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Satellite Imagery of Manitoba's Great Lakes - 2010
The satellite images below were taken by the Moderate Imaging Spectroradiometer (MODIS) on the NASA satellites Terra and Aqua. Image preparation on this site is consistent with previous satellite images prepared by Dr. Greg McCullough. For more background information on the imagery and to view images from 2003, 2004, and 2005, please visit http://home.cc.umanitoba.ca/~gmccullo/LWsat.htm. CLICK HERE TO VIEW IMAGES FROM 2009.
Water bodies, such as Lake Winnipeg, contain particles (silt and clay), dissolved substances and living organisms (algae). These constituents, as well as the water itself, absorb and scatter light. This affects both the transparency (how clear the water is) and colour of the water. In these images, clear water (with few particles) will appear dark since most of the light is absorbed and a small amount of light (of the visible colour) is reflected. For example, very dark brown water is due to high concentrations of dissolved organic carbon, much like a cup of strong, black tea. Increasing inorganic particle concentration will cause a range of colours from blue to green to tan. The south basin of Lake Winnipeg often appears tan in colour due to high turbidity caused by particles carried in from the Red River, as well as high winds which stir up the sediment from the bottom of the lake. Highly turbid water due to an algal bloom will appear bright green in colour due to the algal cells at the surface of the lake. The edges of a bloom will appear crisp in the image when the bloom is at the surface of the lake, and less defined when it is below the surface of the lake.
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CLICK ON THE IMAGE BELOW FOR A HIGHER RESOLUTION VERSION (GENERALLY <1 MB IN SIZE)
APRIL 5, 2010 |
APRIL 7, 2010 |
APRIL 12, 2010 |
The spring breakup is well underway. April 5th and onwards shows a notable crack in the ice from Elk Island north to Hecla Island. Dr. Greg McCullough remarked that the width of this crack probably corresponds to the ice mountains that formed on the western shore, since the ice had to have gone somewhere. There is open water at the mouth of the Winnipeg River and in the Hecla, Black and Deer islands area.
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APRIL 14, 2010 |
APRIL 19, 2010 |
APRIL 26, 2010 |
By April 14th (below left), the snow in the north basin has melted revealing some very striking ice. In the south basin, the plume from the Red River is very visible, contrasting with the clearer east shore waters. It is a very early melt this year compared to last year - see below for May 4th, 2009. |
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| LAST YEAR - MAY 4, 2009 |
MAY 9, 2010 |
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The ice was fully off the lake by May 9th -- a very striking image, worth enlarging to get a better look at how the lake is beginning to mix. The influence of the Red River, with its highly turbid waters, is evident and contrasts nicely with the rest of the basin. Fisher Bay northward is also very turbid.
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JUNE 13, 2010 |
JUNE 15, 2010 |
JUNE 20, 2010 |
There seemed to be a fair amount of cloud in June -- only four images. Apart from the plumes of coloured water (due to high levels o dissolved organic carbon) from the east shore rivers, the south basin and channel appear very turbid. The north basin is relatively clear with the exception of the nearshore areas.
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JUNE 28, 2010 |
JULY 8, 2010 |
JULY 12, 2010 |
July 12 -- first signs of algae appear in the north basin, north of Long Point. There also appears to be some algae north of Berens Island where the water is less turbid. Last year, we saw the first small wisp of algae on July 25th, near Limestone Bay in the north basin. July 20 (below) shows a growing algal bloom in the north basin.
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JULY 20, 2010 |
JULY 23, 2010 |
JULY 24, 2010 |
The north basin bloom continues to develop. There is also a hint of a bloom starting to form in the south basin off Grand Beach (see below for a close-up).
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| JULY 24, 2010 -- S Basin & Channel |
JULY 26, 2010 -- South Basin |
JULY 26, 2010 -- Channel |
Clouds obscured much of the north basin on July 26th, so I cropped the images for more detail in the south basin and channel. The south basin bloom is still faintly visible off the eastern shore between Grand Beach and Victoria Beach. There are also small pockets of algae forming in the channel area. |
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| July 30, 2010 |
July 30, 2010 |
August 1, 2010 |
The July 30 images were taken with different satellites and, therefore, at different times. The north basin bloom is again somewhat obscured by clouds. There is algal growth in the channel area as well. The south basin bloom is clearly visible in the second image; the eastern beaches and Elk Island will not be desirable destinations this long weekend. Of concern to me is the overall appearance of the south basin and channel - the water appears to be less turbid (murky) than usual, likely influenced by the coloured, but still clear, waters of the eastern rivers and settling of particles otherwise suspended in the water column. Algae need nutrients (food) and light to grow -- since there are plenty of nutrients in Lake Winnipeg, the limiting factor in the south basin is usually light. As the water becomes more clear (fewer particles), light can penetrate deeper into the water -- a period of warm, calm weather is then all that is needed to provide the final ingredients for the development of surface algal blooms. The August 1 image does show a considerable bloom in the north, largely off Long Point in the centre and east portion of the basin, down to Berens Island roughly. |
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| August 2, 2010 |
August 2, 2010 |
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| August 6, 2010 |
August 6, 2010 - about 2 hrs later |
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The images from August 6 were taken about two hours apart -- interesting how the lake can change in such a short period. The north basin bloom appears to be primarily in the southern half of the basin, around Reindeer Island and Berens Island and northward along the eastern shore. The south basin bloom remains on the eastern shore south of the Winnipeg River, although you can see a small area developing near the mouth of the river. Unfortunately, the south basin still appears relatively clear compared to how it often looks. Algal taxonomist, Hedy Kling, analyzed last week's bloom sample (from LWRC station 60C) and found that it contained numerous species of cyanophytes, also known as "blue-green algae", including Microcystis cf flos aquae, Anabaena flos aquae, Anabaena lemmermanni and Aphanizomenon flos aquae complex. Provincial water quality modelling specialist, Elaine Page, found levels of microcystin-LR (an algal toxin) at the same site to be 3.16 µg/L. This exceeds the Provincial water quality guideline of 1.5 µg/L for microcystin-LR in drinking water, but is below the proposed guideline of 20 µg/L for recreational activities such as swimming and boating.
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| August 9, 2010 |
August 11, 2010 |
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The south basin bloom persists but has moved offshore somewhat, and the areas of surface algal growth in the channel appear to be increasing in size. The flow of the eastern rivers remains high and continues to influence the clarity of the lake water, especially apparent on August 11th. Rain is forecast in the next few days -- it will be interesting to see how the lake responds, providing us with a visual reminder of how the land and water are integrally linked.
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| August 25, 2010 |
August 25, 2010 |
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There have been few good images in the last two weeks, with the exception of August 25th. Again, two images taken on the same day but from two different satellites a few hours apart. The north basin is a heterogeneous mix of clear water in the far north, varying degrees of turbid water interspersed with areas of algae in the central area,and coloured eastern river plumes. You can also see the clay-rich band along the northern shore from Limestone Point to Playgreen Lake (via both 2-Mile and the main outflow) and down along the north-eastern shore to the Mukutawa River. The south basin appears more turbid than a few weeks ago due to the high winds we have experienced lately, and a small bloom is developing near the mouth of the Red River.
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