大気モニタ R&DAtmospheric Monitoring

for TAM Chikawa, J Kaku ，T Benno, T Nishikaze Kinki Univ. N Hayashida ICRR 　　　　　　　　　　　　　　 and TA group

30th March 2004 : JPS @ 福岡

テレスコープアレイ計画 63

II00 E∝E∝

II

Air Fluorescence

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

Estimate of Mie effect near ground surface (simulation by Ogio(TIT))

without anycut for the data

cut data w/i 3km above ground

3km

EAS

TA

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

Atmospheric Monitoring

- lidar system : transparency of atmosphere as far as possible fluorescence light correction factor : I ⇒I0∝EEAS

feasibility study at AKENO suggests aspect to determine extinction coefficient by 20km : steerable Lidar

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

Observe all sky region → IR camera + convex mirror

- cloud monitoring : fiducial volume IR(infra red) camera

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

These are the issues that Japanese Atmospheric 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

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

Typical examples

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

Lidar exp’t

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

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 FADC 12bit

→ spatial resol.: few 10m

1/2

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

required specification for Lidar system

New LIDAR system

UV透過率測定

0

5

10

15

20

25

30

35

4000

5500

7000

8500

1000

0

1150

0

1300

0

1450

0

1600

0

1750

0

1900

0

2050

0

2200

0

2350

0

2500

0

2650

0

2800

0

2950

0

3100

0

Nd:YAG Laser5 mJ / pulse

Energy meter

telescope

Energy meter

T1=4752±290 T0=128940±798

補正板＋主鏡＋副鏡R = T1/T0 = 0.17±1%

透過率測定

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

calculates of edge of the cloud

differential coeff.

threshold cut

digitize: B&W

Astro dome

• settle an astrodome nearby the telescope station on the ground

install a new LIDAR system inside astrodome

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