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Global Trends in the Earth's Climate from Recent Observations

Seminar at NTU ROCSeminar at NTU ROC

18 July 201218 July 2012

Yuk Ling Yung ( 翁玉林）Caltech

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Professor Jiang Xun (UH)

Dr. Liang Mao-Chang (AS)

Overview

Part 1. Changes in the Hydrological Cycle

Water Vapor and Precipitation

Theory

Part 2. Decadal Record by Aqua over the Tropics

Mode Decomposition (Huang-Hilbert Transform)

Trends

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Hydrological Cycle Project

Collaborators: Jiang Xun, Li Liming (UH)

Li et al. 2011 ERL

Aqua Temperature Project Collaborators: Shi Yuan, Li King Fai, T. Hou, H. Aumann (Caltech,

JPL)

Shi et al. 2012 Climate Dynamics5

705 km altitude sun synchronous, 98.2 inclination, 98.8 minute period

• Global coverage with a 16-day(233 orbit) ground track repeat cycle

TES – T, P, H2O, O3, CH4, CO

MLS – O3, H2O, CO

OMI – O3

Aerosol polarizati

on

3-D Aerosols

AIRS – T, P, H2O,

CO2, CH4

MODIS – clouds,

aerosols,

albedo

CO2 ps, clouds,

aerosols

A-Train

3-D CloudsAerosol

polarization

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Courtesy Brian Soden

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Courtesy Brian Soden

~2%/K

~7%/K

Gross view of the changing water cycle

Courtesy Frank Li ( 李瑞麟 ) + Graeme Stephens et al. 2012

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What Do The Data Tell Us?

GPCP (V2.1) 2.5º× 2.5º monthly precipitation (1979-2009)

SSM/I (V6) 0.25º× 0.25º monthly precipitation (1988-2009)

TRMM (V6) 0.25º× 0.25º monthly precipitation (1998-2011)

I) Precipitation

II) Water vaporSSM/I (V6) 0.25º× 0.25º monthly Water Vapor (1988-2009)

AIRS (V5) and AMSR (V5) 1º× 1º monthly Water Vapor (2002-2009)

NVAP 1º× 1º monthly Water Vapor (2002-2009)

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Precipitation and Water Vapor

ΔP (mm/mon)

ΔW (mm/mon)

(A) Deseasonalized time series of oceanic precipitation from GPCP V2.1 and SSM/I.

(B) Deseasonalized time series of oceanic water vapor from SSM/I, AIRS, AMSR-E, and NVAP.

Trends in Precipitation and Water VaporDeseasonalized & Lowpass Filtered Timeseries

SSM/I+GPCP: 0.26 ± 0.41 %/decade

GPCP: 0.08 ± 0.43 %/decade

SSM/I: 1.01 ± 0.39 %/decade

Weak linear trend in precipitation is much smaller than the linear trend

(1.4 ± 0.5% per decade) in the previous study (Wentz et al., 2007).

[Li et al., ERL 2011]

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Trends in Oceanic Precipitation, Water Vapor, and Recycling RatesDeseasonalized & Lowpass Filtered Timeseries

ENSO Signals have been removed by a multiple regression method.

SSM/I: 0.13 ± 0.63 %/decade

GPCP: 0.33 ± 0.54 %/decade

SSM/I: 0.97 ± 0.37 %/decade

Recycling 1: -0.82 ± 1.11 %/decade

Recycling 2: -0.65 ± 0.51 %/decade

Recycling 1 = (SSM/I P)/(SSM/I W)

Recycling 2 = (GPCP P)/(SSM/I W)

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Precipitation and Water Vapor

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Spatial Pattern of the Mean Precipitation for 1988-2008

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Temporal Variations of Precipitation over High & Low Precipitation Areas

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50-year obs

Figure 3. Patterns of 50-year surface salinity change (PSS-78 50yr-1). A) The 1950-2000 observational result of Durack & Wijffels (2010). B) From an ocean model forced with an idealised surface 5% E-P enhancement (50 yr-1; see text). C) For an ensemble mean from 1950-2000 of the CMIP3 20C3M simulations which warm

less than <0.5°C (24 simulations). D) For an ensemble mean from 1950-2000 of the CMIP3 20C3M simulations which warm greater than >0.5°C (26 simulations). In each panel, the corresponding mean salinity

from each representative data source is contoured in black, with thick lines every 1 (PSS-78) and thin lines every 0.5 (PSS-78). From Durack et al., 2012

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Mechanisms of tropical precipitation changes

Chou et al. 2009

The DLR response to climate warming is the dominant factor in the response of the atmospheric radiative cooling to this warming.

Connection to energy balance

Stephens

& Hu, 2010

ERL

Thus precipitation change is set by the change in

water vapor (a consequence of the water vapor feedback but does not keep pace with the

increases in vapor

Courtesy Graeme Stephens20

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1) Trend in the global precipitation is smaller than the trend in the global water vapor.

2) Precipitation has increased in the ITCZ and decreased in the neighboring regions over the past two decades.

Conclusions

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Overview

Part 1. Changes in the Hydrological Cycle

Water Vapor and Precipitation

Theory

Part 2. Decadal Record by Aqua over the Tropics

Mode Decomposition (Huang-Hilbert Transform)

Trends

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Motivation

What are the Natural Variabilities?

How do we separate them from the Trend?

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Advanced Microwave Sounding Unit (AMSU)

Raw data

Channel 5

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Imf 6

Channel 9

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Channel 14

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Imf 5 QBO

Annual and Semi-annual Cycles

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Seasonal Cycle

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SAO

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QBO

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Trends

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Trend

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Liang et al. 2012

Near Annual (18 mon)

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Near Annual Mode

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Conclusions

• All natural modes found and separated, no spurious modes

• Discovered a new mode ~18 mon

• Decadal trends are significant, probably due to couple Ocean-Atmosphere interaction

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AcknowledgementsAcknowledgements

YungYung’’s Group at Caltech s Group at Caltech

Jiang Xun (UH)Jiang Xun (UH)

Shi Yuan (HKU, Caltech, Princeton)Shi Yuan (HKU, Caltech, Princeton)

Liang Mao-Chang (RCEC) Liang Mao-Chang (RCEC)

NSF/NASA/JPLNSF/NASA/JPL

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Backup Slides

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Courtesy Chou Chia 2012

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QBO mechanism

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QBO induced circulation and its modulation of the Column Ozone

• When the QBO is in the westerly (easterly) phase, there is descending (upwelling) anomalous motion in the tropical stratosphere and upwelling (descending) anomalous motion in the subtropical stratosphere (Plumb and Bell, 1982).

• This results in more (less) ozone at the equator in the westerly (easterly) QBO phase (Tung and Yang, 1994a).

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