Katrina was featured in the CIMSS GOES Gallery back in 2005 (Link).
The GOES-12 Sounder has sent its last data, ending more than 12 years of service. The GOES-12 Sounder was turned off at 1100 UTC on 13 August. GOES-12 was launched on July 23, 2001, and GOES-12 transmitted data from 16 August 2001 – 7 January 2002, and then more or less continuously from January 16, 2003 onward, a lengthy record of data collection for a geostationary satellite. GOES-12 initially served as GOES-East, replacing GOES-8. After April, 2010, when GOES-13 began service as GOES-East, GOES-12 was moved to 60 West longitude and supplied data over South America. The end of its fuel supply after a dozen years in orbit requires a decommissioning that is scheduled for Friday 16 August.
The last GOES Sounder images were centered over Bolivia, as shown above. Sounder data can be used to estimate Total Precipitable Water, or Cloud Top Pressure. A toggle between these last two products from GOES-12 is shown below.
The GOES-12 Imager was turned off at approximately 2330 UTC on 15 August 2013; De-orbit maneuvers are scheduled at 0100 and 1300 UTC on 16 August 2013.
The loss of data flowing from GOES-12 will have an impact on the GOES-13 scanning strategy. During routine GOES-13 scanning, there are six South American images every three hours. However, during past GOES-13 Rapid Scan Operations (RSO), only one South American Image was scanned every three hours — the Southern Hemisphere Short Sector (SHSS) that was south of the Equator, west of South America. (An example is here). In the scanning strategy now, a South American Image over the southern Amazon Basin (the South American ‘A’ Sector; here is a second example) will be produced near the top of the hour, and a South American Image over the southern part of the Continent (the South American ‘B’ Sector; here is a second example) will be produced near the bottom of the hour. An RSO call late on 13 August yielded the following two images in an hour.
The Imager was shut off around 2340 UTC on August 15 2013. The loop above shows the final two days of the Full Disk imagery. The final set of Imager imagery — all five channels — is below.
On the morning of July 22, 2003, a strong derecho moved through metropolitan Memphis, TN, with winds exceeding hurricane-force. The most significant impact of this storm was a loss of power caused in part by the many trees that were downed by the winds. The Storm Report for the day from the Storm Prediction Center shows a cluster of wind reports in and around Memphis and Shelby County. The National Weather Service office in Memphis produced a report on this event that includes radar imagery and a discussion of surface and upper-air observations. More information on this derecho is here. What do satellite data show for this event?
The animation of 10.7 Âµm imagery, above, shows the development of convection in southeast Kansas and northwest Arkansas that then moves eastward into the mid-South, hitting Memphis around 1200 UTC. Several overshooting tops are evident as the storms pass near Memphis, with the coldest brightness temperatures at 196K! Past derechosdiscussed on this blog (such as the one that hit the East Coast in 2012) were characterized by a channel of moisture and instability aligned with the storm motion, allowing the propagating thunderstorm complex access to a rich source of moisture and instability. This event in 2003 was no different. GOES-12 Sounder retrievals — during that year, 3×3 fields-of-view were used (versus single pixels now) — of Total Precipitable Water, Convective Available Potential Energy (CAPE) and Lifted Index (LI), show abundant moisture and instability aligned west-to-east across northern Arkansas. CAPE values exceeded 3000 J/kg, Total Precipitable Water was greater than 2 inches, and Lifted Indices were near -10.
Visible imagery, above, from GOES-12 shows the convection continuing to develop as it moves across the Mississippi River into Memphis. Several Overshooting tops are evident, as well as parallel cloud lines at the cirrus level that are usually associated with turbulence. GOES-10, as GOES-West, was also able to capture the convection as it moved through Memphis (below).
Tropical Storm Dorian has formed in the far eastern Tropical Atlantic, just west of the Cape Verde Islands. The visible imagery above, from GOES-13 (left) and GOES-12 (right) shows the evolution of the storm in the morning on July 25th. The position change in six hours between 0845 UTC and 1445 UTC suggests a steady west-northwest movement. GOES-12 (scheduled to be decommissioned on 16 August) sits above 60 W vs. 75 W for GOES-13. Accordingly, GOES-12 has a more top-down view of the storm (near 35 W on July 25th) and GOES-13’s view is more oblique. This explains the more circular presentation in the GOES-12 imagery compared to GOES-13. A similar difference in geometry is apparent in the 10.7 Âµm imagery shown below. A slow increase in the storm organization is also obvious in the animation below.
Future development of the storm depends strongly on the environment through which the storm will move. Morphed microwave data (above) suggests that the atmosphere ahead of the storm is dryer, as total precipitable water values are less than 40 mm in the central tropical Atlantic. However, there is robust feed of moisture from the Equator near the South American coast into the storm and ocean surface temperatures are progressively warmer along the projected path of the storm. Sounder data from this site, shown below, suggests that Dorian is moving into a dryer and more stable environment. (In the imagery below, Dorian is the small storm at the far eastern edge of the sounder footprint, near 15 N and 35 W)
Scatterometer winds from ASCAT, above, show tropical storm-force winds north of the storm center. The storm itself is embedded within a rich moisture feed from the ITCZ. Further information and graphics on the storm are available at the CIMSS Tropical Weather Website and the CIMSS GOES-R Tropical Overshooting Tops Website. Refer to the National Hurricane Center website for official forecasts and storm discussions. People along the southeast coast of the United States and in the Caribbean Sea should monitor the progress of this early-season storm.