Retrospective Analysis: Measuring the Historical Magnitude of Turbidity Plumes Using
Archived Remotely Sensed Imagery
J.W. Budd1, W. C. Kerfoot2, R.P. Stumpf3, Katherine Strojny2
1MTU/Geological Engineering & Sciences, 2MTU/Biological Sciences, 3NOAA/NOS
The overall goal is to analyze and interpret all available operational remotely sensed
imagery of southern Lake Michigan using state-of-the art image processing techniques.
- analyze and archive historical Advanced Very High Resolution Radiometer (AVHRR) lake
temperature (LST) and remote sensing reflectance (Rrs) imagery.
- provide the first-ever chlorophyll (CSAT) and Rrs (related to turbidity) estimates
from the Sea-viewing
Wide-Field-of-View Sensor (SeaWiFS) imagery using a revised atmospheric correction
by Stumpf et al.
- create year-long, uninterrupted time-series SeaWiFS imagery using a statistically-based time-space in-terpolation
- create multi-sensor visualizations of physical (AVHRR LST) and particle (SeaWiFS CSAT, Rrs) data.
- validate the satellite-derived water parameters with in situ data from intensive
field surveys at sampling locations.
- support modeling groups' efforts (Schwab et al., Chen et al.) by providing synoptic
satellite water pa-rameters for model experiments.
- All available AVHRR (1989 to present) and SeaWiFS (1997 to present) imagery were processed and
are being analyzed. Geotiff images are posted at
- Multi-sensor visualization techniques were employed in comparative studies of the time, duration and
spatial extent of episodic events using statistically-based interpolation techniques, an edge detection al-gorithm
(Diehl and Budd, in review) and data fusion of simultaneously-acquired remotely sensed data.
- A digital bathymetry model was coupled with SeaWiFS sediment maps (as Rrs) to obtain instantaneous
estimates of total mass of resuspended sediments in southern L. Michigan.
- Comparisons of ship-based chl-a and TSS with satellite-derived parameters provide validation of Sea-WiFS
CSAT and Rrs.
- Historical AVHRR Rrs imagery from 1992 to 1999
reveal that episodic resuspension events occur
throughout the fall, winter and spring months from
from September to the end of April.
- Distinct horizontal temperature gradients from
nearshore to offshore were observed in late March
and April in Lake Michigan. The presense of a ther-mal
bar indicated a transition zone between near-shore
(warmer) from offshore (colder) waters.
- Using SeaWiFS chlorophyll and sediment maps of
southern Lake Michigan in late spring, we identi-fied
two chlorophyll maxima in nearshore and off-shore
waters, which were separated by the thermal
bar. Whereas the nearshore chlorophyll maxima
was strongly coupled to resuspended sediment, the
offshore chlorophyll maxima was not.
- Calculations of daily total mass of sediment during
the spring plume event of 1998 range from 2.8x10 9
kg (Fig. 1).
Fig. 1. Total mass of sediment/day in southern L. Michigan
during spring 1998 based on SeaWiFS interpolated TSS
estimates and 1 km 2 bathymetry contours. Gaps in data
represent periods when clouds precluded interpolation.