Black Research Program: General Approach

Black Research Program: General Approach  Characterization, dynamical diagnosis, and validationof the life cycles of extratropical meteorological phenomena • Characterization:Assess statistics, structure & evolution Dynamical Diagnosis: Use dynamical theory to develop mathematical diagnostic tools that are then applied to phenomenological life cycles to test mechanistic hypotheses Validation:Validate life cycle characteristics and dynamical mechanisms in climate models and various reanalysis datasets  Nature of Research:Computational analysis of large multi-dimensional datasets (observations & climate simulations) Datasets: Reanalysis datasets & climate simulation output

Jet Streams in the Extratropical Atmosphere • Strong, narrow and quasi-horizontal “rivers of air” • Typically located in upper troposphere or stratosphere • Thousands of km long; hundreds of km wide; few km deep

Tropospheric Jet Stream Structure: Mid-Winter Daily Snapshot (Jan 15, 2006) Multi-Year Average (Jan 15) 300 hPa winds (vectors - wind direction; shading - windspeed) [Units: m/s] Jet Stream Overview

Tropospheric Jet Stream Structure: Mid-Summer Daily Snapshot (July 15, 2006) Multi-Year Average (July 15) 300 hPa winds (vectors - wind direction; shading - windspeed) [Units: m/s] Jet Stream Overview

Black Research Program: Phenomena  Weather regimes, annular modes, anomalous temperature events, cyclones, seasonal transitions, strat-trop coupling • Northern Annular Mode: variability in polar vortex strength • Polar Annular Mode: variability in polar vortex position

Black Research Program: Phenomena  Weather regimes, annular modes, anomalous temperature events, cyclones, seasonal transitions, strat-trop coupling • Synoptic and dynamic studies of cold air outbreaks • Physical mechanisms and low frequency modulation

Phenomena: Winter Cold Air Outbreaks in Southeast  Weather regimes, annular modes, anomalous temperature events, cyclones, seasonal transitions, strat-trop coupling • ♥ No significant • trend in the • frequency of cold • air outbreaks • ♣ Past 2 winters • (09/10 & 10/11) • rank in the top 5 • among the last • 60 years (!)   

Phenomena: Winter Warm Waves in Southeast  Weather regimes, annular modes, anomalous temperature events, cyclones, seasonal transitions, strat-trop coupling ♥ Statistically Significant downward trend in warm waves ♣ Very low values during last two winter seasons (09/10 & 10/11)

Phenomena: Recent Cold Winters & Arctic Oscillation  Weather regimes, annular modes, anomalous temperature events, cyclones, seasonal transitions, strat-trop coupling • Robust cold air outbreaks continue to be observed • Strongly modulated by annular mode (weak jet stream)

Winters of 2009/10 & 2010/11: Unusual Behavior! Composite Surface Wind Anomalies → (NOAA/ESRL) Composite Surface Air Temperature Anomalies → (NOAA/ESRL) 1/07/2004 Average surface air temperature anomalies 12/15 – 01/14

Phenomena: Spring Onset in the Arctic  Weather regimes, annular modes, anomalous temperature events, cyclones, seasonal transitions, strat-trop coupling • ♥ Temperature change • at high latitudes is • rather abrupt • ♣ Temperature change • appears linked to a • large-scale circulation • change over the • North Atlantic

Phenomena: Spring Onset in the Arctic Precipitation Rate Lower Tropospheric Heights Atmospheric Changes between March 1 and May 1 Jet Stream Overview

Black Research Program: General Approach