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GRIP LIDAR Atmospheric Sensing Experiment (LASE) Table of Contents
NASA's Lidar Atmospheric Sensing Experiment (LASE) system was operated during the Genesis and Rapid Intensification Processes (GRIP) campaign to gather water vapor mixing ratio and aerosol scattering ratio (815 nm) profiles. Other derived parameters include: relative humidity, equivalent potential temperature, virtual potential temperature, precipitable water vapor profiles, aerosol backscatter, aerosol extinction, and aerosol optical thickness profiles (815 nm). Aerosol data are reported as Atmospheric Scattering Ratios on a logarithmic scale. Water Vapor data are reported as mixing ratios (g/kg) on both a Linear and logarithmic scale. LASE was operated from the NASA DC-8 aircraft during the GRIP campaign flights between August 13 and September 25, 2010. CampaignThe Genesis and Rapid Intensification Processes (GRIP) experiment was a NASA Earth science field experiment conducted August 5 to September 30, 2010. The major goal was to better understand how tropical storms form and develop into major hurricanes. NASA used the DC-8 aircraft, the WB-57 aircraft and the Global Hawk Unmanned Airborne System (UAS), configured with a suite of in situ and remote sensing instruments that were used to observe and characterize the lifecycle of hurricanes. This campaign also capitalized on a number of ground networks and space-based assets, in addition to the instruments deployed on aircraft from Ft. Lauderdale, Florida ( DC-8), Houston, Texas (WB-57), and NASA Dryden Flight Research Center, California (Global Hawk). More information about this Campaign can be found on the GRIP web site: http://grip.nsstc.nasa.gov/ Principles of OperationNASA's Lidar Atmospheric Sensing Experiment (LASE) system is an airborne DIAL (Differential Absorption Lidar) system used to measure water vapor, aerosols, and clouds throughout the troposphere. LASE probes the atmosphere using lasers to transmit light in the 815-nm absorption band of water vapor. Pulses of laser light are fired vertically below the aircraft. A small fraction of the transmitted laser light is reflected from the atmosphere back to the aircraft and collected with a telescope receiver. The received light indicates the amount of water vapor along the path of the laser beam. The LASE program was initiated as an effort to produce an autonomous system for measuring water vapor levels from airborne and spaceborne platforms using LIDAR technology. For much more in-depth information about the LASE system, visit this web location: http://asd-www.larc.nasa.gov/lase/ASDlase.html Data Naming ConventionThe data files are represented by the example files below:
The image files are represented by the example files below:
where, Data File Specifics There are two types of data files included in this dataset, and the specifics for each file are listed below. DC-8 Relative Aerosol Scattering Vertical data interval is 30 m., horizontal data interval is 6 seconds. Vertical resolution is 60 m, horizontal resolution is 6 seconds (1.4 km). Nadir and zenith data are combined in this file. The relative aerosol scattering was determined using molecular density profiles derived from the 1986 AFGL mid-latitude summer model. No corrections for molecular, water vapor or aerosol attenuation have been performed in this preliminary analysis. When using these data, the user must be aware that noise increases with range and that there may be under-estimates in the relative aerosol scattering in and on the far side (relative to lidar location) of clouds due to signal saturations, optical attenuation, and/or signal processing methods. These measurements have a maximum estimated error of 5% or 0.1, whichever is larger. This file conforms to the Gaines/Hipskind "2310" format for multi-dimensional data sets. The format requires stop, mid and end times for the averaging intervals without overlap. Therefore, only the Mid time of the 2 minute averages is accurate. DC-8 Water Vapor Mixing Ratio (Nadir) Vertical data interval is 30 m., horizontal interval is 6 seconds or 1.4 km. Nadir and zenith data are combined in this file so the vertical averaging and/or horizontal resolution are different above versus below the aircraft altitude. Nadir: vertical resolution is 330 m., horizontal resolution is 2 minutes or 28 km. Zenith: vertical resolution is 990 m., horizontal resolution is 2 minutes or 28 km. The water vapor mixing ratio was calculated using an air density profile derived from the 1986 AFGL mid-latitude summer model. When using these data, the user must be aware that noise increases with range and that there may be a bias or increase in noise in and on the far side (relative to lidar location) of clouds due to signal saturations, optical attenuation, and/or signal processing methods. LASE measurement accuracy is better than 6 % or 0.01 g/kg, whichever is larger, across the troposphere. This file conforms to the Gaines/Hipskind "2310" format for multi-dimensional data sets. The format requires stop, mid and end times for the averaging intervals without overlap. Therefore, only the Mid time of the 2 minute averages is accurate. Data FormatThe LASE_GRIP data files are stored in ASCII using Gaines-Hipskind "2310" Data Archive Format. Format specification for Data Exchange by Steve E. Gaines and R. Stephen Hipskind may be found in PDF form here: Gaines_Hipskind.pdf (The LASE data use data record format number 2310). These data can be read using the sample read software supplied below. Read SoftwareThere is a sample read program provided which works with all Gaines-Hipskind "2310" formatted LASE data sets. It is written in ANSI C, and has been successfully tested on Sun, SGI, HP, and DEC computer operating systems. This program was written as an example of how to read in the LASE data. It reads in and writes out to the screen the file header information followed by each profile's header and data. This sample program can be downloaded here: read_lase_gh.c Currently the input file name is expected to be no more than 50 characters in length. If you have changed the name of the input file to greater than 50 characters, you will need to modify this program, changing the value of the MAX_FILENAME parameter in the #define statement near the beginning of the file to be at least the maximum length needed + 1. All data files are assumed to be in the current working directory. If the files are located in another directory be sure to include the complete path with the file name. Contact InformationThe data producer is:
To order these data or for further information, please contact:
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