WEEK SIX: 29 February-4 March 2016

ITEMS OF INTEREST

• A change in meteorological seasons -- Monday, 29 February 2016, marks the end of meteorological winter in the Northern Hemisphere, which by convention, is the three-month interval of December, January and February. The following day (1 March 2016) represents the beginning of boreal meteorological spring, the three month interval of March, April and May. At the same time, summer in the Southern Hemisphere ends and autumn begins.
• Leap years and calendars -- This year (2016) is a leap year with 366 days, one more than the "normal" year with 365 days. Since the Earth completes one orbit around the Sun in 365.2422 days, calendars based upon integer days must be adjusted every few years so that recognizable events, such as the occurrence of the vernal equinox, do not progress through the year. In the first century BC the Julian calendar was developed by Julius Caesar who decreed a calendrical reform with a 365-day year that involved the inclusion of an extra day to the end of February (the last month of the old Roman year). However, an additional reform was instituted by Pope Gregory XIII in 1572 that included the requirement that only those centurial years divisible evenly by 400 would be leap years, while the other centurial years (e.g., 1800 and 1900) would not.
  The National Centers for Environmental Information (formerly National Climatic Data Center) recommends that the climate normals for 28 February be used also for 29 February in a leap year.
• Worldwide GLOBE at Night 2016 Campaign resumes -- The third in a series of GLOBE at Night citizen-science campaigns for 2016 will commence on Tuesday (1 March) and continue through 10 March. GLOBE at Night is a worldwide, hands-on science and education program designed to encourage citizen-scientists worldwide to record the brightness of their night sky by matching the appearance of a constellation (Orion in the Northern Hemisphere and Crux in the Southern Hemisphere) with the seven magnitude/star charts of progressively fainter stars. Activity guides are also available. The GLOBE at night program is intended to raise public awareness of the impact of light pollution. The next series in the 2016 campaign is scheduled for 30 March-8 April 2016. [GLOBE at Night]
• High-quality maps of March temperature and precipitation normals across US available -- The PRISM Climate Group at Oregon State University's website has prepared high-resolution maps depicting the normal maximum, minimum and precipitation totals for March and other months across the 48 coterminous United States for the current 1981-2010 climate normals interval. These maps, with a 800-meter resolution, were produced using the PRISM (Parameter-elevation Regressions on Independent Slopes Model) climate mapping system.
• March weather calendar for a city near you -- The Midwestern Regional Climate Center maintains an interactive website that permits the public to produce a ready to print weather calendar for any given month of the year, such as March, at any of approximately 270 weather stations around the nation. (These stations are NOAA's ThreadEx stations.) The entries for each day of the month includes: Normal maximum temperature, normal minimum temperature, normal daily heating and cooling degree days, normal daily precipitation, record maximum temperature, record minimum temperature, and record daily precipitation; the current normals for 1981-2010.
• Viewing atmospheric circulation in three-dimensions -- Read this week's Supplemental Information.. In Greater Depth for information concerning the average circulation in the lower and upper troposphere.
• A Reminder -- Next week (beginning Monday, 7 March 2016) is Spring vacation week for DataStreme Earth Climate System. All the familiar DataStreme ECS products will be available throughout the week. The Investigation and Supplemental Information files from this week will remain on the DataStreme Atmosphere ECS RealTime Climate Portal and the Concept of the Week will be repeated for those who are on spring break. If you have questions, check with your mentor.

CURRENT CLIMATE MONITORING

• Assessing the current El Niño event -- With some areas of the nation, notably California, not receiving the precipitation anticipated during a typical El Niño winter, questions have been raised about the current status of this much heralded event and how it compares with the famous 1997-1998 El Niño One of the staff at NOAA's Climate Prediction Center posted a blog that attempts to answer these questions and provide some insight into how one should interpret the CPC outlook. [NOAA News]
  NASA's Scientific Visualization Studio has produced an animated visualization using computer models that shows the current El Niño develop across the Pacific Ocean in 2015, with sea surface temperatures creating different patterns than those seen in the 1997-1998 El Niño. [NOAA News]
• Historic 100-hour snowstorm of February 1969 ranked number one in Regional Snowfall Index -- Scientists at NOAA's National Centers for Environmental Information (NCEI) and Rutgers University have developed the Regional Snowfall Index (RSI) that is designed as an objective way to rank snowstorms within different regions of the nation country based on snowfall thresholds and population information from within that region. Using these metrics, the RSI takes into consideration that different parts of the country have different expectations of what is considered heavy snow. A recent RSI ranking shows that the 100-hour snowstorm of 22-28 February 1969 across the New England has a RSI of 34.03, while the "Storm of the Century" that disabled the Southeast and Middle Atlantic States on 12-15 March 1993 ranks second with an RSI of 22.12. The recent blizzard of 22 January 2016 comes in fourth place with a RSI of 20.14. [NOAA Climate.gov News Features]
• More historic statistics on Tropical Cyclone Winston -- During the previous weekend, Tropical Cyclone Winston, a category 5 tropical cyclone (on the Saffir-Simpson Scale), devastated the island nation of Fiji in the South Pacific. With maximum sustained surface winds reaching 185 mph, Winston was one of the strongest storms ever measured in the Southern Hemisphere and was one of the strongest tropical cyclones to make landfall anywhere on earth since the modern era of global records began in 1970. Damage estimates and final death toll are yet to be determined from this storm. [NOAA Climate.gov News]
• New satellites to have instruments for better low cloud detection -- NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) describes the improvement of the various instruments that have been placed on NOAA's fleet of geosynchronous and polar orbiting satellites to detect low level clouds and fog. Attention is focused upon the Advanced Baseline Imager (ABI) that is to be placed onboard the GOES-R spacecraft, the next generation of GOES (Geostationary Operational Environmental Satellite) satellites and provide three times more information on the separate wavelengths of light reflected from the atmosphere, offer four times the spatial resolution, and cover areas five times faster than the current technology. GOES-R is scheduled to be launched in October 2016. [NOAA NESDIS News Archive]

CLIMATE FORECASTS

• Uniform definition of heat waves could help public health agencies prepare -- A researcher at the University of Missouri's School of Medicine has developed a uniform definition of a heat wave that may help public health agencies across the nation prepare for episodes of extreme heat that could pose health risks such as dehydration, hyperthermia and death during sustained periods of extreme temperatures. Her definition of a heat wave is based upon relative and absolute heat index thresholds for a given region and time. [University of Missouri School of Medicine News]
• Future searing heat waves are foreseen -- Scientists from the National Center for Atmospheric Research (NCAR) and the US Department of Energy's Lawrence Berkeley National Laboratory warn that if human-produced greenhouse gas emissions continue unchecked, sweltering heat waves that currently strike once every 20 years could become yearly events across 60 percent of Earth's land surface by 2075. They based their findings upon output from computer simulations of 20-year extreme heat events run on the NCAR-based Community Earth System Model. In addition, they found that heat waves with a 1-in-20 chance of occurring during a future year will be much more extreme than heat waves with the same probability of occurring today. [NCAR/UCAR AtmosNews]

CLIMATE FORCING

• Elevated ozone levels over western Pacific Ocean fueled by tropical fires -- NASA scientists and their colleagues recently reported that they have determined that the mysterious pockets of high ozone concentrations nearly three times average in the atmosphere at altitudes of approximately 30,000 feet above the western Pacific Ocean near Guam can be traced back to the large fires burning across southeast Asia approximately 2000 miles away and from Africa approximately 8000 miles distant. They based their conclusions from observations taken in the winter of 2014 during the field campaigns called the Convective Transport of Active Species in the Tropics and the Co-ordinated Airborne Studies in the Tropics. In addition to the elevated ozone, they found low water vapor content. [NASA's Earth Science News Team]
• Global sea level rise during 20th century was most rapid in three millennia -- Scientists from research institutions in the United States, the United Kingdom and Germany have found that global sea level rose at a faster rate than in the last 3000 years. These scientists developed a new database of geological sea-level indicators from marshes, coral atolls and archaeological sites from 24 locations around the globe that spanned these past three millennia, along with 66 tide-gauge records from the last 300 years. The study found that global sea level declined by approximately three inches from 1000 to 1400, a period when the planet cooled by about 0.4 Fahrenheit degrees. They also found that if increases in global temperature attributed to human activity would not have occurred during the 20th century, the sea level would have risen at less than half the observed rate or may have even dropped. [Rutgers University News]

CLIMATE AND THE BIOSPHERE

• Low altitude ozone may not necessarily promote natural ecosystem decline -- Environmental scientists at the University of Virginia recently reported that surface ozone does not necessarily inhibit the productivity of natural ecosystems, even though high concentrations of this gas species near the Earth's surface is known to be toxic to many species of vegetation and to humans. They claim that unmanaged forests remain productive as systems because the forests contain multiple tree species, each with a different sensitivity to ozone. This differential sensitivity to ozone allows the more resistant species to compensate for the damages suffered by the more sensitive ones. [University of Virginia News]
• Coral reef growth being slowed by ocean acidification -- An international team of scientists recently reported on their experiment where they manipulated seawater chemistry in a natural coral-reef community in a lagoon on Australia's southern Great Barrier Reef in order to determine the effect that excess carbon dioxide released by human activity is having on coral reefs. By controlling the alkalinity of the seawater, they were able to examine how fast the reef is growing currently and compare this growth with growth rates in less acidic conditions that existed prior to the Industrial Revolution. They found that ocean acidification is already causing reefs to grow more slowly than they did a century ago. [Rice University News]
• Salt marshes should persist despite rising seas -- A professor at the Virginia Institute of Marine Science and colleagues foresee that salt marshes should persist despite rising sea levels. They reanalyzed 179 previously published records of marsh elevation change from sites in North America and Europe. The researchers argued that traditional assessment methods overestimate the vulnerability of salt marshes to sea-level rise because they do not fully account for processes that allow the marshes to grow vertically and migrate landward as water levels increase. [Virginia Institute of Marine Science News]

CLIMATE AND SOCIETY

• Earthweek -- Diary of the Planet [earthweek.com]

Concept of the Week: Tropospheric westerly winds, north and south

The theoretical existence of upper tropospheric jet stream winds were not confirmed until being encountered by World War II bomber pilots when heading west into strong headwinds at altitudes of approximately 30,000 feet (10,000 m). Wind speeds sometimes exceeded 170 mph causing their relatively slow, heavily laden aircraft to almost stand still. Subsequently, westerly jet stream winds were found to encircle the planet in midlatitudes of both hemispheres above regions of strong temperature contrasts.

The explanation for these winds involves atmospheric mass distributions and forces on a rotating planet. Air in tropical latitudes is warmed, rises and then flows poleward, both north and south. On a rotating planet, moving air is deflected by the Coriolis effect, to the right in the Northern Hemisphere (and left in the Southern). The greater the temperature differences between warm lower and cold higher latitudes, the stronger the air motions and the faster the jet streams. The vertical temperature patterns result in the highest wind speeds near the top of the troposphere.

So Northern Hemisphere air headed northward, deflected to the right ends up headed east, a "westerly wind." In the Southern Hemisphere, southward moving air, deflected left will also go east, as a westerly wind. These "rivers" of strong upper-level winds steer surface weather systems as they move generally eastward across midlatitudes. They also provide boosts for jet aircraft headed eastward with them, but need to be avoided for going west! Of course, the full story is complex as land (especially mountains) and water surfaces interact with the heating of the air and eddies form in the turbulent flows, so jet streams wander. And with them go the storms and the weather patterns that form our short-term climate.

Concept of the Week: Questions

(Place your responses on the Chapter Progress Response Form provided in the Study Guide.)

1. The Northern Hemisphere jet stream winds would be directed such that cold air is [(to the left),(to the right),(directly ahead)] of their forward motion.
2. In the Southern Hemisphere, the jet stream winds to be directed generally toward the [(south), (east), (west)].

Historical Events:

• 29 February 1884: San Diego, California saw its wettest February in history with 9.05 inches. February 1884 is currently the third wettest month on record (wettest: 9.26 inches in 12/1921). The year of 1884 ended as the wettest in San Diego history with 25.97 inches (National Weather Service files)
• 29 February 1964...Thompson Pass, AK finished the month with 346.1 inches of snow, a record monthly total for the state of Alaska. (The Weather Channel)
• 1 March 1910...The deadliest avalanche of record in the U.S. thundered down the mountains near Wellington Station, WA sweeping three huge locomotive train engines and some passenger cars off the tracks, over the side and into a canyon, burying them under tons of snow. This train was snowbound on the grade leading to Stevens Pass. The avalanche claimed the lives of more than 100 people. The station house at Wellington was also swept away. (The Weather Channel)
• 1 March 1993...4.5 inches of snow fell at Dodge City, KS on this date to raise its seasonal snowfall total to 58.8 inches. This set a new all-time seasonal snowfall record for the city. The old record was 57.5 inches set back in the winter of 1911-12. (Intellicast)
• 2 March 1927...Raleigh, NC was buried under 17.8 inches of snow in 24 hours, a record for that location. Nashville, NC received 31 inches of snow. The average snow depth in the state of Carolina was fourteen inches. (The Weather Channel)
• 2 March 1947...The one-day record snowfall of 16 inches of snow buried Canada's capital city of Ottawa, Ontario. The storm left 28.7 inches of snow covering the Ottawa region. (The Weather Doctor)
• 2 March 1996...Another East Coast snowstorm deposited 4.6 inches of snow at Central Park in New York City to bring its seasonal snowfall total to 66.3 inches, breaking the old season snowfall record of 63.2 inches set in 1947-48. (Intellicast)
• 3 March 1896...The temperature in downtown San Francisco, CA fell to 33 degrees, which was the lowest ever for the city in March. (Intellicast)
• 3 March 1971...An extremely intense coastal storm blasted the northeastern US on this day and continued into the 4th. The barometric pressure dropped to 960 millibars (28.36 inches) at Worcester, MA for the lowest pressure ever recorded at the location. The same record was set at Concord, NH with a reading of 963 millibars (28.44 inches). Wind gusts 70 to 100 mph lashed eastern New England with major wind damage occurring. Tides ran 4 to 5 feet above normal resulting in extensive coastal damage and beach erosion. (Intellicast)
• 3 March 1994...A major coastal storm was in progress over the mid-Atlantic and the Northeast. The 8.7 inches of snow at Allentown, PA raised its seasonal snowfall to 69.2 inches for its snowiest winter ever. Boston's 8 inches pushed its seasonal snow to 89.5 inches for its snowiest winter as well. (Intellicast)
• 3 March 2003...The day's low temperature of 30 degrees below zero at Marquette, MI was the lowest temperature ever recorded in March in the city. (The Weather Doctor)
• 4-5 March 1899...Tropical Cyclone Mahina (the Bathurst Bay Hurricane) crossed Australia's Great Barrier Reef and generated produced the highest storm surge ever recorded: 13-14.6 m (42.6-47.8 ft) surge in Bathurst Bay. The Australian pearling fleet was destroyed, over 100 shipwrecks reported and 307 people killed, making Mahina the largest death toll of any natural disaster in Australian history. Minimum central pressure barometric pressure fell to an unofficial reading of estimated at 914 millibars (26.90 inches of mercury). (Accord's Weather Calendar) (The Weather Doctor) (National Weather Service files)
• 4 March 1953...Snow was reported on the island of Oahu in Hawaii. (The Weather Channel)
• 5 March 1960...The greatest March snowstorm of record in eastern Massachusetts began to abate. The storm produced record 24-hour snowfall totals of 27.2 inches at Blue Hill Observatory, 17.7 inches at Worcester, and 16.6 inches at Boston. (The Weather Channel)
• 5 March 2000...The Twin Cities of Minneapolis and St. Paul, MN established a new record for the fewest number of days between 70-degree Fahrenheit temperature reading from the last date in the autumn to the first date in the spring, with only 113 days passed. The previous record was 131 days, while the average has been 175 days. (The Weather Doctor)
• 6 March 1900...A chinook wind blowing down the slopes of the Rockies through Havre, MT raised the temperature 31 degrees in just three minutes. (The Weather Channel)
• 6 March 1954...Florida received its greatest modern-day snowfall of record, with 4.0 inches at the Milton Experimental Station. Pensacola, FL equaled their 24-hour record with 2.1 inches of snow. (The Weather Channel)
• 6 March 1962...Forty-two inches of snow fell at Big Meadows, located in the mountains of Virginia, for a state record as part of the Great Atlantic Coast Storm of 1962. (Intellicast)
• 6 March 1971...The temperature at Palteau Rosa, Italy fell to 30.2 degrees below zero Fahrenheit, Italy's lowest temperature on record. (The Weather Doctor)
• 6 March 1977...The highest recorded wind gust in the United Kingdom was 144 mph at the Cairngorm Weather Station in Scotland. (National Weather Service files)
  

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Prepared by Edward J. Hopkins, Ph.D., email hopkins@aos.wisc.edu
© Copyright, 2016, The American Meteorological Society.