# Presentation: 369422

## Extratropical Cyclone 

**Extratropical Cyclone **
**in the Southern Ocean**
**11 October 2001**

**Notes:**
These images from the Multi-angle Imaging SpectroRadiometer portray an occluded extratropical cyclone situated in the Southern Ocean, about 650 kilometers south of the Eyre Peninsula, South Australia. 
Parts of the Yorke Peninsula and a portion of the Murray-Darling river basin are visible between the clouds near the top of the left-hand image, a true-color view from MISR's nadir (vertical-viewing) camera. Retrieved cloud-tracked wind velocities are indicated by the superimposed arrows. The image on the right displays cloud-top heights. Areas where cloud heights could not be retrieved are shown in black. Both the wind vectors and the cloud heights were derived using data from multiple MISR cameras within automated computer processing algorithms. The stereoscopic algorithms used to generate these results are still being refined, and future versions of these products may show modest changes. 
Extratropical cyclones are the dominant weather system at midlatitudes, and the term is used generically for regional low-pressure systems in the mid- to high-latitudes. In the southern hemisphere, cyclonic rotation is clockwise. These storms obtain their energy from temperature differences between air masses on either side of warm and cold fronts, and their characteristic pattern is of warm and cold fronts radiating out from a migrating low pressure center which forms, deepens, and dissipates as the fronts fold and collapse on each other. The center of this cyclone has started to decay, with the band of cloud to the south most likely representing the main front that was originally connected with the cyclonic circulation. 
These views were acquired on October 11, 2001 during Terra orbit 9650, and represent an area of about 380 kilometers x 1900 kilometers. 

## Birth of a Large Iceberg in Pine Island Bay, Antarctica

**Notes:**
A large tabular iceberg (42 kilometers x 17 kilometers) broke off Pine Island Glacier, West Antarctica (75°S latitude, 102°W longitude) sometime between November 4 and 12, 2001. Images of the glacier were acquired by the Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard NASA's Terra spacecraft. This event was preceded by the formation of a large crack across the glacier in mid 2000. Data gathered by other imaging instruments revealed the crack to be propagating through the shelf ice at a rate averaging 15 meters per day, accompanied by a slight rotation of about one percent per year at the seaward margin of the rift. 
The image set shows three views of Pine Island Glacier acquired by MISR's vertical-viewing (nadir) camera. The first was captured in late 2000, early in the development of the crack. The second and third views were acquired in November 2001, just before and just after the new iceberg broke off. The existence of the crack took the glaciological community by surprise, and the rapid rate at which the crack propagated was also not anticipated. Glaciologists predicted that the rift would reach the other side of the glacier sometime in 2002. However, the iceberg detached much sooner than anticipated, and the last 10-kilometer segment that was still attached to the ice shelf snapped off in a matter of days.
Pine Island Glacier is the largest discharger of ice in Antarctica and the continent's fastest moving glacier. This area of the West Antarctic Ice Sheet is also believed to be the most susceptible to collapse. The evolution of this glacier is therefore of great interest to the scientific community. "The climatic significance of this calving event is not yet clear, but is taking place in an area of Antarctica which is experiencing rapid changes", said glaciologist Eric Rignot of the Jet Propulsion Laboratory. Rignot points out that the grounding line of Pine Island Glacier is retreating, the glacier is thinning rapidly, and its ice flow is accelerating. Additionally, the sea ice cover in front of the glacier has been decreasing steadily for several decades. The newly hatched berg represents nearly seven years of ice outflow from Pine Island Glacier released to the ocean in a single event. Although this has no effect on sea level (the ice is already afloat), it is an exceptional event for this glacier, and provides additional evidence that this area is undergoing rapid change.

## Birth of a Large Iceberg in Pine Island Bay, Antarctica

**September 2000 -**
**November 2001 **

**Notes:**
A large tabular iceberg (42 kilometers x 17 kilometers) broke off Pine Island Glacier, West Antarctica (75°S latitude, 102°W longitude) sometime between November 4 and 12, 2001. Images of the glacier were acquired by the Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard NASA's Terra spacecraft. This event was preceded by the formation of a large crack across the glacier in mid 2000. Data gathered by other imaging instruments revealed the crack to be propagating through the shelf ice at a rate averaging 15 meters per day, accompanied by a slight rotation of about one percent per year at the seaward margin of the rift. 
The animated sequence consists of 11 snapshots acquired by MISR's nadir camera between September 16, 2000 and November 12, 2001. Due to frequent cloud cover, the time interval between successive frames is not uniform. The flow of the glacier, widening of the rift, and subsequent break-off of the iceberg are evident. A "jump" in the position of the rift near the middle of the sequence is due to a gap in image acquisition during Antarctic winter, when the glacier was in continuous darkness.
Pine Island Glacier is the largest discharger of ice in Antarctica and the continent's fastest moving glacier. This area of the West Antarctic Ice Sheet is also believed to be the most susceptible to collapse. The evolution of this glacier is therefore of great interest to the scientific community. "The climatic significance of this calving event is not yet clear, but is taking place in an area of Antarctica which is experiencing rapid changes", said glaciologist Eric Rignot of the Jet Propulsion Laboratory. Rignot points out that the grounding line of Pine Island Glacier is retreating, the glacier is thinning rapidly, and its ice flow is accelerating. Additionally, the sea ice cover in front of the glacier has been decreasing steadily for several decades. The newly hatched berg represents nearly seven years of ice outflow from Pine Island Glacier released to the ocean in a single event. Although this has no effect on sea level (the ice is already afloat), it is an exceptional event for this glacier, and provides additional evidence that this area is undergoing rapid change.

## Wetlands of the Gulf Coast

**15 October 2001**

**Notes:**
This set of images from the Multi-angle Imaging SpectroRadiometer highlights coastal areas of four states along the Gulf of Mexico: Louisiana, Mississippi, Alabama and part of the Florida panhandle. The images were acquired on October 15, 2001 (Terra orbit 9718) and represent an area of 345 kilometers x 315 kilometers.
The two smaller images on the right are (top) a natural color view comprised of red, green, and blue band data from MISR's nadir (vertical-viewing) camera, and (bottom) a false-color view comprised of near-infrared, red, and blue band data from the same camera. The predominantly red color of the false-color image is due to the presence of vegetation, which is bright at near-infrared wavelengths. Cities appear as grey patches, with New Orleans visible at the southern edge of Lake Pontchartrain, along the left-hand side of the images. The Lake Pontchartrain Bridge runs approximately north-south across the middle of the lake. The distinctive shape of the Mississippi River Delta can be seen to the southeast of New Orleans. Other coastal cities are visible east of the Mississippi, including Biloxi, Mobile and Pensacola.
The large image is similar to the true-color nadir view, except that red band data from the 60-degree backward-looking camera has been substituted into the red channel; the blue and green data from the nadir camera have been preserved. In this visualization, green hues appear somewhat subdued, and a number of areas with a reddish color are present, particularly near the mouths of the Mississippi, Pascagoula, Mobile-Tensaw, and Escambia Rivers. Here, the red color is highlighting differences in surface texture. This combination of angular and spectral information differentiates areas with aquatic vegetation associated with poorly drained bottomlands, marshes, and/or estuaries from the surrounding surface vegetation. These wetland regions are not as well differentiated in the conventional nadir views.
Variations in ocean color are apparent in all three views, and represent the outflow of suspended sediment from the seabed shelf to the open waters of the Gulf of Mexico. Major features include the Mississippi Delta, where large amounts of land-derived sediments have been deposited in shallow coastal waters. These deltaic environments form a complex, interconnected web of estuarine channels and extensive coastal wetlands that provide important habitat for fisheries. The city of New Orleans is prone to flooding, with about 45% of the metropolitan core situated at or below sea level. The city is protected by levees, but the wetlands which also function as a buffer from storm surges have been disappearing.

## Ship Tracks in a 

**Stratiform Cloud Layer**
**18 July 2001**