![]() These data sources are coupled with inputs from local, state, regional, and federal levels (e.g., local impact reports) to depict short- and long-term drought conditions. USDM maps are produced weekly through expert synthesis of various data sources, including precipitation, soil moisture, streamflow, snow water equivalent and snowpack, crop and vegetation conditions, and reservoir and groundwater levels. Drought Monitor is a joint effort by NOAA’s CPC and National Centers for Environmental Information, NDMC at the University of Nebraska–Lincoln, and the United States Department of Agriculture. Our objectives are to (1) summarize the characteristics of flash drought events, including when and where these events occur, (2) assess antecedent conditions of these events prior to drought intensification, and (3) identify potential natural precursors for flash drought prediction. In this study, we define a flash drought event as a drought event with greater than or equal to two categories degradation in a four-week period based on USDM. Our goal is to provide a pertinent reference directly aligned with CPC’s work. This approach is different from the approach used by Christian et al. In order to improve our understanding of flash drought and hence better forecast its onset, we carry out a climatological analysis by examining fast-developing drought events identified from USDM. The 2017 Northern Plains Flash Drought caught forecasters off guard and the April MDO and SDO did not verify well. (2018) provided a comprehensive review of flash drought literature to date.Īt the National Oceanic and Atmospheric Administration’s Climate Prediction Center (NOAA/CPC), a primary responsibility is to monitor and predict drought by issuing official weekly USDM (every Tuesday), Seasonal Drought Outlook (SDO in the middle of the month), and Monthly Drought Outlook (MDO at the end of the month). QuickDRI is a short-term drought index that combines multiple input data of P, SM, ET, vegetation health, and landscape characteristics to indicate anomalously dry or wet conditions over the past four weeks. Geological Survey, in collaboration with the National Drought Mitigation Center (NDMC) and others, also released a new operational product-Quick Drought Response Index (QuickDRI)-to provide early detection of flash drought (available at ). (2019) presented a methodology to identify flash drought using Standardized Evaporative Stress Ratio (SESR) values and changes in SESR over some period. (2013) examined the sudden onset of drought using a satellite-derived drought index, and further developed the Rapid Change Index to highlight areas undergoing quick changes in moisture stress. Another topic of research is focused on changes in evaporative stress and its relation to flash drought development. Mo and Lettenmaier (20) identified two types of flash drought, namely heat wave flash drought and precipitation deficit flash drought, based on precipitation (P), temperature (T), evapotranspiration (ET), and/or soil moisture (SM) conditions. (2009) developed a soil moisture index to monitor soil water stress in the top 50 cm soil layer for flash drought alerts. ![]() As a result, monitoring rapid changes in evapotranspiration, along with precipitation and soil moisture conditions, can provide early warnings of flash drought development.Įarly research of flash drought is focused on the meteorological and hydrological conditions leading to flash drought development. Three-month Standardized Precipitation Indexes are mostly dry right before flash drought onset, but large deficits are not required. Comparing to precipitation and soil moisture, evapotranspiration typically has the largest decline rate during the fast-development phase. ![]() In contrast with conventional drought, which is mainly driven by precipitation deficits, anomalously high evapotranspiration rates, caused by anomalously high temperatures, winds, and/or incoming radiation, are usually present before the onset of flash drought. Widespread flash drought over the United States is largely correlated with La Niña episodes. ![]() Unlike conventional drought, which can occur year-round and everywhere in the United States, flash drought has preferred seasons and locations to occur, mostly in the warm season and over the central United States. In this study, we employ a rate-of-change approach and define a flash drought event as a drought event with greater than or equal to two categories degradation in a four-week period based on the U.S. Understanding the characteristics of flash drought events and further predicting the onset of such events on subseasonal timescales is of critical importance for impact assessment, disaster mitigation, and loss prevention. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |