www.reading.ac.uk1

REACT4CWorkpackage 1:Definition of Meteorological Case Studies

Emma Irvine, Keith Shine, Brian Hoskins

Progress Meeting, Munich, January 2012

12.01.11

Structure

Workpackage objectives and status

Results from year 2: North Atlantic Weather types Proxies for climate impact Contrails

Results from year 2: Tropical Atlantic Weather types (why we couldn’t find any…) Contrails

Summary

REACT4C First Progress Meeting, 17-18 Jan 2012 WP1 K Shine

12.01.11

Overall objective of WP1: Definition of Meteorological Case Studies

The main objectives of WP1 were:

• Generation of ECHAM data DONE

• Classify weather patterns over the north Atlantic to generate a set of typically occurring weather types. DONE Sept 2010

• Determine the frequency of each weather type DONE Oct 2010

• Sensitivity analysis DONE Jan 2011

• Classify weather patterns over the tropical Atlantic to generate a set of typically occurring weather types. DONE May 2011

• Determine the frequency of each weather type DONE Aug 2011

• Sensitivity analysis DONE Nov 2011

REACT4C First Progress Meeting, 17-18 Jan 2012 WP1 K Shine

12.01.11

North Atlantic: Key Results

Identified commonly occurring weather types, 5 for winter and 3 for summer:

• The weather types can be characterised by the strength and location of the jet stream, resulting in different time-optimal route locations

• Using simple proxies, we demonstrated that the climate impact associated with flights through each type should be different.

(Irvine et al. 2012, Meteorological Applications, in press)

• The probability of forming a persistent contrail varies both with weather type and altitude

(Plan to write up for publication Spring 2012)

REACT4C First Progress Meeting, 17-18 Jan 2012 WP1 K Shine

Winter weather types are characterised by the jet stream

1. Strong zonal jet

2. Strong tilted jet

3. Weak tilted jet

4. Strong confined jet

Eastbound Westbound

Irvine et al., 2012, Met. Apps., in press6

Climate impact proxies by winter weather type for eastbound and westbound routes

Contrails: distance where Rhi >100%, T<233K

Jet: S=strong, W=weak, Z=zonal, T=tilted, C=confined

CO2: route time

H2O: time in stratosphere

NOx: weighted average of time at each latitude

Cold ISSR frequency over North Atlantic at different altitudes, DJF 1989-2010

300 hPa, FL300 250 hPa, FL340 200 hPa, FL390

• Overall, the frequency of cold ISSRs decreases with altitude• Maxima: storm track, Greenland• Minima: Hudson Bay – stratospheric polar vortex

REACT4C Second Progress Meeting, 17-18 Jan 2012 WP1 K Shine

NEW! ISSR frequency varies by both altitude AND weather type…

300 hPa 250 hPa 200 hPa

W1: strong, zonal jet

%

300 hPa 250 hPa 200 hPa

W1: strong, zonal jet

W2: strong, tilted jet

%

NEW! ISSR frequency varies by both altitude AND weather type…

300 hPa 250 hPa 200 hPa

W1: strong, zonal jet

W2: strong, tilted jet

W3: weak, tilted jet

W4: confined jet

%

NEW! ISSR frequency varies by both altitude AND weather type…

…Probability of contrailing along a route varies by weather type, altitude and direction

12

• Flying higher forms LESS contrails (type W1, eastbound and westbound)• Flying higher forms MORE contrails (types W2 and W3 eastbound)

REACT4C Second Progress Meeting, 17-18 Jan 2012 WP1 K Shine

12.01.11

Tropical Atlantic: Key Results

• NO distinct weather types could be identified!

• Using proxies, the variation in climate impact is likely to be largest for contrails (note we did not try to compute a proxy for NOx)

• The locations where contrails form varies with the location of convection – both a diurnal and sub-seasonal and seasonal variations controlled by different processes on different timescales

REACT4C First Progress Meeting, 17-18 Jan 2012 WP1 K Shine

12.01.11

REACT4C First Progress Meeting, 17-18 Jan 2012 WP1 K Shine

Andes

Jet Stream

South Atlantic

30°N

10°N

10°S

30°S

DEEP- TROPICS

SUB-TROPICS

Influence of mid-latitude weather systems

ITCZ convection

SACZ

ITCZ convection

Influence of trailing cold fronts from mid-lats

L

North Atlantic Oscillation, East Atlantic pattern

Affect jet stream position, weather systems

Madden-Julian Oscillation

Period 30-60 days, cycle of suppressed then enhanced convection

ENSO

Irregular, 3-8 years, El Niño suppresses convection, La Niña enhances convection

What controls the variation in the weather on flight routes to South America?

Ice-supersaturation (and contrails) isrelated to areas of convection

(Not shown: Note that ECHAM shows a much greater frequency of ice-supersaturation than ERA-Interim) 12.01.11

REACT4C Second Progress Meeting, 17-18 Jan 2012 WP1 K Shine

12.01.11

REACT4C Second Progress Meeting, 17-18 Jan 2012 WP1 K Shine

Climatological winds and great circle routes to South America

JANUARY JULY

• Flights to eastern South America are less affected by variation in the wind strength (e.g. jet stream) than flights to western South America

Timeseries of route time, and correlation between them for DJF 2009-10

17

Route r

Sao Paulo – Bogota

0.13

Sao Paulo – Lima 0.23

Bogota – Lima 0.76

Route r

Sao Paulo – Bogota

0.38

Sao Paulo – Lima 0.53

Bogota – Lima 0.83

• The lack of correlation means we cannot classify types according to long route times (high CO2 impact) and short route times (low CO2 impact)

REACT4C Second Progress Meeting, 17-18 Jan 2012 WP1 K Shine

Recommendations for choosing case studies for the Tropical Atlantic

• Consider DJF and JJA separately

• Select case studies by randomly picking days (disadvantage – may not capture the full range of climate impacts)

• Consider flights to eastern and western South America separately. For each group of flights, cases could then be chosen on the basis of:

• High CO2 impact (long route time)

• Low CO2 impact (short route time)

• High contrail impact (lots of contrails formed)

• Low contrail impact (few contrails formed)

12.01.11

REACT4C Second Progress Meeting, 17-18 Jan 2012 WP1 K Shine

12.01.11

Summary

• North Atlantic

• Identified weather types: 5 for winter and 3 for summer

• The types can be characterised by the strength and location of the jet stream, resulting in different optimal route locations

• The climate impact associated with flights through each type should be different

• Tropical Atlantic

• No distinct weather types could be identified!

• Using climate impact proxies the distance contrailing showed the greatest variation

• Provided recommendations for how to choose case studies

REACT4C First Progress Meeting, 17-18 Jan 2012 WP1 K Shine

12.01.11

REACT4C First Progress Meeting, 17-18 Jan 2011WP x , Workpackage Leader

12.01.11

WP1: Definition of Meteorological Case StudiesManagement Overview

Deliverables scheduled in year 2011

• D1.3 – achieved

• D1.5 – achieved

• D1.7 – achieved

Partners and researcher scheduled in year 2011

• UREAD – Keith Shine, Emma Irvine, Brian Hoskins

• UKMO - Helen Wells, Paul Agnew, Andrew Mirza

• DLR – Christine Frӧmming, EUROCONTROL – Peter Hullah

• Resources:

• Effort:

REACT4C First Progress Meeting, 17-18 Jan 2011 WP1 K Shine

The jet stream latitude is related to the North Atlantic Oscillation

22

+ve

-ve

From: http://www.ldeo.columbia.edu/res/pi/NAO/

NAO +ve = northerly jet stream NAO -ve = southerly jet stream

ERA-Interim meteorological re-analysis data from 1989-2010

Comparison of optimal route and NAT track latitudes at 40W

23REACT4C First Progress Meeting, 17-18 Jan 2011 WP1 K Shine

Climate impact varies with route location, weather and season

18 February 2010 26 January 2010

Flight entirely in stratosphere produces no contrails

Flight mostly in troposphere produces persistent contrails

Flight level

tropopause

contrails