January 17th, 2010 Category: Image of the day

Persian Gulf - January 6th, 2010

The Persian Gulf, in the Southwest Asian region, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula. The Gulf has many good fishing grounds, extensive coral reefs, and abundant pearl oysters, but its ecology has come under pressure from industrialization, and in particular, petroleum spillages during the recent wars in the region.

This inland sea of some 251,000 km² is connected to the Gulf of Oman in the east by the Strait of Hormuz; and its western end is marked by the major river delta of the Shatt al-Arab, which carries the waters of the Euphrates and the Tigris.  Here, sediments can be seen pouring into the Gulf from that delta.

The length of the Persian Gulf is 989 kilometres, with Iran covering most of the northern coast and Saudi Arabia most of the southern coast. The Persian Gulf is about 56 kilometres wide at its narrowest, in the Strait of Hormuz. The waters are overall very shallow, with a maximum depth of 90 metres and an average depth of 50 metres.

Countries with a coastline on the Persian Gulf are (clockwise, from the north): Iran, Oman (exclave of Musandam), United Arab Emirates, Saudi Arabia, Qatar on a peninsula off the Saudi coast, Bahrain on an island, Kuwait and Iraq in the northwest. Various small islands lie within the Persian Gulf, some of which are subject to territorial disputes by the states of the region.

Tags: Arabian peninsula Asia Bahrain Gulf of Oman Indian Ocean Iran Iraq Kuwait Middle East Musandam Oman Persian Gulf Qatar Saudi Arabia Sediments Shatt al-Arab Strait of Hormuz United Arab Emirates |  Print This Post |  Email This Post | | Leave a comment

January 11th, 2010 Category: Tropical Storms

Tropical Cyclone Edzani (07S) - January 8th, 2010

Track of TC 07S

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Tropical Cyclone Edzani (07S), located approximately 900 nautical miles east-southeast of La Reunion, has tracked south-southeastward at 13 knots over the past six hours. Maximum significant wave height is 24 feet.

Animated infrared satellite imagery shows the convection has been slowly decreasing over the low level circulation center (LLCC) over the past 12 hours. An upper level mid-latitude trough is currently impinging the outflow along the western half of the system, and has caused convection on the northwestern quadrant to dissipate.

Sea surface temperatures (SST) continue to drop as TC 07S tracks more southward. The track has shifted over the last 6 hours to the south-southeast as the subtropical ridge (STR) to the east has weakened due to the eastward passage of a mid-latitude trough to the South. In the next 24 hours the track is expected to shift back to the Southwest as the STR re-develops to the South of Edzani.

This will persist through TAU 48 when another transitory mid-latitude trough is expected to track to the South of 07S and capture the weakening LLCC. Further interaction with the mid-latitude trough, decreasing SST values of the system, and stifled upper level support will lead to extratropical transition (ET) between TAU 48 and 72, with the completion of the ET process by TAU 96.

Tags: 07S Edzani Indian Ocean La Reunion Tropical Cyclone |  Print This Post |  Email This Post | | Leave a comment

January 9th, 2010 Category: Snapshots

Sri Lanka - December 16th, 2009

The island of Sri Lanka is separated from the Indian subcontinent by two bodies of water: the Gulf of Mannar (below the islands near the bottom edge) and the Palk Strait (occupying the central part of the image). While most of the land in the image belongs to coastal Sri Lanka, India’s Rameswaram island can be seen at the bottom left. Upon opening the full image, the low headland of Point Calimere on India’s Coromandel Coast can also be seen in the upper left corner.

The Gulf of Mannar, best observed upon opening the full image, is a large shallow bay that is an arm of the Laccadive Sea in the Indian Ocean. It lies between the southeastern tip of India and the west coast of Sri Lanka with widths between 160 and 200 km (100 to 125 mi). A chain of low islands and reefs known as Adam’s Bridge, also called Ramsethu, separates the Gulf of Mannar from the Palk Strait, which lies to the north between India and Sri Lanka.

Tags: Adam's Bridge ASAR Coromandel Coast Gulf of Mannar India Indian Ocean Laccadive Sea Orthorectification Palk Strait Point Calimere Rameswaram Island Ramsethu Sri Lanka |  Print This Post |  Email This Post | | Leave a comment

January 8th, 2010 Category: Tropical Storms

Tropical Cyclone Edzani (07S) - January 7th, 2010

Track of TC 07S

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Tropical Cyclone Edzani (07S), located approximately 580 nautical miles southeast of Diego Garcia, has tracked west-southwestward at 7 knots over the past six hours. Maximum significant wave height is 30 feet. The current intensity estimate of 125 knots is consistent with Dvorak T-numbers of 6.5 from PGTW and 6.0 from FMEE.

TC 07S has continued to intensify over the past twelve hours under the influences of high ocean heat content, low vertical wind shear, and excellent upper level outflow. A 15 nautical mile diameter eye is evident in infrared imagery as well as recent microwave passes.

The cyclone is tracking west-southwestward in the peripheral flow around a deep subtropical ridge situated to the south and east. Generally west-southwestward motion is expected to continue through the forecast period, with a poleward stairstep occurring sometime around TAU 72 as a mid-latitude trough approaching from the southeast weakens the steering ridge slightly.

Edzani is expected to approximately maintain intensity over the next 24 hours as it passes over high ocean heat content and strong upper level outflow continues. After TAU 24, a slow but steady weakening trend should commence in response to decreasing along track sea surface temperatures.

Most of the available numerical model guidance is in good agreement with the current forecast, which lies close to the model consensus. However, the UKMET model solution, which is depicting a weaker system than anticipated in the current forecast, is tracking the cyclone with the low to mid-level flow as the sole westward outlier.

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January 4th, 2010 Category: Snapshots

South Africa - November 17th, 2009

The Western Cape Province, in southwestern South Africa, is bordered on the south by the Indian Ocean, and on the west by the Atlantic Ocean. Its total land area is 129,370 km², about 10.6% of the country’s total. The province’s capital is Cape Town and other major cities include Stellenbosch, Worcester, Paarl, and George.

The Western Cape is exceptionally topographically diverse. Most of the province falls within the Cape Fold Belt, a range of sandstone folded mountains of Permian to Carboniferous age that range in height from 1000m to 2300m. The valleys between ranges are generally very fertile and contains alluvial loamy to clay soils.

The far interior forms part of the Karoo Basin and is generally arid and hilly with a sharp escarpment in the north. Coastal areas range from sandy between capes, to rocky to steep and mountainous in places. The Western Cape is also the southernmost region of the African continent with Cape Agulhas as its southernmost point, at 3800km from the Antarctic coastline.

Tags: Africa Atlantic Ocean Cape Agulhas Cape Fold Belt Cape Town George Indian Ocean Karoo Basin Paarl South Africa Stellenbosch Western Cape Province Worcester |  Print This Post |  Email This Post | | Leave a comment

December 15th, 2009 Category: Lakes, Rivers

South Africa - November 30th, 2009

This orthorectified image shows the three different geographic areas of the South African province of KwaZulu-Natal. The lowland region along the Indian Ocean coast is extremely narrow in the south, widening in the northern part of the province. The central region is the Natal Midlands and is an undulating hilly plateau rising towards the west. There are also two mountainous areas, the Drakensberg Mountains in the west and the Lebombo Mountains in the north.

The Drakensberg is a solid wall of basalt rising over 3,000 m (9,800 ft) skyward near the Lesotho border, whilst the Lebombo Mountains are ancient granite mountains forming low parallel ranges running southward from Swaziland. The Tugela River flows west to east across the center of the province and is the region’s largest river.

Visible near the right edge is the reservoir created by the Inanda Dam on the Umgeni River, in the Valley of a Thousand Hills below Hillcrest. The Umgeni River, occasionally called the Mgeni River, rises in the KwaZulu-Natal midlands and meets the sea at Durban. The river is approximately 232 km long with a catchment area of 4,432 km².

Tags: Africa ASAR Drakensberg Mountains Durban Hillcrest Inanda Dam Inanda Reservoir Indian Ocean KwaZulu-Natal Lebombo Mountains Lesotho Mgeni River Natal Midlands Orthorectification South Africa Swaziland Tugela River Umgeni River Valley of a Thousand Hills |  Print This Post |  Email This Post | | Leave a comment

December 15th, 2009 Category: Tropical Storms

Tropical Cyclone Ward (05B) - December 13th, 2009

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Tropical Cyclone Ward (05B), located approximately 140 nm northeast of Colombo, Sri Lanka, has tracked west-southwestward at 3 knots over the past six hours. The current intensity is based on Dvorak estimates of 30 knots. Maximum significant wave height is 10 feet.

Animated multispectral satellite imagery indicates that the low level circulation center (LLCC) has become increasingly disorganized with bursts of deep convection east of the center. A TRMM 37V Ghz image shows that the LLCC is located along the east coast of Sri Lanka with weakly curved banding.

After wandering some time to the east of Sri Lanka, the system made landfall near Trincomalee on December 14th. TC 05B is currently drifting west-southwestward and is expected to continue tracking across the east coast of Sri Lanka, and dissipate within the next 12 hours.

Tags: 05B Colombo India Indian Ocean Sri Lanka Trincomalee Tropical Cyclone Ward |  Print This Post |  Email This Post | | Leave a comment

December 11th, 2009 Category: Tropical Storms

Tropical Cyclone Cleo (03S) - December 9th, 2009

Track of TC 03S

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On December 6th, a tropical disturbance formed in the central Indian Ocean. The storm was expected to strengthen slowly, however, the next day, the disturbance strengthened into a severe tropical storm and was designated Tropical Cyclone 03S. On December 8th, it strengthened rapidly to become the first Intense Tropical Cyclone of the southwest Indian Ocean cyclone season.

TC 03S sustained this strength for a day, as can be observed in this image from December 9th. The following day, it slowly weakened to a category 2 cyclone and continued to weaken throughout the day to a tropical storm.

Currently, Tropical Cyclone Cleo (03S), located approximately 480 nm southwest of Diego Garcia, has tracked west-northwestward at 9 knots over the past six hours. The low level circulation center remains fully exposed, and the remaining deep convection is nearly depleted.

Convection is not expected to rebuild over the center due to the continued effects of vertical wind shear and dry air. Intensity fixes concur that the system is 35 knots or less. Maximum significant wave height is 14 feet.

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November 22nd, 2009 Category: Image of the day

Sri Lanka - November 12th, 2009

The island of Sri Lanka lies in the Indian Ocean, to the southwest of the Bay of Bengal and to the southeast of the Arabian Sea. It is separated from the Indian subcontinent by the Gulf of Mannar and the Palk Strait.

The island consists mostly of flat-to-rolling coastal plains, with mountains rising only in the south-central part. This mountainous area of the country is depicted here in this orthorectified image. Amongst these is the highest point Pidurutalagala, reaching 2,524 metres (8,280 ft) above sea level.

Tags: Bay of Bengal Indian Ocean Pidurutalagala Sri Lanka |  Print This Post |  Email This Post | | Leave a comment