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Climatology, meteorology, atmosphere

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  • We present 60 years of Δ14CO2 measurements from Wellington, New Zealand (41°S, 175°E). The record has been extended and fully revised. New measurements have been used to evaluate the existing record and to replace original measurements where warranted. This is the earliest atmospheric Δ14CO2 record and records the rise of the 14C “bomb spike”, the subsequent decline in Δ14CO2 as bomb 14C moved throughout the carbon cycle and increasing fossil fuel CO2 emissions further decreased atmospheric Δ14CO2. The initially large seasonal cycle in the 1960s reduces in amplitude and eventually reverses in phase, resulting in a small seasonal cycle of about 2 ‰ in the 2000s. The seasonal cycle at Wellington is dominated by the seasonality of cross-tropopause transport, and differs slightly from that at Cape Grim, Australia, which is influenced by anthropogenic sources in winter. Δ14CO2 at Cape Grim and Wellington show very similar trends, with significant differences only during periods of known measurement uncertainty. In contrast, Northern Hemisphere clean air sites show a higher and earlier bomb 14C peak, consistent with a 1.4-year interhemispheric exchange time. From the 1970s until the early 2000s, the Northern and Southern Hemisphere Δ14CO2 were quite similar, apparently due to the balance of 14C-free fossil fuel CO2 emissions in the north and 14C-depleted ocean upwelling in the south. The Southern Hemisphere sites show a consistent and marked elevation above the Northern Hemisphere sites since the early 2000s, which is most likely due to reduced upwelling of 14C-depleted and carbon-rich deep waters in the Southern Ocean. This developing Δ14CO2 interhemispheric gradient is consistent with recent studies that indicate a reinvigorated Southern Ocean carbon sink since the mid-2000s, and suggests that upwelling of deep waters plays an important role in this change. DOI: https://doi.org/10.5194/acp-17-14771-2017 Cite as: Turnbull, J. C., Mikaloff Fletcher, S. E., Ansell, I., Brailsford, G. W., Moss, R. C., Norris, M. W., and Steinkamp, K.: Sixty years of radiocarbon dioxide measurements at Wellington, New Zealand: 1954–2014, Atmos. Chem. Phys., 17, 14771–14784, https://doi.org/10.5194/acp-17-14771-2017, 2017.

  • Ultraviolet radiation measurements over the spectral region 290-450 nm with a high precision spectro-radiometer. The spectro-radiometer was installed at Arrival Heights as a two month (November 2006 – January 2007) blind inter-comparison with the established measurement programme run by Biospherical Instruments for the USAP. The data was compared with the USAP data taken simultaneously. These data are held internally by NIWA. GET DATA: contact dan.smale@niwa.co.nz

  • AntAir ICE is an air temperature dataset for terrestrial Antarctica, the ice shelves, and the seasonal sea ice around Antarctica in a 1km2 spatial grid resolution and a daily temporal resolution available from 2003-2021. AntAir ICE was produced by modelling air temperature from MODIS ice surface temperature and land surface temperature using linear models. In-situ measurements of air temperature from 117 Automatic Weather Stations were used as the response variable. Each day has a bricked spatial raster with two layers, saved as a GeoTIFF format and in the Antarctic Polar Stereographic projection (EPSG 3031). The first layer is the predicted near surface air temperature for that day in degree Celsius * 10 and the second layer is the number of available MODIS scenes for that day ranging from 0 to 4. Areas with cloud contamination or without sea ice are marked with no data. Files for each year (2003-2021) are compressed with a ZIP files for each quarter. Python 3.8 was used for conversion of the MODIS products from HDF files to raster and all data handling and processing was thereafter done in R version 4.0.0. All data processing and modelling procedures are available as R scripts on a public Github repository: https://github.com/evabendix/AntAir-ICE. Using this code it is possible to download new available MODIS LST and IST scenes and apply the model to continue the near-surface air temperature dataset. Related Publication: https://doi.org/10.1038/s41597-023-02720-z GET DATA: https://doi.org/10.1594/PANGAEA.954750

  • Measurements of chlorine monoxide (ClO) made with a Microwave Chlorine Monoxide Millimeter Wave Spectrometer (ground-based). The instrument (ClOe1) was established in January of 1996 at Scott Base and decommissioned in October 2023. A replacement radiometer (ClOe4) was installed at Scott Base in February 2023 (an overlap in the data for timeseries continuity purposes). These data are produced in collaboration with State University of New York (SUNY) Stoney Brook and Naval Research Laboratory (NRL). “Raw” data are times and recorded microwave emission spectra. “Derived” data are column amounts and vertical profile information of chlorine monoxide (ClO). The instrument has acquired the nickname "CloeTechnique" for vertical profile information uses "optimal estimation" to extract information from pressure broadening of ClO emission line. Significant failure in early 2018 only fixed in November 2018. No data in the July - October 2018 period. Data is held at NRL and in the NDACC database. Data are available as monthly .ndm files, and additional metadata are available in the header. Instrument coordinates (-77.85, 166.77). Instrument timeline: - ClOe1 1996-2023 - ClOe4 2023 – present GET DATA: https://www-air.larc.nasa.gov/missions/ndacc/data.html?station=scott.base#

  • Ocean–atmosphere–sea ice interactions are key to understanding the future of the Southern Ocean and the Antarctic continent. Regional coupled climate–sea ice–ocean models have been developed for several polar regions; however the conservation of heat and mass fluxes between coupled models is often overlooked due to computational difficulties. At regional scale, the non-conservation of water and energy can lead to model drift over multi-year model simulations. Here we present P-SKRIPS version 1, a new version of the SKRIPS coupled model setup for the Ross Sea region. Our development includes a full conservation of heat and mass fluxes transferred between the climate (PWRF) and sea ice–ocean (MITgcm) models. We examine open water, sea ice cover, and ice sheet interfaces. We show the evidence of the flux conservation in the results of a 1-month-long summer and 1-month-long winter test experiment. P-SKRIPS v.1 shows the implications of conserving heat flux over the Terra Nova Bay and Ross Sea polynyas in August 2016, eliminating the mismatch between total flux calculation in PWRF and MITgcm up to 922 W m−2. RELATED PUBLICATION: https://doi.org/10.5194/gmd-16-3355-2023 GET DATA: https://doi.org/10.5281/zenodo.7739062

  • Ocean–atmosphere–sea ice interactions are key to understanding the future of the Southern Ocean and the Antarctic continent. Regional coupled climate–sea ice–ocean models have been developed for several polar regions; however the conservation of heat and mass fluxes between coupled models is often overlooked due to computational difficulties. At regional scale, the non-conservation of water and energy can lead to model drift over multi-year model simulations. Here we present P-SKRIPS version 1, a new version of the SKRIPS coupled model setup for the Ross Sea region. Our development includes a full conservation of heat and mass fluxes transferred between the climate (PWRF) and sea ice–ocean (MITgcm) models. We examine open water, sea ice cover, and ice sheet interfaces. We show the evidence of the flux conservation in the results of a 1-month-long summer and 1-month-long winter test experiment. P-SKRIPS v.1 shows the implications of conserving heat flux over the Terra Nova Bay and Ross Sea polynyas in August 2016, eliminating the mismatch between total flux calculation in PWRF and MITgcm up to 922 W m−2. RELATED PUBLICATION: https://doi.org/10.5194/gmd-16-3355-2023 GET DATA: https://doi.org/10.5281/zenodo.7739059

  • The WWLLN Very Low Frequency (VLF) Radio Sensor was installed at Scott Base in November 2015 by Dr. James Brundell and Ms. Emma Douma as part of Antarctica New Zealand Event K060-1516-A. The sensor measures the electric field in the Very Low Frequency radio range (~500 Hz-50 kHz) and passes it to a PC which processes the data for the experiments. The antenna is located behind the Hatherton lab. It was installed due to increasing manmade electromagnetic noise levels in the "quiet zone" at Arrival Heights. The observations from this antenna are now the primary WWLLN feed from Ross Island, the Arrival Height's magnetic field antenna is now a backup. WWLLN, uses the VLF feed but processes it to detect the radio-wave pulses from lightning. WWLLN observations are sent to a central processing computer to determine the time and location of lightning pulses all over the globe. The World Wide Lightning Location Network (WWLLN) is an experimental Very Low Frequency (VLF) network of sensors being developed through collaborations with research institutions across the globe. The network exploits the considerable electromagnetic power radiated by lightning as "sferics" present in the VLF band. By combining radio-pulse observations from at least 5 stations, the WWLLN central processing computers can determine the location of the original lightning discharge. As the radio-pulse observations are immediately sent back across the internet to the central processing computers locations are generated within ~10 s of the discharge, and thus near real time. There are currently about 70 active VLF receiving stations operating in the VLF World-Wide Lightning Location Network, including the Scott Base measurements. WWLLN observations are continuously transmitted to one of the WWLLN primary servers, in this case flash.ess.washington.edu at the University of Washington, Seattle, USA. GET DATA: https://space.physics.otago.ac.nz/aarddvark/

  • The AARDDVARK/WWLLN Very Low Frequency (VLF) Radio Sensor was installed at Arrival Heights from 10-15 December 2008 by Dr Craig J. Rodger and Dr. James Brundell as part of Antarctica New Zealand Event K069a. The sensor measures the magnetic field in the Very Low Frequency radio range (~500 Hz-50 kHz), and passes it to a PC which processes the data for the experiments. The primary experiment is the AARDDVARK observations. The secondary experiment, WWLLN, uses exactly the same VLF feed but processes it to detect the radio-wave pulses from lightning. WWLLN observations are sent to a central processing computer to determine the time and location of lightning pulses all over the globe. The World Wide Lightning Location Network (WWLLN) is an experimental Very Low Frequency (VLF) network of sensors being developed through collaborations with research institutions across the globe. The network exploits the considerable electromagnetic power radiated by lightning as "sferics" present in the VLF band. By combining radio-pulse observations from at least 5 stations, the WWLLN central processing computers can determine the location of the original lightning discharge. As the radio-pulse observations are immediately sent back across the internet to the central processing computers locations are generated within ~10 s of the discharge, and thus near real time. There are currently about 70 active VLF receiving stations operating in the VLF World-Wide Lightning Location Network, including the "Scott Base" measurements made at Arrival Heights or near the Hatherton Lab (depending on noise levels). WWLLN observations are continuously transmitted to one of the WWLLN primary servers, in this case flash.ess.washington.edu at the University of Washington, Seattle, USA. Two near-orthogonal magnetic field loops measuring VLF electromagnetic waves. The centre of the antenna is at 77° 49.790' S, 166° 39.438' E, based on a GPS measurement with 1 m accuracy. Logging is undertaken with standard WWLLN software, with GPS timing. GET DATA: https://wwlln.net/

  • Air temperature, pressure, velocity, relative humidity measurements from near-surface up to around 2km above sea level were taken along the path of four height controlled free floating meteorological balloons released from Terra Nova Bay and flew over the polynya, sea ice and open waters of the Ross Sea. These data were used to investigate localized weather processes that are largely influenced by variable surface cover (ice, polynya, open water, terrain). This metadata record represents flights: 171104a, 171110a, 171117a, and 171122a. Further details are provided at: https://doi.org/10.1029/2019JD030591 GET DATA: https://www.science.smith.edu/cmet/flight.html

  • Our studies investigate the Antarctic middle atmosphere’s response to natural and man-made factors which change climate. The dynamical processes of this region are significant in controlling the circulation at lower altitudes, including the stratospheric ozone layer. The feedbacks in the atmosphere, couple this change to climate change at the surface. The seasonal behaviour of this wave-driven circulation, particularly its dependence on major disturbances in the stratosphere which result in the transport of energy and momentum by waves to higher altitudes are examined. The programme is based on continuous monitoring of winds in the middle atmosphere at altitudes of 60-100km using a ground-based medium frequency radar located at Scott Base. The Scott Base radar has been recording wind measurements since 1982 and is one of the longest duration climate records of this type of data in the world. The measurements made by the Scott Base MF radar provide valuable climate information about how the flow in the middle atmosphere (70-100 km) has changed. This record along with observations from satellite instruments allows the coupling between the middle atmosphere and the surface over Antarctica to be examined, this coupling is often associated with wave-like motions in the atmosphere that the MF radar is particularly good at observing. The circulation is dominated by pole-to-pole flow, from the summer pole to the winter pole. This circulation is largely driven by atmospheric waves with time scales from 15 minutes to 15 days. The large scale of the phenomenon benefits considerably from co-operative observations by our own radar near Christchurch, and by our US colleagues at the South Pole, Admiral Heights (from January 2000) and Tekapo. We also use satellite data for the region between Antarctica and New Zealand. This type of study is important because improvements in the predictive ability of the current generation of climate models may be particularly sensitive to the coupling processes that we examine.