NASA TRMM: Tropical Storm losing its strength

When TRMM passed over Tropical Storm Karina on August 19, there was an isolated area of heavy rain (red) in the western quadrant where rain was falling at a rate of 2 inches/40 mm per hour. 

Credit: NASA /SSAI, Hal Pierce

Tropical Storm Karina continues to weaken in the Eastern Pacific over open waters, and NASA data shows there's not much punch left in the storm.

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite can measure the rate of rainfall from its orbit in space and when it passed over Tropical Storm Karina in the Eastern Pacific it saw an isolated area of heavy rain remaining in the storm.

Tropical Storm Karina weakened during the overnight hours and by Tuesday, August 19, maximum sustained winds had decreased to near 60 mph (95 kph).

When TRMM passed overhead at 03:04 UTC (11:04 p.m. EDT, Aug. 18) on August 19, TRMM Precipitation Radar showed that there was an isolated area of heavy rain in the western quadrant where rain was falling at a rate of 2 inches/50 mm per hour.

Cloud heights in the area of the heaviest rainfall were just under 10 kilometers indicating that the uplift in the storm is weakening, as clouds reached greater heights earlier in the week.

Forecaster Berg at NOAA's National Hurricane Center (NHC) noted today "Water vapour imagery suggests that the outflow from Tropical Storm Lowell may be helping to produce southeasterly shear over Karina, and the low-level center is now exposed to the east of a small area of deep convection."

At 5 a.m. EDT on August 19, the center of Tropical Storm Karina was located near latitude 15.7 north and longitude 134.0 west, about 1,415 miles (2,275 km) east of Hilo, Hawaii. Karina is moving toward the west-southwest near 7 mph (11 kph) and is forecast to turn westward and slow down soon. The estimated minimum central pressure is 999 millibars.

Two computer models used by the NHC to forecast tropical cyclones: the Florida State Super ensemble and HWRF models, weaken Karina to a tropical depression in about 72 hours.

ESA Cryosat: West Antarctica continues to lose ice

West Antarctica continues to lose ice to the ocean and this loss appears to be accelerating, according to new data from Europe's Cryosat spacecraft.

The dedicated polar mission finds the region now to be dumping over 150 cubic km of ice into the sea every year.

It equates to a 15% increase in West Antarctica's contribution to global sea level rise.

Cryosat was launched in 2010 with a radar specifically designed to measure the shape of ice surfaces.

And the instrument's novel design, scientists believe, is enabling the European Space Agency satellite to observe features beyond the capability of previous missions.

The new study, presented here in San Francisco to the American Geophysical Union (AGU) Fall Meeting, confirms the usual suspects to be involved in the increased ice loss.

They are Pine Island, Thwaites and Smith Glaciers.

These major glaciers and their associated tributaries drain the interior of West Antarctica, taking its mass into the Amundsen Sea.

The ice near to their grounding lines - the places where the ice streams lift up off the land and begin to float out over the ocean - is now thinning by between four and eight metres per year.

"Interestingly, Smith Glacier is thinning fastest," said study leader Dr Malcolm McMillan from the UK's Nerc Centre for Polar Observation and Modelling (CPOM).

"It's smaller but its thinning rate is roughly double that of Pine Island or Thwaites, which tend to get all the headlines because they have such huge catchments," he told reporters.

In a recent major review of all satellite data, scientists concluded that ice losses from West Antarctica pushed up global sea levels by some 0.28mm a year between 2005 and 2010.

The new Cryosat data picks up from the end of that period, and suggests the contribution has risen still further.

Professor Andrew Shepherd from the University of Leeds, who led the West Antarctica study, said that part of the increase of ice loss could be due to faster thinning, but that part of it may also be down to CryoSat’s capacity to observe previously unseen terrain.

“Thanks to its novel instrument design and to its near-polar orbit, CryoSat allows us to survey coastal and high-latitude regions of Antarctica that were beyond the capability of previous altimeter missions, and it seems that these regions are crucial for determining the overall imbalance,” he said.