MACPEX Science
Background
The NASA Earth Science Division supports scientific investigations within the Atmospheric Composition focus area that contribute to the understanding of the sources, transformation, and transport of trace species in the Earth’s atmosphere. The research strategy in atmospheric composition encompasses an end-to-end approach for instrument design, data collection, analysis, interpretation, and prognostic studies. NASA expects to provide the necessary monitoring and evaluation tools to assess the effects of climate change, and air quality forecasts that take into account the feedbacks between local, regional and global air quality and global climate change. Drawing on global observations from space, augmented by suborbital and ground-based measurements, NASA is uniquely poised to address these issues. This integrated observational strategy is furthered via modeling studies that together with this suite of observations allow us to test our understanding of atmospheric processes.
Mid-latitude Airborne Cirrus Properties Experiment
Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) is an airborne field campaign to investigate the properties of mid-latitude cirrus cloud, the processes affecting these properties and their impact on radiation. The campaign will take place during the summer of 2010 over central North America with special emphasis in the vicinity of the DoE ARM SGP site in Oklahoma. In addition, flight planning will emphasize coordination with EOS/A-Train satellite observations (e.g., Aqua, Aura, CALIPSO, CloudSat, Glory, PARASOL, OCO, and Terra) for the purposes of scientific utilization of satellite and in-situ data sets as well as satellite validation.
The major science questions to be addressed by MACPEX include:
- How prevalent are small (D < 50 μm) crystals in cirrus, and how important are these small crystals for cirrus extinction, radiative forcing, and radiative heating?
- How are cirrus microphysical properties (particle size distribution, ice crystal habit, extinction, ice water content) related to the dynamical forcing driving cloud formation?
- How are cirrus microphysical properties related to aerosol loading and composition, including the abundance of heterogeneous ice nuclei?
- How do cirrus microphysical properties evolve through the lifecycles of the clouds, and what role do radiatively driven dynamical motions play?
In addition, the field measurements should provide the cirrus microphysical information needed for improvement and evaluation of remote-sensing retrievals and for climate model cloud parameterizations:
- For improvement of remote-sensing retrievals, we need to determine cirrus ice crystal size distributions and habits over the full size range (1 μm - 1cm) for cirrus forced by a variety of dynamical phenomena (orographic waves, frontal systems, aircraft contrails, deep convection, etc.).
- For evaluation of remote-sensing retrievals, we need to measure cirrus properties coordinated in time and space with ground-based and satellite observations.
- For improvement and evaluation of GCM cirrus parameterizations, we need to measure cirrus bulk properties (ice water content, extinction, effective radius) for a variety of cirrus types and cirrus ages.
The measurements required to address the science questions and objectives:
- Ice crystal size distribution: 1 μm – 1 cm (legacy and open-path)
- Ice water content: 0.2 mg m−3 – 5 g m−3
- Cloud extinction: 0.01 km−1 – 100 km−1
- Ice crystal habit: 50 μm – 1 cm
- Aerosol size distribution: 3 nm – 3 μm
- Aerosol composition (single particles)
- Ice nuclei
- Water vapor w/ redundancy
- Water isotopic composition
- Temperature
- Vertical winds
- Horizontal winds
- Chemical tracers (e.g., CO, CO2, O3)
NASA’s WB-57F aircraft will be deployed from its home base in Houston, TX, which will fulfill the requirements to make in situ measurements of cirrus clouds in the vicinity of the ARM SGP site, as well as the necessary range of cirrus clouds.