temperature – Membrane.com

Coastal Change: Hurricanes and Extreme Storm Hazards

Posted on 2013/05/082013/05/08 by admin

Part of the Human Induced Climate Change Experiment

One of the goals of the USGS Coastal and Marine Geology Program is a national assessment of coastal change hazards. Hurricanes provide a powerful force that generates dangerous waves and currents capable of moving large amounts of sand, destroying buildings and infrastructure, and reshaping our nation’s coastline. Our research focuses on understanding the magnitude and variability of the impacts of hurricanes and extreme storms on the sandy beaches of the United States. The overall objective is to improve the capability to predict coastal change that results from severe storms. Such a capability will support management of coastal infrastructure, resources, and safety.

Hurricane Sandy Example

As Hurricane Sandy moved northward along the U.S. Atlantic coast in October 2012, U.S. Geological Survey scientists worked to determine where and how the storm’s waves and surge might dramatically reshape the beaches and dunes that stand between the storm and coastal developments. Through a complex modeling process that uses coastal elevations, wave forecasts, and potential storm surge, they predicted coastal change hazards, such as shoreline and dune erosion, that might be expected during a Sandy landfall.

Using the latest storm information available, USGS predicted the likelihood of a range of coastal change impacts within the region affected by the storm:

Dune erosion was very likely for the majority of the sandy beaches along the Maryland and Delaware coasts with widespread overwash also very likely in many areas.
Most of the New Jersey coast was very likely to experience extensive beach and dune erosion and many areas were very likely to overwash.
Along the south shore of Long Island, New York, the models predicted extensive beach and dune erosion as well as intermittent overwash.

Hurricane Sandy, the largest Atlantic hurricane on record, made landfall on October 30, 2012, and impacted a long swath of the Mid-Atlantic coastline. Many areas that had been hit by Hurricane Irene in August 2011 were again battered by strong waves and surge. The barrier islands were breached in a number of places and erosion of the beach and dunes occurred all along the Mid-Atlantic coast. This was the most destructive storm to impact this coastline since an extremely powerful nor’easter in December of 1992.

Following landfall, oblique aerial photography and lidar surveys of beach elevations were used to document the changes that occurred as a result of the storm. In addition, field measurements of the beaches and dunes were collected immediately after the storm. Comparisons of data collected before the storm show the nature, magnitude and spatial variability of the coastal response. These data will be used to further refine predictive models for storm-induced erosion.

Response Activities

Pre-landfall

Initial assessment of potential coastal-change impacts (web post, updated 10/29/12)

Post-landfall (approx. 3-14 days)

Oblique aerial photos of impacted coast (web post, 11/08/12)
Pre- and post-storm photo comparisons (web post, updated 11/09/12)
Comparison of pre- and post-storm lidar topography and coastal change (web post, 11/16/12)
Field Observations and Measurements of Coastal Change (web post, 11/19/12)

National Snow And Ice For 2012

Posted on 2013/01/10 by admin

State of the Climate
National Snow & Ice
Annual 2012
National Oceanic and Atmospheric Administration
National Climatic Data Center

The 2011/12 winter season was nearly non-existent for much of the eastern half of the nation. The December 2011-February 2012 three-month period was marked by near-record warmth across the U.S.-Canadian border, the Midwest, Mid-Atlantic, and Northeast, limiting seasonal snowfall across those regions. Many locations had near-record low snowfall totals for the winter season. Early spring brought much of the same, when the contiguous U.S. had its warmest March on record, with a monthly temperature 8.6°F above average. The lack of snowfall and snowpack for the winter and spring across the Rockies, Great Plains, and Midwest was a precursor to the large drought episode that impacted two-thirds of the nation during the summer and autumn of 2012. In contrast to the rest of the nation, the Pacific Northwest was closer to average during winter in terms of temperature and precipitation, with several winter storms bringing heavy snowfall to the high elevations. The early-spring was wetter and cooler than average for the Northwest, contributing to above-average snowfall for many locations in the region.

Contiguous U.S. Winter Snow Cover Extent Anomalies
Data Source: Rutgers Global Snow Lab

According to data from the Rutgers Global Snow Lab, both the winter and spring seasons brought below-average snow cover to the contiguous United States. The satellite-derived snow cover extent for December 2011-February 2012 was approximately 237,000 square miles below the 1981-2010 average — the third smallest winter snow cover footprint in the 46-year satellite record. This was the first winter since 2005-2006 with below-average snow cover for the country. Only the winter seasons of 1991/92 and 1980/81 had smaller snow cover extents. The March-May spring snow cover extent was 151,000 square miles below the 1981-2010 average — the third smallest spring snow cover extent on record. The springs of 1968 and 2000 had smaller seasonal snow cover footprints.

Western U.S. Snowpack
April 1, 2012
Source: USDA

Winter and spring mountain snowpack provide a crucial water source across much of the western United States. The total annual water budget for agriculture and human use in the mountainous West is highly dependant on the amount of snow melt that will occur in spring and is proportional to the amount of snow on the ground. The annual snowpack typically reaches its maximum value at the end of March. According to data from the USDA, on April 1^st, 2012, above-normal snowpack was observed through the Cascades of Oregon and Washington, with near-normal snowpack stretching eastward through the northern Rockies of Idaho, Montana, and northern Wyoming. To the south, below and much-below snowpack was observed for the Sierra Nevada Mountains, the Great Basin, and the Central and Southern Rockies. Snowpack totals less than 50 percent of normal were widespread in California, Nevada, Utah, Colorado, Arizona, and New Mexico. In Alaska, snowpack totals were above normal for the Southern coasts and peninsula, and below-normal across the North Slope.

Select Significant Events

A strong and powerful winter storm moved across the Southern Rockies and High Plains of Colorado, New Mexico, Texas, Oklahoma, and Kansas on December 19^th and 20^th of 2011. Snowfall up to 15 inches was reported across the region, and strong winds in excess of 50 mph created blizzard conditions. Parts of Interstates 25 and 70 were closed, and the storm was blamed for six deaths. Dalhart, Texas, shattered its daily snowfall record, where 7.0 inches fell on the 19th, surpassing the 0.1 inch which fell on the date in 1983. The 8.2 inches that accumulated in Pueblo, Colorado during the two-day event contributed to the city having its snowiest December on record, with 18.6 inches falling throughout the month. This surpassed the previous December record of 18.2 inches, which fell in December 1913.

Satellite Image of December 19-20 Snow Cover

Satellite Image of Pacific Northwest Snowcover
Source: NASA

A large and powerful winter storm, accompanied by a surge of moisture from the tropics often referred to as an atmospheric river or the ‘Pineapple Express’, impacted the western U.S. January 18^th–23^rd. The worst impacts were felt across the Pacific Northwest, where several feet of snow accumulated and strong winds were observed, causing icy roads, downed power lines, and avalanches. A state of emergency was declared for much of Oregon and Washington, where over a quarter-million households lost electricity. Impressive wind, snow, and rain measurements were made during the event Mount Hood, Oregon received over 50 inches of snow, winds approaching 90 mph were measured at Summer Lake, Oregon, and over 15 inches of rain fell at Swiss Home, Oregon. The Mary’s River in Philomath, Oregon crested at its highest flood height on record. Seven inches of snow fell in Seattle, which averages only 8 inches of snow a year. To the south, across the high terrain of California and Nevada, the precipitation was a welcome sight, where very dry conditions had previously dominated during the 2011-2012 winter season. Nevada’s Carson River Basin had snowpack only 8 percent of normal before the storm (compared to 224 percent at the same point in January 2011, one year prior).

A record-breaking snow storm impacted eastern Colorado and parts of Nebraska February 2^nd–4^th. The slow moving storm dropped 15.9 inches of snow in Denver, a new February snow storm record, surpassing the previous record of 14.1 inches set in February 1912. The 22.7 inches that fell in Boulder was also a February record. Snow accumulations greater than three feet were widespread across the region’s highest terrain. Storms of this magnitude are more common in the region during the early spring months of March and April. As the storm moved off to the east it dropped upwards of a foot of snow across much of Nebraska. The 11.1 inches that accumulated in Lincoln, Nebraska was the fourth largest 24-hour snowfall on record for the city.

Satellite Image of CO and NE Snow Cover
Source: NWS

A potent storm system on February 28^th and 29^th brought heavy snowfall and blizzard conditions across the Northern Plains, Great Lakes, and into the Northeast. Snowfall totals exceeding one foot fell in a string of states from South Dakota to Maine. The heaviest snow fell across Minnesota and Wisconsin, where snow totals approached two feet, accompanied by winds gusting to 50 mph, creating blizzard conditions for several hours. The snow from this storm was one of the few snow events this season across many of the regions affected. Much of the Northern Plains, Great Lakes

22 March Pacific Northwest Snowfall
Source: National Snow Analysis

During March, as much of the eastern U.S. was basking in record breaking warmth, an upper-level trough brought cooler-than-average conditions and late-season precipitation to the Pacific Northwest. On March 22^nd, a large Pacific extra-tropical cyclone slammed into the West Coast, dumping upwards of three feet of snow across the high elevations of the Washington and Oregon Cascade Mountains. The 0.5 inch of snow that fell at the Portland, Oregon airport was the largest snowfall accumulation this late in the season. Salem and Eugene, Oregon both set new March snow storm records with 2.5 and 7.5 inches of snow, respectively. This storm was part of a larger and persistent weather pattern which brought much-above-average precipitation and below-average temperatures to the region during March. The 7.89 inches of precipitation that accumulated in Portland was a new monthly record.

24 April Northeast Snow Depth
Source: NOAA NNVL

A late-season storm dropped over a foot of snow from West Virginia to Upstate New York, along the higher elevations of central and northern Appalachian Mountains, on April 23^rd and 24^th. To the east, in the lower elevations, heavy rain fell across the large cities of the Northeast. This type of coastal storm, called a Nor’easter, was only the second of the season to impact the eastern seaboard, with the other being very early in the season in October. The snow storm was also on the heels of the warmest March on record for many locations across the region, where most trees already had begun to leaf. The snow falling on trees with leaves caused additional headaches by bringing down limbs and cutting power to at least 75,000 residents. The storm also resulted in at least 48 daily snowfall records. Although the storm did have some negative impacts, it provided drought-relieving precipitation for many locations in the Northeast.

Sandy remnant-low snowfall totals

The remnant low pressure system from Hurricane Sandy dropped copious amounts of snow across the Southern and Central Appalachians as it moved westward after making landfall near Atlantic City, New Jersey on October 29^th. Over a foot of snow was reported in six states from North Carolina to Pennsylvania, shattering October monthly snowfall records. Widespread, heavy snow of this magnitude during October has never been observed across this region. The largest snow totals occurred along the highest elevations of the Appalachians, with Mount Leconte, Tennessee receiving 33 inches of snow and Terra Alta, West Virginia measuring 36 inches. Very strong winds combined with the snow to create blizzard conditions for up to two days in some locations. The largest impacts of the storm were the massive power outages due to downed trees and power lines and building collapses because of the heavy, wet nature of the snow. Flooding was also a concern as warm temperatures returned quickly after the storm causing rapid melt and runoff.

Citing This Report

NOAA National Climatic Data Center, State of the Climate: National Snow & Ice for Annual 2012

Global Warming And Climate Volatility

Posted on 2013/01/052013/01/05 by admin

As part of the Human Induced Climate Change Experiment, we have been predicting the effects of global warming on climate volatility. Indeed, we have seen a marked severity in volatile weather systems.

2012 went down as the hottest year in recorded history. Though we are only several days into January, the year is already setting records. There has been snow in the deserts of China, record heat and wildfires in Australia… while record cold temperatures have killed hundreds in India.

Global Warming Refuge

Posted on 2012/04/30 by admin

Ocean currents may mitigate warming near handful of equatorial islands

Photo of a coral reef near the island nation of Kiribati.

Coral reefs near the island nation of Kiribati may be somewhat protected from global warming.
Credit and Larger Version

Scientists predict ocean temperatures will rise in the equatorial Pacific by the end of the century, wreaking havoc on coral reef ecosystems.

But a new study shows that climate change could cause ocean currents to operate in a way that mitigates warming near a handful of islands right on the equator.

Those islands include some of the 33 coral atolls that form the nation of Kiribati. This low-lying country is at risk from sea-level rise caused by global warming.

Surprisingly, these Pacific islands within two degrees north and south of the equator may become isolated climate change refuges for corals and fish.

“The finding that there may be refuges in the tropics where local circulation features buffer the trend of rising sea surface temperature has important implications for the survival of coral reef systems,” said David Garrison, program director in the National Science Foundation’s (NSF) Division of Ocean Sciences, which funded the research.

Here’s how it could happen, according to the study by Woods Hole Oceanographic Institution (WHOI) scientists Kristopher Karnauskas and Anne Cohen, published today in the journal Nature Climate Change.

At the equator, trade winds push a surface current from east to west.

About 100 to 200 meters below, a swift countercurrent develops, flowing in the opposite direction.

This, the Equatorial Undercurrent (EUC), is cooler and rich in nutrients. When it hits an island, like a rock in a river, water is deflected upward on an island’s western flank.

This upwelling process brings cooler water and nutrients to the sunlit surface, creating localized areas where tiny marine plants and corals flourish.

On color-enhanced satellite maps showing measurements of global ocean chlorophyll levels, these productive patches of ocean stand out as bright green or red spots–for example, around the Galapagos Islands in the Eastern Pacific.

But as you gaze west, chlorophyll levels fade like a comet tail, giving scientists little reason to look closely at scattered low-lying coral atolls in that direction.

These islands are easy to overlook because they are tiny, remote, and lie at the far left edge of standard global satellite maps that place continents in the center.

Karnauskas, a climate scientist, was working with coral scientist Cohen to explore how climate change would affect central equatorial Pacific reefs.

When he changed the map view on his screen in order to view the entire tropical Pacific at once, he saw that chlorophyll concentrations jumped up again exactly at the Gilbert Islands on the equator.

Satellite maps also showed cooler sea surface temperatures on the west sides of these islands, part of Kiribati.

“I’ve been studying the tropical Pacific Ocean for most of my career, and I had never noticed that,” he said. “It jumped out at me immediately, and I thought, ‘there’s probably a story there.'”

So Karnauskas and Cohen began to investigate how the EUC would affect the equatorial islands’ reef ecosystems, starting with global climate models that simulate effects in a warming world.

Global-scale climate models predict that ocean temperatures will rise nearly 3 degrees Celsius (5.4 degrees Fahrenheit) in the central tropical Pacific.

Warmer waters often cause corals to bleach, a process in which they lose the tiny symbiotic algae that live in them and provide vital nutrition.

Bleaching has been a major cause of coral mortality and loss of coral reef area during the last 30 years.

Even the best global models, with their planet-scale views and lower resolution, cannot predict conditions in areas as small as these small islands, Karnauskas said.

So the scientists combined global models with a fine-scale regional model to focus on much smaller areas around minuscule islands scattered along the equator.

To accommodate the trillions of calculations needed for such small-area resolution, they used the new high-performance computer cluster at WHOI called “Scylla.”

“Global models predict significant temperature increases in the central tropical Pacific over the next few decades, but in truth conditions can be highly variable across and around a coral reef island,” Cohen said.

“To predict what the coral reef will experience in global climate change, we have to use high-resolution models, not global models.”

The model predicts that as air temperatures rise and equatorial trade winds weaken, the Pacific surface current will also weaken by 15 percent by the end of the century.

The then-weaker surface current will impose less friction and drag on the EUC, so this deeper current will strengthen by 14 percent.

“Our model suggests that the amount of upwelling will actually increase by about 50 percent around these islands and reduce the rate of warming waters around them by about 0.7 C (1.25 F) per century,” Karnauskas said.

A handful of coral atolls on the equator, some as small as 4 square kilometers (1.54 square miles) in area, may not seem like much.

But Karnauskas’ and Cohen’s results say that waters on the western sides of the islands will warm more slowly than at islands 2 degrees, or 138 miles, north and south of the equator that are not in the path of the EUC.

That gives the Gilbert Islands a significant advantage over neighboring reef systems.

“While the mitigating effect of a strengthened Equatorial Undercurrent will not spare corals the perhaps-inevitable warming expected for this region, the warming rate will be slower around these equatorial islands,” Karnauskas said.

“This may allow corals and their symbiotic algae a better chance to adapt and survive.”

If the model holds true, even if neighboring reefs are hard-hit, equatorial island coral reefs may survive to produce larvae of corals and other reef species.

Like a seed bank for the future, they might be a source of new corals and other species that could re-colonize damaged reefs.

“The globe is warming, but there are things going on underfoot that will slow that warming for certain parts of certain coral reef islands,” said Cohen.

“These little islands in the middle of the ocean can counteract global trends and have a big effect on their own future,” Karnauskas said, “which I think is a beautiful concept.”

-NSF-

Antarctica Ice Loss

Posted on 2012/04/26 by admin

Warm Ocean Currents Cause Majority of Ice Loss from Antarctica

WASHINGTON, DC (USA) — Warm ocean currents attacking the underside of ice shelves are the dominant cause of recent ice loss from Antarctica, a new study using measurements from NASA’s Ice, Cloud, and land Elevation Satellite (ICESat) revealed.

An international team of scientists used a combination of satellite measurements and models to differentiate between the two known causes of melting ice shelves: warm ocean currents thawing the underbelly of the floating extensions of ice sheets and warm air melting them from above. The finding, published today in the journal Nature, brings scientists a step closer to providing reliable projections of future sea level rise.

The researchers concluded 20 of the 54 ice shelves studied are being melted by warm ocean currents. Most of these are in West Antarctica, where inland glaciers flowing down to the coast and feeding into these thinning ice shelves have accelerated, draining more ice into the sea and contributing to sea-level rise. This ocean-driven thinning is responsible for the most widespread and rapid ice losses in West Antarctica and the majority of Antarctic ice sheet loss during the period studied.

“We can lose an awful lot of ice to the sea without ever having summers warm enough to make the snow on top of the glaciers melt,” said the study’s lead author Hamish Pritchard of the British Antarctic Survey in Cambridge, United Kingdom. “The oceans can do all the work from below.”

To map the changing thickness of almost all the floating ice shelves around Antarctica, the team used a time series of 4.5 million surface height measurements taken by a laser instrument mounted on ICESat from October 2003 to October 2008. They measured how the ice shelf height changed over time and ran computer models to discard changes in ice thickness because of natural snow accumulation and compaction. The researchers also used a tide model that eliminated height changes caused by tides raising and lowering the ice shelves.

“This study demonstrates the power of space-based, laser altimetry for understanding Earth processes,” said Tom Wagner, cryosphere program scientist at NASA Headquarters in Washington.” Coupled with NASA’s portfolio of other ice sheet research using data from our GRACE mission, satellite radars and aircraft, we get a comprehensive view of ice sheet change that improves estimates of sea level rise.”

Previous studies used satellite radar data to measure the evolution of ice shelves and glaciers, but laser measurements are more precise in detecting changes in ice shelf thickness through time. This is especially true in coastal areas. Steeper slopes at the grounding line, where floating ice shelves connect with the landmass, cause problems for lower-resolution radar altimeters.

ICESat was the first satellite specifically designed to use laser altimetry to study the Earth’s polar regions. It operated from 2003 to 2009. Its successor, ICESat-2, is scheduled for launch in 2016.

“This study demonstrates the urgent need for ICESat-2 to get into space,” said Jay Zwally, ICESat project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “We have limited information on the changes in polar regions caused by climate change. Nothing can look at these changes like satellite measurements do.”

The new research also links the observed increase in melting that occurs on the underside of a glacier or ice shelf, called basal melt, and glacier acceleration with changes in wind patterns.

“Studies have shown Antarctic winds have changed because of changes in climate,” Pritchard said. “This has affected the strength and direction of ocean currents. As a result warm water is funnelled beneath the floating ice. These studies and our new results suggest Antarctica’s glaciers are responding rapidly to a changing climate.”

A different picture is seen on the Antarctic Peninsula, the long stretch of land pointing towards South America. The study found thinning of the largest ice shelf on the peninsula can be explained by warm summer winds directly melting the snow on the ice shelf surfaces. The patterns of widespread ocean-driven melting and summer melting on the Antarctic Peninsula can be attributed to changing wind patterns.

The study was carried out by an international team from the British Antarctic Survey, Utrecht University in Utrecht, Netherlands, the University of California in San Diego and the non-profit research institute Earth and Space Research in Corvallis, Ore.

For more information, a visualization and related imagery, visit:

http://www.nasa.gov/topics/earth/features/currents-ice-loss.html

For more information about ICESat and ICESat-2, visit:

http://icesat.gsfc.nasa.gov