LGK MIT 2004 Stratosphere-Troposphere Exchange (STE) over Easter Island (27ºS,109ºW, 41 m.a.s.l.) and Cerro Tololo (30ºS,70ºW, 2200 m.a.s.l.): preliminary analysis of an intensive sounding campaign Laura Gallardo Klenner Centro de Modelamiento Matemático Universidad de Chile (UMR-CNRS 2071) Melitta Fiebig, CEAZA/ULS Ana María Córdova, CEAZA Juan Quintana, DMC FONDECYT

LGK MIT 2004 Outline What is (are) this(these) project(s) about? –The problem(s) to be addressed –Approach(es) Test campaign Nov 2003 –Data and synoptical conditions Perspectives and future work

LGK MIT 2004

Rapanui/Easter Island Available Data Instrument: (ECC, standard WMO-GAW) 81 c/o Chilean Met Office since 1996, majority 1996 & c/o NASA from 1995 until 1997 (WODC) 10 during Nov campaign

LGK MIT 2004 Ozone Soundings Rapanui Spring maximum UTLS

LGK MIT 2004 Spring Maximum

LGK MIT Reasons for a spring maximum in O3…. Biomass burning? STJ? Orographic forcing? Subsidence

LGK MIT 2004 STRATOSPHERE-TROPOSPHERE EXCHANGE PROCESSES AND THEIR IMPACT ON THE OZONE BALANCE IN THE SUBTROPICS OF THE SOUTHERN HEMISPHERE: A MULTI-SCALE INTEGRATED STUDY BASED AT CERRO TOLOLO (30ºS, 70ºW, 2200 M.A.S.L) FONDECYT ( ) /FONDECYT-INT (2003)

LGK MIT 2004 Which are the mechanisms that explain the spring ozone maximum observed in the southern subtropics...Tololo and Pascua? a)Stratosphere-troposphere exchange (STE)? b)Biomass burning in the tropics? c)All above When is there STE? And then, which is the relative importance of advection, subsidence and turbulent mixing? Are these phenomena well represented in models? FONDECYT ( ) Questions

LGK MIT 2004 Accomplished so far Ozone data collected at Rapanui and Tololo are being or have been analyzed A CTM model is being used to simulate the dispersion of an ozone like tracer, assuming a Dirichlet BC The same dispersion model is used to simulate the fate of SOx emitted from the Láscar volcano….insights in the UTLS circulation (Ekman et al connection) A meso-scale model is simulating the circulation in the Elqui valley A test campaign has been performed… Logistics? Instruments? Forecast? Training Design of next campaign

LGK MIT 2004 People: Ana María Córdova, Juan Quintana, Alonso Gaete et al.

LGK MIT 2004 Tololo Nov 2003 People: Melitta Fiebig, Clotilde Pizarro, Alejandra Olave, Edwin Medina, Luis Valle Laura Gallardo, Alvaro Amigo, Alvaro Valdebenito, Milenko Obilinovic Ricardo Alcafuz, José NúNez Patricio Serrano, Julio Coloma Standard soundings, using 1200 g, 350 g and 100 g balloons, up to 28 km Installation of a PM10 instrument (7Be)

LGK MIT 2004 …And weather forecast

LGK MIT 2004 Synoptic conditions, 500 hPa analyses Day 08Day 10 Day 12 Day 09 Day 11 Day 13 Anticyclonic-Cyclonic(Trough)-Anticyclonic

LGK MIT 2004 D 08D 10 D 12 D 09 D 11D13 Synoptic conditions, STJ (m/s), 250 hPa

LGK MIT 2004 Evidence for STE? –O 3 changes in the UTLS over Rapanui in connection with STJ …a trough? –Photochemistry? –O 3 changes at Tololo?

LGK MIT /11 ??!

LGK MIT /11

LGK MIT /11

LGK MIT /11

LGK MIT /11 While at TOLOLO...

LGK MIT 2004 Synoptic conditions, PV

LGK MIT 2004 Cut-off low and deep trough induce STE and O3 intrusions at Tololo Rondanelli et al, 2002

LGK MIT 2004 Simulating an ozone like tracer…regional/mesoscales +BC (Dirichlet/Neumann) +IC Photolysis and deposition +Estimating the influx?

LGK MIT 2004

November days, one sounding per day

LGK MIT 2004 Rapanui –A unique record of ozone soundings is available from Easter Island since 1995 under GAW/Chilean Weather Office –The data show not much variability...no significant temporal trends...but there is some interannual variability (ENSO like) –Ocassionally, deep troughs induce STE…and the STJ seems to play a role too 

LGK MIT 2004 Tololo –A nearly continous surface O3 record is available under GAW/Chilean Weather Office –The data is representative of background conditions There is a marked spring maximum possibly linked to STJ…but biomass burning cannot be ruled out –The diurnal cycle is week (5 ppbv) and driven by up/down slope local circulation… –Ocassionally, deep troughs induce significant STE 

LGK MIT 2004 Evidence for STE? –O 3 changes in the UTLS over Rapanui in connection with STJ …a trough?...Nop, but a good chance to test Dirichlet BC and check the model set up –Photochemistry?...Not obvious in the UTLS above Rapanui…lower campaign cost –O 3 changes at Tololo?...Yep…a deep trough and an O3 intrusion

LGK MIT 2004 Future/Ongoing work –Climatology and characterization using proxies (e.g., PV, H2O, 7Be)… –Regional/mesoscale simulation of the test- campaign period… Dirichlet/Neumann… “Source” estimate (Inverse modeling) –10 days campaign at Tololo including O3 soundings and CO…plus forecast and simulation

LGK MIT 2004 Subplinian Eruption April Ca. 0.2 TgS Cuasi permanent fumarolic activity 13 kg/s Láscar (23.3ºS, 67.7ºW, 5590 m.a.s.l.) : One of the ca. 100 active volcanoes along the Andes and one of the 3 whose emissions have been estimated

LGK MIT 2004 Amigo et al, 2004

LGK MIT Megacities STE Aerosols... Welcome!