WEEKLY CLIMATE NEWS

DataStreme ECS WEEK TWO: 16-20 September 2013

ITEMS OF INTEREST

The Autumnal Equinox -- The Autumnal Equinox will occur early this coming Sunday afternoon (officially at 2044Z on 22 September 2013 or 4:44 PM EDT or 3:44 PM CDT, etc.). At that time the noontime sun will appear directly above the equator, representing one of the two times during the year for such an occurrence, with the other being at the vernal equinox in March. The term "equinox" arises from the fact that this time of year represents "equal night" and equal day essentially everywhere. Within the subsequent several days, the length of daylight will become noticeably shorter. This decrease in daylight will continue for another three months to the winter solstice during the midday hours of Saturday, 21 December 2013.
Editor's note: John White, a meteorologist from North Carolina involved with the AMS Education program, reported that the geosynchronous (or geostationary) satellites make an "satellite eclipse" of the sun near the spring and autumnal equinoxes because of their equatorial orbit, such that these satellites pass through the earth's shadow and the satellite is powered down when the solar array does not receive sufficient sunlight. [For more information, consult NWS Southern Region GOES Satellite FAQ] EJH.
One for the record books -- If you would like more background information concerning how various temperature and precipitation extremes are identified as record events from a station's climate record, please read this week's Supplemental Information…In Greater Depth.
Online tool displays more than 150 years of hurricane tracks -- NOAA's Coastal Services Center in partnership with NOAA's National Hurricane Center and National Climatic Data Center has developed a free online tool called "Historical Hurricane Tracks" that allows users to generate maps showing the track of any tropical cyclone (tropical storms and hurricanes) from a search of the database using a place name, storm name or year, or latitude and longitude points. Links have been made to detailed reports on the life histories and effects of US tropical cyclones since 1958, with additional US storm paths traced as far back as 1851. Global hurricane data extend as far back as 1842. Data and information on coastal county hurricane strikes are available through 2012. [NOAA National Ocean Service News]
Record rain produces record flooding in Colorado -- During the last week, a persistent flow of humid air into Colorado produced record setting rainfall totals along the Front Range of the Rockies, which resulted in massive flash flooding events for some area streams that flow from the mountains out onto the Plains. Major damage and loss of life were caused by the floods especially near Boulder. The historic nature of this excessive rain and flood event was discussed by a reporter with the National Center for Atmospheric Research (NCAR). [NCAR/UCAR AtmosNews]

CURRENT CLIMATE STATUS

US national weather and climate reviewed for August and Summer 2012 -- Based upon preliminary data, scientists at NOAA's National Climatic Data Center report that August 2013 was the 28th warmest August across the coterminous United States since sufficiently reliable climate records began in 1895, with a nationwide average of 73.1 degrees Fahrenheit. Four states across the Northwest (Washington, Idaho, Montana and Wyoming) reported much above average statewide temperatures, with Idaho experiencing its second warmest August and Wyoming the third warmest August on record. On the other hand, many of the states from the central Plains across the Midwest, Middle Atlantic and Southeast had below normal statewide August temperatures. Furthermore, the recently concluded meteorological summer of 2013 (June, July and August) was the 15th warmest summer across the coterminous United States since sufficiently reliable climate records began in 1895. Most of the states from the Rockies west to the Pacific Coast reported much above normal summer temperatures, with Utah and Idaho having summer statewide temperatures that were in the top three summers on record. In addition, several states across the Northeast had above to much above average summer temperatures. Conversely, eleven states across the Midwest, Mid-South and the Southeast experienced below average summer temperatures.
The nationwide August 2013 average precipitation was close to the 20th century (1901-2000) average with a nationwide average of 2.63 inches, while the nationwide summer precipitation was above average, making it the eighth wettest summer since 1895. Ten states across the Midwest and the western Gulf Coast reported below to much below average statewide average August precipitation. Illinois, Indiana, Iowa and Minnesota had precipitation totals that were among the ten smallest on record. Many of the states across the northern Rockies, the Plains and the Mississippi Valley experienced below average June through August statewide precipitation totals. On the other hand, many of the states to the east of the Mississippi Valley had much above average summer precipitation, with Florida, Georgia, South Carolina and New York reporting their wettest summer on record. [NOAA/NCDC State of the Climate]
August national drought report -- The National Climate Data Center has posted its August 2013 drought report online. Using the Palmer Drought Severity Index, approximately 19 percent of the coterminous United States experienced severe to extreme drought conditions at the end of August, while 18 percent of the area had severely to extremely wet conditions.

CURRENT CLIMATE MONITORING

Satellite data indicates that the "La Nada" climate pattern lingers in the Pacific -- New sea-surface height data collected from over the Pacific Ocean by NASA's Jason-2 satellite indicate that the equatorial Pacific Ocean is currently in its 16th month since spring 2012 of being locked into a neutral, or "La Nada" state that is neither an El Niño nor La Niña event. A climatologist with NASA's Jet Propulsion Laboratory suggests that the in-between neutral "La Nada" events would make long-range climate forecasting more difficult due to their less predictability especially in fall, winter and summer seasons. NOAA's Climate Prediction Center indicates that ENSO neutral (El Niño –Southern Oscillation) conditions could continue in spring 2014, without a strong El Niño or La Niña event. [NASA Jet Propulsion Laboratory]
Model developed to adjust tornado records --Researchers at Florida State University and colleagues have developed a new statistical model deigned to help determine if the risk of tornadoes were increasing and if they were getting stronger. In their model development, the researchers created a method that accounts for population bias in the reporting of tornadoes, thus correcting the historical data to account for the fewer reports in previous decades. [Florida State University 24/7 News]
Hottest days in sections of Europe have warmed four times more than global average -- Researchers at the United Kingdom's London School of Economics and the University of Warwick claim that their analysis of temperature observations across Europe extending back from present to 1950 indicates that some of the hottest days and coldest nights in parts of Europe have warmed more than four times the global average change during this time span. The 5 per cent of the days with the highest temperatures in summer have warmed fastest in a band from southern England and northern France to Denmark, while little warming was detected in daytime summer temperatures in Norway and Sweden. In additions, some locations and temperature thresholds have seen little change since 1950. The authors suggest that the results highlight the scale of the difference between global change and the local climate changes felt by individuals. [University of Warwick News]
An All-Hazards Monitor -- This Web portal provides the user information from NOAA on current environmental events that may pose as hazards such as tropical weather, fire weather, marine weather, severe weather, drought and floods. [ NOAAWatch]

CLIMATE FORCING

Antarctic Ice Sheet melting from below by warm ocean -- An international team of scientists including those from NASA have finally obtained data from instruments they finally deployed on Antarctica's Pine Island Glacier ice shelf intended to measure how fast the seawater underneath the ice sheet was melting the 37-mile long ice tongue. After several unsuccessful tries, they deployed the instruments in December 2012 and since then they have found that the melt rate at one of the sites halfway down the ice shelf was as high as 6 centimeters (or 2.36 inches) per day [NASA's Earth Science News Team]
Ocean acidification in Arctic progresses at an unprecedented rate and scale -- Researchers with the University of South Florida and their colleagues with other academic institutions and federal agencies, such as the US Geological Survey, have found that their investigations of seawater chemistry from samples collected during three years of research cruises in the Arctic Ocean indicate that the waters of this ocean basin are becoming more acidified at a rate faster than projected. This acidification is due to the absorption of increased levels of atmospheric carbon dioxide by the near surface waters. Melting multi-year sea ice is diluting the seawater and leaving the surface water more exposed to the absorption of carbon dioxide from the atmosphere. Their ocean acidification models indicate that with increased atmospheric carbon dioxide, the Arctic Ocean will have crucially low concentrations of dissolved carbonate minerals, such as aragonite, within the next decade. [USGS Newsroom]
Higher global temperatures could change El Niño strength -- Researchers with Australia's Centre of Excellence for Climate System Science who analyzed coral records claim that increased global temperatures have impacted the ENSO (El Niño Southern Oscillation) cycle, thereby affecting the strength and timing of El Niño events over the last 4300 years. (El Niño events are recurring anomalous changes in worldwide atmospheric and oceanic circulation regimes that are characterized by a warming in the waters of the eastern equatorial Pacific Ocean.) Currently, El Niño events have started earlier in the year and are stronger than in the past. [Australian Research Council Centre of Excellence for Climate System Science]

CLIMATE AND SOCIETY

Website for human dimensions of climate change -- An interagency effort within the US federal government that included NOAA, the Bureau of Land Management and the US Forest Service, has resulted in a website called HD.gov (for HumanDimensions.gov) that provides users, such as natural resource managers, with information on the human dimensions on a variety of topics of interest such as climate change. [HD.gov]
Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Concept of the Week: Feedback in Earth's Climate System

In Earth's climate system, feedback consists of a process where a change in one variable interacts with other variables of the system to alter that original variable. If the change reinforces the original quantity, it is known as a positive feedback. If the change suppresses the original quantity, it is a negative feedback. Feedbacks in Earth's climate system are significant--thought to be responsible for more than half the global warming expected from human activities.

Consider examples of positive and negative feedback. A warming trend in climate is likely to accelerate the rate of melting of snow and ice, producing more bare ground that absorbs more solar radiation, further raising the air temperature. A cooling trend prolongs snow and ice cover in spring and summer so that less solar radiation is absorbed, more reflected to space, bringing about additional cooling. In both cases, feedback is positive because the initial change in temperature is amplified.

Consider an example of negative feedback. While feedbacks among temperature, cloud cover, and radiation are not well understood and depend upon circumstances (e.g., type and height of clouds), they could be either positive or negative. It is thought that a warming trend in climate should increase the rate of evaporation of water from Earth's surface and thereby increase low cloud cover. A thicker and more extensive low-cloud cover reflects more solar radiation to space thereby inhibiting a further rise in surface temperature. Hence, this negative feedback would dampen the initial temperature change.

Understanding feedback in the climate system is essential for modeling and predicting climate change. If some agent or mechanism alters the climate, then feedback may either amplify (positive feedback) or dampen (negative feedback) the change in climate. As demonstrated later in this course, many agents and mechanisms can bring about climate change (e.g., variations in solar energy output, regular fluctuations in Earth-Sun geometry). While these climate forcing agents and mechanisms drive climatic change, processes within the planetary climate system involving feedbacks significantly impact the magnitude of climate change.

Overall, which type of feedback prevails in Earth's climate system, positive or negative? A system in which positive feedback prevails is unstable. For Earth, this would move the climate regime toward an extreme characterized by excessive cold that would encase the planet in snow and ice ("snowball" or "ice ball" Earth) or toward the other extreme resulting in much higher temperatures--the product of a runaway greenhouse effect. Although Earth's climate has varied considerably over the billions of years that constitute geologic time, it appears likely that Earth's climate system has been nearly stable with negative feedbacks generally compensating for positive feedbacks.

Concept of the Week: Questions

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

The magnitude of a climate change [(largely depends upon)(is independent of)] positive and negative feedback phenomena operating in Earth's climate system.
Through much of Earth history, it appears that [(positive feedbacks)(negative feedbacks)(a general balance between positive and negative feedbacks)] have (has) prevailed.

Historical Events

16 September 1881...Iowa's earliest measurable snow of record fell over western sections of the state. Four to six inches was reported between Stuart and Avoca. (The Weather Channel)
16 September 1964...The temperature at Concord, NH dropped to 27 degrees ending the shortest growing season on record (100 days). (Intellicast)
16 September 1988...Hurricane Gilbert made landfall 120 miles south of Brownsville, TX in Mexico during the early evening. During its life span, Gilbert established an all-time record for the Western Hemisphere with a sea-level barometric pressure reading of 26.13 inches. Winds approached 200 mph, with higher gusts. Gilbert devastated Jamaica and Mexico's Yucatan Peninsula. (The National Weather Summary) (Storm Data) (The Weather Channel)
16 September 2004, Birmingham, Alabama: Birmingham, AL set two all-time records for the city as Hurricane Jeanne crossed the city: Lowest sea level pressure on record, 986.8 millibars (29.14 inches of mercury), and the greatest 24-hour rainfall event on record, 9.75 inches. (The Weather Doctor)
17 September 1829...The Siebold Typhoon, Japan's most catastrophic typhoon, inflicted widespread damage over much of Japan. On the southern island of Kyushu, the storm surge off the Ariake Sea kills 10,000. (The Weather Doctor)
17 September 1932...Westerly, RI received 12.13 inches of rain, which set a 24-hour precipitation record for the state. (NCDC)
17 September 1963...Nearly 2.5 inches of rain fell in 24 hours, the most intense rain for Yuma, AZ during the period between 1909 and 1977. (The Weather Doctor)
18 September 1991...2.4 inches of snow fell at Duluth, MN to set a new record for September. (Intellicast)
19 September 2004...The single-day rainfall record at Vancouver (British Columbia) International Airport was set 3.59 inches. The accumulation came in a month when rainfall is exceptional across the region. By mid-month, dozens of stations in British Columbia broke all-time September rainfall totals. (The Weather Doctor)
20-23 September 1942...A rainstorm deluged the Maritime Provinces. Four-day totals included 13.99 inches at Stellarton, Nova Scotia and 10.83 inches at Charlottetown, Prince Edward Island. Halifax, Nova Scotia recorded 9.40 inches of rain on the 21 September climatological day. (The Weather Doctor)
20 September 1967...Hurricane Beulah moved into South Texas, spawning a record 115 tornadoes for a hurricane. (David Ludlum) (Intellicast)
20 September 1973...Britain's greatest September daily rainfall floods Kent with 7.51 inches of rain. (The Weather Doctor)
22 September 1913...Des Moines, IA experienced their earliest freeze of record. (The Weather Channel)
22 September 1934...Edmonton, Alberta reported its greatest September snowstorm to date with 8.7 inches of snow. (The Weather Doctor).

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