Monitoring and forecasting the UK climate and its meteorological changes with analysis

UK Climate Forecasting and Analysis

in association with Weather Analysis organisation UK

Climate Change   UK Weather   Atlantic Storms   Reports & Analysis   Jet Stream   Flooding   Air Quality

The two images Courtesy of NOAA Star show the satellite image of the US Atlantic Coast and the Lower Level Water Vapour on Monday 23 December at 05.51 hours

Why is lower-level water vapour band imagery important? The 7.3 µm “Lower-level water vapour” band is one of three water vapour bands on the ABI. It typically senses farthest down into the mid-troposphere in cloud-free regions, to around 500-750 hPa. It is used to track lower tropospheric winds, identify jet streaks, monitor severe weather potential, estimate lower-level moisture (for legacy vertical moisture profiles), identify regions where the potential for turbulence exists, highlight volcanic plumes that are rich in sulphur dioxide and track Lake effect snow bands.

Due to the rotation of our planet and the Coriolis effect in the Northern Hemisphere winds are blown to the right across the North Atlantic to Ireland the UK and Scandinavia so we have to look at the weather in North America and the direction of the Polar Front Jet Stream. The Coriolis effect increases in strength the nearer you get to the poles and is responsible for large cyclones or depressions. The weather in the North Atlantic is influenced by the 23.4° tilt in the axis of the Earth as the seasons are caused by variations in the angle of the sunlight hitting the Earth and are one of the major causes of Atlantic storms. We will research these meteorological changes and analyse data which effect the UK.

The Atlantic Ocean is the second-largest of the world's oceans. With a total area of about 41,100,000 sq miles it covers approximately 20% of the Earth's surface and about 26% of its water surface area. The average depth of the Atlantic with its adjacent seas is 3,339 metres or 10,950 ft without them it is 3,926 metres or 12,880 ft. The greatest depth is the Milwaukee Deep at 27,500 ft in the Puerto Rico Trench. The Atlantic's width varies from 1,538 nautical miles between Brazil and Sierra Leone to over 3,450 nautical miles in the south. The principal feature of the bottom topography is a submarine mountain range called the Mid-Atlantic Ridge which is moving at 2.5 cm per year. It extends from Iceland in the north to approximately 58° South latitude reaching a maximum width of about 860 nautical miles. The Mid-Atlantic Ridge separates the Atlantic Ocean into two large troughs with depths from 12,000–18,000 ft. Transverse ridges running between the continents and the Mid-Atlantic Ridge divide the ocean floor into numerous basins. Some of the larger basins are the Blake, Guiana, North American, Cape Verde and Canaries basins in the North Atlantic. A great rift valley also extends along the ridge over most of its length. The depth of water at the apex of the ridge is less than 8,900 ft in most places while the bottom of the ridge is three times as deep. The Atlantic Ocean is a major source of atmospheric moisture through evaporation and traps around 30% of the carbon dioxide emitted into the atmosphere by human activity. The waters circulate in a clockwise direction. The Gulf Stream carries more water than all the world’s rivers combined and has it moves north its salinity increases. The Sargasso Sea has above average salinity.

UK Climate Forecast  38 Union Street  Grantham  Lincolnshire NG31 6NZ   

Oceanic currents are driven

 by three main factors

1. The rise and fall of the tides. Tides create a current in the oceans which are strongest near the shore and in bays and estuaries along the coast. These are called "tidal currents." Tidal currents change in a very regular pattern and can be predicted for future dates. In some locations strong tidal currents can travel at speeds of 8 knots or more.

2. Wind. Winds drive currents that are at or near the ocean's surface. Near coastal areas winds tend to drive currents on a localised scale and can result in phenomena like coastal swells. On a more global scale in the open ocean winds drive currents that circulate water for thousands of miles throughout the oceans.

3. Thermohaline circulation. This is a process driven by density differences in water due to temperature and salinity variations in different parts of the ocean. Currents driven by thermohaline circulation occur at deep and shallow ocean levels and move much slower than tidal or surface currents. Currents affect the Earth's climate by driving warm water from the Equator and cold water from the poles around the Earth.

The Florida current can be considered the "official" beginning of the Gulf Stream System. It is defined as that section of the system which stretches from the Florida Straits up to Cape Hatteras. It is a key component of AMOC with low salinity. The current was discovered by Spanish explorer Juan Ponce de León in 1513.

The Florida Current receives its water from two main sources, the Loop Current and the Antilles Current. The Loop current is the most significant and can be considered the upstream extension of the Gulf Stream.  

The Gulf Stream together with its northern extension the North Atlantic Drift is a warm and swift Atlantic ocean current that originates in the Gulf of Mexico and stretches to the tip of Florida and follows the eastern coastlines of USA up to Newfoundland before crossing the Atlantic Ocean to Ireland UK and Western Europe making the region about 5 C warmer.

The image opposite shows the position of the Florida Current.

 

Discussion on Atlantic Ocean Currents

North Atlantic on Monday 23 December

A cold front extends from a couple hundred miles SE of Bermuda to 26N70W, then it becomes a stationary front and snakes its way to the Treasure Coast of Florida. A few light showers are noted near and north of this boundary, especially west of 70W. Moderate to locally strong NE winds are noted north of the frontal boundary,along with seas of 6-9 ft. The strongest winds are occurring off NE Florida. Farther east, another cold front enters the basin near 31N56W and continues southwestward to 25N63W, becoming a stationary front and continuing to northern Haiti. Scattered showers are evident on satellite imagery within 250 nm east of the boundary. A recent scatterometer satellite pass captured moderate to fresh N-NE winds behind the frontal boundary. Seas in these waters are also 6-9 ft. Moderate to fresh southerly winds and seas of 5-8 ft are present ahead of the front to 48W and north of 28N. The remainder of the tropical Atlantic is under the influence of a robust 1043 mb high pressure system positioned NE of the Azores. The pressure gradient between this ridge and lower pressures in western Africa and the deep tropics support fresh to strong NE-E winds north of 11N and east of 35W. This was confirmed by a scatterometer satellite pass from a couple hours ago. Rough seas are found in these waters, peaking near 12 ft west of the Canary Islands. In the rest of the waters between Africa and the Lesser Antilles (south of 20N), moderate to locally fresh easterly trade winds and moderate seas are prevalent. Elsewhere in the basin, moderate or weaker winds and moderate seas prevail. For the forecast W of 55W, a frontal boundary that currently extends from 31N56W to Hispaniola will drift E of the area by midweek. High pressure building behind the front will lead to increasing winds E of the Bahamas, with strong winds and rough seas likely late Mon into Tue night. A surface trough off the SE United States coast may least to fresh to strong winds offshore NE Florida early this week.

Monsoon Trough: The monsoon trough reaches the Atlantic through the coast of Liberia near 07N11W and continues westward to 04N20W. The ITCZ extends from 04N20W to 03N35W and to NE Brazil near 01N50W. Scattered moderate convection is observed from 03N to 06N and between 15W and 25W.

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