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].