DataStreme WES Week Ten: 8-12 November 2004

• Florida lake slow to recover from hurricanes -- Florida's state biologist recently reported that the hurricanes that struck the Sunshine State this season have damaged the wildlife habitat along the state's Lake Okeechobee, undoing much of the recent conservation efforts. He cautions that recovery could take years. [USA Today]
• Flood forecasts criticized -- A recently released report by a National Weather Service panel is critical of the less than adequate coastal flood forecasts issued by a Weather Service Office as Hurricane Isabel moved across the Middle Atlantic States in September 2003. [USA Today]
• A Nebraska town reappears -- The severe Western drought has lowered water levels in many reservoirs to near record low levels. The vast Lake McConaughy in southwestern Nebraska is nearly 75 percent empty, exposing a community that became submerged when the lake was created more than 60 years ago. [USA Today]
• Forty years of weather radar research at Storms Lab -- The NOAA National Severe Storms Laboratory at Norman, OK celebrated its 40^th anniversary in October, noting the advancements in weather radar resulting from the research undertaken at the Laboratory. [NOAA Magazine]
• Acid rain could reduce methane production -- Scientists with NASA and the Open University in the United Kingdom have recently discovered that sulfates in acid rain appears to block some of the bacteria found in wetlands of the US, Sweden and England that produce methane, one of the greenhouse gases. [NASA GSFC]
• Europeans to aid North Korean water projects -- The European Union plans to send a humanitarian aid package worth $7.9 million to North Korea to help repair and upgrade water and sanitation systems. [ENN]
• Better water management could aid Africa -- An official for the United Nation's Food and Agriculture Organization recently told a pan-African conference that the continent's water resources could be used to boost farm productivity and combat the food shortages and poverty that have plagued many African countries. [ENN]
• African water resources to be monitored from space-- A TIGER Initiative that makes satellite data from the European Space Agency available to researchers for integrated water resources management in developing countries has led to numerous research projects that will be discussed in this coming week's workshop in Pretoria, South Africa. [ESA]
• Home water filtering options -- Citizens who are concerned with the quality and safety of their municipal tap water have several options for filtering the water, according to an official with one biotechnology company. [ENN]
• Global and US Hazards/Climate Extremes-- A review and analysis of the global impacts of various weather-related events, including drought, floods, and storms during the current month. [NCDC]
• Global Water News Watch -- Other water news sources can be obtained through the SAHRA Project at the University of Arizona [SAHRA Project]
• Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Concept of the Week: Water in Microclimates

Water is an important component of the planetary-scale climate system, playing a key role in the global radiation balance (e.g., the greenhouse effect) and large-scale transport of heat (e.g., latent heat transfer and ocean currents). The global climate system exhibits considerable spatial variability so that Earth is a mosaic of numerous climate types and water is often an important factor in distinguishing between individual climates. Hence, for example, the climate of a desert differs from that of a rainforest primarily because of differences in precipitation totals and potential evaporation rate.

Climate (long-term average atmospheric conditions) also varies on smaller spatial scales. Here, we consider examples of how the local water and heat energy budget vary on the scale of microclimates, having horizontal dimensions from less than 1 m to 100 m (3.3 ft to 330 ft) and vertical dimension from Earth's surface to an altitude of 100 m (330 ft).

All other factors being equal, afternoon air temperatures tend to be lower over an irrigated farm field than over a non-irrigated field. Where soils are wet, more of the available heat is used to evaporate water (latent heating) leaving less to raise the temperature of the soil surface and overlying air (sensible heating). In the Northern Hemisphere, snow tends to persist longer and the growing season is shorter on the shaded north- and east-facing hill slopes (facing away from the sun) than on south- and west-facing slopes (facing the sun). In portions of the Rocky Mountains, the sunnier, drier, and warmer south-facing slopes are sparsely vegetated by grasses, ponderosa pine, and juniper. Meanwhile, dense stands of fir and spruce grow on the shaded, moist, and cooler north-facing slopes.

Trees, sand dunes, buildings and other obstacles slow the wind and reduce the wind's ability to transport material (including soil particles) in suspension. Farmers take advantage of this effect by constructing shelterbelts (or "windbreaks") that reduce wind erosion of soil and modify the microclimate. A shelterbelt may consist of a fence or multiple rows of trees or bushes planted upwind of an agricultural field--usually perpendicular to the prevailing wind direction. In the winter, snow-bearing horizontal winds slow as they encounter a shelterbelt. The wind's ability to transport snow diminishes and snow accumulates on the field immediately downwind of the shelterbelt. The air spaces within a snow cover make it a relatively poor conductor of heat so that the snow cover protects the underlying soil from deep penetration of subfreezing temperatures. In areas where winter wheat is grown, the snow cover protects the dormant plants from potentially damaging fluctuations in soil temperature. Snow trapped by shelterbelts also increases the local supply of soil moisture that becomes available during the spring thaw. Furthermore, slowing the wind reduces the evaporation of soil moisture. Significant increases in crop yields can be attributed to the microclimatic effects of shelterbelts.

Climatic contrasts are also evident between forested and non-forested areas. Wind speed diminishes considerably within a forest-as much as 60% to 80% at a distance of only 30 m (100 ft) into a deciduous forest. Weaker winds coupled with reduced solar radiation reaching the forest floor (due to the forest canopy) decreases the amount of evaporation from the forest floor. However, the relatively high rate of transpiration by forest vegetation more than compensates for the reduction in evaporation from the forest floor. Overall, the air in a forest tends to be somewhat more humid than the air over a nearby non-forested area. Even tall field crops such as corn have a similar effect on the microclimate.

Concept of the Week: Questions

1. In the Northern Hemisphere, snow is likely to persist longer on the shaded [(north-) (south-)] facing slope of a hill.
2. The relatively high humidity in forested areas is primarily the result of relatively high [(precipitation) (evaporation) (transpiration)] occurring in forested areas.

• 8 November 1876...Two days of rain dumped 4.9 in. on Fredericton, New Brunswick. The rail line near Lawrence Station was washed out causing the derailment of the morning St. John-Fredericton run. (The Weather Doctor)
• 8 November 1914...On this date the longest "official" rain-free time span on record for the U.S. of 767 days ended in Bagdad, CA. Some meteorologists question the accuracy of this record kept by railroad employees at that time. (Accord Weather Calendar)
• 9 November 1913...The "Freshwater Fury," a rapidly deepening midlatitude cyclone, caused unpredicted gales on the Great Lakes. Seventeen ships, including eight large ore carriers on Lake Erie sank drowning 270 sailors. Cleveland, OH reported 17.4 in. of snow in 24 hrs, and a storm total of 22.2 in., both all-time records for that location. During the storm, winds at Cleveland averaged 50 mph, with gusts to 79 mph. The storm produced sustained winds of 62 mph at Port Huron, MI, wind gusts to 80 mph at Buffalo, NY and buried Pickens, WV under three feet of snow. (9^th-11^th) (David Ludlum) (The Weather Channel)
• 9 November 1932...An unnamed hurricane struck Cuba, with winds reaching approximately 210 mph at Nuvitas. However, a storm surge was the main killer of 2500 of the 4000 residents of Santa Cruiz del Sur. Essentially no storm records exist, as the observer drowned, with records and instruments washed away. (Accord Weather Calendar)
• 9-11 November 2001...More than the average month's total (3.7 inches) of heavy rains fell on Algiers, Algeria in just a few hours. The resulting massive floods and mudslides devastated northern Algeria and killed more than 700 people causing nearly $300 million worth of damage. (The Weather Doctor)
• 10 November 1835...A severe storm crossed the Great Lakes with 19 ships lost and 254 sailors killed. (Intellicast)
• 10 November 1975...Another "freshwater fury" hit the Great Lakes. A large ore carrier on Lake Superior, the Edmund Fitzgerald, sank near Crisp Point with the loss of its crew of 29 men. Eastern Upper Michigan and coastal Lower Michigan were hardest hit by the storm, which produced wind gusts to 71 mph at Sault Ste Marie, MI and gusts to 78 mph at Grand Rapids, MI. Severe land and road erosion occurred along the Lake Michigan shoreline. A popular hit song by Gordon Lightfoot was inspired by the storm. (David Ludlum) (Accord Weather Calendar)
  Editors note: The National Weather Service Forecast Office at Marquette, MI created a web page commemorating the 25^th anniversary of the sinking and describing the advances in marine weather forecasting over the last quarter century. EJH
• 10 November 1993...Violent storm over the Black Sea closed the Russian oil terminal port of Novorossisk for 20 days. "Bora" winds reported as high as 112 mph sank at least seven ships. (The Weather Doctor)
• 11 November 1099...Violent storm in the North Sea killed 100,000 people in England and The Netherlands. (The Weather Doctor)
• 12 November 1956...(date approximate) The crew on the icebreaker USCGC Glacier saw what may have been the world's largest iceberg. Observed about 150 miles west of Antarctica's Scott Island, the iceberg was about 60 mi wide by 208 mi long, or roughly the size of Maryland. (Accord Weather Calendar)
• 12 November 1968...New England was battered by the third severe coastal storm in only 5 days. An intense low crossed Long Island and produced wind gusts to 100 mph at Block Island, RI. Tides ran 5 to 10 ft above normal in some places with severe coastal flooding and property damage. Rockland, ME recorded a wind gust of 86 mph. Winds reached 90 mph in Massachusetts. Up to 10 in. of snow fell at some of the higher elevations, bringing the totals for the three storms to as much as 60 in. (David Ludlum) (Intellicast)
• 12 November 1974...A great Alaska storm in the Bering Sea caused the worst coastal flooding of memory at Nome, AK with a tide of 13.2 ft. The flooding caused $12 million damage; however, no lives were lost. (David Ludlum)
• 12 November 1980...A fringe rain band from Hurricane Jeannie in the Gulf of Mexico let loose a deluge of 23.38 in. of rain in 24 hrs at Key West, FL, an all-time 24-hr record. (Intellicast)
• 13 November 1946...General Electric scientists produced snow in the Massachusetts Berkshires in the first modern day cloud seeding experiment. (The Weather Channel)
• 13 November 1970... A cyclone swept over Bangladesh, then known as East Pakistan, pushing a 49-foot storm surge against the coast at high tide. Flooding killed 500,000. Over 50 million people were affected by the storm rain, wind and surge. (The Weather Doctor)
• 13 November 1998...The youngest son of former Canadian Prime Minister Pierre Trudeau and two companions were swept into Kokanee Lake in British Columbia's Kokanee Glacier National Park by an avalanche while on a backcountry ski trip. The companions swam to shore, but the young Trudeau drowned. (Accord Weather Calendar)
• 14-18 November 1979...Approximately 40 in. of rain were measured over northeast Hawaii, with much higher amounts likely in mountainous areas not monitored by rain gauges. The Waipio Valley was hit hard, with more than 90 percent of the valley's farmland covered by flood debris. The new $6.9 million road to Waipio Lookout that had just been dedicated was severely damaged. (Accord Weather Calendar)
• 14-21 November 1991...Tropical Cyclone Tia spent most of its life near the Solomon Islands and Vanuatu. However, it completely destroyed 90 percent of all dwellings on Tikopia Island. The remaining 10 percent of the buildings had collapsed walls or roofs that had been blown off. (Accord Weather Calendar)

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Prepared by AMS WES Central Staff and Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2004, The American Meteorological Society.