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T-NAWDEX

THORPEX North Atlantic Waveguide and

Downstream Impact Experiment

Scientific scope, instrumentation, andplans for an international coordination

• T-NAWDEX was originally proposed by the THORPEX working group Predictability and Dynamical Processes (PDP) in 2006

• T-NAWDEX Workshop in Erding in 2009: Start of International Coordination

• Delay with availability of HALO aircraft

• 2012: New initiative for an international T-NAWDEX in 2016

• April 2013: Planning workshop in Karlsruhe with focus on Scientific Scope

Brief History of T-NAWDEX

Error > 15 m/s

Aircraft obsECMWF analysis NCEP analysisfrom Sandro Buss &Huw C. Davies

Scientific scope

Overarching hypothesis:

There are systematic errors

in model representation of waveguide perturbations

that are attributable to diabatic processes

Errors are manifested as errors in PV distribution (errors in the jet stream)

→ forecast errors of high-impact weather

downstream

Aircraft observations of jet-level winds

PhD Thesis, Uwe Marksteiner (DLR)

PV on 320 K

Grams et al. 2011(QJ)

• Latent heating influencesPV distribution along the WCB

• WCB outflow (neg. PV anomaly) intensifies upper-level ridge

WCB inflow900 hPahigh humidity

WCB outflow300 hPa

WCB ascentstrong precip

Joos and Wernli 2012 (QJ)

1) waveguidemodificationby negative PV anomalies

WCBs andtheirimpact on large-scaledynamics

Scientific scope

‐TPCs are frequent and fairly long‐lived (> week)‐TPCs can trigger / amplify waves along jet‐TPCs are associated with characteristic pattern of radiative heating 

Kew et al. 2010 (MWR)Cavallo& Hakim 2010 (MWR)

radiative heating

2) waveguidemodificationby positive PV anomalies

Tropopause polar cyclonesapproachingfrom polar regions

Scientific scope

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Factors modifying wave-guide disturbances• Tropopause polar vortices (pos. PV anomalies)• WCB outflow (neg. PV anomalies)• ET of tropical cyclones• Precursor wave

packets

Evolution of Rossby waves along the waveguide• Waveguide representation• Downstream evolution of PV anomalies• Modification from Greenland• Local modification of Rossby waves by pos. and neg. PV

anomalies

Downstream impact of diabatically modified PV anomalies• Wave breaking sensitivity

to upstream disturbances• Wave breaking can be

precursor for HIW

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US: GV HIAPER

G: HALO

UK: BAE 146

Partnerso US: NPS, NCAR, OU, Princeton, MIT, NOAAo Germany: DLR IPA, FX, KIT Karlsruhe, Univ. Mainzo France, UK, Canada, Switzerlando Links to weather services: DWD, ECMWF

International cooperation

CAN: NRC Convair 580

Ideal operation period in Sep/Oct 2016: •strong cyclone activity•tropical cyclones•HIW over Europe

US contribution “Downstream” with GV HIAPER

Dynamics and Observations of the Waveguide: North–South Transport

and RossbywaveExcitation over Atlantic Midlatitudes

Instrumentation and Uses

HALO instrumentation

Instruments:

Basic in-situ (BAHAMAS) T, p, q, u, v

ADM-demonstrator (lidar) wind profiles

2 μm wind lidar wind profiles

Dropsondes T, p, q, u, vprofiles

Water vapor (in-situ) q

Temperature (MTP) T profiles

Trace gases in-situ: O3, CO,…

Radiation

Unique aspects of T-NAWDEX

First field experiment

•to examine the development of forecast errors on a transatlanticscale over many days•to study the physical processes responsible for modification, propagation and downstream impact of Rossbywaves•with coordination of 2 GV aircrafts on both sides of the Atlantic to study transatlantic evolution of wave disturbances

•PV measurements (“PV-meter”) by observing MTP temperatures and wind velocities (Doppler radar, lidar)

•Interesting links to other communities (cirrus clouds/UTLS/watervapour transport)

•Synergies with planned satellite missions ADM and EarthCare

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T-NAWDEXContacts:

US: Pat Harr

UK: John Methven

Germany: Andreas Schäfler

France: GwendalRivière

Canada: Ron McTaggert-Cowan