that brought together various disciplines. For instance, the DC3 and SEAC4RS missions are highlighted in both the Weather and Atmospheric Chemistry sections; ARCTAS and ATom are discussed in both the Ecosystem and Atmospheric Chemistry sections; and reference to FIREX-AQ in the Atmospheric Chemistry section specifically points to the use of MASTER for cross-disciplinary benefit.
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ESAS describes some needs of importance: managing air pollution risks, water quality, and food security; improving prediction of extreme weather such as severe storms, tornadoes, hurricanes, winter storms, and wildland fires; measuring the health and productivity of land and oceans globally; assessing risks from sea level rise; and predicting large-scale geological hazards and studying impacts of geological disasters on the Earth system and society (NASEM, 2018a)
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These changes link to many science areas discussed in this report including physics and dynamics for improving weather forecasts; ecosystem change -- land and ocean; sea level rise in a changing climate and coastal impacts; and surface dynamics, geological hazards, and disasters. Extreme rainfall associated with landfalling tropical cyclones and winter storms affect marine and land ecosystem changes across coastal zones.
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These observations have contributed to our understanding of hurricane dynamics and improving hurricane forecasts with increased lead time over the past several decades. The DC-8 has been used in many field campaigns observing tropical cyclones because it can carry the multiple instruments required for the research over long distances.
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. Sea level rise due to climate change will continue to increase the risk of coastal and inland flooding.
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Platforms include multiple aircraft (NOAA P-3 and Air Force C-130) equipped with radar and lidar (indicated by yellow triangle)
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Post-fire burned land surface is prone to landslides especially over the West Coast regions. Recent field campaigns have aimed to address the complexities of wildland fire using aircraft, satellite, and surface-based observations.
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and emissions, weather, hydrology (e.g., soil moisture, changes in surface runoff pre- and post-fire) , and atmospheric chemistry and composition and air quality.
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However, the role of pyrocumulonimbus activity in the climate system is still unclear. Ongoing research on this topic fits multiple scientific disciplines, such as atmospheric chemistry, cloud dynamics and microphysics, fire dynamics, radiation, and interaction with weather conditions.
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Conclusion 4.27. Smaller aircraft and UAS are also critical for meeting interdisciplinary, societally-relevant needs, particularly when science questions do not require colocated, simultaneous observations, such as mudslides occurring after extreme precipitation on land that has burned; pre- and post-tropical cyclone landfall land conditions and flooding; and when aircraft need to be deployed quickly to observe conditions as natural disasters transpire.
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Having airborne research capability provided by a large aircraft is critical for meeting the unanticipated future Earth system science research needs.
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