Title| Summary|Strategy|Impacts/Products|Collaborators/Clients|Task 1|Task 2 |Task 3|Task 4|Task 5|Task 6|Task 7

GEOLOGIC DIVISION CONTINUING PROJECT WORK PLAN - FL 2001

Task: 6
Task Leaders:

Title: Use of remote-sensing satellites to monitor sediment plumes in the Mississippi Bight (USF coop)

Coastal and Marine Geology Programs

New satellite sensors are the best tools available to map riverine influence on the adjacent ocean. The SeaWiFS ocean color sensor (launched in August 1997) has two near-IR bands to aid in the atmospheric correction and six visible bands (20 nm bandwidth) for bio-optical applications. It uses a sophisticated atmospheric-correction algorithm (Gordon and Wang, 1994) to assess the aerosol properties. The MODIS sensor (launched in December 1999) has 10 visible bands and a similar atmospheric-correction scheme. They both provide 2-day coverage of any coastal region barring clouds. Furthermore, MODIS has higher radiometric sensitivity and a few bands with higher spatial resolution (250 and 500 m), making it a better sensor to monitor the coastal areas.

However, the atmospheric correction of the two sensors is based on the assumption that the sensor signal in the near-IR is from the atmosphere only. Thus, in the Mississippi Bight where the near-IR signal is contaminated by suspended sediments, atmospheric correction is no longer valid and incorrect surface signal is obtained. To overcome this difficulty, a "nearest neighbor" method has been proposed to propagate the aerosol information from adjacent clear water to the sediment-dominated water (Hu et al., 2000b). Preliminary results show the success of the procedure, but further effort is needed to make it operational to process large volume satellite data.

Work to be undertaken during the proposal year and a description of the methods and procedures:

In a joint effort with the USGS we propose to study the lower Mississippi sediment-hosted pollutant transport, using SeaWiFS, MODIS, Landsat-7/ETM+, and AVHRR data to provide synoptic monitoring of the sediment distribution and transport in the Mississippi Bight. While SeaWiFS/MODIS data are used to assess suspended sediment, phytoplankton pigment, and Gelbstoff because of their distinctive optical signatures, EMT+ data can provide similar information with fine resolution if used with SeaWiFS/MODIS. Sea surface temperature (SST) can be obtained with AVHRR to understand coastal dynamics, such as coastal upwelling, which will help to assess the sediment-transport process.

A major effort during the first year will be to develop algorithms to estimate the distribution of suspended sediment, phytoplankton pigment, and Gelbstoff using satellite data. This will include implementation of the "nearest neighbor" atmospheric-correction algorithm, and development of valid bio-optical algorithms to distinguish different water constituents for the studied area. Field data will be needed for algorithm development and satellite data validation. We plan to use two field trips each year, during the high and low river runoff seasons, to collect optical data of various water constituents in the lower Mississippi river water.

Real-time SeaWiFS and AVHRR data have been and will be collected by the USF HRPT station. MODIS data will be collected by the newly installed X-band antenna at USF. Landsat-7/ETM+ data will be purchased (a few images per year).

Historical data can be used as well. From the NEGOM program we have collected bio-optical data in the vicinity of the Mississippi delta three times a year since November 1997. These data include surface remote sensing reflectance, water-column optical profiles, pigment absorption, Gelbstoff absorption, surface flow-through data, etc. They will also be used for algorithm development and satellite data validation.

Planned Outreach:

Our goal is to establish a database of imagery of suspended sediment concentration, phytoplankton pigment concentration, Gelbstoff abundance, and SST for the lower Mississippi Bight. These data, used with the bio-chemical data collected by the USGS colleagues, will eventually help to understand the sediment dynamics for the studied area. Part of this effort will also be to provide real-time imagery to the USGS for planning of field experiments.

Publications delivered/completed for this Task:

Publications planned for this task, to be submitted for publication in current or future fiscal years.

• Chuanmin et al. (USF COOP), 2002, Optical properties of large river plumes: Mississippi and Atchafalaya.

Geographic area of task:

United States, Gulf Coastal States

Accomplishments

Current year nonpublication accomplishments and outcomes:
As part of the effort for our contribution, "Use of remote-sensing satellites to monitor sediment plumes in the Mississippi Bight", to Task 6 of the USGS project, "Evaluating Basin/Shelf Effects in the Delivery of Sediment-Hosted Contaminants in the Lower Atchafalaya and Mississippi Rivers", during the March 2001 cruise to the Mississippi Bight (Mississippi and Atchafalaya Rivers) the USF remote sensing group extensively collected water samples at about 40 stations across the salinity transits from 0 to 28 psu. These samples have been analyzed for their optical properties, including particle absorption, chlorophyll concentration, Gelbstoff (or colored dissolved organic matter, CDOM) abundance, and total suspended solids (TSS). Preliminary results show that Gelbstoff absorption coefficient at 400 nm ranged from 0.5 to 4 m-1 while TSS concentration varied from 20 to 300 mg/L. Chlorophyll concentration is generally 2-10 mg/L in the sediment dominant waters. In contrast, the SeaWiFS estimates are several-fold higher, indicating the desire for new remote sensing algorithms for this area. Gelbstoff-salinity relationship is negatively linear following a simple dilution path, confirming our hypothesis of conservative mixing. Remote sensing reflectance was also measured using an ASD spectroradiomter at several stations for algorithm development. The USF group is currently analyzing the field and SeaWiFS data, and is expecting to continue their effort jointly with the USGS colleagues for the fiscal year October 2001 - September 2002.

Highlights - summary of the most significant outcome:
Real-time SeaWIFS imagery of the Mississippi and Atchafalaya River plumes while we were at sea.

New Directions or Major Changes for Proposal Year:
John Brock is formally coming on board this year, to strengthen the USF/USGS coop, as well as to further development of fluvial remote sensing capabilities inhouse.

Title|Summary|Strategy|Impacts/Products|Collaborators/Clients|Task 1|Task 2 |Task 3|Task 4|Task 5|Task 6|Task 7