Marine weather « CIMSS Satellite Blog

Ship condensation trails over the Eastern North Pacfic Ocean

March 31st, 2011

GOES-11 0.65 µm visible channel images (click image to play animation)

McIDAS images of GOES-11 0.65 µm visible channel data (above; click image to play animation) showed a number of well-defined ship condensation trails (or “ship tracks”) propagating southward within the marine boundary layer stratocumulus cloud field over the eastern North Pacific Ocean on 31 March 2011.

A comparison of AWIPS images of 1-km resolution POES AVHRR 0.86 µm visible channel data and the corresponding 1-km resolution POES AVHRR Cloud Particle Effective Radius product (below) revealed that the ship tracks were composed of slightly smaller particles (lighter cyan color enhancement) than the surrounding stratocumulus clouds that they were embedded within. Note that many of the ship tracks could not be seen on the visible image within the more overcast stratocumulus cloud deck that covered the southern portion of the image — but their detection was possible using the Cloud Particle Effective Radius product.

POES AVHRR 0.63 µm visible and Cloud Particle Effective Radius product images

As can be seen below, the ship track features did not show up very well in 1-km resolution images of the POES AVHRR Cloud Type product (showing liquid type clouds, cyan color enhancement), the Cloud Top Temperature product (showing temperatures around +10º C, green color enhancement), or the Cloud Top Height product (showing cloud tops around 2-3 km, purple color enhancement).

POES AVHRR Cloud Type product

POES AVHRR Cloud Top Temperature product

POES AVHRR Cloud Top Height product

CIMSS participation in GOES-R Proving Ground activities includes making a variety of POES AVHRR images and products available for National Weather Service offices to add to their local AWIPS workstations.

Posted in AVHRR, GOES-11, GOES-R, Marine weather, POES | No Comments »

Strong convection in the Gulf of Mexico

March 28th, 2011

GOES-13 10.7 µm IR images (click image to play animation)

AWIPS images of GOES-13 10.7 µm IR data (above; click image to play animation) showed the development of two strong Mesoscale Convective Systems over the Gulf of Mexico on 28 March 2011. These storms prompted the Storm Prediction Center to issue Severe Thunderstorm Watch #70 and #71 for the threat of strong winds and large hail — however, no reports of severe weather were received from these particular storms.

The MODIS Sea Surface Temperature (SST) product from the previous day (below) revealed that the northern edge of the Gulf of Mexico Loop Current (warmer SST values in the upper 70s to around 80º F, red color enhancement) was located near the areas of development of these two Mesoscale Convective Systems — raising the question as to the role that this warmer water may have played in their initiation. In addition, an overlay of the High Resolution Real-Time Global Sea Surface Temperature (RTG_SST_HR) model SST failed to capture the warmer tongue of SSTs located to the east of the main core of the Loop Current. MODIS SST values were 2-3 degrees F warmer than the model SST values in the eastern warm tongue feature — and 3-4 degrees F cooler within the main core of the Loop Current.

MODIS SST product + RGT_SST_HR model SST analysis

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MODIS SST product + MODIS 11.0 µm IR images

A comparison of the MODIS SST product with MODIS 11.0 µm IR images of the first MCS (above) along with a similar comparison of the MODIS SST with a combination of MODIS 11.0 µm IR and POES AVHRR 10.8 µm IR images (below) showed the development of each MCS in the general proximity of the areas of warmer SST values associated with the Loop Current.

MODIS SST + MODIS 11.0 µm IR + POES AVHRR 10.8 µm IR images

A comparison of a 4-km resolution GOES-13 10.7 µm image with the corresponding 1-km resolution POES AVHRR image (below) demonstrated the value of higher spatial resolution for locating the colder cloud top IR brightness temperatures associated with overshooting tops of intense deep convection. The coldest IR temperature on the GOES-13 image was -71º C, compared to -80º C on the POES AVHRR image.

GOES 10.7 µm IR image + POES AVHRR 10.8 µm IR image

CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS and POES AVHRR images and products available for National Weather Service offices to add to their local AWIPS workstations.

Posted in AVHRR, Convective Initiation, GOES-13, GOES-R, Marine weather, MODIS, POES, Severe convection | No Comments »

Gulf of Mexico “Loop Current” affecting cumulus cloud development

February 13th, 2011

GOES-13 0.63 µm visible channel imagery (click image to play animation)

McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed the development of a batch of cumulus clouds over the central Gulf of Mexico during the day on 13 February 2011. Other features of interest on the visible imagery include the rapidly-melting snow cover over the portions of the southern Plains, and a few small smoke plumes drifting northeastward due to fires burning in some of the Gulf Coast states.

A comparison of AWIPS images of the 1-km resolution MODIS 0.65 µm visible channel and the corresponding MODIS Sea Surface Temperature (SST) product (below) indicated that this area of cumulus development was occurring over the warmer waters of the Gulf of Mexico “Loop Current”, where SST values were as warm as 78º F (darker orange color enhancement). As a seasonally cool northeasterly flow of air moved across the warmer Loop Current, enough instability was generated to lead to the formation of shallow cumulus clouds.

MODIS 0.65 µm visible image + MODIS Sea Surface Temperature product

About 3 hours later, a similar comparison of a 1-km resolution POES AVHRR 0.63 µm visible image with the corresponding POES AVHRR Sea Surface Temperature product (below) showed a few more cumulus lines forming over the northern portion of the Loop Current, with the cumulus cloud field becoming more dense in the southern portion.