Tasman Sea Research Articles

Seasonal climate summary for the southern hemisphere (summer 2017–18): an exceptionally warm season for Australia – a short-lived and weak La Niña

This is a summary of the southern hemisphere atmospheric circulation patterns and meteorological indices for summer 2017–18; an account of seasonal rainfall and temperature for the Australian region is also provided. A short-lived and weak La Niña developed but decayed by the end of February 2018. Sea-surface temperatures were exceptionally warm in the Tasman Sea from late 2017 to early 2018. It was an exceptionally warm summer for Australia, and the third-warmest mean temperature on record for the nation. Summer rainfall was close to the long-term average for Australia, with aboveaverage rainfall in west and below-average rainfall in the east.

The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia)

Motivated by the record-breaking heatwaves of early 2017, the synoptic structure and evolution of summer (December–February) heatwaves in the Sydney area is investigated through composite and trajectory analyses. In the upper troposphere, the main features of the composite structure are an isolated upper-tropospheric anticyclonic potential vorticity (PV) anomaly to the south-east of Australia and cyclonic anomalies to the east and south. Back trajectories starting from within the upper-tropospheric anticyclonic PV anomaly on the first day of the heatwave fall into two groups: those that are diabatically cooled in the final 72 h and those that are diabatically heated. Those that are cooled come predominantly from the upstreammiddle troposphere over the Indian Ocean. The change in the potential temperature of these parcels is less than 3K, and so their motion is effectively adiabatic. In contrast, those parcels that are heated in the final 72 h are drawn predominantly from the lower half of the troposphere over the south-western part of the continent. As they ascended, their potential temperature increases by 10K in the mean due to latent heating. At low-levels, the main features of the composite are an anticyclone centred in the Tasman Sea, a broad low over the Southern Ocean and associated anomalous warm northwesterlies over the Sydney area. Five days prior to the heatwave, air parcels that become part of the near surface air mass are located predominantly offshore to the east and south of the continent. The anomalously high surface temperatures can be explained by adiabatic compression and surface sensible heating. For the next 48 h, the air parcels subside and their potential temperature changes little, whereas their temperature increases by around 15Kthrough adiabatic compression. In the final 72 h, as the parcels approach the surface and are entrained into the boundary layer, the potential temperature and temperature both increase by 5K, presumably through surface sensible heating. The record-breaking heatwaves of January and February 2017 are found to be very representative of previous heatwaves in the Sydney area, and in the mean they are synoptically very similar to heatwaves in Victoria, although dynamically there are differences.

Synoptic climatology of hybrid cyclones in the Australian region

In May and September 2016, two intense hybrid cyclones (HCs) developed over the Great Australian Bight damaging infrastructure and causing a state‐wide power outage in South Australia. These two cyclones motivate the compilation of the first synoptic climatology of HCs in the Australian region, including an analysis of their importance for wind and precipitation extremes, and a composite view of the large‐scale flow in which they develop. HCs are identified in ERA‐Interim data from 1979 to 2010 using an objective feature tracking method and a cyclone phase space diagnostic. HCs exhibit a pronounced seasonal cycle with most of them occurring from May to September. During these months, HCs are most frequent over the Tasman Sea and the Great Australian Bight where they account for 50% of all cyclones. A common characteristic of all HCs is that the strongest precipitation, which is locally extreme in 91% of all HCs, falls in the warm sector and along a bent‐back warm front on the poleward side of the cyclones. Moreover, the area affected by extreme precipitation and the maximum precipitation in HCs are no different from non‐hybrid cyclones (NHCs). In contrast, the area affected by extreme wind gusts is significantly larger in HCs than for NHCs. In both HCs and NHCs the strongest near‐surface wind gusts typically occur in the cold air mass in the wake of the cyclones, especially in those over the Great Australian Bight. The upper‐tropospheric structure of HCs is characterized by an elongated cyclonic potential vorticity anomaly embedded between two ridges that eventually cuts off. In contrast, NHCs are characterized by a zonal flow upstream and upper‐tropospheric cyclonic wave breaking.

Chapter 15 Construction of a Paleozoic–Mesozoic accretionary orogen along the active continental margin of SE Gondwana (South Island, New Zealand): summary and overview

Abstract The Western Province is a fragment of the c. 500 Ma SE Gondwana active continental margin. The Eastern Province is a terrane assemblage, which is partly stitched by the Median Batholith. Fragments of the batholith are preserved in the adjacent Drumduan and Brook Street terranes. Permian arc magmatism of the Brook Street Terrane involved both oceanic and continental margin settings. The Permian ( c. 285–275 Ma) supra-subduction zone Dun Mountain ophiolite records subduction initiation and subsequent oceanic-arc magmatism. The Permian Patuki and Croisilles melanges represent detachment of the ophiolitic forearc and trench–seamount accretion. The Murihiku Terrane, a proximal continental margin forearc basin, received detritus from the Median Batholith (or equivalent). The south coast, Early–Late Triassic Willsher Group is another proximal forearc basin unit. The sediments of the Dun Mountain–Maitai Terrane (Maitai basin) represent a distal segment of a continental margin forearc basin. The Caples Terrane is a mainly Triassic trench accretionary complex, dominantly sourced from a continental margin arc, similar to the Median Batholith. The outboard (older) Torlesse and Waipapa terranes are composite subduction complexes. Successively more outboard terranes may restore farther north along the SE Gondwana continental margin. Subduction and terrane assembly were terminated by collision (at c. 100 Ma), followed by rifting of the Tasman Sea Basin.

Chapter 1 Introduction to Paleozoic–Mesozoic geology of South Island, New Zealand: subduction-related processes adjacent to SE Gondwana

This Memoir presents and discusses recent research mainly concerning the Permian and Triassic geological development of South Island in its regional context, which includes New Zealand as a whole, the continent of Zealandia, eastern Australia and Antarctica. The Permian and Triassic geology of the South Island encompasses several geological units which shed light on fundamental geological processes. These include a well-developed oceanic volcanic arc, a classic subduction-related ophiolite (oceanic crust on land) and a very thick succession of continental margin forearc sediments. These, and other related geological units, constitute the oldest extensively outcropping basement of Zealandia, which can be considered as the world's seventh largest continent, albeit 94% submerged (Mortimer et al. 2017). The supercontinent, Gondwana, formed during the Late Neoproterozoic and remained until its progressive break-up into crustal fragments during the Mesozoic. During this prolonged period, New Zealand and adjacent crustal units were located along the SE edge of Gondwana. Subduction took place beneath this margin during the Paleozoic–Mesozoic, until the end of Early Cretaceous time ( c. 100 Ma) when it halted, followed by rifting of the Tasman Sea Basin. This volume consists of 14 contributions, comprising a mix of new-data-based papers (and one note) and several review and synthesis papers. The contributions largely concern igneous and sedimentary geology, tectonics and biostratigraphy. Particular emphasis is placed on field geology, petrography and geochemistry. Some aspects are less well covered (e.g. Permian–Triassic geology of New Zealand's Cordilleran-style Median Batholith; metamorphic geology), primarily because there is a large amount of existing and/or recently published data. While the Permian–Triassic terranes bear imprints of Gondwana break-up and Neogene Alpine Fault development, these topics are outside the scope of this volume. The final chapter discusses various tectonic-based interpretations for the Permian–Triassic development of Zealandia and points the way to an overall synthesis. In this introductory …

The Role of Natural Variability and Anthropogenic Climate Change in the 2017/18 Tasman Sea Marine Heatwave

Two GCM ensembles indicate that the record sea surface temperatures during the 2017/18 Tasman Sea marine heatwave were virtually impossible without anthropogenic influence. However, natural variability was important in the atmospheric initiation of the event.

Palaeomagnetic test of oroclinal rotation in the Dundas Trough, Tasmania

Cambrian to Silurian rocks of the Dundas Trough, Tasmania, including the economically important Mount Read Volcanics, follow a curving trend around the northern margin of the Tyennan Block. This arcuate trend has recently been interpreted to be part of an orocline, the eastern limb of which is obscured below Jurassic dolerite. Other workers consider the arcuate trend of the Dundas Trough to be the result of Cambrian rifting, with the underlying basement continuing north below Bass Strait. We tested the orocline hypothesis by palaeomagnetic sampling of rocks from the Owen, Gordon and Eldon groups. Previous palaeomagnetic studies concluded that these rocks were overprinted. By use of modern demagnetisation protocols and principal component analysis of demagnetisation vectors we were able to isolate a pre-deformation characteristic remanence carried by magnetite and hematite from a normal polarity overprint carried only by hematite. The overprint resembles Cretaceous overprints recognised from the eastern Australian seaboard, and thought to be related to Tasman Sea rifting. The characteristic remanence passes the statistical orocline test, confirming the orocline hypothesis for the Dundas Trough. Rocks equivalent to the Mount Read Volcanics therefore continue under Jurassic dolerite cover below eastern Tasmania.

Quaternary sedimentology and tephrostratigraphy of the lower Pohangina Valley, New Zealand

ABSTRACTShallow-marine to fluvio-estuarine deposits in Pohangina Valley represent an underexplored portion of the Whanganui Basin, a globally significant archive of Quaternary climate change. To address this, we document environments of deposition through facies analysis, tephrostratigraphy and biostratigraphy. The marine shelf environment is characterised by fossiliferous mudstone containing marine Mollusca. Estuarine facies consist of pumiceous sandstone, tephra, lignite and carbonaceous mudstone. Volcaniclastic and tephra-fall deposits record seven eruptions from the Taupo Volcanic Zone between c. 1.6 and 0.9 Ma. We identify and define Awahou Tephra (new) (c. 1.03 Ma), through mapping and geochemical analysis of constituent glass shards. Progressive retreat of the sea (c. 1.6 Ma) is indicated by a change from shallow-marine to fluvio-estuarine sedimentation. An east–west drainage system developed (c. 1 Ma), including ponding near Woodville from which an early ancestor of the Manawatu River exited, establishing an antecedent path to the Tasman Sea across the uplifting paleo-axial range.

Petrological and geochemical characteristics of REE mineralization in the A-type French Creek Granite, New Zealand

The French Creek Granite, New Zealand, is an alkaline intrusion with enrichment in rare earth elements (REE). Petrography and whole-rock geochemical signatures demonstrate that the c. 82–84-Ma French Creek Granite is a composite granitoid, dominated by a ferroan, weakly peraluminous biotite alkali feldspar granite to syenogranite, with subordinate quartz-alkali feldspar (QAF) syenite. Maximum total REE + Y contents are higher in the granite and felsic dikes relative to the marginal QAF syenite, cogenetic mafic Hohonu Dike Swarm, and pegmatites. Our findings suggest that REE and high-field-strength element enrichment in the unaltered French Creek Granite is a function of partial melting from an enriched HIMU-like lithospheric mantle source, minor crustal assimilation, and extensive magmatic differentiation. Primary (magmatic) REE enrichment is defined by the occurrence of allanite, zircon, apatite, fergusonite, monazite, perrierite, and loparite, which are commonly associated with interstitial biotite. French Creek Granite samples from a phyllic-sericitic alteration zone in the Eastern Hohonu River are strongly elevated in REE relative to unaltered French Creek Granite, indicating remobilization and secondary REE enrichment by hydrothermal fluids. The REE are hosted in bastnasite group minerals, monazite, xenotime, and zircon. Quartz protuberances, dilatational microfractures, and dike emplacement indicate that this alteration is structurally controlled. The δ13C and δ18O values of secondary carbonate veinlets are consistent with mixed low-temperature (~ 250–260 °C) magmatic hydrothermal fluids containing mantle-derived carbon. These fluids were likely part of a late-stage porphyry-type system operating during the same mantle degassing and extensional episode that was associated with the emplacement of the French Creek Granite and lamprophyric dikes of the Hohonu Dike Swarm, and initial Tasman Sea spreading. Results from this study provide an important insight into the complex processes responsible for REE enrichment in alkaline igneous systems.

Outlier SNPs detect weak regional structure against a background of genetic homogeneity in the Eastern Rock Lobster, Sagmariasus verreauxi

Genetic differentiation is characteristically weak in marine species making assessments of population connectivity and structure difficult. However, the advent of genomic methods has increased genetic resolution, enabling studies to detect weak, but significant population differentiation within marine species. With an increasing number of studies employing high resolution genome-wide techniques, we are realising that the connectivity of marine populations is often complex and quantifying this complexity can provide an understanding of the processes shaping marine species genetic structure and to inform long-term, sustainable management strategies. This study aims to assess the genetic structure, connectivity, and local adaptation of the Eastern Rock Lobster (Sagmariasus verreauxi), which has a maximum pelagic larval duration of 12 months and inhabits both subtropical and temperate environments. We used 645 neutral and 15 outlier SNPs to genotype lobsters collected from the only two known breeding populations and a third episodic population—encompassing S. verreauxi’s known range. Through examination of the neutral SNP panel, we detected genetic homogeneity across the three regions, which extended across the Tasman Sea encompassing both Australian and New Zealand populations. We discuss differences in neutral genetic signature of S. verreauxi and a closely related, co-distributed rock lobster, Jasus edwardsii, determining a regional pattern of genetic disparity between the species, which have largely similar life histories. Examination of the outlier SNP panel detected weak genetic differentiation between the three regions. Outlier SNPs showed promise in assigning individuals to their sampling origin and may prove useful as a management tool for species exhibiting genetic homogeneity.

Land–sea correlations in the Australian region: 460 ka of changes recorded in a deep-sea core offshore Tasmania. Part 2: the marine compared with the terrestrial record

We present an array of new proxy data and review existing ones from core Fr1/94-GC3 from the East Tasman Plateau. This core is positioned at the southern extreme of the East Australia Current and simultaneously records changes in both oceanography and environments both in offshore and in southeastern Australia. Microfossils, including planktonic and benthic foraminifera, ostracods, coccoliths and radiolarians, were studied to interpret palaeo-oceanographic changes. Sea-surface temperature was estimated using planktonic foraminifera, alkenones and radiolaria. From the silicate sediment fraction, the mean grain size of quartz grains was measured to detect the changes in wind strength. An XRF scan of the entire core was used to determine the elemental composition to identify provenance of the sediment. We also compare these data with a pollen record from the same core provided in an accompanying article that provides the longest well-dated record of vegetation change in southeastern Australia. In an area of slow sedimentation, Fr1/94-GC3 provides a continuous record of change in southeastern Australia and the southern Tasman Sea over approximately the last 460 ka. We determine that the East Australian Current varied in intensity through time and did not reach the core site during glacial periods but was present east of Tasmania during all interglacial periods. The four glacial–interglacial periods recorded at the site vary distinctly in character, with Marine Isotope Stage (MIS) 9 being the warmest and MIS 5 the longest. Through time, glacial periods have progressively become warmer and shorter. Deposition of airborne dust at the core site is more substantial during interglacial periods than glacials and is believed to derive from mainland Australia and not Tasmania. It is likely that the source and direction of the dust plume varied significantly with the wind regimes between glacials and interglacials as mean effective precipitation changed.

Land-sea correlations in the Australian region: 460 ka of changes recorded in a deep-sea core offshore Tasmania. Part 1: the pollen record

Long, well-dated records of climate change in Australia are rare because most of the continent is prone to deflation and sediments are difficult to date beyond 40 ka. Deep-sea cores, containing terrigenous material, provide an ideal alternative to terrestrial records, because of continuous sedimentation and a robust chronology derived from oxygen isotopes. In this paper, the first of a series of two, we present pollen and spores data from core Fr1/94-GC3 from the East Tasman Plateau. This core is positioned at the southern extreme of the East Australia Current and simultaneously records changes in both oceanography and environments both offshore and in southeastern Australia. In an area of slow sedimentation, this core provides a continuous record of vegetation change in southeastern Australia and the southern Tasman Sea over approximately the last half a million years. Through time, glacial periods have progressively become warmer and shorter. Alpine plant taxa become more restricted with time and rainforest taxa expand to a far more restricted degree during the present interglacial period than the previous one, representing a fundamental shift in the vegetation of Tasmania. We apply transfer functions to reconstruct past rainfall and land temperatures based on the palynoflora that are then compared against the marine proxy record.

Variability and Long‐Term Trends in the Shelf Circulation Off Eastern Tasmania

AbstractThis study investigates trends and interannual variability of the marine climate across the continental shelf off eastern Tasmania for 1993–2016. This region is a hotspot for global warming and biodiversity. Eastern Tasmania lies at the boundary between two ocean currents (the East Australian Current Extension, or EAC Extension, and the Zeehan Current, ZC) leading to the local marine climate exhibiting trends and variability from both boundary currents. A numerical ocean model is used to provide high‐resolution (∼2 km) estimates of the temperature, salinity, and circulation for the region. Results indicate significant positive trends in temperature, salinity, and southward flow over the shelf, consistent with an increasing EAC Extension. These trends are particularly strong in autumn, indicating a lengthening of the warm season. The interannual variability in the EAC Extension and ZC was quantified by a simple index, based on a modal analysis of surface circulation, indicating the relative dominance of each current. Strong EAC years were related to significantly more summertime marine heat wave days. Large‐scale remote drivers of variability were considered, and we found weak but significant links with El Niño–Southern Oscillation and Tasman Sea Blocking. El Niño–Southern Oscillation was found to modulate the EAC Extension in summer with a El Niño leading to enhanced southward flow and warming over the shelf. Tasman Sea Blocking was found to drive enhanced southward surface flow, particularly in winter. Nonetheless, large‐scale forcing modes explain less than 25% of the total variability in the EAC‐ZC system indicating that most of the variability is internally generated.

The Morphology of the Tasmantid Seamounts: Interactions Between Tectonic Inheritance and Magmatic Evolution

AbstractBasement structure is known to exert strong magmatic and morphological control on continental volcanoes, but relatively little is known about the structural control of submarine volcanoes. Here we investigate the morphology of the Tasmantid Seamounts, a >2,400 km long chain of age‐progressive intraplate volcanoes, ranging from 56 to 7 Ma. The seamounts are emplaced over the extinct Tasman Sea spreading center, which was active between 84 and 52 Ma. While thick sediment (∼1 km) obscures much of the basement, detailed morphological and geophysical analyses of the seamounts reveal a strong correlation between tectonic setting, seamount orientation, and volcanic structure, despite the ≥20 Ma interval between spreading cessation and seamount emplacement. Seamounts emplaced on fracture zones or spreading segment‐transform fault inside corners are typically large and elongate. Where original morphology is preserved, they often appear rugged and predominantly fissure‐fed. By contrast, comparatively smooth, conical seamounts with isolated dike‐fed flank cones are often found midsegment and at outside corners. Volcanic fabrics also align closely with the expected principal stress directions for strong mechanical coupling across transform faults. This behavior suggests the lithosphere is dissected by numerous deep faults, channeling magma along preexisting structural trends. Generally, low effective elastic thicknesses (<10 km) and lack of correlation with plate age at emplacement suggest that structural inheritance is also a major control on lithospheric strength near the extinct spreading center. Our study clearly demonstrates that, like in the continents, structural inheritance in oceanic lithosphere can exert significant control on the morphology of submarine volcanoes.

Migration dynamics of juvenile southern bluefin tuna

Large scale migrations are a key component of the life history of many marine species. We quantified the annual migration cycle of juvenile southern bluefin tuna (Thunnus maccoyii; SBT) and spatiotemporal variability in this cycle, based on a multi-decadal electronic tagging dataset. Behaviour-switching models allowed for the identification of cohesive areas of residency and classified the temporal sequence of movements within a migration cycle from austral summer foraging grounds in the Great Australian Bight (GAB) to winter foraging grounds in the Indian Ocean and Tasman Sea and back to the GAB. Although specific regions within the Indian Ocean were frequented, individuals did not always return to the same area in consecutive years. Outward migrations from the GAB were typically longer than return migrations back to the GAB. The timing of individual arrivals to the GAB, which may be driven by seasonality in prey availability, was more cohesive than the timing of departures from the GAB, which may be subject to the physiological condition of SBT. A valuable fishery for SBT operates in the GAB, as do a number of scientific research programs designed to monitor SBT for management purposes; thus, understanding SBT migration to and from the area is of high importance to a number of stakeholders.

Impact of data assimilation on vertical velocities in an eddy resolving ocean model

It is expected that the assimilation of data in an ocean model disrupts the model’s dynamical balance. This disruption occurs because the analysis fields are not a precise solution to the equations of the model. Therefore, the model adjusts to the applied increments. With this limitation in mind, we assess the impact of sequential data assimilation (DA) on vertical velocity - chosen because of its sensitivity to model dynamical balances. We investigate vertical velocity within mesoscale eddies in the Tasman Sea and off Tasmania, Australia in an ocean reanalysis that assimilates observations every four days. In a free-running model, with no DA, ocean eddies often show a coherent pattern of alternating upward and downward cells. These cells are induced by eddy distortion (i.e., the eddy becoming more or less isotropic). In this study, we aim to first determine if a data-assimilating model can reproduce these alternating upward and downward cells; and then to investigate how the cells are affected by sequential DA. We view this study as a step towards better understanding the suitability of data-assimilating ocean models for detailed analysis of ocean circulation and ocean dynamics. We show that the vertical velocities are typically two times larger in magnitude on the day after assimilation, compared to subsequent days. Despite the model adjustment, the alternating upward and downward cells are present in the data-assimilating model. In fact, we find that the model adjustment acts like an artificial eddy distortion on the first day after assimilation - when the model is adjusting to the applied increments - amplifying the vertical velocities within the eddies. This artificial distortion impacts temperature and salinity, through vertical advection. The vertical advection terms are about 1.5 times higher on the day after assimilation, compared to other days. The temperature and salinity changes resulting from the stronger vertical advection are mostly 2–10 times smaller than the increments of these properties applied during assimilation. Our findings suggest that a data-assimilating model may be useful for investigating the detailed dynamics of the ocean, but care should be taken when interpreting results. Moreover, we suggest that it is prudent to disregard the model’s fields within the first day after assimilation - particularly in analyses of dynamical balances.

Beyond Capricornia: Tropical Sea Slugs (Gastropoda, Heterobranchia) Extend Their Distributions into the Tasman Sea

There is increasing evidence of poleward migration of a broad range of taxa under the influence of a warming ocean. However, patchy research effort, the lack of pre-existing baseline data, and taxonomic uncertainty for some taxa means that unambiguous interpretation of observations is often difficult. Here, we propose that heterobranch sea slugs provide a useful target group for monitoring shifts in distribution. As many sea slugs are highly colourful, popular with underwater photographers and rock-pool ramblers, and found in accessible habitats, they provide an ideal target for citizen scientist programs, such as the Sea Slug Census. This maximises our ability to rapidly gain usable diversity and distributional data. Here, we review records of recent range extensions by tropical species into the subtropical and temperate waters of eastern Australia and document, for the first time in Australian waters, observations of three tropical species of sea slug as well as range extensions for a further six to various locations in the Tasman Sea.

First Finding of Melamphaes uniformis (Melamphaidae) in the Southwestern Indian Ocean

The catch of a rare species of Melamphaes uniformis (Melamphaidae) is reported for the first time in the southwestern Indian Ocean near the Walters underwater mountain. This species was previously known only by the holotype caught in the Tasman Sea, the Pacific Ocean.

Micronekton assemblages and bioregional setting of the Great Australian Bight: A temperate northern boundary current system

A multi-disciplinary pelagic ecosystem study of the Great Australian Bight (GAB) examined the micronekton communities and bioregionalisation in this area that harbours significant predator populations. Micronekton community structure and biomass differed between the eastern and central regions of the GAB. Regional differences were mainly driven by relatively high abundance of krill (Nematoscelis megalops, Nyctiphanes australis and Euphausia similis) in east GAB and high abundance of Maurolicus australis and chaetognaths in central GAB. Central GAB was also characterised by relatively high abundance of gelatinous zooplankton and small-bodied cephalopods. Lanternfishes were used as a model pelagic group to investigate the bioregional setting of the GAB. The analyses indicated that the oceanic habitats of the GAB had bioregional affinities with the subtropical Indian Ocean. However, over the continental slope, the east GAB had bioregional affinities with the Subtropical Convergence and grouped with western and southern Tasmania and the southern Tasman Sea. Lanternfish assemblage groups were compared against existing regionalisations that are based on physicochemical variables and the Delphi Method. No single existing scheme suitably reflected lanternfish assemblage distributions, but parsimonious boundaries from existing schema were identified. This study demonstrates that the central GAB, where oil-and-gas exploration occurs alongside Marine Protected Area management, needs to be considered as a separate bioregion to the east GAB for the purposes of identifying conservation values and monitoring requirements.

Detecting Lightning Infrasound Using a High‐Altitude Balloon

AbstractAcoustic waves with a wide range of frequencies are generated by lightning strokes during thunderstorms, including infrasonic waves (0.1 to 20 Hz). The source mechanism for these low‐frequency acoustic waves is still debated, and studies have so far been limited to ground‐based instruments. Here we report the first confirmed detection of lightning‐generated infrasound with acoustic instruments suspended at stratospheric altitudes using a free‐flying balloon. We observe high‐amplitude signals generated by lightning strokes located within 100 km of the balloon as it flew over the Tasman Sea on 17 May 2016. The signals share many characteristics with waveforms recorded previously by ground‐based instruments near thunderstorms. The ability to measure lightning activity with high‐altitude infrasound instruments has demonstrated the potential for using these platforms to image the full acoustic wavefield in the atmosphere. Furthermore, it validates the use of these platforms for recording and characterizing infrasonic sources located beyond the detection range of ground‐based instruments.