U.S. Contribution to T-NAWDEX:

“DOWNSTREAM”

Heather Archambault (NPS), Steven Cavallo (OU), Dan Cziczo (MIT), Chris Davis (NCAR), Pat Harr (NPS),

Laura Pan (NCAR), Mark Zondlo (Princeton)

T-NAWDEX WorkshopKarlsruhe, Germany

20 March 2013

“DOWNSTREAM”

Dynamics and Observations of the Waveguide: North–South Transport

and Rossby wave Excitation over Atlantic Midlatitudes

Synergy with T-NAWDEX

• Focused over eastern North America and the western North Atlantic

• Scientific foci:– Stratospheric–tropospheric exchange– Tropical, midlatitude, and polar forcing of

waveguide perturbations – Predictability– Multiscale interactions

Waveguide forcing

PV distribution

“DOWNSTREAM” Science Themes

Synoptic-to-hemispheric scaleRossby wave amplification, dispersion, breaking along North Atlantic

waveguide, tropospheric–stratospheric exchange (water vapor)

Meso-to-sub-synoptic scaleTropopause polar vortices, transitioning tropical cyclones, warm conveyor belts, diabatic Rossby vortices, predecessor rain events

MicroscaleClouds, aerosols, trace constituents, radiation, turbulence

Impacts on medium-range predictability

1. Science Questions Related to Extratropical Transition

Midlatitude impactregion

TC–midlatitudeinterface region

Decaying tropical cyclone core region

• How do sub-synoptic-scale phenomena generate waveguide perturbations?

• What is relative contribution of diabatic heating in frontal zones versus tropical cyclone (TC) core?

• Is TC outflow the primary means of perturbing the waveguide?

• What is the detailed vertical structure of:• TC outflow?• merger of TC outflow and midlatitude jet?•

1. Science Questions Related to Extratropical Transition

Grams et al., 2013: QJRMS

“No radiation” minus “with radiation”

In composite numerical simulated vortices, a weaker TPV occurs without radiation

• Formation and extrusion of tropopause polar vortices (TPV) and sensitivities to diabatic (e.g., radiation) variations:

• How well are these represented?

• How do clouds influence process?

• How do these coherent structures evolve as they approach the jet?

• What happens to the jet itself?

2. Science Questions Related to Polar Vortices

Cavallo and Hakim, 2012: MWR

8 Sep 2012 9 Sep 2012 10 Sep 2012 11 Sep 2012

Potential temperature on 2-PVU surface (0000 UTC) (ET of Leslie)

3. Science Questions Related to Predictability

How do multiple sources of waveguide perturbations influence predictability on synoptic to hemispheric scales?

250-hPa v’

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09120°E 180° 120°W 60°W 0°

+1.0 +1.5 +2.0 +2.5-1.0-1.5-2.0-2.5

NASAOUTFLOW

DOWNSTREAMT-NAWDEX

Flooding rain

4. Science Questions Related to UTLS Transport of Water and Other Constituents

Figure 1 from Pan et al., 2008: BAMS (adapted from Stohl et al. 2003 : (BAMS)

• How are water vapor and other constituents transported into the lower stratosphere in outflow (WCB) regions associated with extratropical and tropical cyclones?

• What are the source regions?

5. Science Questions Related to Cirrus Clouds• What drives the spatial variability of ice, H2O, T, and w on scales of

0.2–20 km?

• How do water and temperature define the spatial distribution of relative humidity?

• How can tracer correlations be used to understand larger-scale dynamics?

5. Science Questions Related to Cirrus Clouds• What are the mechanisms yielding ice supersaturated regions for

cirrus formation?

• How does cirrus formation differ as aerosol characteristics change?

• How do cirrus clouds affect the overall budget of water vapor in the upper troposphere/lower stratosphere region?

Extratropical transition of TC Leslie 0000 UTC 10 Sep 2012

96Cirrus shield extends far downstream of TC

G-V Flight Range

IR satellite

A Candidate DOWNSTREAM Case

Potential temperature on dynamic tropopause

A Candidate DOWNSTREAM Case

Extratropical transition of TC Leslie 0000 UTC 10 Sep 2012

Potential temperature on dynamic tropopause

TC Outflow Layer

Instrumentation and Uses• W-band cloud radar (Doppler)• Ka Band radar (?)• VCSEL – water vapor• Microwave Temperature Profiler (MTP)• Dropsondes• CVI (Counterflow Virtual Impactor)• Fast Ozone• CO• Various trace species

MTP? HCR?

GV Cloud Radar:15°–20° scan

If variation in ‘x’ is slow compared to variation in ‘y’:

• MTP can obtain gradients of potential temperature within “curtain” along flight track

• Cloud radar can obtain velocities below aircraft

• PV estimates with a resolution of <10 km horizontal, roughly 200 m vertical

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Approximate form, if slowly varying along the jet relative to across jet

PV Estimation from MTP Data

Jet Stream

z

NRC (Canadian) Convair-580 The National Research Council (NRC) of Canada operates a twin-

turboprop Convair-580 research aircraft. Operation is on a full cost-recovery basis, so full funding is required even

for government-backed projects.

Service ceiling: 7200 m (23,500 ft)Cruising speed at altitude: ~215 ktRange Out-and-back: 1000 km

One-way: 2000 kmAircrew: 2 peopleResearch crew: ~12 peopleHome page: www.nawx.nrc.gc.ca

The Convair-580 is used heavily for microphysical measurements, particularly for projects related aircraft icing and air quality

Can carry a range of remote sensing equipment: W- and X-band radars (up, down, side views) and a G-band water vapour radiometer

Bulk cloud parameters EC Cloud Extinction Probe (CEP)

Cloud particles SPEC Cloud Particle Imager (CPI), SPEC 2D-S (10-1280um)

NRC (Canadian) Convair-580 The Convair-580 flew into hurricanes Michael (2000), Karen (2000) and

Isabel (2003) during extratropical transition (ET). The Isabel mission was the first to sample an ET with flight level sensors

and dropsondes over land.

(Above) Equipment installed during flight into Hurricane Michael (2000). (Right) Storm track and near-surface winds from dropsondes, and radar cross-section wind dropsonde winds. All panels from adapted from Abraham et al. (BAMS, 2004).

NRC (Canadian) Convair-580 The Convair-580 could be booked for a 2-month period (i.e. Sept-Oct

2016), but deployed only when a feature of interest is predicted. If based in St. John's, Newfoundland, the Convair could be ready for

operation (i.e. ferried from Ottawa) with 3-days notice: may be more consistent with more predictable features.

All previous flights into storms undergoing ET have been round-trip

To extend coverage to 40oN, 40oW (or slightly further south) the Convair could land to refuel in the Azores; however, crew rest requirements probably mean an overnight before the return flight

40oW

Azores

Range rings for Convair-580 based in St. John's, Newfoundland. Red ring is for a round-trip flight, magenta ring is for a one-way flight.

Summary

• DOWNSTREAM: Sept-Oct. 2016• Eastern U.S., Canada and Northwest Atlantic• Dynamics-driven study of origin of waveguide perturbations• Transport and small-scale cloud processes• Effects on PV distribution• Predictability associated with mesoscale features• NSF-NCAR GV aircraft: unique collaborative opportunity with

two G-Vs.