Physical Sciences and Mathematics Commons^™

Lewis And Clark State Park Signs, Robert F. Diffendal Jr., Les Howard

School of Natural Resources: Faculty Publications

Bob Diffendal wrote text and Les Howard created maps for new Lewis and Clark signs at Ponca State Park on the Missouri River.

The Corps of Discovery led by Meriwether Lewis and William Clark reached what is now southeastern Nebraska on July 10, 1804. It arrived at the point on the Missouri River adjacent to what is now Ponca State Park on August 22, 1804; and entered fully into South Dakota on September 8, 1804. Over this span of nearly two months members of the expedition saw and described many geologic features. The locations of some of the more prominent …

Monitoring Maize (Zea Mays L.) Phenology With Remote Sensing, Andrés Viña, Anatoly A. Gitelson, Donald C. Rundquist, Galina P. Keydan, Bryan Leavitt, James Schepers

School of Natural Resources: Faculty Publications

Monitoring crop phenology is required for understanding intra- and interannual variations of agroecosystems, as well as for improving yield prediction models. The objective of this paper is to remotely evaluate the phenological development of maize (Zea mays L.) in terms of both biomass accumulation and reproductive organ appearance. Maize phenology was monitored by means of the recently developed visible atmospherically resistant indices, derived from spectral reflectance data. Visible atmospherically resistant indices provided significant information for crop phenology monitoring as they allowed us to detect: (i) changes due to biomass accumulation, (ii) changes induced by the appearance and development of …

Air Temperature Comparison Between The Mmts And The Uscrn Temperature Systems, K. G. Hubbard, X. Lin

School of Natural Resources: Faculty Publications

A new U.S. Climate Reference Network (USCRN) was officially and nationally commissioned by the Department of Commerce and the National Oceanic and Atmospheric Administration in 2004. During a 1-yr side-by-side field comparison of USCRN temperatures and temperatures measured by a maximum-minimum temperature system (MMTS), analyses of hourly data show that the MMTS temperature performed with biases: 1) a systematic bias–ambient-temperature-dependent bias and 2) an ambient-solar-radiation- and ambient-wind- speed-dependent bias. Magnitudes of these two biases ranged from a few tenths of a degree to over 1􏰈C compared to the USCRN temperatures. The hourly average temperatures for the USCRN were the dependent …

Structures And Dynamics Of Quasi-2d Mesoscale Convective Systems, Matthew D. Parker, Richard H. Johnson

School of Natural Resources: Faculty Publications

Recently, three distinct archetypes for midlatitude linear mesoscale convective systems (MCSs) have been identified. This article focuses on the fundamentals of two of these archetypes: convective lines with trailing stratiform (TS) precipitation and convective lines with leading stratiform (LS) precipitation. Both the TS and LS modes typically exhibit quasi-2D reflectivity patterns and quasi-2D environmental storm-relative wind fields. Ongoing work has revealed that there are three common flow structures for these quasi-2D MCSs: front-fed TS systems (which are sustained by front-to-rear storm-relative inflow), as well as front-fed LS and rear-fed LS systems (which are sustained by rear-to-front storm-relative inflow). This paper …

A Self-Calibrating Palmer Drought Severity Index, Nathan Wells, Steve Goddard, Michael Hayes

School of Natural Resources: Faculty Publications

The Palmer Drought Severity Index (PDSI) has been used for more than 30 years to quantify the long-term drought conditions for a given location and time. However, a common critique of the PDSI is that the behavior of the index at various locations is inconsistent, making spatial comparisons of PDSI values difficult, if not meaningless.

A self-calibrating Palmer Drought Severity Index (SC-PDSI) is presented and evaluated. The SC-PDSI automatically calibrates the behavior of the index at any location by replacing empirical constants in the index computation with dynamically calculated values. An evaluation of the SC-PDSI at 761 sites within Nebraska, …

Notes And Correspondence Uncertainties Of Derived Dewpoint Temperature And Relative Humidity, X. Lin, Kenneth Hubbard

School of Natural Resources: Faculty Publications

This paper presents an evaluation of derived dewpoint temperature and derived relative humidity, in which the dewpoint temperature is calculated using measured ambient air temperature and measured relative humidity variables and the derived relative humidity is calculated from measured dewpoint temperature. The derived dewpoint temperature and relative humidity are calculated using algorithms provided by the World Meteorological Organization. The method of uncertainty analysis, provided by the National Institute of Standards and Technology, is applied to calculate the uncertainties of an indirect measurement of derived dewpoint temperature and derived relative humidity. The results from the uncertainty analyses of derived and observed …

Sensor And Electronic Biases/Errors In Air Temperature Measurements In Common Weather Station Networks*, X. Lin, Kenneth Hubbard

School of Natural Resources: Faculty Publications

The biases of four commonly used air temperature sensors are examined and detailed. Each temperature transducer consists of three components: temperature sensing elements, signal conditioning circuitry, and corresponding analog-to-digital conversion devices or dataloggers. An error analysis of these components was performed to determine the major sources of error in common climate networks. It was found that, regardless of microclimate effects, sensor and electronic errors in air temperature measurements can be larger than those given in the sensor manufacturer’s specifications. The root-sum-of-squares (RSS) error for the HMP35C sensor with CR10X datalogger was above 0.2􏰆C, and rapidly increases for both lower (􏰋􏰂20􏰆C) …

Variations In The Teleconnection Of Enso And Summer Rainfall In Northern China: A Role Of The Indian Summer Monsoon*, Song Feng, Qi Hu

School of Natural Resources: Faculty Publications

Observational studies have created a dilemma on how El Nin ̃o–Southern Oscillation (ENSO) may have affected interannual variations of summer rainfall in northern China; some suggested a consistent effect while others showed a complete lack of effect. This dilemma is resolved in this study, which shows that ENSO has affected the summer rainfall in northern China and the effect has varied at multidecadal scales. The question of how the ENSO teleconnection with northern China rainfall variation was established is addressed, and an answer pointing to the Indian summer monsoon as a ‘‘facilitator’’ connecting ENSO and northern China rainfall variation is …

Late Albian Dinosaur Tracks From The Cratonic (Eastern) Margin Of The Western Interior Seaway, Nebraska, Usa, R. M. Joeckel, J. M. Cunningham, R. G. Corner, P. L. Phillips, G. A. Ludvigson

School of Natural Resources: Faculty Publications

No abstract provided.

Accounting For Stream-Aquifer Interactions In The State-Space Discretization Of The Kmn-Cascade For Streamflow Forecasting, Jozsef Szilagyi

School of Natural Resources: Faculty Publications

No abstract provided.

Achieving Bat Conservation Through Tourism, Lisa A. Pennisi, Stephen M. Holland, Taylor V. Stein

School of Natural Resources: Faculty Publications

No abstract provided.

Using Visitors Motivations To Provide Learning Opportunities At Water-Based Recreation Areas, Taylor V. Stein, Christine B. Denny, Lisa A. Pennisi

School of Natural Resources: Faculty Publications

No abstract provided.

Heuristic Continuous Base Flow Separation, Jozsef Szilagyi

School of Natural Resources: Faculty Publications

No abstract provided.

White-Tailed Deer, Kurt C. Vercauteren, Scott E. Hygnstrom

School of Natural Resources: Faculty Publications

The white-tailed deer (Odocoileus virginianus) is one of two members of the deer family (Cervidae) commonly found in the Great Plains. When alarmed, white-tailed deer hold their tails erect, baring their white underside and white rump. Bucks (males) begin growing bonelike antlers early each summer and by early fall the antlers stop growing and harden. The antlers have a main beam with tines erupting from the top and are used for fighting and establishing rank in the social hierarchy.

Comparison Of Modis And Avhrr 16-Day Normalized Difference Vegetation Index Composite Data, Kevin P. Gallo, Lei Ji, Brad Reed, John Dwyer, Jeffrey Eidenshink

School of Natural Resources: Faculty Publications

Normalized difference vegetation index (NDVI) data derived from visible and near-infrared data acquired by the MODIS and AVHRR sensors were compared over the same time periods and a variety of land cover classes within the conterminous USA. The relationship between the AVHRR derived NDVI values and those of future sensors is critical to continued long term monitoring of land surface properties. The results indicate that the 16-day composite values are quite similar over the 23 intervals of 2001 that were analyzed, and a linear relationship exists between the NDVI values from the two sensors. The composite AVHRR NDVI data were …

Animal Anti–Apoptotic Genes Enhance Recovery From Drought Stress In Tobacco, Tala Awada, David D. Dunigan, Martin B. Dickman

School of Natural Resources: Faculty Publications

The anti–apoptotic nematode CED–9 gene and a 3’ non–coding mRNA region of the human Bcl–2 gene, referred to as 161–1, enhanced resistance to drought and recovery after re–watering in transgenic Nicotiana tabacum L. CV Glurk plants. The effect of drought on plant functions was investigated by withholding water from pots for 6, 8, 10 and 13 days. Results showed that controls and transgenic tobacco did not differ among each other under well–watered conditions. Differences appeared however, on day 3 of water deprivation, where controls exhibited a significantly steeper decline in photosynthesis (A) compared to the transgenic lines. On day 10 …

Regional Modis Analysis Of Abandoned Agricultural Lands In The Kazakh Steppes, Kirsten M. De Beurs, Geoffrey M. Henebry, Anatoly A. Gitelson

School of Natural Resources: Faculty Publications

The institutional consequences of the Soviet Union’s collapse in 1991 have been greatly underestimated as a significant forcing on the boundary layer through changes in land surface phenology. Upon independence, Kazakhstan lost the centralized agricultural planning, crop subsidy system, and access to international markets that the Soviet Union had been providing. These institutional changes led to substantial decreases in livestock populations, especially sheep, and in arable land area cultivated, especially rain-fed spring wheat in northern Kazakhstan. As a result the fallow fields reverted to weedy species and idle pastures produced denser grass cover.

In this case study we used MODIS …

The Wide Dynamic Range Vegetation Index And Its Potential Utility For Gap Analysis, Geoffrey M. Henebry, Andrés Viña, Anatoly A. Gitelson

School of Natural Resources: Faculty Publications

In this brief note, the authors illustrate the prevalence of reduced sensitivity of the Normalized Difference Vegetation Index (NDVI), introduce the Wide Dynamic Range Vegetation Index (WDRVI), and illustrate the advantages of the WDVRI over the NDVI using Landsat ETM+ data that spans a range of canopy densities.

Non-Destructive Assessment Of Chlorophyll Carotenoid And Anthocyanin Content In Higher Plant Leaves: Principles And Algorithms, Anatoly A. Gitelson, Mark N. Merzlyak

School of Natural Resources: Faculty Publications

Leaf pigment content provides valuable information about the physiological status of plants. Reflectance measurement makes it possible to quickly and non-destructively assess, in situ, the pigment content in leaves. The objective was to investigate the spectral behavior of the relationship between reflectance and pigment content (total chlorophyll, carotenoids and anthocyanins, which are the main pigments of leaves, and provide valuable information about plant physiological status) and to develop techniques for non-destructive pigment estimation in leaves using reflectance in a few spectral bands.

Satellite Monitoring Of Vegetation Dynamics: Sensitivity Enhancement By The Wide Dynamic Range Vegetation Index, Andrés Viña, Geoffrey Henebry, Anatoly A. Gitelson

School of Natural Resources: Faculty Publications

Synoptic monitoring of vegetation dynamics relies on satellite observations of the distinctive spectral contrast between red and near infrared reflectance that photosynthetically active green vegetation exhibits. It has long been recognized that the Normalized Difference Vegetation Index (NDVI) suffers a rapid decrease of sensitivity at moderate-to-high densities of photosynthetic green biomass. This decrease can conceal detection of vegetation change in croplands, woodlands, and productive grasslands.We applied a recent, straightforward modification of the NDVI, the Wide Dynamic Range Vegetation Index (WDRVI), to a standard AVHRR dataset to assess its sensitivity to variability within ecoregions and across years, relative to NDVI. In …

Remote Estimation Of Net Ecosystem Co2 Exchange In Crops: Principles, Technique Calibration And Validation, Anatoly A. Gitelson, Andrés Viña, Shashi Verma, Donald C. Rundquist, Timothy J. Arkebauer, Galina P. Keydan, Bryan Leavitt, Veronica Ciganda, George G. Burba, Andrew E. Suyker

School of Natural Resources: Faculty Publications

Accurate and synoptic estimation of spatially distributed CO2 fluxes is of great importance for regional and global studies of carbon balance. A technique solely based on remotely sensed data was developed and tested for estimating net ecosystem CO2 exchange (NEE) in maize and soybean. The model is based on the reflectance in two spectral channels: the near-infrared and either the green or red-edge around 700 nm. The technique provides accurate estimations of mid-day NEE in both crops under either rainfed or irrigated conditions, explaining more than 85% of NEE variation in maize and more than 81% in soybean, and shows …

Collecting Spectral Data Over Cropland Vegetation Using Machine-Positioning Versus Hand-Positioning Of The Sensor, Donald Rundquist, Richard L. Perk, Bryan Leavitt, Galina P. Keydan, Anatoly A. Gitelson

School of Natural Resources: Faculty Publications

The paper describes an all-terrain motorized platform for deploying sensors and compares data collected by means of that system with those collected by means of hand-held sensors. The results not only highlight the greater variability in spectra that can be expected when deploying field radiometers by hand but, more importantly, they quantify the difference. Researchers should be aware of the potential for diminishing the validity of findings based on reflectance spectra acquired by means of hand-held sensors.

Forecasting Vegetation Greenness With Satellite And Climate Data, Lei Ji, Albert J. Peters

School of Natural Resources: Faculty Publications

A new and unique vegetation greenness forecast (VGF) model was designed to predict future vegetation conditions to three months through the use of current and historical climate data and satellite imagery. The VGF model is implemented through a seasonality-adjusted autoregressive distributed-lag function, based on our finding that the normalized difference vegetation index is highly correlated with lagged precipitation and temperature. Accurate forecasts were obtained from the VGF model in Nebraska grassland and cropland. The regression R² values range from 0.97–0.80 for 2–12 week forecasts, with higher R² associated with a shorter prediction. An important application would be to …

Empirical Measurement Of Parasite Transmission Between Groups In A Colonial Bird, Charles R. Brown, Mary Bomberger Brown

School of Natural Resources: Faculty Publications

While epidemiological models have suggested that the spread of parasites
and infectious diseases often depends critically on the extent of movement by infected
individuals between populations, there is little empirical information for any organism on
the frequency of between-group parasite transmission or how it varies spatially. The transmission
of parasites between discrete social groups or populations may also help determine
a host’s total parasite or pathogen exposure. We measured the introduction of parasitic bugs
(Oeciacus vicarius) into colonies of Cliff Swallows (Petrochelidon pyrrhonota) by transient
birds from outside each group. The transmission of bugs increased strongly …

Application Of Snowfall And Wind Statistics To Snow Transport Modeling For Snowdrift Control In Minnesota, Martha Shulski, Mark W. Seeley

School of Natural Resources: Faculty Publications

Models were utilized to determine the snow accumulation season (SAS) and to quantify windblown snow for the purpose of snowdrift control for locations in Minnesota. The models require mean monthly temperature, snowfall, density of snow, and wind frequency distribution statistics. Temperature and precipitation data were obtained from local cooperative observing sites, and wind data came from Automated Surface Observing System (ASOS)/Automated Weather Observing System (AWOS) sites in the region. The temperature-based algorithm used to define the SAS reveals a geographic variability in the starting and ending dates of the season, which is determined by latitude and elevation. Mean seasonal snowfall …

Response Of Nebraska Sand Hills Natural Vegetation To Drought, Fire, Grazing, And Plant Functional Type Shifts As Simulated By The Century Model, Jennifer Mangan, Jonathan T. Overpeck, Robert S. Webb, Carol Wessman, Alexander Goetz

School of Natural Resources: Faculty Publications

The Nebraska Sand Hills exist in a semi-arid climatic environment and the land surface is grassland growing on sandy soils. These soils have been periodically active throughout the Holocene, but are currently stabilized by the vegetation. However, a shift in climate could cause grassland death and eventual sand dune remobilization. Our studies used the CENTURY nutrient cycling and ecosystem model to investigate the impacts of drought, plant functional type, fire, grazing, and erosion on Nebraska Sand Hills vegetation and dune stability. Fire and grazing alone had little impact on the vegetation, but when combined with mild drought, biomass decreased. Overall …

An Analysis Of Simulated Long-Term Soil Moisture Data For Three Land Uses Under Contrasting Hydroclimatic Conditions In The Northern Great Plains, Rezaul Mahmood, Kenneth Hubbard

School of Natural Resources: Faculty Publications

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. …

Ogallala Aquifer, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

The Ogallala Aquifer, or High Plains Aquifer, is a porous body of complex sediments and sedimentary rock formations that conducts groundwater and yields significant quantities of water to wells and springs. The principal sediments and rocks of the aquifer range in age from 33 million years old to sediments being deposited today, but the majority is less than 12 million-years old. Much of the aquifer is composed of the Ogallala Group or Formation. The dominant sediments in the Ogallala and the other hydrogeologic units in the aquifer are riverand wind-deposited sands. The aquifer underlies about 174,000 square miles of the …

Topographic Maps, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

Topographic maps show the general configuration of the land surface, including its relief and the position of natural and man-made features. The configuration is shown commonly by contour lines, imaginary lines connecting all points of equal elevation on the earth's surface above or below a datum plane such as mean sea level. When the land slope is steeper the contour lines are closer together. Topographic maps at scales of one inch to a mile or greater (shown as 1:63,360 on the map) are used in many ways. They are particularly important in preparation of various types of geologic maps and …

Modification Of Growing-Season Surface Temperature Records In The Northern Great Plains Due To Land-Use Transformation: Verification Of Modelling Results And Implication For Global Climate Change, Rezaul Mamood, Kenneth G. Hubbard, Christy Carlson

School of Natural Resources: Faculty Publications

Land-use and land-cover change can modify near-surface atmospheric condition. Mesoscale modelling studies have shown that modification in land use affects near-surface soil moisture storage and energy balance. Such a study in the Great Plains showed that changes in land use from natural grass to irrigated agriculture enhanced soil water storage in the root zone and increased latent energy flux. This increase in latent energy flux would correspond to a decrease in sensible heat flux and, therefore, modify near-surface temperature records. To verify this deduction, we have investigated the changes in the historical near-surface temperature records in Nebraska, USA. We have …