Sunday, 12 January 2025
Hall C (New Orleans Ernest N. Morial Convention Center)
This study employs a novel WRF ensemble framework to attribute the influence of anthropogenic climate change on a multi-hazard convective event that occurred in eastern Texas on 21 March 2022. A pseudo-global warming approach is used to examine how changes in the climate system from the mid-19th century through the end of the 21st century affect the scope and severity of the event. The case is simulated using WRF, with output from the full suite of the Global Ensemble Forecast Systems (GEFS) providing initial and lateral boundary conditions for an ensemble of contemporary simulations.
Thereafter, diurnally varying deltas of fundamental variables for two future periods (2035-2064 and 2071-2100) under intermediate and pessimistic emission pathways were calculated from the Community Earth System Model (version 2; CESM2), a member of CMIP6. These diurnally varying deltas were added to the respective means from the 1985-2014 “contemporary” period. Further, deltas from 1850-1879 and 1935-1964 were subtracted from the contemporary period to explore any attributable changes since the mid-19th century.
Epoch-specific deltas were then added to each GEFS member from the contemporary period’s simulations, to generate an ensemble for each epoch. Statistical tests for epoch differences in various model output metrics used to prescribe the scope and severity of the event (e.g. reflectivity, updraft helicity, synthetic hail and tornadoes, precipitation rates, etc.) are expected to reveal the influence, or attribution, of climate change on the event. The hypothesis is that statistically significant changes in the metrics between epochs will illustrate that climate change has affected, and will continue to affect, the scope and severity of this and similar events.
Thereafter, diurnally varying deltas of fundamental variables for two future periods (2035-2064 and 2071-2100) under intermediate and pessimistic emission pathways were calculated from the Community Earth System Model (version 2; CESM2), a member of CMIP6. These diurnally varying deltas were added to the respective means from the 1985-2014 “contemporary” period. Further, deltas from 1850-1879 and 1935-1964 were subtracted from the contemporary period to explore any attributable changes since the mid-19th century.
Epoch-specific deltas were then added to each GEFS member from the contemporary period’s simulations, to generate an ensemble for each epoch. Statistical tests for epoch differences in various model output metrics used to prescribe the scope and severity of the event (e.g. reflectivity, updraft helicity, synthetic hail and tornadoes, precipitation rates, etc.) are expected to reveal the influence, or attribution, of climate change on the event. The hypothesis is that statistically significant changes in the metrics between epochs will illustrate that climate change has affected, and will continue to affect, the scope and severity of this and similar events.
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