is climate change in asia pacific attributed to human activities n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Is Climate Change in Asia-Pacific Attributed to Human Activities? PowerPoint Presentation
Download Presentation
Is Climate Change in Asia-Pacific Attributed to Human Activities?

Loading in 2 Seconds...

play fullscreen
1 / 34

Is Climate Change in Asia-Pacific Attributed to Human Activities? - PowerPoint PPT Presentation


  • 118 Views
  • Uploaded on

Is Climate Change in Asia-Pacific Attributed to Human Activities?. Chang-Hoi Ho School of Earth and Environmental Sciences Seoul National University. Acknowledgments. Main collaborators

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Is Climate Change in Asia-Pacific Attributed to Human Activities?' - mahon


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
is climate change in asia pacific attributed to human activities

Is Climate Change in Asia-Pacific Attributed to Human Activities?

Chang-Hoi Ho

School of Earth and Environmental Sciences

Seoul National University

acknowledgments
Acknowledgments
  • 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
changes in the rainfall distribution of korea
Changes in the rainfall distribution of Korea

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.

slide4

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.

daily precipitation contributed by typhoon
Daily precipitation contributed by typhoon

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.

long term change in summer rainfall
Long-term change in summer rainfall

(Cases for  30 mm/day)

(Cases for  0.1 mm/day)

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.

5870 gpm contour lines for each summer
5870 gpm contour lines for each summer

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.

interdecadal variability of tc tracks
Interdecadal variability of TC tracks

Increase

decrease

Increase

decrease

Recent summer-mean 500-hPa 5870m gpm

Previous one

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.

summary
Summary
  • 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 china

Some 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).

long term trend of the rainfall event in summer and the increase in air pollution
Long-term trend of the rainfall event in summerand the increase in air pollution

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.

different aerosol effects on precipitation
Different aerosol effects on precipitation

Semi-direct Effect

BC aerosols heat up the low-level atmosphere, and stabilize it

Burn cloud droplets by UV absorption

1) suppress warm precipitation

Indirect Effect

Increase cloud droplets

OH

Reduce cloud droplet size

SO2 +

 H2SO4

Brighter Cloud

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

slide13

The increase in aerosol concentrations in China, via aerosol indirect and semi-direct effects, may affectthe long-term variations in precipitation

Southern China (Cheng et al. 2005 JC)

Eastern-central China (Zhao et al. 2006 GRL)

the long term trend of precipitation and aerosol and scientific question
The long-term trend of precipitation and aerosoland scientific question

Question

Increased aerosol reduced precipitation

(Zhao et al. 2006 GRL)

Or

Less precipitation more aerosol in the air

employed surface pm10 observations
Employed 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

PM10 and precipitation station

Beijing

Chengdu

Shanghai

Guangzhou

PM10 station

aerosol precipitation interaction
Aerosol-precipitation interaction

The significant correlation suggests that the increase in aerosol concentrationincreases rainfall frequency, which in turn removes aerosols from the atmosphere. This process is referred to “aerosol self-cleansing effect”.

rainfall intensity aerosol relationship
Rainfall intensity-aerosol relationship

Difference of the rain-day frequencies in terms of rainfall intensity in between the cases of high (100190 g m3) and low aerosol concentrations (090 g m3).

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.

the possible role of aerosols in precipitation
The possible role of aerosols in precipitation

7

6

5

4

3

2

1

IN

CCN

SEEDERZONE

Height (km)

Cold-rain process

enhances moderate rain

FEEDERZONE

Warm-rain process

suppresses light rain

Additional moisture & aerosols

the self cleansing system of aerosols
The self-cleansing system of aerosols

Ice cloud

Formation

Increase

Increase

A self-cleansing

system

Air

pollutants

Rain

frequency

Wet scavenging

contradictory long term trend in rainfall event
Contradictory long-term trend in rainfall event

Rainfall event (in days/10-yr)

19501979

19802006

-1.3

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.

< 6

6 ~ 3

3 ~ 0

0 ~ 3

3 ~ 6

 6

-2.8

long term trends in rh and sh
Long-term trends in RH and SH

19501979

Relative humidity (in %/10-yr), NCEP

Relative humidity (in %/10-yr), observation

19802006

19802006

Specific humidity (in g/10-yr), observation

19802006

detrainmental effect of human activities on the nature over east asia
Detrainmental effect of human activities on the nature over East Asia

Local sources of aerosoldue to industrialization

Regional climate variationson decadal time scale

An increase in aerosols

A decrease in rain frequency

Aerosol self-cleansing system

An increase in rain frequencydue to cloud ice nuclei

Aerosols

Rain

frequency

An increase in wet scavenging

due to a increase in rain frequency

A decrease in wet scavenging

due to a decrease in rain frequency

summary1
Summary
  • 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

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.

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.

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).

weekly 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)
evidences of weekly cycles in urban region
Evidences 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

evidences of weekly cycles in the globe
Evidences of weekly cycles in the globe

weekend-weekday

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).

scientific question
Scientific question
  • Why do aerosol concentrations show a maximum on Wednesday or Thursday in China?
summary2
Summary
  • 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.
concluding remarks
Concluding 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.