OSSE impact analysis of airborne ocean surveys for improving upper-ocean dynamical and thermodynamical forecasts in the Gulf of Mexico

Abstract A prototype, rigorously validated ocean Observing System Simulation Experiment (OSSE) system is used to evaluate the impact of different sampling strategies for rapid-response airborne ocean profile surveys in the eastern interior Gulf of Mexico. Impacts are assessed with respect to improving ocean analyses, and forecasts initialized from those analyses, for two applications: improving oil spill forecasts and improving the ocean model response to tropical cyclone (TC) forcing. Rapid model error growth in this region requires that repeat surveys be conducted frequently in time, with separation of less than 4 days required to approach maximum error reduction in model analyses. Substantial additional error reduction in model dynamical fields is achieved by deploying deep (1000 m) AXCTDs instead of shallow (400 m) AXBTs. Shallow AXBTs constrain the ocean thermal field over the upper 400 m nearly as well as deep AXCTDs. However, in addition to constraining ocean fields over a greater depth range, AXCTDs also measure salinity profiles and more accurately constrain upper-ocean density than AXBTs, leading to a more accurate representation of upper ocean pressure and velocity fields. Sampling AXCTD profiles over a one-half degree array compared to one degree leads to substantial additional error reduction by constraining variability with horizontal scales too small to be corrected by satellite altimetry assimilation. A 2-day lag in availability of airborne profiles does not increase errors in dynamical ocean fields, but it does increase errors in upper-ocean thermal field including Tropical Cyclone Heat Potential (TCHP), demonstrating that these profiles must be rapidly made available for assimilation to improve TC forecasts. The additional error reduction in ocean analyses achieved by assimilation of airborne surveys translates into significantly improved forecasts persisting over time intervals ranging between 1 and 2 weeks for most model variables but several weeks for TCHP. In particular, upper-ocean temperature forecasts can be significantly improved for an extended interval of time by conducting airborne profile surveys.

[1]  E. Uhlhorn,et al.  Loop Current Mixed Layer Energy Response to Hurricane Lili (2002). Part II: Idealized Numerical Simulations , 2013 .

[2]  L. Shay,et al.  The Response of Quasigeostrophic Oceanic Vortices to Tropical Cyclone Forcing , 2011 .

[3]  Robert Atlas,et al.  Rigorous Evaluation of a Fraternal Twin Ocean OSSE System for the Open Gulf of Mexico , 2014 .

[4]  C. Schultz.  Monitoring and Modeling the Deepwater Horizon Oil Spill: A Record‐Breaking Enterprise , 2013 .

[5]  P. Black,et al.  Real-Time Upper-Ocean Temperature Observations from Aircraft during Operational Hurricane Reconnaissance Missions: AXBT Demonstration Project Year One Results , 2013 .

[6]  L. Shay,et al.  Oceanic heat content variability in the eastern pacific ocean for hurricane intensity forecasting , 2010 .

[7]  A. H. Murphy,et al.  Skill Scores Based on the Mean Square Error and Their Relationships to the Correlation Coefficient , 1988 .

[8]  D. Roemmich.  Ocean Heat Content , 2011 .

[9]  Robert Atlas,et al.  Atmospheric Observations and Experiments to Assess Their Usefulness in Data Assimilation , 1997 .

[10]  Gary B. Brassington,et al.  APPLICATIONS OF GODAE OCEAN CURRENT FORECASTS TO SEARCH AND RESCUE AND SHIP ROUTING , 2009 .

[11]  John A. Knaff,et al.  Further improvements to the Statistical Hurricane Intensity Prediction Scheme (SHIPS) , 2005 .

[12]  Chuanmin Hu,et al.  Tracking the Deepwater Horizon Oil Spill: A Modeling Perspective , 2011 .

[13]  N. Walker,et al.  The dynamics of the Mississippi River plume: Impact of topography, wind and offshore forcing on the fate of plume waters , 2011 .

[14]  L. Shay,et al.  Development and analysis of the systematically merged atlantic regional temperature and salinity climatology for oceanic heat content estimates , 2014 .

[15]  Keith Haines,et al.  Altimetric assimilation with water property conservation , 1996 .

[16]  Clifford H. Dey,et al.  Observing-Systems Simulation Experiments: Past, Present, and Future , 1986 .

[17]  Robert Atlas,et al.  Impact Of Satellite Temperature Sounding And Wind Data On Numerical Weather Prediction , 1985 .

[18]  E. Uhlhorn,et al.  Loop Current Mixed Layer Energy Response to Hurricane Lili (2002). Part I: Observations , 2012 .

[19]  Douglas Volgenau.  Hurricane Heat Potential of the Gulf of Mexico , 1972 .

[20]  Rainer Bleck,et al.  An oceanic general circulation model framed in hybrid isopycnic-Cartesian coordinates , 2002 .

[21]  V. Kourafalou,et al.  Simulating the dynamics and intensification of cyclonic Loop Current Frontal Eddies in the Gulf of Mexico , 2012 .

[22]  G. Halliwell,et al.  Evaluation of vertical coordinate and vertical mixing algorithms in the HYbrid-Coordinate Ocean Model (HYCOM) , 2004 .

[23]  A. Barth,et al.  Impact of GODAE products on nested HYCOM simulations of the West Florida Shelf , 2009 .

[24]  Benjamin Jaimes,et al.  Airborne Ocean Surveys of the Loop Current Complex From NOAA WP-3D in Support of the Deepwater Horizon Oil Spill , 2013 .

[25]  Gustavo Goni,et al.  Application of Oceanic Heat Content Estimation to Operational Forecasting of Recent Atlantic Category 5 Hurricanes , 2008 .

[26]  E. Uhlhorn,et al.  Loop Current Response to Hurricanes Isidore and Lili , 2008 .

[27]  K. Taylor.  Summarizing multiple aspects of model performance in a single diagram , 2001 .

[28]  S. Tav O G O N I, M A R K D E M A R I A,et al.  Applications of Satellite-Derived Ocean Measurements to Tropical Cyclone Intensity Forecasting , 2009 .

[29]  Assimilating 20 years of Atlantic XBT data into HYCOM: a first look , 2004 .

[30]  R. Weisberg,et al.  Evaluation of Global Ocean Data Assimilation Experiment products on South Florida nested simulations with the Hybrid Coordinate Ocean Model , 2009 .

[31]  Eric P. Chassignet,et al.  North Atlantic Simulations with the Hybrid Coordinate Ocean Model (HYCOM): Impact of the Vertical Coordinate Choice, Reference Pressure, and Thermobaricity , 2003 .

[32]  J. Price.  Metrics of hurricane-ocean interaction: vertically-integrated or vertically-averaged ocean temperature? , 2009 .

[33]  Robert Atlas,et al.  Simulation studies of the impact of future observing systems on weather prediction , 1985 .

[34]  Gustavo Goni,et al.  Effects of a Warm Oceanic Feature on Hurricane Opal , 2000 .

[35]  G. Madec,et al.  Assessing the oceanic control on the amplitude of sea surface cooling induced by tropical cyclones , 2012 .

[36]  J. Knaff,et al.  Ocean heat content for tropical cyclone intensity forecasting and its impact on storm surge , 2013, Natural Hazards.