ISS Science for Everyone
Science Objectives for Everyone
Lightning flashes somewhere on Earth about 45 times per second, according to detailed observations from space-borne lightning detectors developed and flown by National Aeronautics and Space Administration (NASA) over the past twenty years. The Space Test Program-H5-Lightning Imaging Sensor (STP-H5 LIS) continues these important observations using a similar sensor on the International Space Station (ISS) to measure the amount, rate, and energy of lightning around the world. Improved understanding of lightning and its connections to weather provides crucial insight for weather forecasting, climate change, atmospheric chemistry and physics, and aircraft and spacecraft safety.
Science Results for Everyone
The following content was provided by Richard Blakeslee, and is maintained in a database by the ISS Program Science Office.
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Richard Blakeslee, Marshall Space Flight Center, MSFC, AL, United States
Hugh Christian, NSSTC, Huntsville, AL, United States
Marshall Space Flight Center, MSFC, AL, United States
The National Space Science and Technology Center, University of Alabama in Huntsville, Huntsville, AL, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Technology Demonstration Office (TDO)
Earth Benefits, Scientific Discovery
ISS Expedition Duration
- February 2018
An identical LIS was flown on the Tropical Rainfall Measuring Mission (TRMM), which was launched in November 1997 and continued until April 2015 (17+ years). Prior to TRMM LIS, space-qualified engineering model of LIS called the Optical Transient Detector (OTD) was launched in April 1995 and acquired observations for five years through a NASA data buy until April 2000. A well established infrastructure for processing, archival, and distribution is in place and insures that the data will be quickly placed in the hands of users.
A space-based lightning sensor provides important benefits from its ability to detect and locate total (both cloud and ground) lightning over a large area of the Earth. A lightning sensor in low Earth orbit measures lightning actively globally, allowing seasonal and inter-annually distributions to be examined. Better understanding of lightning and its connections to weather and related phenomena can provide unique and affordable gap-filling information across a wide range of science disciplines including weather, climate, atmospheric chemistry and lightning physics.
The Space Test Program-H5-Lightning Imaging Sensor (STP-H5 LIS) extends the time series of space-based lightning observations, expands the latitudinal coverage into the climate sensitive middle-latitudes, provides real-time lightning data to operational users, and enables simultaneous and cross-sensor observations for enhanced science and climate studies.
Observations from STP-H5 LIS improve and enhance regional and global weather, climate, and atmospheric chemistry models, studies, and assessments. Real time observations support operational and research activities in data sparse regions, such as over the oceans. Data comparison with other space based lightning instruments, such as the GOES Geostationary Lightning Mapper, improve long term climate monitoring. The simultaneous synergistic and complementary observations with specific ISS payloads mutually enhance the science return from each of these payloads. It is anticipated that the STP-H5 LIS lightning products, statistics, and global climatology will be recognized and used extensively by the international science community.
At the broadest level, Space Test Program-H5-Lightning Imaging Sensor (STP-H5 LIS) science goals and objectives are to acquire and investigate the global distribution and variability of total (i.e., both ground and cloud) lightning and advance the understanding of underlying and interrelated processes (i.e., precipitation and storm processes, release and transport of latent heat, atmospheric chemistry, global electric circuit, ionospheric and magnetospheric physics, and lightning physics). Specific research topics of scientific importance include: (1) provide information on the total rain volume and degree of convective activity in the core regions of tropical and extra-tropical storms and storm systems, particularly as relevant to severe weather occurrence; (2) study the global distribution of lightning and its relationship to storm microphysics and dynamics, its dependence on regional climatic environments and their changes, its relationship to precipitation and cloud type, and the incorporation of these relationships into diagnostic and predictive models of global precipitation, the general circulation and the hydrological cycle; (3) develop global lightning climatology in order to study the distribution and variability in lightning frequency as an indicator of the intensity of the Walker and Hadley circulations and assess the impact of sea surface and land surface temperature changes on the distribution and intensity of thunderstorms, including extreme weather events; (4) study the production, distribution, and transport of trace gases attributed to lightning and determine the contribution (and the sources of variability) to the global amount of trace gases; and (5) conduct observational and modeling studies of the global electric circuit and the factors that cause it to change. This last topic also includes investigating the relationship of lightning with ionospheric/magnetospheric processes, as well as basic lightning physics. Although it was not stated as a specific goal, NASA TM 4350 also discussed using LIS data sets for cross validation studies with other measurement systems including a potential future geostationary lightning instrument such as the GOES-R Geostationary Lightning Mapper (GLM) or the Meteosat Third Generation (MTG) Lightning Imager (LI).
There are several unique and highly valuable science contributions gained by taking the STP-H5 LIS to ISS, and represent key reasons why STP-H5 LIS was selected to fly on ISS. These contributions, which are referred to here as the ISS unique STP-H5 LIS science goals/objectives, trace to the ISS orbital characteristics (i.e., especially its higher inclination), the ISS communication advantages, as well as various other factors. The ISS unique STP-H5 LIS science objectives include: (1) availability of higher latitude lightning coverage greatly enhances and expands several core science objectives noted above; (2) reception/distribution of real-time (minutes with STP-H5 LIS versus hours with TRMM LIS) lightning data via the ISS Low Rate Telemetry (LRT) communications channel, primarily for delivery to operational users for forecast and warning applications in data sparse regions such as over the oceans; (3) simultaneous/complementary lightning observations with other payloads, especially during day time. This is a contingent goal dependent on other payload schedules--e.g., ESA’s Atmosphere-Space Interaction Monitor (ASIM) that is presently scheduled to operate on ISS in a similar timeframe as STP-H5 LIS; and (4) cross-sensor validation with other space-based, airborne or ground-based measurement systems.
The STP-H5 LIS mission contributes to the NASA Global Precipitation Mission (GPM) by helping improve quantitative precipitation estimates over land. Lightning is quantitatively correlated with ice production with peak production over land. GPM rain rate retrieval algorithms strongly depend on passive microwave retrievals over land where the retrieval algorithms are weakest. STP-H5 LIS lightning data complement the microwave data leading to improved rain fall estimates over land. Lightning is also coupled to severe weather hazards (winds, floods, tornadoes, hail, wild fires) can contribute to improvements to forecast models.
Another area where the STP-H5 LIS makes important scientific contributions includes climate change. Lightning is an excellent variable for climate monitoring because its production (and the occurrence of intense convection) is sensitive to small changes in temperature and atmospheric forcing. A decade of TRMM LIS measurements shows relatively flat lightning activity over the continental United States, mirroring the wet-bulb temperature trend of the same period. The STP-H5 LIS will not only extend this data base but will expand it to higher latitudes where the lightning-temperature relationship should be most sensitive.
Lightning observations from STP-H5 LIS helps to improve estimates of lightning produced nitrogen oxides (NOx) for climate and air quality models and assessments on both a global and region basis. Lightning produced NOx, in turn, impacts the concentration of ozone (O3), an important greenhouse gas. Climate is most sensitive to O3 in the upper troposphere where lightning is the most important source of NOx.
The STP-H5 LIS on ISS would be capable for the first time of observing the individual lightning strokes responsible for Terrestrial Gamma-ray Flash (TGF) events and record this information on a millisecond time scale, by correlating its lightning observations with the TGF observations from the ISS Atmosphere-Space Interaction Monitor (ASIM) experiment. The type of thunderstorm, the altitude of origin and the beaming angle of the hypothesized electron beam could then be determined, leading to a greatly improved understanding of the TGF process. The present ASIM instrument suite is incapable of detecting optical lightning events on the millisecond time scale that is required for one–to-one comparisons with TGFs. Further, the ASIM can only detect lightning at night, while as STP-H5 LIS detects lightning well during both day and night. This capability alone leads to an 80% increase in the probability of simultaneous observations. TGFs could pose significant radiation hazard to aircraft pilots and passengers. The joint missions help clarify the potential safety hazard posed by TGFs, and, if necessary, guide mitigation strategies.
The STP-H5 LIS provides key observations for on-orbit validation and characterization of the Geostationary Lightning Mapper (GLM), a cutting-edge lightning sensor that supports NASA weather and climate research. The GLM uses a detection approach based on the LIS. The inter-calibration between GLM and LIS, which is well characterized from 17+ years of TRMM LIS, improves the long term climate record provided by all of these systems (i.e., OTD, TRMM LIS, STP-H5 LIS and GLM). Finally, depending on how long STP-H5 LIS operates on ISS, there may be an opportunity to provide similar on-orbit calibration with the European geostationary lightning mapper, Meteosat Third Generation-Lightning Imager (MTG-LI).
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A space-based lightning sensor can detect and locate both cloud- and ground-based lightning over a large area of Earth, improving global climate and atmospheric chemistry models. Measuring lightning from space removes any observational bias from the land or oceans. Flying an instrument aboard the ISS provides improved coverage for higher latitudes, which are particularly sensitive to climatic changes. Lightning can help scientists study climate change because the storms that produce lightning are sensitive to small changes in temperature and atmospheric conditions. In addition, improved understanding of lightning and its connection to severe weather contributes to improved lightning protection efforts at NASA centers and launch facilities.
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Observations from this investigation improve regional and global weather, climate and atmospheric chemistry models. The instrument’s high sensitivity and millisecond observation capability improves data collection in remote areas, including over the oceans. This data improves hurricane rapid intensification studies and benefits oceanic aviation. More than 40 countries use existing LIS data from the Tropical Rainfall Measuring Mission (TRMM) satellite, and new data from the ISS are beneficial to climate scientists.
Operational Requirements and Protocols
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Operation and commanding of the STP-H5 LIS experiment is conducted from the LIS POCC via TReK workstations by the LIS Science Team. Nominal operation involves continuously observing the Earth. Based on TRMM LIS experience, bi-weekly commanding to reset the instrument may be necessary Data are processed, archived, and distributed by the Global Hydrology Research Center (GHRC), one of NASA's Distributed Active Archive Centers (DAAC). Quality control is conducted by the STP-H5 LIS Science Team, as well as the generation of higher level data lightning products, which will be archived and distributed by the GHRC.
Decadal Survey Recommendations
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