A Statistical Comparison of Small-Scale Features in Simulated Tropical Cyclones and High-Resolution Observational Data
Lynn Sparling and Samuel Trahan, Department of Physics, UMBC, and Scott Braun, NASA Goddard Space Flight Center
A Statistical Comparison of Small-Scale Features in Simulated Tropical Cyclones and High-Resolution Observational Data abstract: Over the past few decades, there has been significant improvement in tropical cyclone track prediction but not much improvement in intensity prediction. There is evidence that small-scale processes in the inner core may play an important role in hurricane intensity but these processes, and what triggers them, are only partially understood. The features – eyewall vorticity waves, mesovortices and hot towers – are on the order of kilometers wide and rapidly varying. Hence high-resolution models are thought to be necessary, but it is not clear how well high-resolution features in simulated tropical cyclones match those in the real world. It is also unclear what resolutions are necessary to allow a simulation to accurately model the effects of these features on the large-scale state.
This research uses WRF-based numerical weather prediction models to imulate tropical cyclones that have been observed to have periods of strong inner core activity. We compare statistical properties of high-resolution features in the simulation to the same statistical properties in observational data. Using that methodology, we analyze how these periods are represented in the model under different large-scale flow patterns and using different model resolutions and parameterizations.
An Assessment of the Physiographical Impacts in the Mid-Atlantic Region on the Marine Boundary Layer Wind Profile
Lynn Sparling, Department of Physics
Edward Strobach, Department of Physics
It is well understood that a need for continuously operating profiling instruments is critical for offshore regions. As of yet an observational network of this kind has not been established in the United States. Since offshore wind farm construction is expected within the next few years along the east coast, it becomes more important than ever to examine the spatiotemporal characteristics of the wind profile, and to determine the role that the broader meteorology and nearby physiography has on wind evolution. This is particularly evident when assessing both the wind profile and turbulence generation on power output.
A two-month study during the summer of 2013 provides a unique opportunity to analyze offshore wind in Maryland’s Wind Energy Area (MDWEA). Several case studies have been selected to understand how the physiography, like the Appalachian Mountains and land-sea coastal transitions, as well as large-scale systems, such as frontal boundaries, impacts wind in the marine boundary layer. In order to get a relative assessment of offshore shore v. onshore response, a broader network of instrumentation, which includes several onshore profiling platforms, are used for a spatial context of wind systems moving across the region. In addition, several models are also considered, such as North American Regional Reanalysis (NARR), Weather Research and Forecasting (WRF), and various trajectory models, to observe the timing of wind regimes entering MDWEA as well as to understand the properties of an air parcel as moves from on- to offshore.
Two main case studies are considered: July 19th – July 21st, 2013, and July 27th. The first involves the role of the Appalachian Mountains, with the first day occurring under ‘light synoptic’ conditions, while the second two days occur under ‘strong synoptic’ conditions. The second case study centers around a sea breeze event during the late afternoon. A Doppler LIDAR and radiometer is used to capture the small scale changes, both along the vertical and with turbulent generation, as the new wind regime crosses MDWEA. It is found that each case results in significant changes in the wind profile that would substantially impact power output and possibly turbine integrity.
Improving estimates of CO emissions from biomass burning using FRP and its applicability to atmospheric models
Lynn Sparling, Department of Physics
Thishan Dharshana Karandana Gamalathge, Department of Physics
Ray Hoff, Department of Physics
Vanderlei Martins, Department of Physics
Charles Ichoku, NASA
Biomass burning is getting increasing attention because large areas of the globe burn each year, and these fires emit large amounts of smoke and trace gases. In an attempt to find a relationship between total carbon monoxide (CO) production and fire radiative energy (FRE), a previous study has found proportionality between these two variables with a relatively high correlation coefficient. However, that study was performed under laboratory conditions, which might not replicate actual conditions in forest fires. In our work, we are using CO total columns retrieved from Terra-MOPITT and fire radiative power (FRP) measurements from Terra-MODIS to investigate a similar relationship for actual landscape fires. As a preliminary study for this task, we selected a few prominent fires that were observed from the Terra satellite. Interestingly, based on the analysis so far for the California fires in 2007, we have seen a convincing graphical association between CO total
column and FRP. Once the process is completed for other fires, we are planning on utilizing this quantitative relationship between CO emission rates and FRP to derive CO emissions from fires globally for use in atmospheric models to forecast CO distribution. In this way, we will help improve forecast tools for biomass burning emissions, based on satellite data, which we can access in near real time. Moreover, this would positively contribute to the estimates of biomass burning contribution to global warming.
Analysis of Extra-Tropical Hurricane Transition using the Lagrangian Frame
Lynn Sparling and Ross Dixon, UMBC Department of Physics, and Jeffrey Halverson, UMBC Department of Geography and Environmental Science
Our goal is to better predict intensity changes and forecast extreme precipitation events in the extra-tropical transition of hurricanes. Freshwater flooding is the number one killer associated with land falling hurricanes. Our approach uses the North American Regional Reanalysis to examine fields such as potential vorticity, diabatic heating, and frontogenesis. Because these fields vary to a large degree temporally and spatially, we intend to run trajectories in order to view the evolution of these fields in a Lagrangian frame.