The Drought Monitor

There is a need for improved drought monitoring and assessment methods in the United States. Drought is the most costly natural disaster [Federal Emergency Management Agancy (FEMA 1995; Wilhite 2000)], but it is often neglected by developers of assessment and forecast products. Drought is more nebulous than other disasters and does not lend itself to traditional assessments or forecast methods. Its relatively slow onset and the complexity of its impacts are reasons for the new assessment methodology. Improvements in drought monitoring and forecasting techniques will allow for better preparation, lead to better management practices, and reduce the vulnerability of society to drought and its subsequent impacts. The Drought Monitor (additional information available online at http://drought.unl/edu/dm) was created with the goal of tracking and displaying the magnitude and spatial extent of drought and its impacts across the United States. The Drought Monitor is produced weekly and classifies drought severity into four major categories, with a fifth category threshold assigned to locations on a map are determined from a number of indicators, or tools, blended with subjective interpretation

Microwave Remote Sensing of Soil Moisture Science and Applications

Soil moisture is a fundamental link between global water and carbon cycles and has major applications in predicting natural hazards such as droughts and floods (National Research Council, 2007). From precipitation data, soil wetness can be estimated by hydrological land-surface models. In the United States, preliminary precipitation data are based on measurements gathered from many active stations nationwide each month, and it takes 3–4 months to assemble final, quality-controlled data. In the western United States, some climate divisions may have no stations reporting in a particular month or may lack first- or second-order stations, and significant blockages by mountains limit the capability of precipitation measurement by surface rain radars (Maddox et al., 2002)

The Drought Monitor

There is a need for improved drought monitoring and assessment methods in the United States. Drought is the most costly natural disaster [Federal Emergency Management Agancy (FEMA 1995; Wilhite 2000)], but it is often neglected by developers of assessment and forecast products. Drought is more nebulous than other disasters and does not lend itself to traditional assessments or forecast methods. Its relatively slow onset and the complexity of its impacts are reasons for the new assessment methodology. Improvements in drought monitoring and forecasting techniques will allow for better preparation, lead to better management practices, and reduce the vulnerability of society to drought and its subsequent impacts. The Drought Monitor (additional information available online at http://drought.unl/edu/dm) was created with the goal of tracking and displaying the magnitude and spatial extent of drought and its impacts across the United States. The Drought Monitor is produced weekly and classifies drought severity into four major categories, with a fifth category threshold assigned to locations on a map are determined from a number of indicators, or tools, blended with subjective interpretation

Microwave Remote Sensing of Soil Moisture Science and Applications

Soil moisture is a fundamental link between global water and carbon cycles and has major applications in predicting natural hazards such as droughts and floods (National Research Council, 2007). From precipitation data, soil wetness can be estimated by hydrological land-surface models. In the United States, preliminary precipitation data are based on measurements gathered from many active stations nationwide each month, and it takes 3–4 months to assemble final, quality-controlled data. In the western United States, some climate divisions may have no stations reporting in a particular month or may lack first- or second-order stations, and significant blockages by mountains limit the capability of precipitation measurement by surface rain radars (Maddox et al., 2002)

Direct NMR Detection of Bifurcated Hydrogen Bonding in the α‑Helix N‑Caps of Ankyrin Repeat Proteins

In biomolecules, bifurcated H-bonds typically involve the interaction of two donor protons with the two lone pairs of oxygen. Here, we present direct NMR evidence for a bifurcated H-bonding arrangement involving <i>nitrogen</i> as the acceptor atom. Specifically, the H-bond network comprises the Nδ1 atom of histidine and both the backbone N–H and side-chain Oγ-H of threonine within the conserved TXXH motif of ankyrin repeat (AR) proteins. Identification of the H-bonding partners is achieved via solution NMR H-bond scalar coupling (HBC) and H/D isotope shift experiments. Quantitative determination of ^2h<i>J</i>_NN HBCs supports that Thr N–H···Nδ1 His H-bonds within internal repeats are stronger (∼4 Hz) than in the solvent exposed C-terminal AR (∼2 Hz). In agreement, p<i>K</i>_a values for the buried histidines bridging internal ARs are several units lower than those of the C-terminus. Quantum chemical calculations show that the relevant ^2h<i>J</i> and ^1h<i>J</i> couplings are dominated by the Fermi contact interaction. Finally, a Thr-to-Val replacement, which eliminates the Thr Oγ-H···Nδ1 His H-bond and decreases protein stability, results in a 25% increase in ^2h<i>J</i>_NN, attributed to optimization of the Val N–H···Nδ1 His H-bond. Overall, the results provide new insights into the H-bonding properties of histidine, a refined structural rationalization for the folding cooperativity of AR proteins, and a challenging benchmark for the calculation of HBCs