Atmospheric Monitoring

of TA[Japanese WG]

M Chikawa, J Kaku Kinki UniversityN Hayashida ICRR and TA group

26th Feb 2004 : ICRRsympo

tcoefficien extinction :1/ length,n attenuatio

:

,,

exp4

0

20

MieRaileighiEASi

EAS

EEII

R

R

AEI

Atmospheric structurechange its transmittance in spatial and vary with time → important to know its structure and time variation → back scatt., side scatt., sunphoto meter etc.

cloud aerosol dust, vapour, mist, fog

wind

z

density ρ(z)scattering processRayleigh(molecule) depends on ρ(z)

Mie(aerosol) depends on aerosol

wide and local areatime

atmosphere

Air fluorescence light

　　

UV

luminescence from Nitrogen 315.9 nm (N2) 337.1 (N2) 357.1 (N2) 391.4 (N2

+)

Estimate Mie leffect near ground surface (Simulation by Ogio(TIT))

without anycut for the data

cut data w/i 3km on the ground

3km

EAS

TA

Fluorescence light generated events = 100, arrival zenith angle : uniformenergy =10^20 ev (fixed)

Atmospheric Monitoring• Contribution by Japanese Atmospheric Monitoring group [our future plan for final design] - lidar system : transparency of atmosphere as far as possible feasibility study at AKENO suggests aspect to determine extinction coefficient by 20km : fix Lidar

How to… shoot, DAQ, analyze ， and calibrate, etc.

Observe all sky region → IR camera + convex mirror

- IR(infra red) camera available to use cloud monitor

- astro dome will be settled on the roof of each three stations in order to install Liar systems

These are the issues that Japanese Atmosperic WG is going to do for TA.

back scattering (LIDAR method)　　　　　　　 & side scattering (phase function method)

R

drrT

d

dT

R

AlPP

0

18020

')'(2exp

4)(

θ=180 0<θ<180

Laser

θ

3

8:

)cos1( 2

)( R

R

total

constd

d

• Mie scattering coefficient0.001 km-1

• Mie Phase function Modified Henyey-Greenstein

Utah 7 telescope (3mφ) + HiRes laser : 1999

Infrared Camera5mJ

16cm

Lidar Experiment at AKENO

Inclined Laser shots

Lidar

laser pulse vertical , horizontal, and arbitrary direction ↓detect using PMT w/mirror scattered light intensity elapsed time → distance from laser

明野 Lidar による観測

Horizontal Measurement

Assumption for analysis

1, only Rayleigh Scattering>10km

2, AtmosphereAlmost Uniform

In Horizontal direction

3, Measure Horizontal: Rayleigh+Mie

Inclined Laser shots

Lidar

To evaluate the extinction coeff. from Lidar data, Simple & convenient assumption for structure of atmosphere is applied.

Assume this behaviour,develop a new Lidar system

Akeno data 15/Oct/2003

• Lidar exp’t at Akeno• Typical sample of

good results• Corrected intensity of

scattered light PxR2

vs. light path length

0 2 4 6 8

101

102

path length(km)

P×

R2

path length v.s. P× R22003/10/16Observed at Akeno

Extinction length vs. height from ground surface

constant empirical :

length extinction :

tcoefficienscatter back :

k

kconst

horizontal

another sample

0 100

0.1

0.2

α消

散係

数(1

/km

)

Height from Laser(km)

2003/10/16Fine

θ = 90°θ = 40°Rayliegh

0 2 4 6 8

0.05

0.1

0.15

α消

散係

数(1

/km

)

Height from laser(km)

k=1.5k=1.0k=0.5

Back scattered exp’t [ Lidar ]

R&D @ Akeno w/ steerable system　　　　　　　 Mirror diameter 15cm, laser power 5mJ　　　　　　　 3-dimension measurement : 10km in vert. & ≦

horiz.

condition 　　　 α ± Δα fine 0.0639 ± 0.0005 hazy 0.1394 ± 0.0005 0.1645 ± 0.0010 cloudy 0.3254 ± 0.0016

⇒ should be measured far distance ～ 20km solution : install larger mirror, higher power laser

Experiment LIDAR method LIDAR method Side scatter method

location Akeno(1997-2004) Utah TA(2004- : Chikawa) Utah TA(2004- : Fukushima)

Laser NdYAG:355nm NdYAG:355nm NdYAG:355nm

Laser power 5 mJ 5 mJ mJ ?

Absolute measurement No Yes Yes

Steerable system Yes Yes No

PMT 3/4”(UV) [1 PMT] 3/4”(UV) [1 PMT] Multi(UV) [Multi-PMT]

Mirror 16 cm 30 cm 3 m

Electronics Digital oscilloscope (8bit)

FADC(12bit)

FADC(12bit)

Att. length 13km – 2km - -

Ext. length 0.06 – 0.32 - -

Accuracy 0.1 %(stat), few %(sys) < 10 % < 10 %

Horizontal Range 7 – 8 km < 20 km < 20 km

Assumptions of atmospheric structure

Uniform in horizontal uniform in horizontal uniform in horizontal

Assumption >10km above : only Rayleigh

>10km above : only Rayleigh >10km above : only Rayleigh

Assumption β ＝ αk - 1+cos2θ(Mi)

Analysis method Klett’s & Slope method Absolute method Absolute method

R&D : Meade LX200GPS Schmidt-Cassegrain Telescope w/ UHTC(ultra high transmission coating)

• RS232C controllable by PC linux thru Network

prototype just begin to study at Kinki Univ. will have next devices piggy back YAG laser : ( 355nm 2-3mJ 5ns pulse width) + PMT 3/4” diameter + mirror + Digital Oscilloscope (+ Energy meter ) • FOV : approx. 1 degree

A new lidar system

parameters of the lidar system

to determine extinction coeff. approx. 20km

with few % error

Nd/YAG laser

355nm, 4 mJ

5ns pulse laser

mirror 30cmφ

PMT 3/4”

Gain ～ 106

ADC 9bits : time&signal

(digital oscillo) 　resol.: few 10m, few

p.e.

→ FADC 12bit

1/2

Off-line analysis :analyze Lidar data from each station independently

required specification for Lidar system

FOVFOV ：： 25.825.8 ゜（゜（ HH ）） ×1×19.59.5 ゜（゜（ VV ））

320320×236 ×236 pixelpixel

Sensitivity : Sensitivity : 8 8 -14μm-14μm

-20 -20 ゜ ゜ ～ ～ 300 300 ゜゚digital value digital value temperapure temperapure

IR Camera Cloud monitoring

IR Camera

• IR camera on a steerable system: Akeno Lidar system

• IR camera use 2-dimensional cloud monitor and measure distance by Lidar 3-dimensional cloud monitoring

• option : VTR(visible light) for all-sky waether monitor

Cloud monitoring

IR camera on AKENO lidar system

distribution oftemperature

1000 1100 12000

1000

2000

Fre

quen

cy

Data［digits］

各ピクセルが表す温度のヒストグラム

1000 1100 12000

1000

2000

Fre

quen

cy

Data［digits］

各ピクセルが表す温度のヒストグラム

The cloud region is warmer than background sky !

calculates of edge of the cloud

differential coeff.

threshold cut

digitize: B&W

Astro dome

• Settle an astrodome nearby the telescope station

(not roof top)

install a new LIDAR system inside astrodome

4th Lidar Station

後方散乱 Lidar の守備範囲

（ 20 km 以内）

垂直射出側方散乱の守備範囲

（２ヶ所でサンドイッチ）

大気透明度モニターの配置案　（後方＋側方散乱の併用で誤差１０％　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　以内を

目標。）

Ovservation room : square (left) and round shape(right)

Round type is better than square type for protection of wind, snowfall, etc.

Astro dome

Discussion• Range of extinction length : 20km may be OK, but enough? feasibility study at Akeno supports 20km measurement: realistic limit value for our Lidar system during laser shooting to measure might be serious problem for DAQ of E>1018eV, EAS rate from AGASA ★ ext. length α has large dependence of the empirical parameter k (=0.6 to 1.3) in the model

　　 feasibility study to measure absolute light intensity by PMT free from model dependence for Rayleigh scattering

• LIDAR : steerable system need to establish robust system using commercial product

• Astro dome : settle on the ground nearby the TA station • IR camera all sky monitoring and off-line data analysis can be available

And I really understand it’s very difficult to know atmospheric properties in detail.→ challenging subject!!