The Data Assimilation Research Testbed (DART) is an open-source community facility for data assimilation education, research, and development. DART's ensemble algorithms, careful software engineering, diagnostic tools allow atmospheric scientists, oceanographers, hydrologists, chemists, other geophysicists to build state-of-the-art systems with unprecedented ease. For global numerical weather prediction, DART produces ensemble-mean analyses comparable from major centers while also providing...

Many applications exist within the fields of agriculture, forestry, land management, and hydrologic assessment for routine estimation surface energy fluxes, particularly evapotranspiration (ET), at spatial resolutions order 10 1 m. A new two‐step approach (called disaggregated atmosphere exchange inverse model, or DisALEXI) has been developed to combine low‐ high‐resolution remote sensing data estimate ET on –10 2 m scale without requiring any local observations. The first step uses...

Disaggregation of regional-scale (103 m) flux estimates to micrometeorological scales (101–102 facilitates direct comparison between land surface models and ground-based observations. Inversely, it also provides a means for upscaling flux-tower information into regional context. The utility the Atmosphere–Land Exchange Inverse (ALEXI) model associated disaggregation technique (DisALEXI) in effecting local downscaling is demonstrated an application thermal imagery collected with Geostationary...

Abstract One aspect of implementing a limited-area ensemble Kalman filter (EnKF) involves the specification suitable lateral boundary conditions. Two classes methods to populate condition are proposed. In first class, conditions is provided by an EnKF on larger domain and approximately random draw from probability distribution function for forecast (or analysis) boundary. The second class perturbs around deterministic estimate state using assumed spatial temporal covariance relationships....

Abstract The sensitivity of forecasts to observations is evaluated using an ensemble approach with data drawn from a pseudo-operational Kalman filter. For Gaussian statistics and forecast metric defined as scalar function the variables, effect on quantified by changes in mean variance. single observation, expressions for these involve product quantities, which can be rapidly large numbers observations. This technique applied determining climatological predicting impact sea level pressure...

The principal hypotheses of a new model tropical cyclogenesis, known as the marsupial paradigm, were tested in context Atlantic disturbances during National Science Foundation (NSF)-sponsored Pre-Depression Investigation Cloud Systems Tropics (PREDICT) experiment 2010. PREDICT was part tri-agency collaboration, along with Aeronautics and Space Administration's Genesis Rapid Intensification Processes (NASA GRIP) Oceanic Atmospheric Intensity Forecasting Experiment (NOAA IFEX), intended to...

Abstract With the growing use of tropical cyclone (TC) best-track information for weather and climate applications, it is important to understand uncertainties that are contained in TC position intensity information. Here, an attempt made quantify uncertainty using National Hurricane Center (NHC) advisory information, as well during times without aircraft data, by verifying Dvorak minimum sea level pressure (SLP) maximum wind speed estimates with reconnaissance 2000–09. In a climatological...

Abstract Although infrequent, tropical cyclones (TCs) can intensify under moderate vertical wind shear (VWS). A potential hypothesis is that other factors—associated with both the TC and its environment—can help offset effects of VWS aid intensification. This was tested a large dataset 6-hourly best tracks environmental diagnostics for global TCs between 1982 2014. Moderate objectively defined as 4.5–11.0 m s−1, which represents 25th–75th percentiles distribution 200–850-hPa magnitude around...

Abstract The extratropical transition (ET) of tropical cyclones often has an important impact on the nature and predictability midlatitude flow. This review synthesizes current understanding dynamical physical processes that govern this highlights relationship downstream development during ET to high-impact weather, with a focus regions. It updates previous from 2003 identifies new emerging challenges future research needs. First, mechanisms through which transitioning cyclone impacts flow...

Abstract The representation of tropical cyclone track, intensity, and structure in a set 69 parallel forecasts performed at each two horizontal grid increments with the Advanced Research Hurricane (AHW) component Weather Forecasting Model (WRF) is evaluated. These covered 10 Atlantic cyclones: 6 from 2005 season 4 2007. were integrated identical initial conditions produced by cycling ensemble Kalman filter. high-resolution used moving, storm-centered nests 4- 1.33-km spacing....

Abstract An ensemble Kalman filter (EnKF) combined with the Advanced Research Weather and Forecasting model (ARW-WRF; hereafter WRF) on a 36-km Atlantic basin domain is cycled over six different time periods that include 10 tropical cyclones (TCs) selected for NOAA High-Resolution Hurricane (HRH) test. The analysis generated every 6 h by assimilating conventional in situ observations, synoptic dropsondes, TC advisory position minimum sea level pressure (SLP) data. On average, observation...

Since the advent of meteorological satellite, a large research effort within community earth scientists has been directed at assessing components land surface energy balance from space. The development these techniques first efforts to present time are reviewed, and integrated system used estimate radiative turbulent fluxes is described. This now running in real over continental United States resolution 10 km, producing daily time-integrated flux components.

The 2-yr performance of a pseudo-operational (real time) limited-area ensemble Kalman filter (EnKF) based on the Weather Research and Forecasting Model is described. This system assimilates conventional observations from surface stations, rawinsondes, Aircraft Communications Addressing Reporting System (ACARS), cloud motion vectors every 6 h domain that includes eastern North Pacific Ocean western America. Ensemble forecasts this deterministic output operational numerical weather prediction...

Abstract Medium-range forecasts of Hurricane Sandy’s track were characterized by widely diverging solutions, with some suggesting that Sandy would make landfall over the mid-Atlantic region United States, while others forecast storm to move due east north Bermuda. Here, dynamical processes responsible for eastward-tracking are diagnosed using an 80-member ensemble experimental Global Forecast System (GFS) initialized five days prior landfall. Comparing members tracks against those west...

Abstract The Mesoscale Predictability Experiment (MPEX) was conducted from 15 May to June 2013 in the central United States. MPEX motivated by basic question of whether experimental, subsynoptic observations can extend convective-scale predictability and otherwise enhance skill short-term regional numerical weather prediction. Observational tools for included National Science Foundation (NSF)–National Center Atmospheric Research (NCAR) Gulfstream V aircraft (GV), which featured Airborne...

Abstract The mechanisms responsible for tropical cyclone (TC) intensification in the presence of moderate vertical shear magnitudes are not well understood. To investigate how TCs intensify spite shear, this study employed a 96-member ensemble generated with Advanced Hurricane Weather Research and Forecasting (AHW) Model. In first part, AHW forecasts TC Katia (2011) were evaluated when was weak storm an environment 12 m s−1 easterly shear. 5-day characterized by large variability intensity,...

Abstract A major open issue in tropical meteorology is how and why some cyclones intensify under moderate vertical wind shear. This study tackles that by diagnosing physical processes of cyclone intensification a moderately sheared environment using 20-member ensemble idealized simulations. Consistent with previous studies, the shows onset largely depends on timing vortex tilt reduction symmetrization precipitation. new contribution this work process-based analysis following shear-induced...

Abstract The ability of Atmospheric Emitted Radiance Interferometer (AERI) and Doppler lidar (DL) wind profile observations to impact short-term forecasts convection is explored by assimilating retrievals into a partially cycled convection-allowing ensemble analysis forecast system. AERI DL were obtained over 12 days using mobile platform that was deployed in the preconvective near-storm environments thunderstorms during afternoon U.S. Great Plains. observation locations guided real-time...

Abstract Perturbations to the potential vorticity (PV) waveguide, which can result from latent heat release within warm conveyor belt (WCB) of midlatitude cyclones, lead downstream radiation Rossby waves, and in turn high-impact weather events. Previous studies have hypothesized that forecast uncertainty associated with diabatic heating WCBs large variability; however, these not established a direct connection between two. This study evaluates impact variability WCB on subsequent forecasts...

Abstract An ensemble Kalman filter based on the Weather Research and Forecasting (WRF) model is used to generate analyses forecasts for extratropical transition (ET) events associated with Typhoons Tokage (2004) Nabi (2005). Ensemble sensitivity analysis then evaluate relationship between forecast errors initial condition at onset of transition, objectively determine observations having largest impact these storms. Observations from rawinsondes, surface stations, aircraft, cloud winds,...

Abstract An ensemble Kalman filter (EnKF) based on the Weather Research and Forecasting model is applied to generate analyses forecasts of Hurricane Katrina (2005) surrounding area every 6 h over lifetime storm a nested domain. Analyses are derived from assimilating conventional in situ observations, reconnaissance dropsondes, including data taken during Rainband Intensity Exchange Experiment (RAINEX), tropical cyclone position estimates. Observation assimilation at individual times...

ABSTRACT Accurate tropical cyclone (TC) track forecasts depend on having skillful numerical model predictions of the environmental wind field. Given that and temperature are related through thermal balance, structural errors in processes determine profile, such as shallow convection, can therefore lead to biases TC position. This paper evaluates influence convection Advanced Hurricane Weather Research Forecasting Model (AHW) by cycling an ensemble data assimilation during a 1-month period...

Abstract The dynamical mechanisms that led to downstream ridging during the extratropical transition (ET) of Typhoons Tokage and Nabi are evaluated using data drawn from a cycling ensemble Kalman filter coupled with Weather Research Forecasting Model (WRF). During both transitions, covariances indicate 350-K potential vorticity (PV) at apex ridge, which is used define ridge structure, proportional amount precipitation along baroclinic zone northeast tropical cyclone (TC), some times...

Abstract Real-time analyses and forecasts using an ensemble Kalman filter (EnKF) the Advanced Hurricane Weather Research Forecasting Model (AHW) are evaluated from 2009 North Atlantic hurricane season. This data assimilation system involved cycling observations that included conventional in situ data, tropical cyclone (TC) position, minimum SLP synoptic dropsondes each 6 h a 96-member on 36-km domain for three months. Similar to past studies, observation systematically reduces TC position...

Abstract An ensemble of Weather Research and Forecasting Model (WRF) forecasts initialized from a cycling Kalman filter (EnKF) system is used to evaluate the sensitivity Hurricanes Danielle Karl’s (2010) genesis vortex environmental initial conditions via analysis. Both Karl are sensitive 0-h circulation associated with pregenesis over deep layer temperature water vapor mixing ratio within comparatively shallow layer. Empirical orthogonal functions (EOFs) kinematic thermodynamic fields...