Search Results

You are looking at 1 - 4 of 4 items for

  • Author or Editor: Michael A. Crimmins x
  • Refine by Access: All Content x
Clear All Modify Search
Alison M. Meadow, Michael A. Crimmins, and Daniel B. Ferguson

To make decisions about drought declarations, status, and relief funds, decision makers need high-quality local-level drought impact data. In response to this need in Arizona the Arizona DroughtWatch program was created, which includes an online drought impacts reporting system. Despite extensive and intensive collaboration and consultation with the intended public participants, Arizona DroughtWatch has had few consistent users and has failed to live up to its goal of providing decision makers or the public with high-quality drought impacts data. Based on an evaluation of the DroughtWatch program, the authors found several weaknesses in the public-participation reporting-system model including that participation was reduced because of participants' over-commitment and time constraints, consultation fatigue, and confusion about the value of qualitative impact reports. Based on these findings, the authors recommend that professional resource agency personnel provide the backbone of drought impacts monitoring to ensure that decision makers receive the high-quality, consistent information they require. Public participation in impacts monitoring efforts can also be improved using this model. Professional observers can help attract volunteers who consider access to high-quality data an incentive to visit the Arizona DroughtWatch site and who may be more likely to participate in impacts monitoring if they see examples of how the information is being used by decision makers.

Full access
Daniel B. Ferguson, Anna Masayesva, Alison M. Meadow, and Michael A. Crimmins

Abstract

Drought monitoring and drought planning are complex endeavors. Measures of precipitation or streamflow provide little context for understanding how social and environmental systems impacted by drought are responding. Here the authors report on collaborative work with the Hopi Tribe—a Native American community in the U.S. Southwest—to develop a drought information system that is responsive to local needs. A strategy is presented for developing a system that is based on an assessment of how drought is experienced by Hopi citizens and resource managers, that can incorporate local observations of drought impacts as well as conventional indicators, and that brings together local expertise with conventional science-based observations. The system described here is meant to harness as much available information as possible to inform tribal resource managers, political leaders, and citizens about drought conditions and to also engage these local drought stakeholders in observing, thinking about, and helping to guide planning for drought.

Full access
Michael A. Crimmins, Daniel B. Ferguson, Alison M. Meadow, and Jeremy L. Weiss

Abstract

Monitoring drought conditions in arid and semiarid regions characterized by high levels of intra- and interannual hydroclimatic variability is a challenging task. Typical drought-monitoring indices that are based on monthly-scale data lack sufficient temporal resolution to detect hydroclimatic extremes and, when used operationally, may not provide adequate indication of drought status. In a case study focused on the Four Corners region of the southwestern United States, the authors used recently standardized World Meteorological Organization climate extremes indices to discern intra-annual hydroclimatic extremes and diagnose potential drought status in conjunction with the simple metric of annual total precipitation. By applying data-reduction methods to a suite of metrics calculated using daily data for 1950–2014, the authors identified five extremes indices that provided additional insight into interannual hydroclimatic variability. Annual time series of these indices revealed anomalous years characterized by shifts in the seasonal distribution of precipitation and in the intensity and frequency of individual events. The driest 4-yr intervals over the study period, characterized by similar annual and interval total precipitation anomalies, represent dramatically different assemblages of index values, which are interpreted as different “flavors” of drought. In turn, it is expected that varying drought impacts on ecosystems, agricultural systems, and water resources would emerge under these different flavors of drought. Results from this study indicate that operational drought monitoring and historical drought assessments in arid and semiarid regions would benefit from the additional insight that daily-based hydroclimatic extremes indices provide, especially in light of expected climate change–driven changes to the hydrologic cycle.

Full access
A. Park Williams, Richard Seager, Max Berkelhammer, Alison K. Macalady, Michael A. Crimmins, Thomas W. Swetnam, Anna T. Trugman, Nikolaus Buenning, Natalia Hryniw, Nate G. McDowell, David Noone, Claudia I. Mora, and Thom Rahn

Abstract

In 2011, exceptionally low atmospheric moisture content combined with moderately high temperatures to produce a record-high vapor pressure deficit (VPD) in the southwestern United States (SW). These conditions combined with record-low cold-season precipitation to cause widespread drought and extreme wildfires. Although interannual VPD variability is generally dominated by temperature, high VPD in 2011 was also driven by a lack of atmospheric moisture. The May–July 2011 dewpoint in the SW was 4.5 standard deviations below the long-term mean. Lack of atmospheric moisture was promoted by already very dry soils and amplified by a strong ocean-to-continent sea level pressure gradient and upper-level convergence that drove dry northerly winds and subsidence upwind of and over the SW. Subsidence drove divergence of rapid and dry surface winds over the SW, suppressing southerly moisture imports and removing moisture from already dry soils. Model projections developed for the fifth phase of the Coupled Model Intercomparison Project (CMIP5) suggest that by the 2050s warming trends will cause mean warm-season VPD to be comparable to the record-high VPD observed in 2011. CMIP5 projections also suggest increased interannual variability of VPD, independent of trends in background mean levels, as a result of increased variability of dewpoint, temperature, vapor pressure, and saturation vapor pressure. Increased variability in VPD translates to increased probability of 2011-type VPD anomalies, which would be superimposed on ever-greater background VPD levels. Although temperature will continue to be the primary driver of interannual VPD variability, 2011 served as an important reminder that atmospheric moisture content can also drive impactful VPD anomalies.

Full access