Arctic Mechanisms of Interaction Arctic Mechanisms of Interaction Between the Surface and AtmosphereBetween the Surface and Atmosphere

Don Cavalieri, Code 614.1, NASA GSFCDon Cavalieri, Code 614.1, NASA GSFC

A NASA funded International Polar Year (IPY) summer Arctic airborne campaign named Arctic Mechanisms of Interaction between the Surface and Atmosphere (AMISA) was completed in August.

AMISA was the remote sensing component of a Swedish IPY sponsored program called the Arctic Summer Cloud Ocean Study (ASCOS). This combined AMISA / ASCOS field campaign provided coordinated measurements by the NASA DC-8 airborne laboratory and the Swedish Icebreaker Oden located at about 87o N latitude.

The goals of the AMISA campaign were to determine processes linking atmospheric properties to sea-ice loss and formation and to validate and improve EOS Aqua AMSR-E sea ice algorithms.

Figure 1: NASA DC-8 airborne laboratory

Figure 2: Swedish Icebreaker OdenHydrospheric and Biospheric Sciences Laboratory

References: The ASCOS website at http://www.ascos.se/ provides an overview of the IPY sponsored program.

Data Sources: The AMISA campaign was an international effort with universities and government agencies contributing the sensors flown on the NASA DC-8 airborne laboratory and near-real time satellite imagery: the University of Colorado provided both scanning and fixed-beam radiometers for mapping sea ice and measuring atmospheric cloud liquid water and water vapor, the University of Leeds (UK) provided the Volatile Aerosol Concentration and Composition (VACC) for making in-situ measurements of boundary layer structure and aerosol spectra, NASA Langley Research Center provided the Cloud, aerosol, and precipitation spectrometer (CAPS) for measuring cloud droplet and ice particle spectra, liquid water content, and droplet/ice discrimination, the University of Colorado (CIRES) also provided expendable digital dropsondes for measuring sub-aircraft profiles of temperature, pressure, humidity, and wind, the NASA Marshall Space Flight Center provided near-real time Aqua AMSR-E sea ice concentrations, the NASA Goddard Space Flight Center provided near-real time MODIS imagery, and the National Ice Center provided near-real time SAR sea ice analyses.

Technical Description of Image:Figure 1: The NASA DC-8 Airborne Laboratory photographed shortly after take-off from Palmdale, CA on its way to Kiruna, SE (Photo courtesy Jim Mumaw). Between August 8th and August 27 th, the DC-8 flew four data flights coordinated with the Swedish Icebreaker Oden located near the North Pole and a fifth data flight over the Fram Strait ice edge.Figure 2: Swedish Icebreaker Oden (Photo courtesy Erik Swietlicki). The Oden deployed an ice-drift camp used for atmospheric measurements. The focus of the Oden campaign was on the physical processes leading to cloud formation.

Scientific significance: The primary goals of the AMISA campaign were to: determine processes linking atmospheric properties to sea-ice loss and formation; validate and improve current algorithms used by NASA satellites (Aqua AMSR-E) to correct for the impact of cloud liquid water and moisture; evaluate sensor abilities to distinguish between melt ponds within sea-ice and sea-ice/ocean boundaries. The scientific significance of this work will help us understand better the atmospheric processes influencing sea ice loss and growth as well as improving our capability to monitor the changing Arctic sea ice cover.

Relevance for future science: Results from this campaign will enable us to assess the mechanisms leading to future climate change in the Arctic and to improve the Aqua AMSR-E sea ice concentration retrievals under summertime Arctic conditions in order to monitor current and future changes in the Arctic sea ice cover.

Name: Don Cavalieri (Co-PI), Al Gasiewski (PI, Univ. Colorado), Thorsten Markus (Co-PI), Ola Persson (Co-PI, CIRES, Univ. Colorado)E-mail: Donald.J.Cavalieri@nasa.govPhone: 301-614-5901

Hydrospheric and Biospheric Sciences Laboratory

Retrieval of coastal water turbidity from CALIOP and MODIS Jonathan S. Barton, NASA Postdoctoral Fellow (ORAU), NASA GSFC

Michael F. Jasinski, CODE 614.3, NASA GSFC

Hydrospheric and Biospheric Sciences Laboratory

Turbidity is an important indicator of the health of an ecosystem. It is an important control on the amount of light that penetrates the water column, affecting the amount of photosynthesis that the water body can support. Turbidity is also a good surrogate measurement for suspended sediment load in moving water.

CALIOP lidar data, which can penetrate the water surface to a depth of about 7 meters, can provide insight into the degree of turbidity affecting the water being observed.

Figure 2. Normalized turbidity index from CALIOP data, compared with an estimate of turbidity.

Figure 1. MODIS surface reflectance image of the Irish Sea, from 02 May 2007.

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Scotland

N. Ireland

Because both the MODIS and the CALIOP signals are dependent both on absorption and turbidity in the water, it is hoped that further research will enable the separation of the two effects.

Name: Jonathan S. Barton, ORAU, NASA GSFC

Email: jonathan.barton@nasa.gov

Phone: 301-614-6705

References:

Chen, Z., C. Hu, and F. Muller-Karger, 2007: Monitoring turbidity in Tampa Bay using MODIS/Aqua 250-m imagery, Remote Sensing of Environment, 109, 207-220, doi:10.1016/j.rse.2006.12.019.

Gray, J. R., and G. D. Glysson (2003), Proceedings of the Federal Interagency Workshop on Turbidity and Other Sediment Surrogates, Reno, NV, April 30-May 2, 2002, U.S. Geological Survey Circular 1250, 56 p.

Data Source:

CALIOP and MODIS. We estimated the turbidity using the 250m-resolution MODIS data following the method of Chen (2007). We then combined the perpendicularly-polarized 532nm CALIOP return and the infrared CALIOP return to produce a normalized index. We then compared the two to determine if the variability in the index was correlated with the variablility in turbidity.

Technical Description of Image:

Figure 1. MODIS surface reflectance image of the Irish Sea, from 02 May 2007, showing turbidity concentrated off of southern Ireland and northwestern Wales. The track of the CALIOP overpass is from southeast to northwest along the yellow line.

Figure 2. Normalized turbidity index from CALIOP data compared with an estimate of turbidity after Chen (2007), which is based on 250m-resolution MODIS data. The correlation coefficient is 0.92. Data shown is from 02 May 2007, and corresponds to the track shown in Figure 1.

Scientific Significance: The U.S. Environmental Protection Agency (2002) (cited in Gray and Glysson, 2003) has ranked siltation (and by implication, turbidity) as one of the most widespread pollutants in the United States. It affects rivers, streams, lakes, reservoirs, estuaries and coastal waters, adversely impacting aquatic habitat, drinking water treatment facilities, recreational use, and commercial navigation and fisheries. High levels of sediment in the water column reduce spawning grounds and deplete food sources for aquatic life. High concentrations of sediment may lead to rapid deposition andrapid changes in coastal or fluvial morphology, which may lead to navigational hazards as well as increasing flood risks for the region. Regions of abnormally low turbidity (and therefore low suspended sediment concentration) may experience rapid erosion, and subsequent alteration ofmorphology, often accompanied by entrenchment and bank failure in the case of rivers or by beach erosion and barrier island collapse in the coastal environment. (Gray and Glysson, 2003)

Relevance for future science and relationship to Decadal Survey:Planned research seeks to test a theoretical relationship linking the fundamentally different dependence on turbidity evident in MODIS and CALIOP data to extract the absorption and scattering coefficients of the turbid water, intrinsic optical properties of the water. Measuring such properties, instead of effects of the properties (turbidity is one such effect) could produce a globally applicable monitoring algorithm that is insensitive to the type of material suspended in the water column, which has historically been a stumbling block for water quality algorithms. This type of algorithm, combining lidar and spectroradiometer technology is directly applicable to the Decadal Survey-recommended ACE mission, which employs both of these sensors on a single platform. Because ACE is a second-tier mission, an agorithm such as this would enable progress towards goals outlined for coastal water quality monitoring considerably earlier than either of the recommended Inland and Coastal Water Quality missions.

Hydrospheric and Biospheric Sciences Laboratory