December 7, 2020
Drought and heat waves both have a range of severe societal and ecosystem impacts. In the Northeast U.S., these phenomena have caused adverse effects on human health, including heat stress and heat stroke, an increased demand for energy and therefore higher energy costs, damage to managed systems such as forestry and agriculture, increased wildfire risk, and disruption of aquatic and terrestrial biology. Our research seeks to understand the causes of droughts and heat waves and how they interact with one another to better predict their occurrence and help manage their impacts in the Northeast U.S.
We often associate heat waves and drought with hot, dry weather. While that association is correct, there are many different types of heat waves and drought, each with different causes and impacts. Flash droughts, for instance, form rapidly and with little warning after several weeks of abnormally hot weather. Other droughts develop over several months or years of below-average rainfall. Heat waves can be hot and dry, causing water stress in plants, or hot and humid, causing heat stress in humans. To better predict these different heat wave and drought types, we need to understand what they have in common and what makes them different.
Our research uses machine learning techniques to objectively identify and classify heat waves and droughts in the Northeast U.S. into different types based on the atmospheric conditions associated with the events. These classifications provide a starting point to investigate the shared and unique characteristics of different heat wave and drought types. One such aspect we focus on is the moisture source (or lack thereof) for drought and heat wave events of different types. For example, rainfall in the Northeast U.S. comes from water vapor evaporated in the Midwest, the Atlantic Ocean, the Gulf of Mexico, etc., that travels to the Northeast in the atmosphere’s winds. A change in evaporation from these source regions, or a change in the atmospheric circulation connecting these regions to the Northeast, can therefore alter the amount of rainfall in the Northeast. With the use of numerical models that allow us to track the movement of water through the atmosphere, we are exploring whether certain source regions are more important than others in driving different types of drought in the Northeast. Our hope is that, in the future, if we observe anomalies in the amount of evaporation from these source regions, or a specific change in the atmospheric circulation, we may be able to better predict the onset of drought in the Northeast, helping to mitigate the negative impacts of the event.