Future NASA Atmospheric Missions: Adding to the A-Train James Gleason NASA Goddard Space Flight Center, Mail Code 613.3, Greenbelt, MD 20771, United States Abstract Following on the successful launch of Aura in July 2004, NASA will continue to add to the Atrain with the spring 2006 launch of the CALIPSO and Cloudsat missions, followed by the fall 2008 launch of the Orbiting Carbon Observatory (OCO), the Glory mission, and the Fall 2009 launch of the NPOESS Preparatory Project (NPP). The CALIPSO mission has three nadir- viewing instruments: a cloud-aerosol lidar for measuring aerosol and cloud height and properties, a 3-channel thermal infrared imaging radiometer, and a wide field cloud camera. The Cloudsat mission has a 94 GHz cloud profiling radar, returning cloud structure vs. height profiles. Orbiting Carbon Observatory (OCO) is a mission focused on precision measurements of total column CO2 using reflected sunlight.. A brief report from a community workshop on future atmospheric science missions will also be presented.
The Following missions and their launch dates are newly added to or planned for the afternoon constellation. Calipso April 2006 OCO Fall 2008 NPP Winter 2009 (new) CloudSat April 2006 Glory Fall 2008 (new)
The afternoon constellation will focus on science of clouds, and coupled climate/aerosol/chemistry science and enable near-simultaneous correlative measurements The science community faces a considerable challenge to match the variety of vertical and horizontal resolutions resulting from this unprecedented multi-instrument satellite system.
CALIPSO (formerly Picasso-CENA) Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation IIR 20
km 10
Laser WFC 0 Distance LITE measurements over convection • 2-wavelength (532 and 1064 nm) polarization-sensitive LIDAR that provides 30 m vertical resolution profiles of aerosols and clouds.
• Imaging infrared radiometer (IIR) that provides calibrated infrared radiances at 8.7 µ, 10.5 µ and 12 µ. These wavelengths are optimized for combined IIR/lidar retrievals of cirrus particle size.
• High-resolution wide field camera (WFC) that acquires high spatial resolution imagery for meteorological context (620 to 670 nm).
Cloudsat
94 GHz Cloud Profiling Radar (CPR) • Nadir-viewing • 500 m vertical resolution • 1.2 km cross-track, 3.5 km along track • Sensitivity: -30 to -36 Data Products dBZ •Radar reflectivity •Visible and near-IR radiances •Cloud base and top heights •Optical depth •Atmospheric heating rates •Cloud water content •Cloud ice content •Cloud particle size •Precipitation Occurrence NPOESS Preparatory Project: NPP
• Sun - synchronous, polar • Altitude - 824 km nominal • Inclination - 98 degrees • Ascending node - 10:30 a.m. • Launched – April 2008
Instruments •Cross Track Infrared Sounder (CrIS) •Advanced Technology Microwave Sounder (ATMS) •Visible Infrared Imaging Spectrometer (VIIRS) •Ozone Mapping and Profiler Suite (OMPS)
OMPS Scanning Track
(Limb Profiler)
(Nadir TC) The Orbiting Carbon Observatory (OCO)
OCO will acquire the space-based data needed
to identify CO2 sources and sinks and quantify their variability over the seasonal cycle Approach: • Collect spatially resolved, high resolution
spectroscopic observations of CO2 and O2 absorption in reflected sunlight • Use these data to resolve spatial and temporal variations in the column averaged
CO2 dry air mole fraction, XCO2 over the sunlit hemisphere • Employ independent calibration and
validation approaches to produce XCO2 estimates with random errors and biases no larger than 1 - 2 ppm (0.3 - 0.5%) on regional scales at monthly intervals
5, OCO May 2006 Page 5
Making Precise CO2 Measurements from Space
• High resolution spectra of reflected sunlight in near IR CO2 and O2 bands are combined to retrieve the column average CO2 dry air mole fraction, XCO2
– 1.61 μm CO2 bands – Column CO2 with maximum sensitivity near the surface
–O2 A-band and 2.06 μm CO2 band • Surface pressure, albedo, atmospheric temperature, water vapor, clouds, aerosols • Why high spectral resolution? – Enhances sensitivity, minimizes biases
CO2 2.06 μm
O2 A-band CO2 1.61μm
Clouds/Aerosols, Surface PressureColumn CO2 Clouds/Aerosols, H2O, Temperature
6, OCO May 2006 Page 6 Glory mission provides timely key data for climate change research
The Glory Mission Objectives are to: 9 Quantify the role of aerosols as natural and anthropogenic agents of climate change by flying APS
9 Continue measuring the total solar irradiance to determine its direct and indirect effects on climate by flying TIM
7, OCO May 2006 Page 7
Glory APS summary
Type: Passive multi-angle photopolarimeter Fore-optic: Rotating polarization-compensated mirror assembly scanning along orbit-track +50.5° to –63° (fore-to-aft) from nadir Aft-optic: 6 bore-sighted optical assemblies, each with a Wollaston prism providing polarization separation, beamsplitters & bandpass filters producing spectral separation, and paired detectors sensing orthogonal polarizations Directionality: ~250 views of a scene APS angular scanning Approx. dimensions: 60 x 58 x 47 cm Mass/power/data rate: 53 kg / 36 W / 120 kbps Spectral range: 412–2250 nm Measurement specifics: 3 visible (412, 443, 555 nm), 3 near-IR (672, 865, 910 nm), and 3 short-wave IR (1378, 1610, 2250 nm) bands; three Stokes parameters (I, Q, and U) Ground resolution at nadir: 6 km SNR requirements: 235 (channels 1 – 5, 8, and 9), 94 (channel 6), and 141 (channel 7) Polarization accuracy: 0.0015 at P = 0.2, 0.002 at P = 0.5 Repeat cycle: 16 days APS spectral channels
8, OCO May 2006 Page 8 Community Input to the NRC Decadal Survey from the NCAR Workshop on Air Quality Remote Sensing From Space: Defining an Optimum Observing Strategy
Submitted by the Workshop Organizing Committee (David Edwards, NCAR; Philip DeCola, NASA HQ; Jack Fishman, NASA LaRC; Daniel Jacob, Harvard University; Pawan Bhartia, NASA GSFC; David Diner, JPL; John Burrows, U. Bremen; Mitch Goldberg, NOAA/NESDIS) after input from the Workshop Participants.
Executive Summary
The Community Workshop on Air Quality Remote Sensing from Space was held in Boulder, Colorado, February 21-23, 2006, to examine what observational characteristics are required for the successful use of satellite remote sensing to measure environmentally significant pollutant trace gases and aerosols. Air quality (AQ) measurements are urgently needed to understand the complex consequences of increasing anthropogenic emissions, the biogenic response to changing temperature and humidity, and the escalating incidence of fire. The acknowledged urgency of this endeavor was reflected in the fact that the Workshop engaged more than 150 scientists and other AQ stakeholders with the primary goal of developing a strategy for future space-based capabilities. Four principal areas in which satellite observations are crucial for future AQ basic research and operational needs were identified: (1) AQ characterization for retrospective assessments and forecasting to support air program management and public health advisories; (2) Quantification of emissions of ozone and aerosol precursors; (3) Long-range transport of pollutants extending from regional to global scales; and (4) Large puff releases from environmental disasters. The recent advances in tropospheric remote sensing from low-Earth orbit (LEO) instruments such as MOPITT, GOME, MODIS, MISR, SCIAMACHY, OMI and TES have demonstrated the value of using satellites for both scientific studies and environmental applications. The Workshop agreed that the measurement capabilities for tropospheric O3, CO, NO2, HCHO, SO2 and aerosols need to be continued and, at the same time, instrument capabilities and measurement algorithms for these species improved. Ideally, the AQ community envisions a scientific and observing framework for atmospheric composition that is analogous to that achieved for weather forecasting. In particular, our national weather prediction system relies on the combination of observations from geostationary Earth orbit (GEO), LEO, suborbital and surface platforms to derive a 4-dimensional view (3 spatial plus temporal) of the physical state of the atmosphere. Similar capability for AQ constituents will be required for AQ characterization and “chemical weather” forecasting. Workshop participants reached a consensus that multi-spectral sentinel missions (GEO or Lagrangian (L-1) orbit) that have high spatial and temporal resolution, and which are able to provide some species concentrations within the boundary layer, would be most beneficial to the AQ community. At the present time, GEO meets this measurement capability with the least amount of risk, and the greatest societal benefit from a U.S. perspective would be derived from placing such a satellite in an orbit capable of observing North America. The NOAA GOES-R operational suite of measurements from GEO will have some AQ relevant capability for ozone, carbon monoxide and aerosol. However, since NOAA's primary objective is improving weather forecasting, observations are not currently optimized for AQ applications and critical multi-spectral measurements in the UV and near-IR are not planned. Thus the Workshop stated the need for a new generation of dedicated AQ satellite missions that will also be part of an integrated observing system including air monitoring networks, in situ research campaigns, and 3-D chemical transport models. The continued collaboration with NOAA to determine the most efficient and synergistic use of resources to meet AQ observational objectives from both GEO and LEO was emphasized by the Workshop. This is particularly important since GEO AQ observations will need to be complemented by operational global measurements of tropospheric gases and aerosols from NPOESS and other NOAA and European satellite systems. Over the longer term, global measurements for AQ with a sentinel capability could be obtained from L-1 orbit, but this approach requires more technical development to ensure the essential multi-spectral measurements and mitigate risk. Other approaches for AQ measurements discussed at the Workshop included multiple satellites flying in LEO formation and satellites perched in mid-Earth orbit (MEO), which can provide time-resolved observations (about 5 per day at mid-latitudes for all longitudes) but with UV/visible switching monthly between north and south. Each of these approaches has value and may provide synergy with objectives put forth by other Earth system science disciplines. The LEO-formation and multiple MEO instruments with limb viewing capability provide better vertical resolution in the middle and upper troposphere needed for understanding the impact of tropospheric and stratospheric chemistry on climate, and the resolution in the stratosphere needed to monitor the stability of the atmospheric ozone layer. The Workshop also concurred that a LEO would be the best platform for gaining an understanding of the composition and size characteristics of atmospheric aerosols by means of multi-angle, spectropolarimetric and stereoscopic-imaging techniques in conjunction with active (high spectral resolution lidar) measurements, which could provide aerosol information throughout the troposphere.
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