An Anomalous Phytoplankton Bloom in the Patagonian Shelf: A 10-year Event Observed by Ocean Color Satellites Time Series of Chl-a, Nitrate (NO 3 ), and Light (P Figure 1 Figure 2 ery strong and persistent phyto- nkton bloom was observed by ocean or satellites during September- ember 2003 along the Patagonian lf. The bloom had the highest extent 0900 km) and Chl-a concentration 20 mg/m 3 ) of the entire SeaWiFS sion (1997-present). sonal and Interannual changes in tical mixing, shelf intrusions of the vinas Current, and the position of the zil-Malvinas confluence zone, are the t likely mechanisms responsible for rient enrichment on the shelf region , consequently, the elevated agonian Shelf biomass. harles R. McClain, Code 614.2, NASA GSFC and Sergio R. Signorini, SAIC, Code 614.2, NA drospheric and Biospheric Sciences Laboratory
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An Anomalous Phytoplankton Bloom in the Patagonian Shelf: A 10-year Event Observed by Ocean Color Satellites
Time Series of Chl-a, Nitrate (NO3), and Light (PAR)
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A very strong and persistent phyto-plankton bloom was observed by oceancolor satellites during September-December 2003 along the PatagonianShelf. The bloom had the highest extent(300900 km) and Chl-a concentration(> 20 mg/m3) of the entire SeaWiFS mission (1997-present).
Seasonal and Interannual changes in vertical mixing, shelf intrusions of the Malvinas Current, and the position of the Brazil-Malvinas confluence zone, are the most likely mechanisms responsible for nutrient enrichment on the shelf region and, consequently, the elevated Patagonian Shelf biomass.
Charles R. McClain, Code 614.2, NASA GSFC and Sergio R. Signorini, SAIC, Code 614.2, NASA GSFC
Signorini S. R., V. M. T. Garcia, A. R. Piola, H. Evangelista, C. R. McClain, C. A. E. Garcia, and M. M. Mata, An anomalous phytoplankton Bloom on thePatagonian Shelf: A 10-year event observed by ocean color satellites, Continental Shelf Research, in review, 2008.
Signorini S. R., V. M. T. Garcia, A. R. Piola, C. A. E. Garcia, M. M. Mata, and C. R. McClain, Seasonal and interannual variability of calcite in the vicinityof the Patagonian shelf break (38oS−52oS), Geophysical Research Letters, 33, L16610, doi:10.1029/2006GL026592, 2006.
Garcia V. M. T., C. A. E. Garcia, M. M. Mata, R. C. Pollery, A. R. Piola, S. R. Signorini, C. R. McClain, D. Iglesias-Rodriguez, Environmental factorsControlling the phytoplankton blooms at the Patagonia shelf-break in spring, Deep Sea Research Part I, in press, 2008.
Data Sources: The satellite remote sensing data consisted of 9-km SeaWiFS Chl-a and PAR, 4-km MODIS-Aqua SST, 0.5o0.5o QuikScat winds, and4-km Pathfinder AVHRR SST. Mixed layer thickness, mixed layer velocity components, and sub-surface temperature and salinity were obtained from the Hybrid Coordinate Ocean Model (HYCOM).
Technical Description of Image:Figure 1: Monthly composites of SeaWiFS Chl-a for December 2003 (left) and December 2004 (right). Surface currents from HYCOM are superposed onboth maps. Note the large region of high Chl-a occupying the shelf region west of the Malvinas Current during December 2003 (left map). In contrast, theDecember 2004 Chl-a map shows the bloom more confined to the shelf break and on the shelf south of 45oS. A strong intrusion of nutrient-rich MalvinasWater on the shelf region north of 45oS is the likely reason for the elevated Chl-a during December 2003.
Figure 2: Time series of Chl-a, nitrate (NO3), and surface light (PAR), shown in color, for September 1997 − June 2007 along the cross-shelf transectindicated by the white line in the Chl-a maps of Figure 1. The superposed white lines in Figure 2 represent the transect-averaged time series for each parameter. The vertical axis show the distance from the coast and the black line across each time series represents the location of the shelf break. This figure shows that the 2003 bloom was the strongest and largest. Also note that the years 2002, 2003, and 2004 show elevated Chl-a when comparedwith the other years. These years coincide with positive ENSO index and stronger Malvinas Current.
Scientific Significance: The Patagonian shelf is a region of high productivity that sustains stocks of several species of commercial fish and squid. It isalso a region of high uptake of atmospheric CO2 and thus an important contributor to the global carbon cycle. This study shows that physical mechanismsthat sustain the Patagonian shelf productivity can be altered on an interannual basis to make major impacts on the regional plankton productivity.
Relevance for Future Science and Relationship to Decadal Survey: The knowledge of interannual changes of phytoplankton productivity has amajor consequence in the assessment of fish stocks, species composition, and biological drawdown of atmospheric CO2.
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Vegetation scattering model
Active microwave Passive microwave
Surface roughness
Temperature
Surface emission
Soil moisture
Single scattering albedo Transmissivity
Semi-empirical radiative transfer equation
Development of a combined passive/active microwave soil moisture retrieval algorithm based on a vegetation scattering model employing discrete random medium techniques
Alicia Joseph, Code 614.3, NASA GSFC
Legend
TB ~ brightness temperature T ~ temperature of the emitting layer Rs ~ surface reflectivity _ ~ single scattering albedo _ ~ transmissivity _pq~ scattering coefficient_i ~ angle of incidence _s~ angle of scattering in the direction of the observer d_ s ~ solid angle subtended in the scattered directionk ~ propagation contentp indicates the polarization orthogonal to q
BackgroundLow-frequency microwave observations have shown to
be sensitive to changes in soil moisture!
A JPL / GSFC Partnersh ip for an
Earth Science Decadal Survey
M ission
Soil Moisture Active and Passive (SMAP) Mission
SMOS (ESA)Aquarius (NASA)SMAP (NASA)
Future soil moisture missions:
One of the challenges in retrieving soil moisture globally is to account for vegetation effects!
Proposed methodology is based on O’Neill et al. (1996)Hydrospheric and Biospheric Sciences Laboratory
Microwave vegetation parameters are directly estimated from active microwave observations using a physically-based scattering approach
By creating Look-Up-Tables (LUTS) linking active microwave observations to the vegetation parameters using collected data sets, it is possible to apply this developed methodology to large scale study areas
References:•P.E. O’Neill, N.S. Chauhan and T.J. Jackson, “Use of active and passive microwave remote sensing for soil moisture estimation through corn”, International Journal of Remote Sensing, vol. 17, no. 10, pp. 1851-1865, 1996.•R.H. Lang, and J.S. Sidhu, “Electromagnetic backscattering from a layer of vegetation: a discrete approach,” IEEE Transactions on Geoscience Remote Sensing, vol. GE-21,pp. 62-71, Jan. 1983. •N.S. Chauhan, and R.H. Lang, “Radar backscattering from alfalfa canopy: a clump modelling approach,” International Journal of Remote Sensing, vol. 20, pp. 2203-2220, July, 1999.
Data Sources: -OPE3: combined L-band active/passive microwave field campaign conducted throughout the corn growth cycle;- ComRad: multi-year combined L-band active/passive microwave field campaign conducted usng various tree species.
These field campaigns are a joint effort composed of multiple agencies including: USDA-Agricultural Research Service Hydrology Lab (watershed, remote-sensing data), NASA-GSFC Hydrological Science Branch (Truck mount L-band radar/radiometer instrument) and George Washington University Department of Electrical and Computer Engineering.
Scientific significance: Passive microwave soil moisture retrieval algorithms applied at large scale employ semi-empirical approaches to obtain parameterizations used to correct for the effects of vegetations. In densely vegetated areas, the assumption made within the semi-empirical approach are often not valid resulting in large soil moisture retrieval uncertainties. Through estimating the passive microwave vegetation properties from active microwave observations using physically based vegetation scattering model, it is expected to increase the accuracy of the soil moisture retrievals.
Relevance for future science and relationship to Decadal Survey:
In the Decadal Survey, global soil moisture monitoring from space has been identified as an important field of research having applications within numerical weather prediction, drought monitoring and flood forecasting. Based on extensive field campaigns low-frequency (L-band) microwave observations have been found to be best suited for soil moisture retrieval because of their ability to penetrate the vegetation deeper than at higher frequencies. Currently, two combined active/passive L-band microwave missions are being prepared for launch by NASA; Aquarius and Soil Moisture Active/Passive (SMAP). Despite the progress that has been made in the development of global soil moisture retrieval algorithms, correcting for the effects of vegetation remains one of the challenges. In this research, the development of a combined active/passive soil moisture retrieval algorithm will be pursued by employing a vegetation scattering model using a discrete random medium technique. This will enable the direct retrieval of vegetation parameters used within semi-empirical soil moisture retrieval approaches and will improve the retrieval accuracy over densely vegetated areas.
The funding will be used to:
- apply and enhance the proposed methodology to data sets collected during plot-scale field campaign (e.g. OPE3 (2002), ComRad (2006-2008));- develop a Look-Up-Table based approach that will be applied to data sets collected during large-scale calibration/validation field campaigns.
Hydrospheric and Biospheric Sciences Laboratory
Agricultural Research and Training Supported by Unique Unmanned Aircraft System (UAS)Agricultural Research and Training Supported by Unique Unmanned Aircraft System (UAS)
The (ASTI) AeroTech program is focused on developing an Unmanned Aircraft Systems (UAS) training curriculum at the University of Maryland Eastern Shore (UMES).
The TwinCam UAS is an affordable airborne imaging system that is tailored for agricultural observations, including mapping and deriving a Normalized Difference Vegetative Index (NDVI) as a quantitative assessment of crop health.
Figure 1: TwinCam UAS in-flight and at UMES Aviation Science Training Facility
Figure 2: TwinCam Visible and Near-Infrared images of Experimental Wheat Field
Nagchaudhuri, A., Mitra, M., Brooks, C., Earl, T., Ladd, G., Bland, G., 2006, Integration of Mechatronics, Geospatial Information Technology, and, Remote Sensing in Agriculture and Environmental Stewardship, Presentation and Proceedings: ASME International Mechanical Engineering Congress and Exposition, Chicago, IL, Nov. 2006
Bland, G., Coronado, P., Miles, T., Bretthauer, P., 2005, The AEROS Project – Experiments with Small Electric Powered UAVs for Earth Science, Presentation and Proceedings: AIAA “Infotech@Aerospace” Technical Conference, Alexandria VA, September 2005
Nagchaudhuri, A., and Bland, G. 2002. UMES-AIR: A NASA-UMES Collaborative Project to Promote Experiential Learning and Research in Multidisciplinary Teams for SMET Students, Journal of SMET Education: Innovation and Research, July-Dec. 2002
Technical Description of Images:
Figure 1: The TwinCam Unmanned Aircraft System (UAS) is a small, easy-to-field airborne instrument system specifically tailored for agricultural observations. Students and faculty will be also use this unique system for UAS training and curriculum development. The TwinCam is the result of the Airborne Science and Training Initiative (ASTI) AeroTech project, supported by the Goddard Space Flight Center’s Internal Research and Development (IRAD) program. The image of the team with the first TwinCam UAS created for UMES, was taken in the university’s Aviation Sciences simulator facility where training and analysis activities will be conducted. Left-to-Right are: Simeon Richardson (Alumni/Piedmont Aviation), Prof. Chris Hartman (Engineering and Aviation Sciences), Xavier Henry (Student/Aviation Sciences), Anthony Stockus (Engineering and Aviation Sciences), Dr. Ali Eydgahi (Engineering and Aviation Sciences), Ted Miles (NASA), Dr. Abhijit Nagchaudhuri (Engineering and Aviation Sciences). Photo by Geoff Bland (NASA).
Figure 2: The electric powered TwinCam includes two downward (nadir) viewing video cameras; one providing imagery in the visible spectrum, and one tailored for imaging in the near-infrared portion of the spectrum. The pair of images was obtained over an experimental wheat field, and clearly shows the varied distribution of nitrogen fertilizer. A Normalized Difference Vegetative Index (NDVI) can be computed and mapped as a qualitative assessment of crops. The TwinCam is typically flown at altitudes below 400 feet which results in provides high spatial resolution observations.
Significance: UAS technology is evolving rapidly and new systems such as TwinCam offer high resolution and low cost for detailed studies. The partnership with UMES is addressing the need for trained teams capable of deploying these systems globally for scientific research, environmental monitoring, and agricultural applications. A multidisciplinary approach engages students and faculty from several areas including Aviation, Agriculture, Environmental and Marine Sciences, Engineering, Technology, and Geographic Information Systems (GIS).
Relevance for future science and relationship to Decadal Survey: There is significant interest in using UASs for a variety of research and observational needs within NASA and other agencies such as USDA and NOAA. The (ASTI) AeroTech project is providing a foundation for future use of these systems by identifying and formulating specific elements required to effectively capitalize on emerging UAS technologies, and incorporating relevant training into a formal aviation curriculum.
