LIDAR Atmospheric Remote Sensing

Junior NkrumahProf. Ben Herman Dept. of Engineering,

CCNY

Abstract

Experimental setup Procedure

Materials

Results

Discussion

Conclusion

References

Acknowledgement

1.ND:YAG Laser

2.Telescope: diameter 500-mm 3.Detector: PMTs and Si-APD 4.Data acquisition: 12-bit ADC and Photon-counting

Prof. Ben HermanDept. of Engineering, The City College of New York

Yonghua WUGraduate student, Dept. of EngineeringThe City College of New York

Prof. Barry GrossDept. of EngineeringThe City College of New York

Dr. Franck Scalzo NASA GISS Director

Mrs. Charlene ChanNASA COSI Summer Program Instructor

Ms. Galia EspinalNASA COSI Summer Program Instructor

asd-www.larc.nasa.gov/lidar/lidar.htmlwww.csc.nwww.oea.larc.Nasa.gov/paisa/laser sensoring.html oaa.gov/crs/rs_apps/sensors/lidar.htm www.earth.engr.ccny.cuny.edu/noaa/wc/Lidar.html http://www.ncat.edu/~iset/research/presentations.php

Text book:“Lidar”, edited by C. Weitkamp, Springer, ISBN 0342-4111,2005 “Laser Remote Sensing: Fundamentals and Applications”by Raymond Measures, Krieger Pub Co., ISBN:0894646192, 1991, Optics, electronics, mechanics, programming, atmospheric physics

An optical remote sensing technology that measures properties of scattered light to find range and/or other information of a distant target.It uses the same principle as RADAR except that it uses a laser instead of radio waves.

Lidar uses lasers to determine the characteristics of the target such as its distance and the component of its speed toward or away from the lidar.

The laser transmits electromagnetic energy and a telescope receives whatever energy is reflected to the lidar.By timing the collected light and measuring how much reflected light is received by the telescope, we can determine its location, distribution and nature of the particles.

LIDAR: Light Detection And Ranging

Light detection and ranging (lidar) is a technique in which a beam of light is used to make range-resolved remote measurement. A lidar emits a beam of light, that interacts with the medium or object under study. Some of this light is scattered back toward lidar. The backscattered light captured by the lidar receiver is used to determine some properties. Lidar for Atmosphere Remote Sensing gives a general introduction to lidar, it focus on the differential absorption and techniques as well as monitoring aerosols, water vapor and minor species in troposphere and lower stratosphere.

Introduction

Aerosol-cloud (particle) detectionPlanetary boundary layer detectionWater vapor distributionMeteorological visibilityOzone and SO2 detectionTemperature profiles

Application in Atmospheric Remote Sensing Observation Examples

What are Aerosols?

Aerosols are suspensions of small solid or liquid particles. An aerosol may come from sources as various as a volcano, dust storms and grassland fires.

They are located in our troposphere and cause acid rain as well as cardiovascular and respiratory problems.

Due to the increasing population and

pollution in New York City aerosol concentration is increasing.

LaserNd:YAG

Optical Analyzer/Detector

Telescope

355 532 1064

Sky

Dichroic mirrors

Transmitter

Receiver

LaserND: YAG

Figure 3

Figure 1

Figure 2

Figure 4

Lidar has established itself as one of the most important measurements techniques for the atmosphere composition and dynamics from the surface to the upper atmosphere. It also has important uses in mapping and natural resource management. Lidar solutions offer themselves for a wide range of environmental monitoring problems. The Next decade promises the launch of several significant space-based lidar systems include experiments to measure clouds on a global scale. These space-based missions complement existing ground-based systems by increasing global coverage.

Reset the lidar, detectors and fix the lidar mirrors.

Two people are needed in the lab, one on the roof and the other at the lab. ( Two hours shifts)

Uses walkie-talkies to keep in contact with each other. ( if an airplane or a helicopter fly over the Lidar, the person on the roof turns of a switch, the alarm in the lap goes off and then the person in the lab is contacted to reset the lidar)

Collect and save all the files on the computer Mentors and the scientist look at all the data’s to determine the position, characteristics, distance and etc

Dust plume

Cloud

Typical observation example

23

4

1

Figure 5

Figure 6

Figure 6 show a data example of April 19, 2006. The data shows that the clouds intensity are higher in which allowed us to get a high signal to determine these particles. The area with all the dust plumes, shows a large amount of dust or aerosols that were found due to the turbulence. In addition, we observe a well mixed PBL layer with a height of approximately 1 km increasing to about 2 km during the afternoon allowing for an interaction between the PBL and the aloft plume.