Flash drought in Australia and its relationship to evaporative demand

Flash droughts can be distinguished by rapid intensification from near-normal soil moisture to drought conditions in a matter of weeks. Here, we provide the first characterisation of a climatology of flash drought across Australia using a suite of indices. The experiment is designed to capture a range of conditions related to drought: evaporative demand describes the atmospheric demand for moisture from the surface; precipitation, the supply of moisture from the atmosphere to the surface; and evaporative stress, the supply of moisture from the surface relative to the demand from the atmosphere. We show that regardless of the definition, flash droughts occur in all seasons. They can terminate as rapidly as they start, but in some cases can last many months, resulting in a seasonal-scale drought. We show that flash-drought variability and its prevalence can be related to phases of the El Ni&ntilde;o&ndash;Southern Oscillation, highlighting scope for seasonal-scale prediction. Using a case study in southeast Australia, we show that monitoring precipitation is less useful for capturing the onset of flash drought as it occurs. Instead, indices like the Evaporative Demand Drought Index and Evaporative Stress Index are more useful for monitoring flash-drought development. &nbsp;</p

Getting ahead of Flash Drought: From Early Warning to Early Action

Flash droughts, characterized by their unusually rapid intensification, have garnered increasing attention within the weather, climate, agriculture, and ecological communities in recent years due to their large environmental and socioeconomic impacts. Because flash droughts intensify quickly, they require different early warning capabilities and management approaches than are typically used for slower-developing “conventional” droughts. In this essay, we describe an integrated research-and-applications agenda that emphasizes the need to reconceptualize our understanding of flash drought within existing drought early warning systems by focusing on opportunities to improve monitoring and prediction. We illustrate the need for engagement among physical scientists, social scientists, operational monitoring and forecast centers, practitioners, and policy-makers to inform how they view, monitor, predict, plan for, and respond to flash drought. We discuss five related topics that together constitute the pillars of a robust flash drought early warning system, including the development of 1) a physically based identification framework, 2) comprehensive drought monitoring capabilities, and 3) improved prediction over various time scales that together 4) aid impact assessments and 5) guide decision-making and policy. We provide specific recommendations to illustrate how this fivefold approach could be used to enhance decision-making capabilities of practitioners, develop new areas of research, and provide guidance to policy-makers attempting to account for flash drought in drought preparedness and response plans

Establishing Relationships between Drought Indices and Wildfire Danger Outputs: A Test Case for the California-Nevada Drought Early Warning System

Relationships between drought indices and fire danger outputs are examined to (1) incorporate fire risk information into the National Integrated Drought Information System California&ndash;Nevada Drought Early Warning System and (2) provide a baseline analysis for application of drought indices into a fire risk management framework. We analyzed four drought indices that incorporate precipitation and evaporative demand (E0) and three fire indices that reflect fuel moisture and potential fire intensity. Seasonally averaged fire danger outputs were most strongly correlated to multi-scalar drought indices that use E0 (the Evaporative Demand Drought Index (EDDI) and the Standardized Precipitation Evapotranspiration Index (SPEI)) at approximately annual time scales that reflect buildup of antecedent drought conditions. Results indicate that EDDI and SPEI can inform seasonal fire potential outlooks at the beginning of summer. An E0 decomposition case study of conditions prior to the Tubbs Fire in Northern California indicate high E0 (97th percentile) driven predominantly by low humidity signaled increased fire potential several days before the start of the fire. Initial use of EDDI by fire management groups during summer and fall 2018 highlights several value-added applications, including seasonal fire potential outlooks, funding fire severity level requests, and assessing set-up conditions prior to large, explosive fire cases.</p

What Drives the Spatial and Temporal Variability of Potential Evaporation Across CONUS and the Colorado River Basin?

Because the distribution of soil and vegetative moisture is essentially unknowable at operationally useful temporal and spatial scales, hydrologists interested in quantifying actual evapotranspiration (ET) use potential evaporation (E0) to quantify ET’s upper limit. ET is then estimated by scaling down from E0 using simple vegetation-related coefficients or land-surface models. This paradigm underpins much of operational hydrology, including streamflow prediction, water management in municipalities and agriculture, and other decision-making enterprises that rely on real-time quantification of surface water availability. This widespread use of E0 motivates a need for measures that rely on physically appropriate forcings, that yield accurate results at time and space scales relevant to operational goals, and that avoid extraneous modeling uncertainty or the omission of key sources of variability. The primary goal of our study is to meet this need To understand the sources of variability of E0, a mean-value, second-moment uncertainty analysis is applied to a 30-year, CONUS-distributed dataset of daily synthetic pan evaporation derived from the “PenPan” model, a combination equation that mimics observations from US Class A evaporation pans. For drivers, we use six North American Land Data Assimilation System variables: temperature, specific humidity, station pressure, wind speed, and downwelling shortwave and longwave radiation. The variability of E0 is decomposed across various time scales into contributions from these drivers. We find that, contrary to popular expectation and much hydrologic practice, temperature is not always the most significant driver of temporal variability in E0, particularly at sub-annual time scales. Instead, depending on the region and the season, one of four drivers (temperature, specific humidity, downwelling shortwave radiation, and wind speed) dominates across different regions of CONUS. Temperature, specific humidity, downwelling shortwave radiation, and wind speed must together be examined, with downwelling longwave radiation as a secondary input. If any variable may be ignored, it is atmospheric pressure. While temperature generally dominates in the northern continental interior, parameterizations based solely on temperature should be avoided over large areas and at sub-annual time scales. Our results have clear implications for modeling E0 in operational hydrology or as a metric of climate change and variability; not least in assisting land surface modelers find a balance between parameter parsimony and physical representativeness. In our presentation, we will describe the analysis concept across CONUS and then concentrate on the implications of our results across the Colorado River basin

Establishing Relationships between Drought Indices and Wildfire Danger Outputs: A Test Case for the California-Nevada Drought Early Warning System

Relationships between drought indices and fire danger outputs are examined to (1) incorporate fire risk information into the National Integrated Drought Information System California–Nevada Drought EarlyWarning System and (2) provide a baseline analysis for application of drought indices into a fire risk management framework. We analyzed four drought indices that incorporate precipitation and evaporative demand (E0) and three fire indices that reflect fuel moisture and potential fire intensity. Seasonally averaged fire danger outputs were most strongly correlated to multi-scalar drought indices that use E0 (the Evaporative Demand Drought Index (EDDI) and the Standardized Precipitation Evapotranspiration Index (SPEI)) at approximately annual time scales that reflect buildup of antecedent drought conditions. Results indicate that EDDI and SPEI can inform seasonal fire potential outlooks at the beginning of summer. An E0 decomposition case study of conditions prior to the Tubbs Fire in Northern California indicate high E0 (97th percentile) driven predominantly by low humidity signaled increased fire potential several days before the start of the fire. Initial use of EDDI by fire management groups during summer and fall 2018 highlights several value-added applications, including seasonal fire potential outlooks, funding fire severity level requests, and assessing set-up conditions prior to large, explosive fire cases

Complementary relationship in the estimation of regional evapotranspiration: an enhanced advection-aridity model

Includes bibliographical references

Mitigation and Adaptation Measures

Climate change has directly and indirectly impacted natural and human systems across the globe in recent decades

Anticipatory care planning for community-dwelling older adults at risk of functional decline: a feasibility cluster randomized controlled trial

OBJECTIVES: To determine the feasibility, implementation and outcomes of an Anticipatory Care Planning (ACP) intervention in primary care to assist older adults at risk of functional decline by developing a personalized support plan. DESIGN: Feasibility cluster randomized control trial. SETTING AND PARTICIPANTS: Eight primary care practices (four in Northern Ireland, United Kingdom and four in the Republic of Ireland) were randomly assigned to either intervention or control arm. Eligible patients were those identified in each practice as 70 years of age or older and assessed as at risk of functional decline. Study participants (intervention n = 34, control n = 31) and research staff were not blinded to group assignment. ANTICIPATORY CARE INTERVENTION: The intervention delivered by a registered nurse including: a) a home-based patient assessment; b) care planning on the basis of a holistic patient assessment, and c) documentation of a support plan. OUTCOME MEASURES: A conceptual framework (RE-AIM) guided the assessment on the potential impact of the ACP intervention on patient quality of life, mental health, healthcare utilisation, costs, perception of person-centred care, and reduction of potentially inappropriate prescribing. Data were collected at baseline and at 10 weeks and six months following delivery of the intervention. RESULTS: All pre-specified feasibility indicators were met. Patients were unanimous in the acceptance of the ACP intervention. Health care providers viewed the ACP intervention as feasible to implement in routine clinical practice with attending community supports. While there were no significant differences on the primary outcomes (EQ-5D-5L: -0.07 (-0.17, 0.04) p = .180; CES-D: 1.2 (-2.5, 4.8) p = .468) and most secondary measures, ancillary analysis on social support showed responsiveness to the intervention. Incremental cost analysis revealed a mean reduction in costs of €320 per patient (95% CI -31 to 25; p = 0.82) for intervention relative to the control. CONCLUSIONS: We successfully tested the ACP intervention in primary care settings and have shown that it is feasible to implement. The ACP intervention deserves further testing in a definitive trial to determine whether its implementation would lead to better outcomes or reduced costs. TRIAL REGISTRATION: Clinicaltrials.gov, ID: NCT03902743. Registered on 4 April 2019. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12877-022-03128-x

Impact of precipitation and increasing temperatures on drought trends in eastern Africa

In eastern Africa droughts can cause crop failure and lead to food insecurity. With increasing temperatures, there is an a priori assumption that droughts are becoming more severe. However, the link between droughts and climate change is not sufficiently understood. Here we investigate trends in long-term agricultural drought and the influence of increasing temperatures and precipitation deficits. Using a combination of models and observational datasets, we studied trends, spanning the period from 1900 (to approximate pre-industrial conditions) to 2018, for six regions in eastern Africa in four drought-related annually averaged variables: soil moisture, precipitation, temperature, and evaporative demand (E0). In standardized soil moisture data, we found no discernible trends. The strongest influence on soil moisture variability was from precipitation, especially in the drier or water-limited study regions; temperature and E0 did not demonstrate strong relations to soil moisture. However, the error margins on precipitation trend estimates are large and no clear trend is evident, whereas significant positive trends were observed in local temperatures. The trends in E0 are predominantly positive, but we do not find strong relations between E0 and soil moisture trends. Nevertheless, the E0 trend results can still be of interest for irrigation purposes because it is E0 that determines the maximum evaporation rate. We conclude that until now the impact of increasing local temperatures on agricultural drought in eastern Africa is limited and we recommend that any soil moisture analysis be supplemented by an analysis of precipitation deficit.ISSN:2190-4987ISSN:2190-497