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Water Data and Science Committee Meeting Summary: June 29th, 2023

Link to Recording: https://youtu.be/oPyaIncDRn0

  • Call to Order: Chair Amy Shallcross, Delaware River Basin Commission
  • Introductions of participants on the call – Amy Shallcross, Art DeGaetano NRCC Cornell, Beth Callaway, Chad Pindar , Jeremy Conkle, John Yagecic, Kristen Bowman Kavanagh, Michael Thompson, Owen Mills, Shuhai Zheng,Wade Loseman , Amanda Khalil, Andy Schiller, Bailey Adams, Becca Emery, Bob Bacon, Chrystel Hillier, David K, Drew Dehoff,Edward Swaim, Elizabeth Kerby, Gouri M., Hannah Somers, Jason Moeckel  Jessi Wilson, Katie, Goff, Laura St Pierre, Li Zheng, Namsoo Suk, Robby Short, Sara Sayed, Sarah, Stefan Schaepe, Thomas Amidon, Thomas Amidon,Tom, Littlepage, Tom Riley, Trevor Lawson
  • Guest presentation

Topic: “NOAA’s intensity–duration–frequency (IDF) tool and incorporation of climate science”

 Speaker: Art DeGaetano, Cornell University Professor Earth and Atmospheric Sciences and Director, NOAA Northeast Regional Climate Center

Estimating current rainfall extremes is like calculating probabilities, like poker without knowing the values and suites of all the cards.

NOAA bases its estimates on partial duration series in Atlas 14. They determine the 72 biggest rainfall events, multiple rainfall events in one year are allowed. Then there is a fit to a statistical distribution. GEB distribution is governed by 3 parameters: location (mean distribution), scale (standard deviation), shape. They look at distribution on a regional basis because the subtle changes in scale and shape can make a big difference. Uncertainty increases as time scale increases.

Question1: are the longest record lengths the holy grail (i.e. 20 year vs 100 year storm)? That was a good premise if there was no trend in the data series. The natural uncertainty you would expect would fit the confidence interval better for a longer time period of time. However (with some considerations), that isn’t the case when trended records are taken into account, in which case shorter time periods are better.

Q2: How often should we update things in a changing climate? When NOAA did Atlas 14 they did it regionally different so there are subtle differences. Example of 50 vs 70 year data analysis shows more data improve estimate fit. Conclusion is that the big events have a measurable effect on the record; by adding more data you change the values by quite a bit in the observed record.

Q3: how will design storms change in the future? A number of climate projections models are used by NOAA: emissions, global climate model, dynamical/statistical downscaling that feed into an impacts model that ultimately provides projections. Uncertainties are introduced in each step of the process. Downscaling is done to account for biases, add spatial detail or localized info not present in the coarse resolution.

Projections used are localized constructed analogs (LOCA) and coordinated regional climate downscaling experiment (CORDEX).

Art reviewed the simulation outcomes modeled for the Delaware River Basin Commission. Take home is that we don’t see a different change in event factors for the events compared to the daily data. There isn’t anything that indicates that adjustments for shorter duration should be adjusted for longer storms (i.e. 1 hour vs 1 day). The final project of the DRBC product will be publicly available on the DRBC website soon.

NOAA’s plans are to roll out this approach and methodology on a contract basis. NOAA is on the cusp of releasing projections from SIemens 6. Currently doing work with the City of New York. TMethod would be the same so just adding new projection data into the newer suite of models for the next National Climate Assessment.

Follow up questions can be directed to Art at: atd2@cornell.edu. Some additional information: https://www.weather.gov/media/owp/hdsc_documents/NOAA_Atlas_15_Flyer.pdf.

  • Committee discussion

Amy mentioned that the committee may want to weigh in on NOAA’s FY2024 Hydrologic Ensemble Forecasting – maintaining the platform; universities and coop program.

Cutting funding for cooperative research program – really important for NOAA to work with universities.

  1. Advanced Hydrologic Prediction Service (flood warning and inundation mapping)
  2. Hydrologic Ensemble system – flat funding or reducing funding to that budget. There will be no room to keep that service maintained.


  • Next meeting: July 25th @ 1pmCT