Image Overview

The following pages show a few of the many images the LDCM TIRS has collected since being activated March 7. The two TIRS channels centered at IR wavelengths of about 10.9 and 12 microns measure the power of IR radiation from the Earth’s surface and atmosphere. The black and white TIRS images that follow illustrate this. The darker regions correspond to areas where less power is being emitted. The power level observed in each channel can be related to an equivalent blackbody temperature (the Brightness Temperature) and these are shown in the color images, where blue represents lower temperatures and red represents higher.

Mid-Atlantic Seaboard

This image of the eastern coastal region of the USA illustrates how TIRS images are obtained as a swath 185 km in width whose length (~600 km in this case) is determined by the time interval over which data are obtained (~1.5 minutes here). The black regions are clouds in a region of the cold upper atmosphere where the temperature is < -20º C.

Mid-Atlantic Seaboard 10.9 µm Radiance [W/m²/sr/µm] 10.9 µm Brightness Temperature [C]

(185km width)

Salton Sea Area in Southern CA

These images show both arid and crop growing areas in a region by the Salton Sea, a saline body of water in southern CA. The places where crops are actively growing are much cooler than the surrounding countryside because water is evaporating off the leaves after being drawn up through the plant’s roots (a process called evapotranspiration). The relative cooling can be related to the surface water amount which, in areas such as this, is directly related to the amount of irrigation. This measurement is one of the prime purposes of TIRS. Notice also that the 10.9 and 12 micron brightness temperatures are slightly different. This is primarily caused by the different sensitivities of these two channels to atmospheric effects. The split-window analysis technique utilizes this difference to improve surface temperature estimates. TIRS is the first Landsat thermal sensor to have two channels and thus the LDCM (Landsat-8) will be the first Landsat mission to have this capability.

Salton Sea, CA, USA10.9 µm Radiance [W/m²/sr/µm] 10.9 µm Brightness Temperature [C]

12.0 µm Radiance [W/m²/sr/µm] 12.0 µm Brightness Temperature [C]

(185km width)

Salton Sea, CA, USA – Growing Fields

10.9 µm Brightness Temperature [C] 12.0 µm Brightness Temperature [C]

(~40km width)2 km

Center Pivot Irrigation Fields in Saudi Arabia

These images once again show the effect of irrigation and growing plants on the surface brightness temperature. The center pivot irrigation process is also used extensively in the USA and these data illustrate the global utility of Landsat data.

Center Pivot Irrigation Fields, Saudi Arabia10.9 µm Brightness Temperature [C]

12.0 µm Brightness Temperature [C]

Close-up of growing and non-growing fields

(~60km width)

~0.5 km

Cape Canaveral & Merritt Island, Florida, USA

These images show the ability of TIRS to observe the effects of human activity. Here the warm effluent from an electrical generation plant is clearly seen as an area of increased temperature in the inlet between the mainland and Merritt Island. Several bridges are also evident in these pictures. These bridges are typically on the order of 20 meters wide, or about 20% of the width of a TIRS image pixel, and demonstrate the excellent sensitivity of TIRS.

Cape Canaveral & Merritt Island, Florida, USA10.9 µm Brightness Temperature [C] 12.0 µm Brightness Temperature [C]

Close-up of power plant water discharge

(~60km width)

900 m

Greenland Coastal Region

The next set of images show the transition from the icy shore of Greenland to the near shore ocean and then into the deeper ocean. This being Greenland, some of the temperatures are pretty cold. The brightness temperature maps show swirls of different effective temperature regions in the off-shore ocean. Temperature gradients of ~0.1 K are clearly apparent.

Greenland Coastal Region10.9 µm Radiance [W/m²/sr/µm] 12.0 µm Radiance [W/m²/sr/µm]

(185km width)

Close up of North Atlantic Ocean near Greenland Coast

10.9 µm Brightness Temperature [C] 12.0 µm Brightness Temperature [C]

(~60km width)

Contrail over Canada

This image illustrates the complementary nature of TIRS thermal IR images and the visible/near IR images of OLI. Jet aircraft produce contrails due to the condensation of the combustion products from their engines. In OLI images which depend on the amount of solar radiation reflected from the scene, these typically show up as bright trails because they are regions of enhanced reflection. Contrails typically show up as dark in TIRS images because they are formed high in the atmosphere where the temperature is much lower than that of the land surface, thus lowering the emitted power.

Contrail over Canada 10.9 µm Radiance [W/m²/sr/µm]

(~60km width)

The Reason for TIRS success

This image shows the primary reason the TIRS instrument effort was successful.

IT TAKES A GREAT TEAM

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WITH INDUSTRIAL PARTNERS ACROSS THE NATION