Weather Modification Studies: The Potential for Creating and Utilizing Ice Crystals in Weather Modification Activities

A method utilizing ice crystals to circumvent nucleation processes in cloud seeding activities is discussed in the framework of nuclei activation concepts. Ice, in the form of small crystals, would be a highly efficient cloud seeding materia up to 0 degrees Celsius. The lower limit on humidity would necessitate dispensing the crystals into air that is saturated with respect to ice but no requirement for 100 percent RH(relative humidity) was found. In fact, the lower limit varies with temperature linearly from about 95 percent RH at -5 degrees Celsius to 75 percent RH at -30 degrees Celsius. Preparation of small crystals was found possible at liquid nitrogen temperatures and the volume which could potentially be seeded seems to be large enough to seriously consider the ice crystals as a possible triggering material

Climatology of Hailstorms in Utah--The Hail Suppression Potential by Cloud Seeding

Hail damage in Utah was examined for individual counties and the entire state. A survey of informal observes was taken and the resulting data base was analyzed. Data from NWS was also examined. County hail damage figures average 4 to 5 percent of production and ranking of counties according to dollar damage occurs in only 4 of the 29 counties (Box Elder, Utah, Millard, and Cache). In many cases the highest dollar damage occurred in the counties of greatest dollar damage should receive the greatest concentration of hail suppression effort. In addition storm severity and crop growth stage were identified as important elements

Availability of climate data for water management

Presented at the Central Plains irrigation conference on February 17-18, 2004 in Kearney Nebraska.Includes bibliographical references.Evapotranspiration from crops causes depletion of soil water reserves and without rainfall or irrigation to replenish the soil moisture serious crop stress can occur. The Nebraska Automated Weather Data Network (AWDN) was initiated in 1981 in order to provide information on weather variables that effect crop water use: air temperature, humidity, solar radiation, wind speed/direction, soil temperature, and precipitation. By 2003 the public access to AWDN and related products reached 12M per year. This paper describes the Automated Weather Data Network (AWDN) and the interfaces that provide near real time climate services with emphasis on evapotranspiration (ET) or crop water use. Currently, automated weather stations are monitored daily at 54 locations in Nebraska and 10 new stations have been purchased with federal drought funds. There are over 150 stations available in a nine state region

Tabulation and Application of Pan Evaporation Data for Utah Through 1976

Monthly values of evaporation, wind movement and water temperatures are presently for all available station in Utah. A brief review is given of factors which effect evaporation along with several examples of how pan evaporation data ware used

An Analysis of Simulated Long-Term Soil Moisture Data for Three Land Uses under Contrasting Hydroclimatic Conditions in the Northern Great Plains

Soil moisture (SM) plays an important role in land surface and atmosphere interactions. It modifies energy balance near the surface and the rate of water cycling between land and atmosphere. The lack of observed SM data prohibits understanding of SM variations at climate scales under varying land uses. However, with simulation models it is possible to develop a long-term SM dataset and study these issues. In this paper a water balance model is used to provide a quantitative assessment of SM climatologies for three land uses, namely, irrigated corn, rain-fed corn, and grass, grown under three hydroclimatic regimes in Nebraska. These regimes are stops along an east–west decreasing precipitation gradient of the Great Plains. The simulated SM climatologies are provided for the root zone as a whole and for the five layers of the soil profile to a depth of 1.2 m. As expected, the soil water content in the root zone of irrigated corn was higher than rainfed corn or grass. The lowest levels of soil water depletion were found under rain-fed corn cultivation due to its complete reliance on naturally available SM. The annual total evapotranspiration (ET) was 34% and 36% higher for irrigated corn than for rain-fed corn and grass, respectively. The study suggests that due to interannual variability the SM variability is higher for deeper depths, as compared to near-surface depths. Growing season SM depletion and prevailing soil water content at various depths of the soil profile varies with crops, soils, and prevailing hydroclimatic conditions. The results show that land use affects the magnitude of SM variability at all time scales. At a daily temporal scale, SM variability is less under irrigated land use and sharply increases under rain-fed land uses. At the monthly scale, SM variability largely follows the trend of the daily time scale. Year-to-year SM variability is significant. Extremely dry or wet conditions enhance and reduce, respectively, the forcing of land use on SM variability at an annual time scale. Thus, large-scale interannual climate variations and land use jointly affect SM variability at this scale

Climate Model for Winter Wheat Yield Simulation

Winter wheat yields were simlulated by a model requiring climatic data as input for estimating crop evapotranspiration and phenological development. An assumed relationship between the winter wheat yields and the amount and timing of crop water use was optimized to simulate yields for two case studies: a single season, irrigated wheat study, and a multi-year, dryland wheat study. The model explained more than 90% of the variance of wheat yields in the irrigated study where total irrigation amounts varied between 0 and 55 cm. About 40% of the variance was explained for annual yields from a 21-year, dryland winter wheat study

The Great Basin Climate Study for Range Fire Management

The BLM (Bureau of Land Management) fire management personnel routinely use a fire danger computer program to estimate the effects of recent weather upon the fire hazard on the BLM rangeland sites. The program used for this purpose is the National Fire Danger Rating System (NFDRS) which was developed by the National Forest Service (Deeming, 1978). The NFDRS was used in conjunction with fire weather stations in the Great Basin for the dual purposes of evaluating the ability of NFDRS to predict fire danger and of determining the effectiveness of the present fire station network in detecting fire weather on the Great Basin rangelands. Seasonal fire frequency and real time fire occurrence were examined with respect to climatic and weather variable to determine the meteorological parameters which are most closely related to fire occurrence. These parameters were then used to delineate zones within the Great Basin of approximately equal fire climate. The climate relationships are also discussed with regard to the possible development of pre-season fire projection models

Airflow Characteristics of Commonly Used Temperature Radiation Shields*

The air temperature radiation shield is a key component in air temperature measurement in weather station networks; however, it is widely recognized that significant errors in the measured air temperature exist due to insufficient airflow past the air temperature sensor housed inside the shield. During the last several decades, the U.S. National Weather Service has employed a number of different shields in air temperature measurements. This paper focuses on the airflow characteristics inside air temperature shields including the Maximum–Minimum Temperature System (MMTS), the Gill shields, and the Cotton Region Shelter (CRS). Average airspeed profiles and airflow efficiency inside the shields are investigated in this study under both windtable and field conditions using an omnidirectional hot-wire sensor. Results from the windtable measurements indicate that the average airspeeds inside the shields oscillated along the center line of the Gill and MMTS shields as the ‘‘windtable air’’ speed was changed from 1.03 to 2.62 m s1; the MMTS airflow efficiency demonstrated a nearly constant value, but the Gill’s airflow efficiency increased. A linear transfer equation between the airspeed measured at the normal operating position for the temperature sensor inside the shield and the ambient wind speed was found under field conditions for all three nonaspirated air temperature radiation shields (CRS, Gill, and MMTS). Results indicate that the naturally ventilated temperature radiation shields are unable to provide sufficient ventilation when the ambient wind speed is less than 5 m s 1 at the radiation shield height

IRRIGATED AND RAINFED CROPS Zea mays L. (MAIZE) AND Glycine max (SOYBEAN) ACTING AS A SOURCE OR SINK FOR ATMOSPHERIC WARMING AT MEAD, NEBRASKA

Land Use and Land Cover Change (LULCC) influence the climate at a global and local scale. Using long term microclimate data (2002-2009, 2011-2012) from the Carbon Sequestration Project (CSP), Mead, NE, this study examines how crop selection and water management can mitigate heat in the atmosphere. Mitigation of global warming is dependent on the management of crop lands, and the amount and timing of rainfall during the growing season. Rainfed crops were found to heat the passing air. The irrigated maize crop was able to mitigate 20 to 62% of the sensible heat (H) compared to the rainfed maize counterpart, the lower value for wet years and the larger value for dry years. Soybeans under irrigation, on the other hand, extracted a maximum of 37% of cumulated H in comparison to rainfed soybean. The irrigated maize field can reduce the warming by as much as 76% compared to the rainfed soybean crop. In addition to increasing yields, irrigation of maize greatly reduces the heating of air, thus moderating regional climate in east central Nebraska

Regional Climate Centers: New Institutions for Climate Service and Climate- Impact Research

In response to the need climate services at the local, state, and regional levels, a national network of regional climate centers has developed. This provides the background to this development, and outlines the functions of the centers and identifies their benefits and beneficiaries. The centers are a source of climate expertise and maintain multifaceted interfaces with the public and private sectors. Each center a) performs services, including the management of the basic data for its region and the delivery of specialized products; b) conducts applied climate studies, including the monitoring of anomalous conditions and the promotin of regional research; and C) acquires and maintains specialized regional datasets. Examples are given for each function. The paper concludes by elaborating on the potential for focused, applied research to enhance the service provided by the regional centers. This includes reference to the current irrigation scheduling information service operated by the HIgh Plains Regional Climate Center