Post on 14-Jan-2016
description
transcript
1
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
2
33
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
4
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
6
7
Courtesy Brian Soden
8
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
10
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)
11
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]
12
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)
13
Precipitation and Water Vapor
14
15
Spatial Pattern of the Mean Precipitation for 1988-2008
16
Temporal Variations of Precipitation over High & Low Precipitation Areas
17
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
18
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
21
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
22
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
23
24
Motivation
What are the Natural Variabilities?
How do we separate them from the Trend?
25
26
Advanced Microwave Sounding Unit (AMSU)
Raw data
Channel 5
28
29
Imf 6
Channel 9
30
Channel 14
31
32
Imf 5 QBO
Annual and Semi-annual Cycles
33
34
Seasonal Cycle
35
36
SAO
37
QBO
38
39
40
Trends
41
Trend
42
43
Liang et al. 2012
Near Annual (18 mon)
44
45
Near Annual Mode
46
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
47
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
48
4949
50
Backup Slides
51
Courtesy Chou Chia 2012
53
54
QBO mechanism
55
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).
56
好雨知時節,當春乃發生。
隨風潛入夜,潤物細無聲。
野徑雲俱黑,江船火獨明。
曉看紅濕處,花重錦官城。
春夜喜雨 杜甫