Compare the annual severity of Chesapeake Bay hypoxia
Each year, the Virginia Institute of Marine Science and Anchor QEA, LLC release a retrospective seasonal analysis of the severity of hypoxia in the Chesapeake Bay. The Annual Chesapeake Bay Dead Zone Report Card—one component of the Chesapeake Bay Environmental Forecast System—summarizes dissolved oxygen concentrations in the Bay as estimated by the team's 3-D, real-time hypoxia forecast model. The modeling team also generates the same dissolved oxygen statistics for previous years for comparative purposes.
The forecast and report card use multiple metrics to quantify and compare hypoxic severity:
Maximum Daily Hypoxic Volume (km 3) : The maximum volume of Chesapeake Bay water experiencing hypoxic conditions on any given day
Average Summer Hypoxic Volume (km 3) : The average volume of hypoxic water from June through September
Hypoxic Duration (days): The number of days in a given year between the first and last day of hypoxic conditions exceeding 2 km 3 in volume
Total Annual Hypoxic Volume (km 3 days) : The total amount of hypoxia in the Bay for a given year, calculated by summing the hypoxic volume on each day
Hypoxia in summer 2024 began around the usual time in the beginning of May. Hypoxia increased throughout May and peaked in the first half of June, following a period of relatively calm winds. Elevated winds in the second half of June likely resulted in a decrease in hypoxia from the early-June peak. The relatively large amount of hypoxia in June was early in the summer compared to historical conditions, which show hypoxia generally peaking in July or even early August. Hypoxia decreased following the passage of the remnants of Hurricane Debby but did not end for the year; a relatively low amount of hypoxia persisted through September into early October when cooling temperatures helped hypoxia end for the year. Overall, even though the duration of hypoxia was less than the long-term (39 year) average, the total annual amount of hypoxia was somewhat higher than the long-term average.
Summed Annual Estimates
Here we describe the severity of hypoxia as estimated by the forecast model. We define hypoxia as dissolved oxygen concentrations less than 2 milligrams/Liter (mg/L).
