Richard M. Yablonsky

Limitation of One-Dimensional Ocean Models for Coupled Hurricane-Ocean Model Forecasts

Abstract Wind stress imposed on the upper ocean by a hurricane can limit the hurricane’s intensity primarily through shear-induced mixing of the upper ocean and subsequent cooling of the sea surface. Since shear-induced mixing is a one-dimensional process, some recent studies suggest that coupling a one-dimensional ocean model to a hurricane model may be sufficient for capturing the storm-induced sea surface temperature cooling in the region providing heat energy to the hurricane. Using both a one-dimensional and a three-dimensional version of the same ocean model, it is shown here that the neglect of upwelling, which can only be captured by a three-dimensional ocean model, underestimates the storm-core sea surface cooling for hurricanes translating at <∼5 m s−1. For hurricanes translating at <2 m s−1, more than half of the storm-core sea surface cooling is neglected by the one-dimensional ocean model. Since the majority of hurricanes in the western tropical North Atlantic Ocean translate at <5 m s−1, the...

Improving the Ocean Initialization of Coupled Hurricane–Ocean Models Using Feature-Based Data Assimilation

Abstract Coupled hurricane–ocean forecast models require proper initialization of the ocean thermal structure. Here, a new feature-based (F-B) ocean initialization procedure in the GFDL/University of Rhode Island (URI) coupled hurricane prediction system is presented to account for spatial and temporal variability of mesoscale oceanic features in the Gulf of Mexico, including the Loop Current (LC), Loop Current eddies [i.e., warm-core rings (WCRs)], and cold-core rings (CCRs). Using only near-real-time satellite altimetry for the “SHA-assimilated” case, the LC, a single WCR, and a single CCR are assimilated into NAVOCEANO’s Global Digitized Environmental Model (GDEM) ocean temperature and salinity climatology along with satellite-derived daily sea surface temperature (SST) data from 15 September 2005 to produce a more realistic three-dimensional temperature field valid on the model initialization date (15 September 2005). For the “fully assimilated” case, both near-real-time altimetry and real-time in sit...

Impact of a Warm Ocean Eddy's Circulation on Hurricane-Induced Sea Surface Cooling with Implications for Hurricane Intensity

AbstractUpper oceanic heat content (OHC) in advance of a hurricane is generally superior to prestorm sea surface temperature (SST) for indicating favorable regions for hurricane intensification and maintenance. OHC is important because a hurricane’s surface winds mix the upper ocean and entrain cooler water into the oceanic mixed layer from below, subsequently cooling the sea surface in the region providing heat energy to the storm. For a given initial SST, increased OHC typically decreases the wind-induced sea surface cooling, and a warm ocean eddy (WCR) has a higher OHC than its surroundings, so conditions typically become more favorable for a hurricane to intensify when the storm’s core encounters a WCR. When considering hurricane intensity, however, one often-neglected aspect of a WCR is its anticyclonic circulation. This circulation may impact the location and magnitude of the hurricane-induced sea surface cooling. Using an ocean model, either prescribed hurricane wind stress or wind stress obtained ...

Description and Analysis of the Ocean Component of NOAA’s Operational Hurricane Weather Research and Forecasting Model (HWRF)

AbstractThe Princeton Ocean Model for Tropical Cyclones (POM-TC), a version of the three-dimensional primitive equation numerical ocean model known as the Princeton Ocean Model, was the ocean component of NOAA’s operational Hurricane Weather Research and Forecast Model (HWRF) from 2007 to 2013. The coupled HWRF–POM-TC system facilitates accurate tropical cyclone intensity forecasts through proper simulation of the evolving SST field under simulated tropical cyclones. In this study, the 2013 operational version of HWRF is used to analyze the POM-TC ocean temperature response in retrospective HWRF–POM-TC forecasts of Atlantic Hurricanes Earl (2010), Igor (2010), Irene (2011), Isaac (2012), and Leslie (2012) against remotely sensed and in situ SST and subsurface ocean temperature observations. The model generally underestimates the hurricane-induced upper-ocean cooling, particularly far from the storm track, as well as the upwelling and downwelling oscillation in the cold wake, compared with observations. No...

Community Support and Transition of Research to Operations for the Hurricane Weather Research and Forecasting Model

AbstractThe Hurricane Weather Research and Forecasting Model (HWRF) is an operational model used to provide numerical guidance in support of tropical cyclone forecasting at the National Hurricane Center. HWRF is a complex multicomponent system, consisting of the Weather Research and Forecasting (WRF) atmospheric model coupled to the Princeton Ocean Model for Tropical Cyclones (POM-TC), a sophisticated initialization package including a data assimilation system and a set of postprocessing and vortex tracking tools. HWRF’s development is centralized at the Environmental Modeling Center of NOAA’s National Weather Service, but it incorporates contributions from a variety of scientists spread out over several governmental laboratories and academic institutions. This distributed development scenario poses significant challenges: a large number of scientists need to learn how to use the model, operational and research codes need to stay synchronized to avoid divergence, and promising new capabilities need to be ...

Ocean modeling with flexible initialization for improved coupled tropical cyclone-ocean model prediction

This paper introduces the Message Passing Interface Princeton Ocean Model for Tropical Cyclones (MPIPOM-TC), created at the University of Rhode Island (URI). MPIPOM-TC is derived from a combination of the parallelized version of the Princeton Ocean Model (POM), called the Stony Brook Parallel Ocean Model (sbPOM), and URIs non-parallelized POM for Tropical Cyclones (POM-TC), which has been used for many years as the ocean component of NOAAs and the U.S. Navys operational hurricane forecast models. In addition to parallelization, the flexible initialization capabilities of MPIPOM-TC and other elements of its architecture will facilitate further improvements to the ocean component of research-based and operational tropical cyclone (hurricane) forecast models worldwide. Display Omitted MPIPOM-TC is a new, parallelized ocean model that merges POM-TC and sbPOM.MPIPOM-TC has flexible initialization options and worldwide regional domains.MPIPOM-TC can be used for both research-based and operational hurricane prediction.MPIPOM-TC can be configured and initialized for both real and idealized hurricanes.MPIPOM-TC can be configured with full 3-D dynamics or simplified 1-D dynamics.

Hurricane Weather Research and Forecasting (HWRF) Model: 2017 Scientific Documentation

1NOAA/NWS/NCEP Environmental Modeling Center, College Park, MD, 2NOAA Earth System Research Laboratory, CIRES / University of Colorado, and Developmental Testbed Center, Boulder, CO, 3National Center for Atmospheric Research and Developmental Testbed Center, Boulder, CO, 4University of Rhode Island, 5IMSG Inc, 6Geophysical Fluid Dynamics Laboratory, Princeton, NJ, 7Hurricane Research Division, AOML, Miami, FL,and RSMAS, CIMAS, University of Miami, Miami, FL