THE ATMOSPHERE Tereza Cavazos Department of Physical Oceanography Ensenada, Baja California, Mexico The Science of Climate Change: a focus on Central America and the Caribbean Islands Antigua, Guatemala, 14-16 de marzo de 2017
Ve Ver%cal Structure Atmosphere: is the layer of gases that surrounds the Earth and stays in place due to gravity . Up to 80 km the atmosphere is uniform: AIR O 3 O 3 (Fig. 1.9, Wallace & Hobbs, 2006)
Earth’s Clima mate System m Depends on many processes that occur and interact between the different spheres producing feedbacks GHGs GHGs Atmosphere HYDROSPHERE
Earth’s Atmo mosphere GHGs: � Global Ta = 15 o C ◦ Unique composition of gases CO 2 (0.04%) CH 4 , N 2 O, water vapor (& GHGs) favors life as we know it No GHGs � T = -17 o C ◦ Unique weather & climate ◦ Transports heat, momentum, and humidity (hydrological cycle) ◦ Transports aerosols and other contaminants (O 3 , CFC, NO x , black carbon, etc.)
� External Forcings CO 2 & Temperature in Antarctica since 420,000 yr ago Atmospheric CO 2 (ppm) Vostok, Antarctica 2015: 15 o C 400 Surface Temperature in Antarctica Pre-industrial concentrations of CO 2 Human contribution to atmospheric CO 2 Temperature ( Last Interglacial +3°C Holocene -9°C ° C) Thousands of years before present Last glaciation (Tan = -16°C) (Petit et al., 1999, Nature , 399, p. 431. Ver Fig. 2.31, W&H, 2006, p. 52)
Con Concen centra% a%on on of Gr of Green eenhou ouse Gases (GHGs) se Gases (GHGs) Concentración de GEIs Carbone Dioxide (CO 2 ) Methane (CH 4 ) Nitrous Oxide (N 2 O) 1850
OBS: Global Air Temperature Anomaly and Ocean Heat Content 1970 Global Air Tmean = 15 o C 0-700 m
Radiative Forcings in the Atmosphere (Watts/m 2 ) Attribution to climate change Processes ANTHROPOGENIC - GHGs - Land-use change - Tropospheric Ozone SO 2 NATURAL - Solar radiation - Volcanoes - Water vapor (AR4 WG1, IPCC 2007 – Sci Basis)
CLIMATE CHANGE Perturbation of the Earth’s climate due to several forcing mechanisms: NATURAL: Solar radiation, Tectonic plates, Volcanism, El Niño, Decadal Oscillations... Human Activity: Population growth, Industrial development �� Land-use change, and Fossil fuel burning
Weather and Clima mate Weather: Atmospheric phenomena that occur from seconds to few weeks; this is the deterministic limit for weather forecast. It is the state of the troposphere at any moment. “Weather is what we feel right now” Climate: Atmospheric phenomena that occur from one month to much longer time periods. It is the average weather in a place over more than thirty years. “Climate is what we expect”
Scales of Variability of Weather and Clima mate (PDO, AMO) Droughts , Monsoons Sunspots Days Planetary scale
Sc Scale ales s of f Variability ariability and A and AAribu%o Aribu%on t n to Clima mate Change 2016
Atmo mospheric Circula%on Ferrel Cell: Thermally indirect circulation Jet Stream Hadley Cell: Direct circulation ITCZ
rt Meridio Meridional C nal Cir ircula%o ula%on and Hea n and Heat T t Transpo ansport Jet Hadley Cell Ferrel Cell H
Annual Temp mperature Range Large seasonal contrasts � Rossby and planetary waves
Thermo modynami mic Equa%on Local change T = Horiz ADV + vertical ADV + radiative + convective diabatic heating (7.37 Q Q T T T W&H) ⎛ ⎞ ∂ κ ∂ V T rad con D = − ⋅ ∇ + ω ⎜ − ⎟ + + + ⎜ ⎟ H t p p c c ∂ ∂ ⎝ ⎠ p p dQ cpdT dp = − α Warming/diabatic dissipation T � Sigma (Static Stability): ∂ V T = − ⋅ ∇ + σω � + Stable, - unstable, 0 neutral t ∂ MIDLATITUDES: Horiz ADVECTION of Temp dominates TROPICS: Vert ADV dominates ( ω σ � compression expansion). Local change and horiz ADV are small from day to day. Easterly waves � .
Tropical Atmo mosphere 30N
Semi miperma manent Highs and Lows J Jan anuar ary S y SLP LP See Fig. 1.18, Wallace and Hobbs, 2006, p. 17
Semi miperma manent Highs and Lows J July S ly SLP LP See Fig. 1.19, Wallace and Hobbs, 2006, p. 17
January Precipita%on Clima matology 1998-2015, TRMM SPC SPCZ Precipitation (mm hr -1 ) Figure from George Kiladis
July Precipita%on Clima matology 1998-2015, T 1998-2015, TRMM RMM Precipitation (mm hr -1 ) Figure from George Kiladis
Mean A Mean Annual Pr nnual Prec ecipit ipita%o a%on, n, IT ITCZ CZ 1998-2012, T 1998-2012, TRMM RMM SPC SPCZ Figure from George Kiladis
January and July Precipita%on (mm) derived from CMAP ITCZ IT CZ Jan SPC SPCZ IT ITCZ CZ H H Jul H H Fig. 1.25, Wallace & Hobbs, 2006, p. 20.
e Winds E Eas asterly W erly Waves in es in t the T e Trad ade Win Inverted troughs
E Eas asterly W erly Waves 23 Au es 23 Aug 1995 g 1995 http://apollo.lsc.vsc.edu/classes/met130/notes/chapter15/graphics/ATL_WAVES_VIS.gif
Zo Zonal Walker Circ rcula%on During Norma mal to La Niña Condi%ons � Low level Easterlies Div Pacific Ocean: the tropical Conv climate is coupled (+ feedback)
Close rela%on amo mong SST, convec%on and winds High cloud fraction (deep convection) and surface winds " " Z T C ! I ! In the tropics, convection coincides with warm SST and surface wind convergence. All three define the SST and surface winds West Pacific warm pool and the Intertropical Convergence Zone (ITCZ). Warm Pool East Pacific Cold Tongue (Reynolds SST, ISCCP high clouds, Quikscat winds)
Januar January y Me Mean an SLP SLP during during La La Niña iña win winters s uthern US � Z Dr Dry in Me y in Mexic ico, the Caribbean and so , the Caribbean and southern US Zon onal cir al circu cula% la%on on (e. (e.g., 2008, 1999, 1989 y 1976) g., 2008, 1999, 1989 y 1976) L L H H L
Atmo mospheric Rivers and Storms ms Autumn mn-Winter 2016-2017 during a very unusual unusual La La Niña iña (La (La Niña iña Mo Modo doki? ki?) )
Div Canonical La Niña Div El Niño Conv
Te Teleconnec%on during Strong El Niño winters (Strong subtropical je jet and extreme me rainfall, 1976-2000) an STRF200 (m 2 s -1 ) (STRF = Ψ = gz/f) L L H (Cavazos and Rivas, 2004)
El Niño El Niño 2015-2016: A 2015-2016: An unusual e n unusual even ent t SST, 200 hPa Geopotential Figure from George Kiladis. Courtesy Tao Zhang, PSD Precipitation, ESRL 200 hPa Wind
Sub Subtr tropic pical al Westerly rly Je Jet t during during El El Niño iño
The Madden-Julian Oscillation (MJO) and Kelvin Waves The MJO is also referred to as the 30-60 day or 40-50 day - OLRan oscillation and is the main intraseasonal/intra-annual fluctuation that explains weather variations near the equatorial regions. It may also affect weather systems in the extratropics, such as the west coast of the U.S. in winter. In its simplest form, the MJO consists of coherent variations (Matthews 2000)
Atmospheric Kelvin Waves and the MJO Life cycle of the MJO during boreal summer (48 days) OLRan (W m -2 ) every 3 days Convection Clear Sky http://envam1.env.uea.ac.uk/met_ocean_climate.html (Matthews 2000)
ENSO and EP ENSO and EPAC T C Tropic pical Cy al Cyclo lones nes HUR1-3 May-Nov HUR4-5 LN (72) N (142) EN (98)
ENSO ENSO and EP and EPAC T C Tropic pical Cy al Cyclo lones nes Ma May-Nov 1979- v 1979-2010 2010 Warm Pool: SST > 28˚C U200-U850mb (m/s) LN 10 9 12 Martinez-Sanchez y Cavazos 2014 N 12 9 12 16 EN 9
AMO a AM O and NA NAT T T Trop opical Cy Cycl clon ones es 28.5 o +AMO -AMO 28.5 o http://www.aoml.noaa.gov/phod/research/tav/awp/
Dec Decadal P adal PaAerns o aAerns of the A f the Atlan%c and P tlan%c and Pacific acific +PDO +AMO
Te Teleconnec%on PaAern: The North Atlan%c Oscilla%on Temperate and Very cold humid (snow & Temperate Cold & dry rain) Cold & dry (less Temperate snow in the Alps) and humid
Teleconnec%ons of the North Atlan%c Oscilla%on Te NAO Pos NAO Neg & wet Cold Cold & wet Sahara dust Figure 2A. The North Atlantic Oscillation (NAO). Its "high index" state is shown above, this corresponds to particularly high atmospheric pressure over the Azores, an intense low over Iceland. Ocean winds are stronger and winters milder in the eastern U.S. When the NAO index is low, ocean winds are weaker and the U.S. winter more severe. Changes in ocean temperature distributions are also observed. (Illustration by Fritz Heide & Jack Cook, WHOI)
Relevant Phenome mena for the Central Ame merican – – Caribbean Region NAO / AMO PDO Monzón CFs SST MSD EWs CLLJ ITCZ El Niño/La Niña (m)
Thank You tcavazos@cicese.mx
Recommend
More recommend
