A5017911926- Climate variability and models
- Tropical and Extratropical Cyclones Research
- Meteorological Phenomena and Simulations
- Oceanographic and Atmospheric Processes
- Ocean Waves and Remote Sensing
- Geophysics and Gravity Measurements
- Atmospheric aerosols and clouds
- Precipitation Measurement and Analysis
- Advanced Control Systems Optimization
- Atmospheric and Environmental Gas Dynamics
- Aeolian processes and effects
- Spacecraft and Cryogenic Technologies
- demographic modeling and climate adaptation
- Arctic and Antarctic ice dynamics
- Geomagnetism and Paleomagnetism Studies
- Atmospheric chemistry and aerosols
- Marine and coastal ecosystems
- Gas Dynamics and Kinetic Theory
- Climate Change Policy and Economics
- Advanced Mathematical Modeling in Engineering
- Geological formations and processes
- Solar Radiation and Photovoltaics
- Aquatic and Environmental Studies
- Data Management and Algorithms
- Advanced Thermodynamics and Statistical Mechanics
National Oceanic and Atmospheric Administration
2009-2024
University of Colorado Boulder
2009-2023
Cooperative Institute for Research in Environmental Sciences
2013-2023
NOAA Physical Sciences Laboratory
2017-2023
NOAA Earth System Research Laboratory
2007-2020
NOAA Chemical Sciences Laboratory
2020
Physical Sciences (United States)
2013-2015
NSF National Center for Atmospheric Research
2009
Colorado State University
2000-2001
Abstract Two univariate indices of the Madden–Julian oscillation (MJO) based on outgoing longwave radiation (OLR) are developed to track convective component MJO while taking into account seasonal cycle. These compared with all-season Real-time Multivariate (RMM) index Wheeler and Hendon derived from a multivariate EOF circulation OLR. The gross features OLR composite MJOs similar regardless index, although RMM is characterized by stronger circulation. Diversity in amplitude phase individual...
Abstract The evolution of total cloud cover and types is composited across the Madden–Julian oscillation (MJO) using CloudSat data for June 2006–May 2010. Two approaches are used to define MJO phases: 1) local phase determined at each longitude time from filtered outgoing longwave radiation, 2) global defined a popular real-time multivariate (RMM) index, which assigns tropics an day. In terms phase, results show familiar type predominance: in growing stages shallow clouds coexist with deep,...
Abstract This paper describes an analysis of large-scale [O(1000 km)] convectively coupled gravity waves simulated using a two-dimensional cloud-resolving model. The develop spontaneously under uniform radiative cooling and approximately zero-mean-flow conditions, with wavenumber 2 the domain appearing most prominently right-moving components dominating over left-moving for random reasons. discretizes model output in two ways. First, vertical-mode transform projects profiles winds,...
Abstract Multiscale convective wave disturbances with structures broadly resembling observed tropical waves are found to emerge spontaneously in a nonrotating, two-dimensional cloud model forced by uniform cooling. To articulate the dynamics of these waves, outputs objectively analyzed discrete truncated space consisting three types (shallow convective, deep and stratiform) dynamical vertical wavelength bands. Model experiments confirm that diabatic processes stratiform regions essential...
Abstract Weather forecasts made with imperfect models contain state‐dependent errors. Data assimilation (DA) partially corrects these errors new information from observations. As such, the corrections, or “analysis increments,” produced by DA process embed about model An attempt is here to extract that improve numerical weather prediction. Neural networks (NNs) are trained predict corrections systematic error in National Oceanic and Atmospheric Administration's FV3‐GFS based on a large set...
Abstract A three-dimensional cloud-resolving model, maintained in a statistically steady convecting state by tropics-like forcing, is subjected to sudden (10 min) stimuli consisting of horizontally homogeneous temperature and/or moisture sources with various profiles. Ensembles simulations are used increase the statistical robustness results and assess deterministic nature model response for domain sizes near contemporary global resolution. The middle- upper-tropospheric perturbations...
Abstract The coupling between tropical convection and zonally propagating gravity waves is assessed through Fourier analysis of high-resolution (3-hourly, 0.5°) satellite rainfall data. Results show the familiar enhancement in power along dispersion curves equatorially trapped inertia–gravity with implied equivalent depths range 15–40 m (i.e., pure wave speeds 12–20 s−1). Here, such signals are seen to extend all way down zonal wavelengths around 500 km periods 8 h, suggesting that...
This study evaluates the performance of a regional climate model in simulating two types synoptic tropical weather disturbances: convectively-coupled Kelvin and easterly waves. Interest these wave modes stems from their potential predictability out to several weeks advance, as well strong observed linkage between waves cyclogenesis. The is recent version research forecast (WRF) system with 36-km horizontal grid spacing convection parameterized using scheme that accounts for key convective...
Abstract Recent theories of the dynamics Madden‐Julian Oscillation (MJO) have been building on its multiscale structure. While it is observed that much convection within MJO envelope related to higher frequency equatorial waves, not known what extent this organization systematic from one event another. For instance, interest know whether favors waves particular types and propagation direction, how variability changes seasonally. This work presents a wavenumber‐frequency spectral analysis...
High-resolution global simulations over zonally symmetric aqua planets are examined using Fourier analysis in the zonal direction. We highlight tropics, where large-scale weather consists of convectively-coupled waves so that explicit convection is an especially topical novelty.Squared differences between pairs runs grow from initially tiny values to saturation at twice climatological variance. For wavelengths shorter than 103 km, saturate within about a day. tropical long waves, time...
Abstract This paper describes a general method for the treatment of convective momentum transport (CMT) in large‐scale dynamical solvers that use cyclic, two‐dimensional (2‐D) cloud‐resolving model (CRM) as “superparameterization” convective‐system‐scale processes. The approach is similar concept to traditional parameterizations CMT, but with distinction both scalar and diagnostic pressure gradient force are calculated using information provided by 2‐D CRM. No assumptions therefore made...
Abstract The organization of tropical convection is assessed through an object-based analysis satellite brightness temperature data Tb, a proxy for convective activity. involves the detection contiguous cloud regions (CCRs) in three-dimensional space latitude, longitude, and time where Tb falls below given threshold. A range thresholds considered only CCRs that satisfy minimum size constraint are retained analysis. Various statistical properties documented including their zonal speed...
Abstract Numerous studies using both global and regional models of the atmosphere have found daunting sensitivities structure dynamics intertropical convergence zone (ITCZ) to representations unresolved processes, particularly convective parameterization (CP). Evaluations these results by comparison high‐resolution simulations with explicit convection been rather limited, due large computational burden grid spacings less than 10 km over domains representative Earth's tropics. This study...
Abstract There is a longstanding challenge in numerical weather and climate prediction to accurately model tropical wave variability, including convectively coupled equatorial waves (CCEWs) the Madden–Julian oscillation. For subseasonal prediction, European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS) has been shown be superior NOAA Global Forecast (GFS) simulating suggesting that ECMWF better at interaction between cumulus convection large-scale...
Abstract Forecasts by mid-2015 for a strong El Niño during winter 2015/16 presented an exceptional scientific opportunity to accelerate advances in understanding and predictions of extreme climate event its impacts while the was ongoing . Seizing this opportunity, National Oceanic Atmospheric Administration (NOAA) initiated Rapid Response (ENRR), conducting first field campaign obtain intensive atmospheric observations over tropical Pacific Niño. The overarching ENRR goal determine response...
Abstract In the atmosphere, convection can organize from smaller scale updrafts into more coherent structures on various scales. bulk‐plume cumulus parameterizations, this type of organization has to be represented in terms how resolved flow would “feel” if were present subgrid. This subgrid acts as building blocks for larger tropical convective known modulate local and remote weather. work a parameterization (and cross‐grid) scheme is proposed using stochastic, self‐organizing, properties...
Abstract A global model with superparameterized physics is used to shed light on the observed regionality of convectively coupled Kelvin waves and Madden‐Julian Oscillation (MJO). series aquaplanet simulations over zonally uniform sea‐surface temperatures performed, in which axisymmetric structure background zonal flow altered through nudging, while maintaining a quasi‐fixed rainfall climatology. Results show that nudging at equator match profiles typical Indo‐Pacific or eastern Pacific...
Three idealized simulations of thunderstorm outflows are presented. Each outflow is a response to an instantaneous low-level cooling. The vertical structures the coolings differ as do environments in which form, and consequently dynamics differ. One gravity current, another wave, third comprises both current wave. horizontal transport mass important for advance gravity-current outflow, but not wave it suggested that this defining dynamical distinction between two outflows. compared...
Abstract Observational evidence of two extratropical pathways to forcing tropical convective disturbances is documented through a statistical analysis satellite-derived OLR and ERA5 reanalysis. The mechanism the resulting are found strongly depend on structure background zonal wind. Although Rossby wave propagation prohibited in easterlies, modeling studies have shown that can still excite equatorial waves resonance between tropics extratropics. Here this “remote” pathway investigated for...
Abstract A set of 30-day reforecast experiments, focused on the Northern Hemisphere (NH) cool season (November–March), is performed to quantify remote impacts tropical forecast errors National Centers for Environmental Prediction (NCEP) global system (GFS). The approach nudge model towards reanalyses in tropics and then measure change skill at higher latitudes as function lead time. In agreement with previous analogous studies, results show that midlatitude predictions tend be improved...
Abstract The composite structure of the Madden–Julian oscillation (MJO) has long been known to feature pronounced Rossby gyres in subtropical upper troposphere, whose existence can be interpreted as forced response convective heating anomalies presence a westerly jet. question interest here is whether these gyre circulations have any subsequent effects on divergence patterns tropics and Kelvin-mode component MJO. A nonlinear spherical shallow water model used investigate how introduction...
Abstract Convectively coupled Kelvin waves (CCKWs) represent a significant contribution to the total variability of Intertropical Convergence Zone (ITCZ). This study analyzes structure and propagation CCKWs simulated by Weather Research Forecasting (WRF) model using two types idealized domains. These are “aquachannel,” flat rectangle on beta plane with zonally periodic boundary conditions length equal Earth's circumference at equator, “aquapatch,” square domain zonal extent one third...
Abstract Boreal‐wintertime hindcasts in the Unified Forecast System with tropics nudged toward reanalysis improve United States (US) West Coast precipitation forecasts at Weeks 3–4 lead times when compared to those without nudging. To diagnose origin of these improvements, a multivariate k‐means clustering method is used group into subsets by their initial conditions. One cluster characterized an initially strong Aleutian Low demonstrates larger improvements nudging others. The greater for...