Meteorology Commons^™

Climatology And Change Of Extreme Precipitation Events In Taiwan Based On Weather Types, Yi-Chao Wu, Shih-Yu (Simon) Wang, Yi-Chiang Yu, Chu-Ying Kung, An-Hsiang Wang, Sebastian A. Los, Wan-Ru Huang

Plants, Soils, and Climate Faculty Publications

Taiwan's most significant natural hazards are caused by hydrological extremes resulting from excessive precipitation. The threat of extreme precipitation is posed by several different types of weather patterns that affect Taiwan. This study examined the bi‐decadal changes in rainfall by defining an extreme precipitation occurrence (EPO) for a range of event durations from 1 to 24 hr. Three major weather types affecting EPO in Taiwan were identified from 1993 to 2015: the front type consisting of either a frontal zone or convective systems developing with an apparent Meiyu cloudband, diurnal rainfall events when no apparent synoptic features are present, and …

On The Propagation Of Atmospheric Gravity Waves In A Non-Uniform Wind Field: Introducing A Modified Acoustic-Gravity Wave Equation, Ahmad Talaei

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Atmospheric gravity waves play fundamental roles in a broad-range of dynamical processes extending throughout the Earth’s neutral atmosphere and ionosphere. In this paper, we present a modified form for the acoustic-gravity wave equation and its dispersion relationships for a compressible and non-stationary atmosphere in hydrostatic balance. Importantly, the solutions have been achieved without the use of the well-known Boussinesq approximation which have been used extensively in previous studies.

We utilize the complete set of governing equations for a compressible atmosphere with non-uniform airflows to determine an equation for vertical velocity of possible atmospheric waves. This intricate wave equation is simplified …

Multi-Decadal Drought Cycles In The Great Basin Recorded By The Great Salt Lake: Modulation From A Transition-Phase Teleconnection, Shih-Yu (Simon) Wang, Robert R. Gillies, Thomas Reichler

Plants, Soils, and Climate Faculty Publications

This study investigates the meteorological conditions associated with multidecadal drought cycles as revealed by lake level fluctuation of the Great Salt Lake (GSL). The analysis combined instrumental, proxy, and simulation datasets, including the Twentieth Century Reanalysis version 2, the North American Drought Atlas, and a 2000-yr control simulation of the GFDL Coupled Model, version 2.1 (CM2.1). Statistical evidence from the spectral coherence analysis points to a phase shift amounting to 6–9 yr between the wet–dry cycles in the Great Basin and the warm–cool phases of the interdecadal Pacific oscillation (IPO). Diagnoses of the sea surface temperature and atmospheric …

Evapotranspiration Of Kentucky Bluegrass, Lynda L. Fenton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rapid population growth in arid regions of the western US is placing increased demand on water resources. Variability in precipitation and common occurrence of drought have promoted scrutiny of water use in urban lawns and gardens. However, few reliable measurements of water use of these landscapes exist. Quantifying the amount of water used vs. required by landscapes such as turfgrass would allow significant water conservation. Evapotranspiration (ET) is affected by biophysical factors such as: available energy, turbulent mixing, saturation deficit, soil water, and stomatal conductance. In order to simulate the water use by turfgrass, the relative importance of these processes …

Sudden Surface Warming/Drying Events Caused By Typhoon Passages Across Taiwan, T. C. Chen, Shih-Yu (Simon) Wang, M. C. Yen, A. J. Clark, J. D. Tsay

Plants, Soils, and Climate Faculty Publications

Typhoon passages across Taiwan can generate sudden surface warming in downslope regions. Special characteristics and mechanisms for 54 such warming events that were identified during the 1961–2007 period are examined. Preferred warming regions were identified in northwest Taiwan, where warming is generated by downslope flow from east or northeast winds in westward-moving typhoons, and in southeast Taiwan, where it is generated by downslope flow from west or northwest winds in northwestward-moving typhoons. In addition to the orographic effect, warmings occurred exclusively within nonprecipitation zones of typhoons. Most northwest (southeast) warmings occur during the day (night) with an average lifetime of …

Evaluations Of Nam Forecasts On Midtropospheric Perturbation-Induced Convective Storms Over The U.S. Northern Plains, Shih-Yu (Simon) Wang, T. C. Chen, S. E. Taylor

Plants, Soils, and Climate Faculty Publications

In the U.S. northern plains, summer progressive convective storms that occur in weakly forced environ- ments are often coupled with short-wave perturbations that are embedded in the midlevel northwesterly flow. These midtropospheric perturbations (MPs) are capable of inducing propagating convection that contributes to a majority of the rainfall over the northern plains during July and August. There is a possibility that the difficulties of numerical weather prediction models in forecasting summer convective rainfall over the northern plains are partly attributed to their deficiency in forecasting MPs. The present study tests this possibility through examining operational forecasts by the North American …

Impact Of The Intraseasonal Variability Of Large-Scale Circulation Over The Western North Pacific On The Characteristics Of Tropical Cyclone Track, T. C. Chen, Shih-Yu (Simon) Wang, M. C. Yen, A. J. Clark

Plants, Soils, and Climate Faculty Publications

The life cycle of the Southeast Asian–western North Pacific monsoon circulation is established by the northward migrations of the monsoon trough and the western Pacific subtropical anticyclone, and is reflected by the intraseasonal variations of mo nsoon westerlies and trad e easterlies in the form of an east–west seesaw oscillation. In this paper, an effort is made to disclose the influence of this monsoon circulation on tropical cyclone tracks during its different ph ases using composite charts of large-scale circulation for certain types of tracks. A majority of straight-moving (recurving) tropical cyclones appear during weak (strong) monsoon west- erlies and …

Summary Of The Noaa/Utah Atmospheric Modification Program: 1990-1996, United States Department Of The Interior, Bureau Of Reclamation

Meterology

This final report summarizes physical investigations into the artificial nucleation ("seeding") of winter mountain clouds in central Utah during 1990-96. Program goals were to evaluate the effectiveness of the Utah operational cloud seeding program and to recommend improvements. Field programs employed a wide variety of instrumentation systems. Sophisticated numerical modeling was used in conjunction with the observational programs. Amounts and distributions of SLW (supercooled liquid water) cloud were investigated, as was transport and dispersion of ground-released seeding agents and tracer gases. Several experiments directly monitored ice crystals and snowfall rates resulting from either silver iodide (Agl) or liquid propane seeding. …

Precipitation Gauge Testing On The Wasatch Plateau, Utah, During Early 1993, United States Department Of The Interior, Bureau Of Reclamation

Meterology

The Bureau of Reclamation performed an independent evaluation of an ETI (Electronic Techniques, Inc.) precipitation gauge at the High Altitude Site on the western slope of the Wasatch Plateau in central Utah. The ETI gauge could provide a desirable alternative to conventional recording gauges in several applications, including evaluation of cloud seeding projects, if it performs as advertised. The testing program was intended to determine its performance in a winter mountain environment. The ETI precipitation gauge proved to be reliable from time of installation in late November 1992 until removal in late March 1993. The only problem found was an …

Interpretation Of Selected Soil Data From The Central Part Of Utah, Amjad T. El-Rihani

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Seventy-eight soil samples belonging to 15 sites were sampled by SEAM project in 1976. These 15 pedons represent different soil types which cover the Manti-LaSal area in the central part of Utah. The 15 pedons were described in standard notation. Complete soil analysis was done. The soil analysis includes the following determinations: particle size distribution, moisture retention, soil pH, organic matter, electrical conductivity, calcium carbonate equivalent, cation exchange capacity , base saturation, extractable cations and saturation extract soluble. Also x-ray diffraction for selected horizons was done.

The 15 pedons were classified according to the currently used system. This report includes …

Mesoscale Atmospheric Circulation And Diffusion Characteristics, Ronan I. Ellis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Constant volume superpressure pillow balloons were flown over a mountain valley downwind from a sharp ridge line. Balloon trajectories revealed and atmospheric soundings confirmed a persistent turbulently mixed adiabatic layer over the valley at approximately ridge top height except in the immediate lee of the ridge where strong vertical motions were observed. Temporary stationarity of the relative mesoscale turbulence was found to exist on a time scale exceeding 4 hours. Power spectrum analysis of component relative velocities showed greater variance in lower wave numbers and anisotropy in mesoscale turbulence. Eddy diffusivity coefficients for turbulence above the ridge height were K …

Model For Estimating Soil Water Flow, Water Content, Evapotranspiration And Root Extraction, Musa N. Nimah

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A mathematical model was developed to predict water content profiles, evapotranspiration, water flow from or to the water table, root extraction and root water potential at the surface as functions of time under unsteady state conditions.

The model was tested in the field at The Hullinger Farm near Vernal, Utah, in 1970 and 1971. Comparison of water content-depth profiles show excellent agreement at the end of a 9- day run in 1970 on oats seeded to alfalfa. In 1971 with alfalfa as the crop, the data show best agreement, between predicted and computed water content-depth profiles, 48 hours after any …

Role Of Transition Metals In Nitrite Decomposition In Soil, J. S. Bajwa

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Iron and copper increased the decomposition of nitrite significantly during the first two hours of reaction when 150 parts per million (ppm) of nitrite and nitrogen was added to an acidic soil. Manganese was found to have a slight effect. There was no additional effect of the added metals after two hours reaction time.

The higher concentration of metals was not effective in catalyzing the decomposition of the added nitrite in nitrogen. All the added nitrite nitrogen was not recovered and the deficit could be due to the formation of nitrogen gas.