Proposal Information

The following proposals are in response to NASA Research Announcement NRA-97-MTPE-03:

Research Proposals:

• Interpretation of Lightning Observations for Understanding the Meteorological Properties of Clouds
• Cross-Sensor Validation of the Lightning Imaging Sensor
• LIS Validation Studies Using Lightning at the KSC-ER

Investigators:

The emphasis of this proposed research program is the interpretation of total lightning observations to understand the meteorological properties of clouds. In this context, our focus will be to explore quantifiable relationships between lightning and other cloud and environmental variables. Using these relationships, we will then develop algorithms that can use lightning observations on a global scale to diagnose cloud kinematics, morphology, and storm severity. This improved understanding of the relationships among the processes that lead to the electrification of clouds and subsequent lightning activity is highly desired to better interpret global cloud measurements.

We propose to take advantage of currently available surface and space based data sets to jump start the development, testing, assessment and validation of algorithms that employ total lightning observations. Initial data sets will be acquired at the Tropical Rainfall Measuring Mission (TRMM) ground truth site in Florida. In 1999, similar multi-sensor data bases (including total lightning) will be available from Huntsville, AL, the Rondonia region of the Brazilian Amazon, and the Kwajalein Atoll region of the Pacific Ocean as part of future validation campaigns. Thus, total lightning and storm observations will be collected from extratropical land, tropical land, and tropical ocean environments. The new knowledge from this study will be applicable to lightning observations acquired from future missions such as the proposed Lightning Mapper on GOES N-P.

Cross-Sensor Validation of the Lightning Imaging Sensor

Investigators:

An effort to perform a detailed, quantitative validation of the Lightning Imaging Sensor (LIS) is being proposed as a collaborative effort between personnel of the National Aeronautics and Space Administration (NASA), Marshall Space Flight Center (MSFC) and the Universities Space Research Association (USRA) at the Global Hydrology and Climate Center (GHCC) and the University of Arizona. The focus of the study will be the determination of LIS precision, accuracy, sensitivity (detection efficiency), biases and variance in previously unexplored lightning regimes and problematic observation zones. The investigation will build on preliminary work and lessons learned during validation of the prototype Optical Transient Detector (OTD). The benefits of this study to the Mission to Planet Earth (MTPE) program will be the delivery of a well-calibrated, bias free dataset of tropical and mid-latitude total lightning, with specified observation variances (errors). Such a dataset will play an important role in quantifying tropical surface temperature changes and lightning-related NO_x emissions, and key rate-related meteorological parameters such as convective mass flux and cirrus anvil detrainment rates, which are difficult to determine by passive (IR and microwave) measurements during rapid flybys.

The specific objectives of this proposal are to: 1) rigorously assess the reduction in LIS detection efficiency due to noise contamination, 2) optimize the existing adaptive noise filters, 3) assess the largely unknown intracloud (IC) flash detection efficiencies of both OTD and LIS, 4) cross-calibrate the OTD and LIS sensors to extend the temporal baseline of global lightning observations, 5) validate and/or improve the flash grouping algorithms currently employed to delineate convective cells, 6) assess the sampling-related variance in observations of global and regional flash rates, and 7) utilize concurrent TRMM ground truth and satellite data and fully validated LIS observations to lay a groundwork for relating observed flash rates to other convective parameters. The proposed work makes extensive use of existing algorithms and methodology developed for OTD, as well as observations from sensors already fielded or planned in other field campaigns.

LIS Validation Studies Using Lightning at the KSC-ER

Investigators:

• E. Philip Krider (University of Arizona)
• William J. Koshak (MSFC)

The ground based electric field mill (FM) network and the Lightning Detection and Ranging (LDAR) system at the NASA Kennedy Space Center (KSC) and USAF Eastern Range (ER) will be used to characterize and validate the Lightning Imaging Sensor (LIS) data set. The validation activities will focus on quantifying and improving the LIS geolocation accuracy and lightning detection efficiency. As part of this activity, an intensive investigation will be made of the characteristics of lightning charges, lightning radio sources, thunderstorm current sources, and theoretical (model) calculations of photon transport inside clouds. Also, measurements of the absolute radiance on the ground will be correlated with LIS. Particular emphasis will be given to possible relationships between the amount of charge involved in a lightning flash (derived from the FM network) and the total optical energy that is measured by the LIS.