3.4 ISS LIS data products and user community
Unlike its predecessor, ISS LIS has the ability to transmit and disseminate lightning data in near real time. This ability is significant as it enables usage of ISS LIS in operational applications. The near-realtime capabilities are particularly beneficial in data-sparse regions, such as over oceans, to contribute to storm warnings, nowcasts, oceanic aviation, and international Significant Meteorological advisories (SIGMETs).
The near-realtime ISS LIS data are provided to the US National Weather Service (NWS) and other interested users in partnership with both NASA’s Land, Atmosphere Near real-time Capability for EOS (LANCE) project and the Short-term Prediction Research and Transition (SPoRT) center [Jedlovec , 2013]. As ISS LIS detects total lightning (near globally) with high detection efficiency, it can therefore fill gaps in the depiction of lightning activity of interest to NWS forecasters over land and ocean areas. These data, as well as non-real-time analyses are being used by several applied and operational institutions to improve decision-making and to benefit humankind. These institutions include, for example, the NWS Pacific Region, the Aviation Weather Center (AWC), the National Hurricane Center (NHC), the Ocean Prediction Center (OPC), the World Weather Research Program (WWRP), and other government, business, and military organizations.
The GHRC DAAC coordinates with the LIS science team to process and archive ISS LIS datasets. The ISS LIS mission currently produces four products: (1) Near-realtime (NRT) science lightning data [Blakeslee , 2019a], (2) NRT background cloud scene data [Blakeslee , 2019b], (3) Non-quality-controlled (NQC) version 1 science lightning data [Blakeslee , 2019c], and (4) NQC background cloud scene data [Blakeslee , 2019d].
The NRT data are available within two minutes of observation and are appropriate for applications requiring low-latency data (e.g., AWC and NHC). NRT data and browse images age off the server after ten days and are not a static archived data collection. Due to the nature of NRT data transmission, some data may be missing. Hence, the NQC data are produced daily and are more complete than the NRT data. Although the version 1 NQC data have not been reviewed to assure data quality, they are more appropriate for science and applications with less stringent latency requirements. The version 1 NQC data have been validated, however, as described in Section 3.1, and are currently undergoing quality control that will be included in a future release.
These ISS LIS observations can be used to derive multiple products. Traditionally, the flash observation has been the most widely used, particularly in near real-time operations. This is a latitude/longitude point showing the centroid of the flash. This flash centroid is typically plotted as a density product (i.e., number of flash centroids per unit area).
The ISS LIS dataset has had widespread use in the past 3 years, with over 6,100 users to date. Specifically, the GHRC DAAC has tallied downloads of the data based on the end user’s stated application (e.g., weather, climate, atmospheric composition, etc.). As with the OTD and TRMM LIS predecessors, there has always been an enthusiasm from the user community to apply lightning data in diverse ways, especially in weather and chemistry/climate studies. For the most recent full calendar year (2019), ISS LIS data made up two of the top five most downloaded datasets at GHRC DAAC. Two others, including the top dataset, were from the ISS LIS predecessor, TRMM LIS.
While not exhaustive, several uses of ISS LIS are described below, and demonstrate a variety of impacts by these observations. As mentioned previously, the NRT ISS LIS data are provided to the AWC. The AWC’s area of responsibility covers vast oceanic regions. Just a single flash observation provides confirmation of a convective system to the AWC, enabling aircraft to be rerouted safely around these systems. Due to reduced DE during the day, as well as coarser pixel resolution off boresight, weaker and smaller size flashes are not as well detected by the GLM instruments [Zhang and Cummins , 2020]. For these reasons AWC and other NWS service centers have found that ISS LIS augments their confidence in GLM (and ground-based) detection of lightning especially over oceanic regions [Goodman et al. , 2020a]. AWC is able to display ISS LIS, GLM, and ground-based lightning data concurrently in a 10-min flash density grid overlay in their forecaster workstation displays. Goodman et al. [2020b] showed how the smaller pixel size, and more nadir view (relative to GLM), of ISS LIS can often detect lightning (and thus convective initiation) in developing storms sooner than other lightning datasets. Thus, while ISS LIS flash observations are vital to provide lightning observations in locations where ground networks and GLM are unavailable or have limited detection efficiency, they also are able to provide valuable information to forecasters even when other lightning observations are available.
The NRT data have also been an integral component of the World Meteorological Organization’s (WMO) High Impact Weather Lake Systems (HIGHWAY) project [Virts and Goodman , 2020]. Centered on Lake Victoria in East Africa, the NRT ISS LIS data from NASA LANCE are used to monitor and provide quality assurance for ground-based total lightning data from the ENGLN to better characterize storms as observed by the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) Meteosat Second Generation (MSG) satellite. The goal of this effort is to better characterize, monitor, and predict thunderstorm development in this region to provide early warning to at-risk communities. This also serves as an operational demonstration to help prepare the community for MTG-LI.
Another collaborative project was with NASA DEVELOP (not an acronym) and GHRC DAAC. Here, data from both TRMM and ISS LIS were used to develop a lightning risk assessment for Bangladesh and Nepal [Evans et al. , 2018]. The LIS data provided the necessary lightning observations for the project. Instead of simply creating a lightning climatology, the DEVELOP team combined the lightning observations with socioeconomic information. The result (Fig. 11) gave the government authorities an easy-to-interpret view of where lightning was the greatest threat due to a combination of lightning activity, available shelter, and types of jobs. Such information can help government decision-makers direct funds to improve lightning safety in the most at-risk locations.
Lastly, the WMO has deemed lightning an Essential Climate Variable (ECV). Space-based observations play an integral role in providing global lightning coverage. The ISS LIS observations extend the record of the earlier OTD and TRMM LIS instruments, and are included with those instruments in the Global Climate Observing System (GCOS). As part of this, ISS LIS observations will be used as part of a proposed 10x10 km2, global product that blends both space- and ground-based lightning observations into daily and monthly time scales [Aich et al. , 2018]. Additionally, these data extend the OTD and TRMM LIS period of record for use in understanding trends in global thunder days [Lavigne et al , 2019]. This supports continuing work to identify significant shifts in global lightning activity [e.g., Williams , 2020].