@article{gao_liu_ma_jacobs_childs_wang_2019, title={Variational Bias Correction of TAMDAR Temperature Observations in the WRF Data Assimilation System}, volume={147}, ISSN={["1520-0493"]}, DOI={10.1175/MWR-D-18-0025.1}, abstractNote={AbstractA variational bias correction (VarBC) scheme is developed and tested using regional Weather Research and Forecasting Model Data Assimilation (WRFDA) to correct systematic errors in aircraft-based measurements of temperature produced by the Tropospheric Airborne Meteorological Data Reporting (TAMDAR) system. Various bias models were investigated, using one or all of aircraft height tendency, Mach number, temperature tendency, and the observed temperature as predictors. These variables were expected to account for the representation of some well-known error sources contributing to uncertainties in TAMDAR temperature measurements. The parameters corresponding to these predictors were evolved in the model for a two-week period to generate initial estimates according to each unique aircraft tail number. Sensitivity experiments were then conducted for another one-month period. Finally, a case study using VarBC of a cold front precipitation event is examined. The implementation of VarBC reduces biases in TAMDAR temperature innovations. Even when using a bias model containing a single predictor, such as height tendency or Mach number, the VarBC produces positive impacts on analyses and short-range forecasts of temperature with smaller standard deviations and biases than the control run. Additionally, by employing a multiple-predictor bias model, which describes the statistical relations between innovations and predictors, and uses coefficients to control the evolution of components in the bias model with respect to their reference values, VarBC further reduces the average error of analyses and short-range forecasts with respect to observations. The potential impacts of VarBC on precipitation forecasts were evaluated, and the VarBC is able to indirectly improve the prediction of precipitation location by reducing the forecast error for wind-related synoptic circulation leading to precipitation.}, number={6}, journal={MONTHLY WEATHER REVIEW}, author={Gao, Feng and Liu, Zhiquan and Ma, Juhui and Jacobs, Neil A. and Childs, Peter P. and Wang, Hongli}, year={2019}, month={Jun}, pages={1927–1945} }
 @article{jacobs_raman_lackmann_childs_2008, title={The influence of the Gulf Stream induced SST gradients on the US East Coast winter storm of 24-25 January 2000}, volume={29}, ISSN={["0143-1161"]}, DOI={10.1080/01431160802175561}, abstractNote={This study presents an investigation of the influence of remotely sensed high resolution sea surface temperature (SST) and the SST gradient on the formation and evolution of the 24–25 January 2000 East Coast winter storm. A numerical model was employed for experimental simulation replaced SST analysis with a 1.1 km gridded data set. The most significant improvements were seen in the forecast deepening rate and track. Reduced development of the storm in the control simulation, as compared to the experimental simulation, appears to be due to the coarse grid SST representation, which fails to capture key thermal gradient features of the Gulf Stream. The simulations suggest that the high resolution remotely sensed SST data affect the track by changing the location of lower‐tropospheric frontal boundaries through thermally‐induced near‐surface convergence and differential turbulent heat flux. Enhanced vortex stretching associated with the convergence along the lower frontal boundary appears to contribute to a stronger storm in the experimental simulations.}, number={21}, journal={INTERNATIONAL JOURNAL OF REMOTE SENSING}, author={Jacobs, N. A. and Raman, S. and Lackmann, G. M. and Childs, P. P., Jr.}, year={2008}, pages={6145–6174} }
 @article{jacobs_lackmann_raman_2005, title={The combined effects of Gulf Stream-induced baroclinicity and upper-level vorticity on US east coast extratropical cyclogenesis}, volume={133}, ISSN={["1520-0493"]}, DOI={10.1175/MWR2969.1}, abstractNote={Abstract
               The Atlantic Surface Cyclone Intensification Index (ASCII) is a forecast index that quantifies the strength of low-level baroclinicity in the coastal region of the Carolinas. It is based on the gradient between the coldest 24-h average air temperature at Cape Hatteras and Wilmington, North Carolina, and the temperature at the western boundary of the Gulf Stream. The resulting prestorm baroclinic index (PSBI) is used to forecast the probability that a cyclone in the domain will exhibit rapid cyclogenesis. The initial ASCII study covered the years 1982–90. This dataset was recently expanded to cover the years 1991–2002, which doubled the number of cyclone events in the sample. These additional data provide similar position and slope of the linear regression fits to the previous values, and explain as much as 30% of the variance in cyclone deepening rate.
               Despite operational value, the neglect of upper-tropospheric forcing as a predictor in the original ASCII formulation precludes explanation of a large fraction of the deepening rate variance. Here, a modified index is derived in which an approximate measure of upper-level forcing is included. The 1991–2002 cyclone events were separated into bins of “strongly forced,” “moderately forced,” and “weakly forced” based on the strength of the nearest upstream maximum of 500-mb absolute vorticity associated with the surface low. This separation method reduced the scatter and further isolated the contributions of surface forcing versus upper-level forcing on extratropical cyclogenesis. Results of the combined upper-level index and surface PSBI demonstrate that as much as 74% of the deepening rate variance can be explained for cases with stronger upper-level forcing.}, number={8}, journal={MONTHLY WEATHER REVIEW}, author={Jacobs, NA and Lackmann, GM and Raman, S}, year={2005}, month={Aug}, pages={2494–2501} }