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Clase 8: La atmósfera cambiante: una perspectiva sistémica

Paradigmas y métodos

GF 777Otoño 2002

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Contenidos de hoy• Integrando observaciones y modelación

• Observaciones y mediciones

• Modelación

• Paradigmas y métodos para abordar la ciencia y la gestión de la atmósfera cambiante (Ejemplo: INDOEX)

• Ejercicio “(to be) made in Chile”

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Modelación

Mediciones

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Mediciones •In situ•Percepción remota•Laboratorios

•Campañas...Procesos•Monitoreo...Tendencias

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•Módulos químicos•Módulos meteorológicos•Métodos numéricos y resolución de EDP•Datos de entrada•Implementaciones computacionales•Evaluación y validación

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LGK GF777LGK Nov 98LGK Nov 98

Definición delProblema

Elección delmodelo

Recopilación dedatos

Implementación

Definición deescenarios

Ejecución delmodelo

Evaluación deresultados

VALIDACIÓN:• Comparación

sistemática contra observaciones

• Intercomparación

• Análisis de sensibilidad

LGK GF777 http://www-indoex.ucsd.edu/

•INDOEX is a $25M international experiment with

contributions from over 60 institutions from 13 nations

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Greenhouse Warming or Aerosol Cooling?"The balance of evidence suggests a discernible human influence on global climate.“ (IPCC, 1994)

The project's goal is to study natural and anthropogenic climate forcing by aerosols and feedbacks on regional and global climate.

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Objetivos principales

• Assess the significance of sulfates and other continental aerosols for global radiative forcing.

• Assess the magnitude of solar absorption in ITCZ cloud systems.

• Assess the role of the ITCZ in the transport of trace species and pollutants.

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Y de pasada ...(Targets of Opportunity )

• Meteorology of the Asian winter monsoon period

• Indian Ocean warm pool SST regulation

• Microphysical and radiative properties of cirrus clouds

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Grupos de trabajo

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Los responsables..

T.N. Krishnamurti8 J. Kuettner6 J. Lelieveld9

S.C. Liu10 A.P. Mitra11 J. Prospero12

R. Sadourny13 A.F. Tuck10

F.P.J. Valero14

AuthorsV. Ramanathan1 P.J. Crutzen1,2 M.O. Andreae2 J. Coakley1,3 R. Dickerson1,4 J. Heinzentberg5 A. Heymsfield1,6 J.T. Kiehl1,6 D. Kley1,7

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http://www-c4.ucsd.edu/c4publications/indoex_publication.html

Lelieveld, J., P.J. Crutzen, V. Ramanathan, M.O. Andreae, C.A.M. Brenninkmeijer, T. Campos, G.R. Cass, R.R. Dickerson, H. Fischer, J.A. de

Gouw, A. Hansel, A. Jefferson, D. Kley, A.T.J. de Laat, S. Lal, M.G. Lawrence, J.M. Lobert, O. Mayol-Bracero, A.P. Mitra, T. Novakov, S.J.

Oltmans, K.A. Prather, T. Reiner, H. Rodhe, H.A. Scheeren, D. Sikka and J.

Williams, 2001. The Indian Ocean Experiment: Widespread Air Pollution from South and Southeast Asia. Science,

291(5506):1,031-1,036.

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Rapa Nui

STE processes and their impact on the O3 balance in the subtropics of the Southern Hemisphere: A

multi-scale integrated study based at Cerro Tololo (30ºS, 70ºW, 2200 m.a.s.l)

CIALS/CMM/DMC

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At Cerro Tololo (30ºS, 70ºW, 2200 m.a.s.l.), continuous measurements of surface ozone (O3), radiation and meteorological

parameters have been performed since early 1996 under the auspices of the World Meteorological Organization (WMO) and through the Chilean Weather Office in cooperation with the Interamerican Southern Astronomical Observatory. This station belongs to a set of background regional stations intended to survey global change that are run under the Global Atmospheric Watch (GAW) program of the WMO. The chemical composition of the air arriving at the Cerro Tololo site appears to be generally representative of background conditions of free-tropospheric air in the subtropics of the Southern Hemisphere (SH). The O3 data collected at Tololo show a seasonal variation with maximum mixing ratios in late winter and spring, which appear to

be related with the intrusion of O3-rich air in connection with the tilting of isentropic surfaces near the subtropical jet stream

(SJT). Cut-off lows and deep troughs appear also to be major contributors to the O3 measured at Cerro Tololo. Stratosphere-

troposphere exchange (STE) processes are key factors for the balance of the radiatively and chemically important trace species (e.g., O3). STE processes seem also crucial for the formation of new particles. Moreover, these processes up-wind of the Andes

barrier play a key role for the occurrence of heavy precipitation events over Central and Northern Chile. Despite their importance, STE processes are still poorly understood, particularly over the SH. Hereby, we propose a study intended to assess STE processes over Cerro Tololo in the subtropics of the SH by means of an integrated approach that includes in situ measurements as well as regional and meso-scale modeling. Our aim is to identify the mechanisms that explain the O3 spring maximum at Tololo. Also, we want to assess the relative

importance of the mechanisms responsible for the transport of O3-rich air from intrusion areas, where STE occurs, to the Tololo

site, i.e., advection, large-scale subsidence and turbulent mixing. To identify characteristic patterns of STE, a climatology of typical air-masses arriving at Tololo will be built-up on the basis of composite analyses of reanalysis data using potential vorticity (PV), water vapor and the like as STE proxies. Further details will be identified by using high-resolution (ca. 0.1º, 3 hourly) climatological fields, dynamically interpolated from reanalysis data for nine months in the years 1997, 1998, 1999 and 2000, which cover typical meteorological situations over the Tololo area, including El Niño and La Niña years. In situ vertical soundings of O3 will be carried out three times a day, daily during a 10-days long campaign in the spring of 2004 at Tololo.

Complementarily, meteorological soundings will be performed during the campaign. Also, measurements of a beryllium isotope (7Be), sampled for 24 hours every three days along one year, and carbon monoxide (CO), continuously sampled during the campaign, will be concurrently performed in order to discriminate the origin of air masses. Regional and meso-scale numerical simulations of stratospheric intrusions as expressed in dynamical variables (e.g., PV) and in transport of an O3-like tracer will be

performed. These simulations will be done for typical spring conditions as identified by the climatological data and for selected events according to the data collected during the campaign. Meteorological models will be used to produce dynamically interpolated three-dimensional (3-D) regional and meso-scale meteorological fields, which will drive a 3-D Eulerian transport model that will simulate the intrusion and subsequent dispersion of an O3-like tracer subject to photolysis and dry deposition. The

simulations will be evaluated against in situ and available satellite measurements of O3, water vapor and other relevant STE

tracers.

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1.1. General objective        To identify the mechanisms that explain the seasonal variation and spring maximum in O3 mixing ratios in the subtropics of the SH, particularly at the Tololo

GAW regional station1.2. Specific objectives

         To contribute to the characterization of the origin of the air masses observed at the Tololo GAW station        To identify characteristic patterns of STE over Cerro Tololo in connection with the tilting of isentropic surfaces near the subtropical jet stream (SJT) and cut-off lows and deep troughs that affect the area.        To document the vertical distribution of ozone in the subtropics of the SH off the coast of South America and the Andes barrier, particularly for late winter and spring        To assess the relative importance of the mechanisms responsible for the transport of O3-rich air from intrusion areas where STE occurs to the Tololo site, i.e.,

advection, large-scale subsidence and turbulent mixing.        To validate the representation of STE in regional and meso-scale meteorological and Eulerian transport models         To perform sensitivity analyses with respect to advection and diffusion (turbulent mixing) numerical schemes

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Global NWP modelECMWF/NCEP-NCAR

Regional NWP modelRCA/HIRLAM/MM5

Boundary conditions 6 hours, T, q, u, v, SST, ...

T, u, v, q, CLW, CC,

prec, ..

Tracer’s distribution,deposition, etc.

Dispersion modelMATCH

Meso-scale meteorological modelKAMM

T, u, v, q, CLW, CC,

prec, ..

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ECC O3 sensoru,v,T, etc

Surface measurements of:O3, CO, 7Be, UV

u,v,T, etc

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Ejercicio: Evaluar el proyecto

Juan Quintana lo defiende

Los demás hacen de abogados del diablo

¿Es este un enfoque sistémico?

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Próxima semana

•Borrador de trabajo y esquema de presentación

•Tareas corregidas (!) y última tarea (se entrega el día del examen)