LIDAR Atmospheric Remote Sensing Junior Nkrumah Prof. 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 Herman Dept. of Engineering, The City College of New York Yonghua WU Graduate student, Dept. of Engineering The City College of New York Prof. Barry Gross Dept. of Engineering The City College of New York Dr. Franck Scalzo NASA GISS Director Mrs. Charlene Chan NASA COSI Summer Program Instructor Ms. Galia Espinal NASA COSI Summer Program Instructor asd- sensoring.html oaa.gov/crs/rs_apps/sensors/lidar.htm Text book: “Lidar”, edited by C. Weitkamp, Springer, ISBN ,2005 “Laser Remote Sensing: Fundamentals and Applications” by Raymond Measures, Krieger Pub Co., ISBN: , 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) detection Planetary boundary layer detection Water vapor distribution Meteorological visibility Ozone and SO 2 detection Temperature 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. Laser Nd:YAG Optical Analyzer/Detector Telescope Sky Dichroic mirrors Transmitter Receiver Laser ND: 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 Figure 5 Figure 6 Figure 6 show a data example of April 19, 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.