New developments for SKYNET Chiba/Japan & Phimai/Thailand sites by utilizing the MAX-DOAS technique Hitoshi Irie Center for Environmental Remote Sensing (CEReS) Chiba University, Japan 1T. Takamura, 1P. Khatri, 1T. Muto, 1T. Kato, and 2S. Itahashi 1Chiba University, 2Central Research Institute of Electric Power Industry

SKYNET In recent years, Chiba Univ. is reinforcing An observation network dedicated for aerosol-cloud-radiation interaction researches. (e.g., Takamura et al., 2004; Nakajima et al., 2007) Initiated under the WCRP/GAME project and expanded focusing on East Asia as ADEOS/GLI validation activity. A growing network linking more than 100 sites (as of 2015) all over the world. Still expanding with one main focus on satellite validations. 　(GCOM-C, EarthCARE, GOSAT, GOSAT-2, Himawari-8, GEMS, ...). Chiba Univ. is playing the leading role in SKYNET. Sky radiometer (AOD, SSA, COD, O3, H2O, ...) MAX-DOAS (AOD, NO2, SO2, H2O, O3, HCHO, ...) In recent years, Chiba Univ. is reinforcing the capability of SKYNET as the leading institute. http://atmos2.cr.chiba-u.jp/skynet/ http://atmos.cr.chiba-u.ac.jp/

Air quality research under SKYNET The idea to reinforce the capability of SKYNET SKYNET International Network Atmospheric chemistry Atmospheric physics trace gases (inorganic/organic) aerosols clouds radiation We have a further uniqueness with our observations as follows...

Explored the potential for multi-component observations by MAX-DOAS (Irie et al., 2011, 2015) Aerosols Inorganic Organic JM2 Irie et al. (2011,2015) Lower-tropospheric vertical profile information for 8 quantities: Aerosols at 357 & 476 nm NO2(UV&vis), SO2, O3, H2O HCHO, CHOCHO

The two sites equipped with MAX-DOAS as part of growing network SKYNET Chiba Phimai

SKYNET/Chiba site & 4AZ-MAXDOAS Chiba site: 35.63ºN, 140.10ºE, 21 m a.s.l. Located in Chiba University Sky radiometer Lidar Pyranometer Directo solar rad obs Pyrgeometer Microwave radiometer Cloud camera Met obs. 4AZ-MAXDOAS Chiba Chiba Earth’s city lights To understand spatial inhomogeneity of trace gases and aerosols in an urban environment, the 4AZ-MAXDOAS system has been in operation since November 7, 2014.

Differences in AOD by a factor of 6! According to the sky radiometer obs., AOD was slowly changing in daytime. factor 6! 4AZ-MAXDOAS Large deviations (by a factor of 6) were observed with the north-looking MAX-DOAS.

The large deviations were due to high spatial inhomogeneity produced by the transport of polluted airs from Tokyo! GOME-2 NO2 OMI NO2 MODIS AOD Back trajectory wind

Selected other interesting features seen from observations at Chiba site NO2 H2O factor 4! For NO2 VCD, very high spatial inhomogeneity with a difference by a factor of 4 was observed. For H2O, spatial inhomogeneity was not high. Temporal variations was well captured by CMAQ (27-km resolution). → This gives a hint to explain large deviations often seen from validation comparison between satellite and MAX-DOAS at urban sites. → This gives some confidence with our MAX-DOAS observations.

The two sites equipped with MAX-DOAS as part of growing network SKYNET Chiba Phimai

SKYNET/Phimai site Phimai site: 15.18ºN, 102.56ºE, 212 m a.s.l. In Bureau of Royal Rainmaking and Agricultural Aviation (BRRAA), Phimai, Thailand. Supported by Chulalongkorn Univ. Sky radiometer Lidar Pyranometer Directo solar rad obs Pyrgeometer Microwave radiometer Cloud camera Met obs. MAX-DOAS Satellite-retrieved HCHO VCD (1015 molec. cm-2) (De Smedt et al., 2010) We started continuous observations by MAX-DOAS at Phimai on Sep. 18, 2014.

Diurnal variations (the first 3 days) Rapid diurnal variation in NO2 and SO2 VMRs. →　can models reproduce these diurnal variations? HCHO VMR is much higher than NO2 VMR. →　significant biogenic contributions

Evaluation of MAX-DOAS retrievals Apr.14 Apr.22 Aerosols H2O Late wet season Dry season MODIS fire maps (Tsuruta et al., 2008) LIDAR attenuated backscatter coefficient Cloud-free conditions Aerosol below ~2 km

Seasonal variations (Oct.2014 – Feb.2015) Aerosols NO2 O3 SO2 From the late wet season through the dry season, aerosols, NO2, SO2, and O3 were enhanced.

Seasonal variations for HCHO&CHOCHO Jan. 31-Feb. 9, 2008 Dry season MODIS fire maps (Tsuruta et al., 2008) RGF = [CHOCHO]/[HCHO] HCHO and CHOCHO VMRs were also enhanced. RGF was at a moderate level of 0.03. → mixed contributions from BVOC and BB emissions

Summary As an option for AQ study, the 4AZ-MAXDOAS and MAX-DOAS have been in operation at SKYNET/Chiba and SKYNET/Phimai sites, respectively, since last autumn. At Chiba site, the 4AZ-MAXDOAS detected spatial inhomogeneity with differences in AOD (NO2 VCD) by a factor of 6 (4). At Phimai site, the MAX-DOAS showed that aerosols, NO2, SO2, O3, HCHO, and CHOCHO VMRs were all enhanced from the late wet season through the dry season. RGF was at a moderate level of 0.03, suggesting mixed contributions from BVOC and BB emissions in the dry season. As a next step, it is interesting to evaluate if these are reproduced by a model quantitatively.

The large deviations were caused by spatial inhomogeneity! Ground-based surface PM2.5 data Back trajectory wind Satellite data MODIS AOD GOME-2 NO2 OMI NO2

Spatial inhomogeneity increased due to the transport from Tokyo Nov. 13, 2014 Back trajectory wind MODIS AOD Nov. 13, 2014 On Nov. 13, strong winds blew from west, bringing polluted air originated from Tokyo to around northern region of Chiba. For precise validation, spatial inhomogeneity needs to be carefully considered in detail.

Principle of MAX-DOAS observations (Multi-AXis Differential Optical Absorption Spectroscopy) ■ High sensitivity to trace gases in the boundary layer ■ Long-term operation ■ Easy to handle ■ Inexpensive ■ Low power consumption UV/Vis. spectrum ~10-20 km

MAX-DOAS instrument Outdoor unit (telescope, etc.） Indoor unit（spectrometer, etc.） 10-m fiber optic cable movable mirror ・Maya2000Pro (Ocean Optics) ・FWHM: about 0.3 nm ・Wavelength: 310-520nm ・Temperature kept at 40℃ ・Integ. time constant throughout the day ・Field of view < 1 deg ・Elevation angles = 2, 3, 4, 6, 8, 70 deg