Florida Institute of Technology Effect of Wind Reduction Factors on Forecasting Circulation in an Estuary 2016 AMS Annual Meeting January 14th , 2016 Atousa Saberi, Robert J. Weaver, Peyman Taeb, Steven M. Lazarus, Michael E. Splitt, Bryan P. Holman and Jeff Colvin Florida Institute of Technology Good afternoon everybody. My name is Atousa Saberi recently graduated student from Florida Institute of Tech. and I’m presenting our team’s research the on effect of wind reduction factors on forecasting wind driven Circulation in an Estuary.

Overview Statement of the Problem Study Site Methodology and Numerical Modeling Results and Discussion Conclusions Next Steps

Importance of Wind Resolution in Hydrodynamics Modeling Using high resolution WRF model for forecasting wind is computationally expensive Could we develop a new method that deals with wind over land that is not as expensive as WRF? ADCIRC hydrodynamics model is able to do the downscaling. Does ADCIRC perform well in the regions where we have the land mask? What are the errors involved? The resolution of the wind inputted to a hydrodynamics model is very important to truly estimate the circulation, water level and strength of the current. The more the resolution the better the forecast, but it is computationally expensive to come up with a high resolution WRF model…. What are the error involves with ADCIRC? To answer these questions, 3 different test cases with different wind resolutions are studied which will be explain in further slides…

Indian River Lagoon Length: 250 Km Width: 2- 4 km Average Depth: 1.2 m Max. Depth: 4 m Inlet You heard a lot about the IRL earlier in the conference.

Methodology Initial Grid WRF GFS SMS Meteorological Forcing Modified Grid ADCIRC So here is our approach to study the effect of wind resolution on our hydrodynamics model. SMS: has a graphical user interface for developing computational grids and we used it for grid refinement in the vicinity of inlets and channels… WRF: modeling different resolution of winds Elevation Time-series

Addition of the Causeways Grid Development Addition of the Causeways Eau Gallie Causeway Pineda Causeway Railroad bridge Nasa Causeway 528 Causeway Merritt Island Causeway The maximum resolution in the IRL was in the order of 100 m and this resolution was not enough in the vicinity of the inlets and in narrow canals like the Barge Canal that have a width of 80 m. the environmental impacts of these causeways on the IRL have been debated for many years (Morris et al., 2003). The causeways can restrict normal flow of water and alter local circulation patterns. In this study, the causeways along the IRL Since some of the causeways are narrow, the minimum edge size of the mesh is reduced down to 30 meters. Titusville Causeway Melbourne Causeway

The Final High Resolution IRL EC95d northwest Atlantic domain. The final grid has: 160 000 nodes 309, 000 elements

ADCIRC Simulations Wind-only Simulation: WRF Low Resolution Wind 3 series of wind only simulations with run time of 3 days (March 5th to 8th, 2015) Wind-only Simulation: WRF Low Resolution Wind Spatial Resolution: 0.1 deg. Temporal Resolution: 3 hrs Wind-only Simulation: WRF High Resolution Wind Spatial Resolution: 0.005 deg. Temporal Resolution: 3 hrs Wind-only Simulation: WRF Low Res. Wind with the addition of ADCIRC’s reduction factors Surface Canopy Surface Directional Roughness

Wind Speed difference between hi-res and low-res WRF runs

Depiction of Wind Speed difference B Red means hi-res WRF run has faster wind speeds. Blue means low-res WRF run has faster wind speeds.

Time-series of Wind Speed Difference Point A Point A- resolved as land in the LO-RES WRF run. Much higher wind speeds in the hi-res WRF throught the event.

Time-series of Wind Speed Difference at Point B Point B – Resolved as Water in LO-RES run but land in HI-RES run. Much lower wind speeds in the hi-res WRF throught the event. B … and we are going to see how does this difference are being reflected in our hydrodynamic model as we force our model with these winds…

Elevation Time-series at Point A Because Point A was resolved as land in the lo-res wind, due to the land mask we have the adcirc double downscales the wind as a result adcirc elevation is as low as lo-res wind…

Elevation Time-series at Point B

Validation

Summary and Conclusion In the regions LO-RES wind has the land mask the downscaling with ADCIRC is doubling the downscaling The wind magnitude is being underestimated and causes error in forecasting In the regions LO-RES wind has no land mask the downscaling with ADCIRC is working properly Could we develop an integrated approach by using WRF model where we have land mask and use ADCIRC to reduce the wind where we don’t have land mask? Could the meteorologists give us a potential wind file where there is land mask, so that ADCIRC do the downscaling?

ST. Johns River Water Management District Acknowledgement I’d like to thank NOAA CSTAR for funding our research NOAA Collaborative Science, Technology, and Applied Research (CSTAR) Program grant #NA14NWS4680014 Department of Marine and Environmental Systems at the Florida Institute of Technology ST. Johns River Water Management District

References Smith, N. P. 1996. Tidal and Low Frequency Flushing of a Coastal Lagoon Using a Flexible Grid Model. Coastal and Estuarine Studies, 50, 171-183. www.earth.google.com Luettich, Rick A., Westerink, J. J., & Schener, Norman W. 1992. ADCIRC: An Advanced three-dimensional circulation model for shelves, coasts and estuaries, report 1: theory and methodology of ADCIRC-2DDI and ADCIRC-3DL. Tech. Rept. Dredging Research Program, DRP. Zundel, Alan K. 2006. Surface-water Modeling System reference manual: Version 9.2. Brigham Young University Environmental Modeling Research Laboratory.

Thank You Any Question?