Is Climate Change in Asia- Pacific Attributed to Human Activities? Chang-Hoi Ho School of Earth and Environmental Sciences Seoul National University
Jan 13, 2016
Is Climate Change in Asia-Pacific Attributed to Human Activities?Is Climate Change in Asia-Pacific Attributed to Human Activities?
Chang-Hoi HoSchool of Earth and Environmental Sciences
Seoul National University
Chang-Hoi HoSchool of Earth and Environmental Sciences
Seoul National University
2
AcknowledgmentsAcknowledgments
Main collaborators Climate Physical Laboratory, Seoul National
University, Korea: Drs. Y.-S. Choi, J.-H. Kim, J.-H. Jeong- Website: http://cpl.snu.ac.kr
Bejing Normal University, China: Prof. D.-Y. Gong National Central University, Taiwan: Prof. C.-H. Sui Ewha Womans University, Korea: Prof. Seon-Ki Park University of California, Los Angeles, USA: Dr. J. Kim Seoul National University, Korea: Prof. R. J. Park
3
Ho, C.-H., J.-Y. Lee, M.-H Ahn, and H.-S. Lee, 2003: A sudden change in summer rainfall characteristics in Korea during the late-1970s. International Journal of Climatology, 23, 117−128.
Changes in the rainfall distribution of KoreaChanges in the rainfall distribution of Korea
4
5-year average precipitation and number of rainy days during summer for rain rate 1 mm day-1 (a) and rain rate 30 mm day-1 (b). Solid line indicates the number of rainy days and bar represents the summer total precipitation.
5
Daily precipitation contributed by typhoonDaily precipitation contributed by typhoon
0
100
200
300
1950 1960 1970 1980 1990 2000Year
Pre
cipitation (
mm
/day)
1 0 0 E 1 2 0 E 1 4 0 E 1 6 0 E 1 8 0 E
0 N
2 0 N
4 0 N
6 0 N
E q
Kim, J.-H., C.-H. Ho, M.-H. Lee, J.-H. Jeong, and D. Chen, 2006: Large increase in heavy rainfall associated with tropical cyclone landfalls in Korea after the late 1970s. Geophysical Research Letters, 33, L18706, doi:10.1029/2006GL027430.
6
Long-term change in summer rainfallLong-term change in summer rainfall
Ho, C.-H., J.-H. Kim, K.-M. Lau, K.-M. Kim, D.-Y. Gong, and Y.-B. Lee, 2005: Interdecadal changes in heavy rainfall in China during the northern summer. The Journal of Terrestrial, Atmospheric and Oceanic Sciences, 16, 1163−1176.
100E 105E 110E 115E 120E 125E 130E20N
25N
30N
35N
40N
45N
Latitu
de
Longitude100E 105E 110E 115E 120E 125E 130E
20N
25N
30N
35N
40N
45N
Longitude
Latitu
de
(a) Total rainfall (b) Accumulative rainfall(≥30mm/day)
Difference (1980-95 minus 1961-79)
100E 105E 110E 115E 120E 125E 130E20N
25N
30N
35N
40N
45N
Latit
ude
Longitude100E 105E 110E 115E 120E 125E 130E
20N
25N
30N
35N
40N
45N
Longitude
Latit
ude
(a) Total rainfall (b) Accumulative rainfall(≥30mm/day)
Difference (1980-95 minus 1961-79)
(Cases for (Cases for 0.1 mm/day) 0.1 mm/day) (Cases for (Cases for 30 mm/day) 30 mm/day)
7
1 0 0 E 1 2 0 E 1 4 0 E 1 6 0 E 1 8 0 E0 N
1 0 N
2 0 N
3 0 N
4 0 N( a) 1 9 5 8 -7 9
1 0 0 E 1 2 0 E 1 4 0 E 1 6 0 E 1 8 0 E0 N
1 0 N
2 0 N
3 0 N
4 0 N(b ) 1 9 8 0 -9 9
Gong, D.-Y. and C.-H. Ho, 2002: Shift in the summer rainfall over the Yangtze river valley in the late 1970s, Geophysical Research Letters, 29, 78.
5870 gpm contour lines for each summer5870 gpm contour lines for each summer
8
-11 to -7
-7 to -4
-4 to -2
-2 to -1
1 to 2
2 to 4
4 to 7
< -7
1980- 2001 minus 1951- 1979 (%)
Recent summer-mean 500-hPa 5870m gpm
Previous one
Increase
decrease
decreaseIncrease
Interdecadal variability of TC tracksInterdecadal variability of TC tracks
Ho, C.-H., J.-J. Baik, J.-H. Kim, D.-Y. Gong, and C.-H. Sui, 2004: Interdecadal changes in summertime typhoon tracks. Journal of Climate, 17, 1767−1776.
9
SummarySummary
A number of our findings indicate the presence of considerable changes in summertime rainfall, typhoon, and large-scale circulation over East Asia.
However, the periods of the data are limited to the past few decades. Thus it remains insoluble whether these changes are due to climate change or climate variation.
Is there any decisive evidence showing that human activities alter the climate system?
Some studies on rain-aerosol relation over ChinaSome studies on rain-aerosol relation over China
Choi, Y.-S., C.-H. Ho, D.-Y. Gong, R. J. Park, and J. Kim, 2007, The Impact of Aerosols on the Summer Rainfall Frequency in China, Journal of Applied Meteorology and
Climatology (in press).
Choi, Y.-S., C.-H. Ho, D.-Y. Gong, R. J. Park, and J. Kim, 2007, The Impact of Aerosols on the Summer Rainfall Frequency in China, Journal of Applied Meteorology and
Climatology (in press).
11Long-term trend of the rainfall event in summer
and the increase in air pollution
Long-term trend of the rainfall event in summer
and the increase in air pollution
80E 90E 100E 110E 120E 130E
20N
30N
40N
50N
80E 90E 100E 110E 120E 130E
20N
30N
40N
50N
1955 1979
1980 2005
< 6 6 ~ 3 3 ~ 0
0 ~ 33 ~ 66
-16 to -6 -6 to -3 -3 to 0 0 to 3 3 to 6 6 to 16
80E 90E 100E 110E 120E 130E
20N
30N
40N
50N
80E 90E 100E 110E 120E 130E
20N
30N
40N
50N
1955 1979
1980 2005
< 6 6 ~ 3 3 ~ 0
0 ~ 33 ~ 66
-16 to -6 -6 to -3 -3 to 0 0 to 3 3 to 6 6 to 16
< 6 6 ~ 3 3 ~ 0
0 ~ 33 ~ 66
-16 to -6 -6 to -3 -3 to 0 0 to 3 3 to 6 6 to 16
Southern China (from Cheng et al. 2005)
Long-term trend of the number of rainfall event (in days/10-yr) in summer for 1955−1979 (upper) and 1980−2005 (lower).
The red (blue) circle indicates positive (negative) value. Stations significant at the 90% level are indicated by filled circles. In contrast to the situation before 1979, the number of rainfall event has rapidly decreased since 1980.
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Different aerosol effects on precipitationDifferent aerosol effects on precipitation
Indirect Effect
OHSO2 + H2SO4
Increase cloud droplets
Reduce cloud droplet
sizeBrighter Cloud
Semi-direct Effect
Burn cloud droplets by UV absorption
2) increase cloud lifetime, suppress warm precipitation
3) more aerosols and moisture are allowed to reach higher altitudes by updrafts, more cold precipitation from intense convective storms
BC aerosols heat up the low-level atmosphere, and stabilize
it 1) suppress
warm precipitation
13The increase in aerosol concentrations in China, via aerosol indirect and semi-direct effects, may
affectthe long-term variations in precipitation
The increase in aerosol concentrations in China, via aerosol indirect and semi-direct effects, may
affectthe long-term variations in precipitationEastern-central China (Zhao et al. 2006 GRL)Eastern-central China (Zhao et al. 2006 GRL)Southern China (Cheng et al. 2005 JC)Southern China (Cheng et al. 2005 JC)
14The long-term trend of precipitation and aerosol
and scientific question
The long-term trend of precipitation and aerosol
and scientific question
Question
Increased aerosol reduced precipitation
(Zhao et al. 2006 GRL)
Or
Less precipitation more aerosol in the air
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Employed surface PM10 observationsEmployed surface PM10 observations
Air pollution Index (API) data Period: June 5, 2000 to July 31, 2006 (summers only) Available online at http://www.sepa.gov.cn/quality/air.php3
90E 100E 110E 120E 130E
20N
30N
40N
50N
Beijing
Shanghai
Guangzhou
Chengdu
PM10 station
PM10 and precipitation station
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Aerosol-precipitation interactionAerosol-precipitation interaction
The significant correlation suggests that the increase in aerosol concentration
increases rainfall frequency, which in turn removes aerosols from the atmosphere. This process is referred to “aerosol self-cleansing
effect”.
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Relation with MODIS cloud propertiesRelation with MODIS cloud properties
Aerosol concentration (g/m3)
0 40 80 120 160 200
Clo
ud
co
ver
(%)
0
10
20
30
4060
80
Total R = 0.95
Water R = 0.95
Ice R = 0.68
Mixed R = 0.85
Aerosol concentration (g/m3)
0 40 80 120 160 200
Ice
clou
d e
ffec
tive
radi
us ( m
)
23
24
25
26
27
28
Wat
er c
loud
eff
ect
ive
rad
ius
(m
)
14
15
16
17
18
19
Water
Ice
a
d
c
e f
b
18
Rainfall intensity-aerosol relationshipRainfall intensity-aerosol relationship
Difference of the rain-day frequencies in terms of rainfall intensity in between the cases of high (100190 g m3) and low aerosol concentrations (090 g m3).
A positive anomaly indicates that the frequency associated with the high aerosol cases dominates that associated with the low aerosol concentration. The error bar corresponds to the standard error of the anomaly. Bars significant at the 90% levels are indicated by red and blue colors.
RC*R
-5
0
5
RCCC*R
-5
0
5
RCC*R
-5
0
5
90%
95%
< 5 5 10 10 20 20Rainfall (mm/day)
Diff
eren
ce o
f ra
in-d
ay
fre
quen
cie
s (%
)
90%
Large smallaerosol concentrations
RC*R
-5
0
5
RCCC*R
-5
0
5
RCC*R
-5
0
5
90%
95%
< 5 5 10 10 20 20Rainfall (mm/day)
Diff
eren
ce o
f ra
in-d
ay
fre
quen
cie
s (%
)
90%
Large smallaerosol concentrations
19
The possible role of aerosols in precipitationThe possible role of aerosols in precipitation
Hei
ght
(km
)
1
2
3
4
5
6
7
SEEDERZONE
FEEDERZONE
IN CCN
Warm-rain processsuppresses light rain
Cold-rain processenhances moderate rain
Additional moisture & aerosols
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The self-cleansing system of aerosolsThe self-cleansing system of aerosols
A self-cleansing system
Ice cloudFormationIce cloudFormation
Airpollutants
Airpollutants
Rainfrequency
Rainfrequency
Wet scavenging
IncreaseIncrease
21Contradictory long-term trend in rainfall event
Contradictory long-term trend in rainfall event
80E 90E 100E 110E 120E 130E
20N
30N
40N
50N
80E 90E 100E 110E 120E 130E
20N
30N
40N
50N
< 66 ~ 33 ~ 0 0 ~ 3 3 ~ 6 6
19501979
19802006
Rainfall event (in days/10-yr)
-1.3
-2.8
Despite the aerosol self-cleansing effect, aerosol concentration has been increasing in China, accompanied by a decrease in rainfall events, over the last few decades.
22
Long-term trends in RH and SHLong-term trends in RH and SH
19501979
19802006
Relative humidity (in %/10-yr), NCEP
7 0 8 0 9 0 1 0 0 1 1 0 1 2 0 1 3 0 1 4 0
2 0
3 0
4 0
5 0
- 5 ~ - 2 . 5 - 2 . 5 ~ 0 0 ~ 2 . 5 2 . 5 ~ 5
Relative humidity (in %/10-yr), observation
19802006
7 0 8 0 9 0 1 0 0 1 1 0 1 2 0 1 3 0 1 4 0
2 0
3 0
4 0
5 0
- 2 0 ~ - 0 . 5 - 0 . 5 ~ - 0 . 2 5 - 0 . 2 5 ~ 0 0 ~ 0 . 2 5 0 . 2 5 ~ 0 . 5 0 . 5 ~ 0 . 7 5
Specific humidity (in g/10-yr), observation
19802006
23Detrainmental effect of human activities on the nature over East Asia
Detrainmental effect of human activities on the nature over East Asia
Aerosol self-cleansing system
A decrease in wet scavengingdue to a decrease in rain frequency
An increase in wet scavengingdue to a increase in rain frequency
An increase in rain frequencydue to cloud ice nuclei
AerosolsRain
frequency
Local sources of aerosoldue to industrialization
Regional climate variationson decadal time scale
A decrease in rain frequencyAn increase in aerosols
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SummarySummary
The aerosol self-cleansing effect is another important mechanism involved in aerosol-cloud-rainfall interaction in the summertime in China.
Despite the presence of aerosol self-cleansing effect, aerosol concentration has been increasing in China, accompanied by a decrease in rainfall events, over the last few decades.
These results show that the impact of reduced RH dominates the aerosol self-cleansing mechanism in determining the long-term trend in rainfall frequency, and additionally contributing to the increase in aerosol concentrations since the beginning of the industrialization of China in 1980s.
A weekly cycle of aerosol-meteorology interaction over China
A weekly cycle of aerosol-meteorology interaction over China
1. Gong, D.-Y., G. Dong, and C.-H. Ho, 2006: Weekend effect in diurnal temperature range in China: Opposite signals between winter and summer. Journal of Geophysical Research, 111, D18113.
2. Gong, D.-Y., C.-H. Ho, D. Chen, Y. Qian, Y.-S. Choi, and J. Kim, 2007: A weekly cycle of aerosol-meteorology interaction over China. Journal of Geophysical Research, 112, D22202.
3. Choi, Y.-S., C.-H. Ho, D. Chen, Y.-H. Noh, and C.-K. Song, 2007, Spectral analysis of weekly variation in PM10 mass concentration and environment conditions over China, Atmospheric Environment (in press).
1. Gong, D.-Y., G. Dong, and C.-H. Ho, 2006: Weekend effect in diurnal temperature range in China: Opposite signals between winter and summer. Journal of Geophysical Research, 111, D18113.
2. Gong, D.-Y., C.-H. Ho, D. Chen, Y. Qian, Y.-S. Choi, and J. Kim, 2007: A weekly cycle of aerosol-meteorology interaction over China. Journal of Geophysical Research, 112, D22202.
3. Choi, Y.-S., C.-H. Ho, D. Chen, Y.-H. Noh, and C.-K. Song, 2007, Spectral analysis of weekly variation in PM10 mass concentration and environment conditions over China, Atmospheric Environment (in press).
26Weekly cycle of aerosol-meteorology interaction
Weekly cycle of aerosol-meteorology interaction
Scientists began to pay attention to find more clear evidence of anthropogenic effect.
Weekly cycle of aerosol and meteorology is only a clear evidence of anthropogenic effect on the nature.
Satellite-observed gas/aerosol (Delene and Ogren 2002; Beirle et al. 2003)
Surface-observed gas/aerosol: carbon oxide (Hies et al. 2000; Cerveny and Coakley 2002), nitrogen oxide (Marr and Harley 2002), and PM (Jin et al. 2005; Gong et al. 2007)
DTR (Forster and Solomon 2003; Gong et al. 2006) Cloud and precipitation (Cerveny and Balling Jr. 1998; Jin et al.
2005)
27
Evidences of weekly cycles in urban regionEvidences of weekly cycles in urban region
Jin et al. (2005), Urban aerosols and their variations with clouds and rainfall: A case study for New York and Houston, JGR
Cerveny and Balling (1998), Weekly cycles ofair pollutants, precipitation and tropical cyclones
in the coastal NW Atlantic region, Nature
1946-96
1970-96
28
Evidences of weekly cycles in the globeEvidences of weekly cycles in the globe
Weekend effect for stations outside the U.S., using 1980–1999 data. Filled circles are temporally significant at the 95% confidence level. The diameter of the circle is related to the size of the DTR weekend effect in Kelvin (Forster and Solomon, 2003 PNAS).
weekend-weekday
29
Scientific questionScientific question
Why do aerosol concentrations show a maximum on Wednesday or Thursday in China?
30
Relation with low-level wind fieldRelation with low-level wind field
31
Relation with temperature profileRelation with temperature profile
32
Relation with DTR and rain frequencyRelation with DTR and rain frequency
33
SummarySummary
The PM10 (aerosol particulate matters of diameter < 10 m) concentrations in China show significant weekly cycles with the largest values around midweek and smallest values in weekend.
Accompanying this weekly PM10 cycle, the meteorological variables such as wind speed, air temperature, show notable and consistent weekly cycles.
We hypothesize that the changes in the atmospheric circulation may be triggered by the accumulation of PM10 through diabatic heating of the lower troposphere.
34
Concluding RemarksConcluding Remarks
The impact of aerosols on the regional hydroclimate, as a part of anthropogenic effects together with greenhouse gases, involves a number of processes on a wide range of time scales
Aerosol-cloud interaction (hourly or shorter) Aerosol-accumulation-rainfall and wet scavenging (a few
days) Aerosol-meteorology interaction (weekly) Long-term variations in the atmospheric RH modulate the
formal effects (decadal or longer)
We believe that these processes are going on, and will be clearer, at least over East Asia, in the future.