519 publications from this institution
The offshore stage of the Maul project began with the arrival from Japan in December 1975 of the tower that forms the base for Maui Platform A. After a period of inspection, performed in Golden Bay, the tower was ready to be towed to the installation site on 23 December 1975. It was finally upended, after some delays due to bad weather, on 4 January 1976. When level, pin piles were to be driven through the centre of each leg to secure the tower permanently.' This work was also delayed, largely because of the weather, and it has been stated that the weather in the South Taranaki Bight was the worst experienced in the past 20 years. This paper considers these statements and investigates some aspects of the weather in the South Taranaki Bight, mainly during the period January yo May 1976, compared with previous years.
No abstract is provided for this article.
As global surface temperatures have increased with human‐induced climate change, notable compound climate extremes in the New Zealand (NZ) region associated with atmospheric heatwaves (AHWs) and marine heatwaves (MHWs) have occurred in the past 6 years. Natural modes of variability that also played a key role regionally include the Interdecadal Pacific Oscillation (IPO), El Niño/Southern Oscillation (ENSO) and changes in the location and strength of the westerlies as seen in the Southern Annular Mode (SAM). Along with mean warming of 0.8°C since 1900, a negative phase of the IPO, La Niña phase of ENSO and a strongly positive SAM contributed to five compound warm extremes in the extended austral summer seasons (NDJFM) of 1934/35, 2017/18, 2018/19, 2021/22 and 2022/23. These are the most intense coupled ocean/atmosphere (MHWs/AHWs) heatwaves on record with average temperature anomalies over land and sea +0.8°C to 1.1°C above 1991–2020 averages. The number of days above 25°C and above the 90th percentile of maximum temperature has increased, while the number of nights below 0°C and below the 10th percentile has decreased. Coastal waters around NZ recently experienced their longest MHW in the satellite era (1982‐present) of 289 days through 2023. The estimated recurrence interval reduces from 1 in 300‐years for the AHW event during the 1930s climate to a 1 in 25‐year event for the most recent decade. Consequences include major loss of ice of almost one‐third volume from Southern Alps glaciers from 2017 to 2021 with rapid melt of seasonal snow in all four cases. Above‐average temperatures in the December/January grape flowering period resulted in advances in veraison (the onset of ripening); and higher‐than‐average grape yields in 2022 and 2023 vintages. Marine impacts include widespread sea‐sponge bleaching around northern and southern NZ.
The usual interpretation of the quasi-geostrophic omega equation can be ambiguous, and an alternative but complementary approach is suggested. In the middle troposphere, upward motion is shown to he the consequence of the cyclonic advection of vorticity by the thermal wind. This relates to several empirical-dynamical rules of synoptic meteorology.
Kalnay and Cai1 claim that urbanization and land-use change have a major effect on the climate in the United States. They used surface temperatures obtained from NCEP/NCAR 50-year reanalyses (NNR) and their difference compared with observed station surface temperatures as the basis for their conclusions, on the grounds that the NNR did not include these anthropogenic effects. However, we note that the NNR also overlooked other factors, such as known changes in clouds and in surface moisture, which are more likely to explain Kalnay and Cai's findings. Although urban heat-island effects are real in cities, direct estimates of the effects of rural land-use change indicate a cooling rather than a warming influence that is due to a greater reflection of sunlight.
No abstract is provided for this article.
New estimates of freshwater discharge from continents were derived using stream-flow records from the world's largest 921 rivers, supplemented with estimates of discharge from unmonitored areas based on the ratios of runoff and drainage area between the unmonitored and monitored regions. The farthest downstream river-flow data were extrapolated to the river mouth using river transport model simulations forced by a runoff field. This new continental discharge estimate was then applied to estimate the meridional transport of freshwater within the oceans. The relatively new estimates of net water fluxes (P-E) over ocean surfaces derived from atmospheric moisture budget analyses based on the NCEP/NCAR and ECMWF reanalyses were used in the calculation of oceanic freshwater transport. Our results, which are improved in many aspects compared with previous estimates, show that global continental discharge is about 37288 km 3 yr -1 (1.2 Sv, 1 Sv = 1×10 6 m 3 s -1 ) or about 35% of terrestrial precipitation. Compared with earlier indirect estimates of oceanic freshwater transport, our new estimates derived using the 921- river based discharge and the ECMWF reanalysis based P-E show improved agreement with available direct estimates for the Atlantic, Pacific, and Indian Ocean basins. The new estimates also show increased southward transports in the Atlantic Ocean and increased northward transports in the South Pacific Ocean.
Current climate models suggest that global warming will result in more frequent extreme hydrological events (floods and droughts). These results, however, must be tempered with the fact that current climate models do not realistically represent many of the processes important to the formation of clouds and precipitation at various time and space scales. For instance, the diurnal cycle of precipitation is poorly represented in most climate models. The proper representation of precipitation is a major challenge to global climate models, which typically only resolve processes at 200- to 400-km scales, and is a focus of current scientific research. This chapter addresses the current understanding of the likely climate impact on precipitation, as well as some of the key challenges facing climate modelers with regard to improving future projections of precipitation.
The largest increases in surface temperatures over the Northern Hemisphere in the decade prior to 1988 were in Alaska, while substantial decreases occurred in the North Pacific Ocean. This illustrates the considerable geographic spatial structure to interdecadal temperature variations associated with changes in the atmospheric circulation. In particular, from 1977 to 1988, there was a deeper and eastward-shifted Aleutian low-pressure system in the winter half year, which advected warmer and moister air into Alaska and colder air over the North Pacific. Associated changes in surface-wind stress and wind-stress curl altered the North Pacific Ocean currents, as revealed by the Sverdrup transport. The North Pacific changes appear to be linked through teleconnections to tropical atmosphere–ocean interactions and the frequency of El Niño versus La Niña events. Consequently, the question of why it was so warm in Alaska becomes changed to one of why there were three tropical Pacific Warm Events, but no Cold Events, from 1977 to 1988, and whether changes in El Niño frequency will be altered during climate change. At the very least, these linkages and the resulting strongly regional structure of surface-temperature variations complicate any search for a greenhouse effect and global warming.
The climate varies on multiple timescales, but now humans are the main agents of change and are likely to remain so for the next few centuries. It is generally understood that human-induced climate change causes global warming, but what is not adequately appreciated are the direct influences on heavy rainfalls, drought and storms, at great cost to society and the environment. Although the climate change effects are modest, perhaps five to 15 per cent for these events, once thresholds are crossed, things break and damage increases non-linearly. These aspects are not properly factored into costs of climate change, and preparation for expected effects is woefully inadequate, exacerbating damage.
To explore the role of hurricanes in the climate system, a detailed analysis is made of the bulk atmospheric moisture budget of Ivan in September 2004 and Katrina in August 2005 from simulations with the Weather and Research Forecasting (WRF) model at 4 km resolution without parameterized convection. Heavy precipitation exceeding 20 mm h −1 in the storms greatly exceeds the surface flux of moisture through evaporation, and vertically integrated convergence of moisture in the lowest 1 km of the atmosphere from distances up to 1600 km is the dominant term in the moisture budget, highlighting the importance of the larger‐scale environment. Simulations are also run for the Katrina case with sea surface temperatures (SSTs) increased by +1°C and decreased by −1°C as sensitivity studies. For hours 42 to 54 after the start of the simulation, maximum surface winds increased about 4.5 m s −1 (9%), and sea level pressure fell 11.5 hPa per 1°C increase in tropical SSTs. Overall, the hurricane expands in size as SSTs increase, the environmental atmospheric moisture increases at close to the Clausius‐Clapeyron equation value of about 6% K −1 and the surface moisture flux also increases mainly from Clausius‐Clapeyron effects and the changes in intensity of the storm. The environmental changes related to human influences on climate since 1970 have increased SSTs and water vapor, and the results suggest how this may have altered hurricanes and increased associated storm rainfalls, with the latter quantified to date to be of order 6 to 8%.
No abstract is provided for this article.
Changes in ocean heat content (OHC), salinity, and stratification provide critical indicators for changes in Earth's energy and water cycles. These cycles have been profoundly altered due to the emission of greenhouse gasses and other anthropogenic substances by human activities, driving pervasive changes in Earth's climate system. In 2022, the world's oceans, as given by OHC, were again the hottest in the historical record and exceeded the previous 2021 record maximum. According to IAP/CAS data, the 0-2000 m OHC in 2022 exceeded that of 2021 by 10.9 ± 8.3 ZJ (1 Zetta Joules = 1021 Joules); and according to NCEI/NOAA data, by 9.1 ± 8.7 ZJ. Among seven regions, four basins (the North Pacific, North Atlantic, the Mediterranean Sea, and southern oceans) recorded their highest OHC since the 1950s. The salinity-contrast index, a quantification of the "salty gets saltier-fresh gets fresher" pattern, also reached its highest level on record in 2022, implying continued amplification of the global hydrological cycle. Regional OHC and salinity changes in 2022 were dominated by a strong La Niña event. Global upper-ocean stratification continued its increasing trend and was among the top seven in 2022.由于人类活动排放温室气体, 全球能量和水循环已经发生了显著的变化, 驱动了气候系统的一系列变异. 海洋热含量、 盐度和层结变化是地球系统能量和水循环的重要指针. 2022 年, 全球海洋上层 2000 米热含量再破记录, 海洋成为有现代记录以来最热的一年. 据中国科学院大气物理研究所的测算, 2022 年 0–2000 米海洋热含量超过 2021 年 10.9 ± 8.3 泽塔焦耳 (1 泽塔焦耳= 1021焦耳). 与之一致, 美国国家海洋和大气管理局国家环境信息中心的测算为 9.1 ± 8.7 泽塔焦耳. 在所研究的 7 个海盆中, 北太平洋、 北大西洋、 地中海、 南大洋这 4 个海盆的 2022 年度热含量均创下了自上世纪 50 年代以来的新记录. 此外, 定量化测算海洋盐度 “咸变咸, 淡变淡” 变化趋势的 “盐度差指数” 也在 2022 年达到过去半世纪以来的最高值, 反映了全球水循环在不断加速. 在区域尺度, 海洋热含量和盐度变化显示出较强的拉尼娜事件的影响. 最后, 全球上层 2000 米海洋层结也持续加强, 2022 年全球海洋层结处于有现代记录以来的第 7 高位.
