Search

Instrumental meteorological measurements from periods prior to the start of national weather services are designated "early instrumental data." They have played an important role in climate research as they allow daily to decadal variability and changes of temperature, pressure, and precipitation, including extremes, to be addressed. Early instrumental data can also help place twenty-first century climatic changes into a historical context such as defining preindustrial climate and its variability. Until recently, the focus was on long, high-quality series, while the large number of shorter series (which together also cover long periods) received little to no attention. The shift in climate and climate impact research from mean climate characteristics toward weather variability and extremes, as well as the success of historical reanalyses that make use of short series, generates a need for locating and exploring further early instrumental measurements. However, information on early instrumental series has never been electronically compiled on a global scale. Here we attempt a worldwide compilation of metadata on early instrumental meteorological records prior to 1850 (1890 for Africa and the Arctic). Our global inventory comprises information on several thousand records, about half of which have not yet been digitized (not even as monthly means), and only approximately 20% of which have made it to global repositories. The inventory will help to prioritize data rescue efforts and can be used to analyze the potential feasibility of historical weather data products. The inventory will be maintained as a living document and is a first, critical, step toward the systematic rescue and reevaluation of these highly valuable early records. Additions to the inventory are welcome. [ABSTRACT FROM AUTHOR]

Millions of sub‐daily sea‐level pressure observations taken between 1919 and 1960 over the British and Irish Isles were transcribed from paper records in the early 2000s but were not published and subsequently forgotten. A chance discussion led to the rediscovery of the transcribed data and 5.47 million observations from 160 locations are now made available, although the data have not been fully quality‐controlled. Much of the data are 3‐hourly, allowing for detailed examinations of synoptic weather variations for this region and time period, and will be invaluable for constraining future reanalyses. We illustrate the value of the data using a stormy period during October and November 1928 and discuss the remaining quality‐control issues. [ABSTRACT FROM AUTHOR]

Instrumental data from the pre–Industrial Revolution period are important to -understand climate change. In this paper, the observations made by the French missionary J. Amiot in present-day central Beijing during 1757–62 were processed and analyzed. The observations represent the earliest continuous dataset of meteorological records found in China that have been digitized recently. Comparisons between the Amiot annual temperature range and extreme values with modern observations showed that the observations were read at approximately 0800 and 1500 local solar time (LST) in a well-ventilated outdoor site. The daily maximum, minimum, and mean temperatures (T-max, T-min, and T-mean, respectively) during 1757–62 were determined by examining the relationship between temperature at 0800 and 1500 LST and T-max, T-min, and T-mean in modern reference series. Nearly 260 years ago, Beijing's climate was typical of an inland temperate monsoon zone with annual T-mean, annual mean T-max, and annual mean T-min being 11.5°, 17.8°, and 6.1°C, respectively; further, the temperatures did not vary considerably from the 1951–1980 temperatures, but differed evidently compared to relatively recent decades (1981–2020). The difference was larger than the magnitudes of global and regional temperature changes. Thus, climate warming since the pre–Industrial Revolution period in the urban areas of Beijing has dominantly occurred over the last four decades. Uncertainties related to the thermometer and observational conditions 260 years ago and the interpolation method used have also been discussed in this paper. [ABSTRACT FROM AUTHOR]

The article talks about the International Atmospheric Circulation Reconstructions over the Earth (ACRE) initiative, which focuses on facilitating climate data reanalyses research. It states ACRE is led by seven core partners who provide funding including the U.S. North Atlantic Oceanic and Atmospheric Administration's National Climatic Data Center and Earth System Research Laboratory and Great Britain's Meteorological Office. It mentions ACRE's data recovery, imaging and digitization programs.

The article analyzes the environmental implication of extreme and severe storms in British Isles every January, February and March. The worsening impact of global warming has been the growing concern in the climate science with the aim of establishing initiatives to protect biodiversity. Results of environmental and temperature monitoring and modeling show that storm patterns has been affected by unstable climate. Severe storms across the isles are primarily caused by the worsening global condition and the pattern in mean sea level pressure (MSLP) reflect these storms.

The article focuses on the importance of digitization programs in the observation of historical weather data from ships and naval vehicles. It explains that programs for the digitization of marine observations from some logbooks or specialized meteorological forms have started in the twentieth century. It provides information on the Climatological Database for the Worlds Oceans, 1750-1850 (CLIWOC) program, which has begun the recovery of large quantity of logbook data in the archives. The digitization of historical marine observations that are archived in Great Britain is also noted. Discussions on the program to restore data during World War II, as well as the imaging and digitizing of logbooks are also offered.

An upgraded version of the Hadley Centre’s monthly historical mean sea level pressure (MSLP) dataset (HadSLP2) is presented. HadSLP2 covers the period from 1850 to date, and is based on numerous terrestrial and marine data compilations. Each terrestrial pressure series used in HadSLP2 underwent a series of quality control tests, and erroneous or suspect values were either corrected, where possible, or removed. Marine observations from the International Comprehensive Ocean Atmosphere Data Set were quality controlled (assessed against climatology and near neighbors) and then gridded. The final gridded form of HadSLP2 was created by blending together the processed terrestrial and gridded marine MSLP data. MSLP fields were made spatially complete using reduced-space optimal interpolation. Gridpoint error estimates were also produced. HadSLP2 was found to have generally stronger subtropical anticyclones and higher-latitude features across the Northern Hemisphere than an earlier product (HadSLP1). During the austral winter, however, it appears that the pressures in the southern Atlantic and Indian Ocean midlatitude regions are too high; this is seen in comparisons with both HadSLP1 and the 40-yr ECMWF Re-Analysis (ERA-40). Over regions of high altitude, HadSLP2 and ERA-40 showed consistent differences suggestive of potential biases in the reanalysis model, though the region over the Himalayas in HadSLP2 is biased compared with HadSLP1 and improvements are required in this region. Consistent differences were also observed in regions of sparse data, particularly over the higher latitudes of the Southern Ocean and in the southeastern Pacific. Unlike the earlier HadSLP1 product, error estimates are available with HadSLP2 to guide the user in these regions of low confidence. An evaluation of major phenomena in the climate system using HadSLP2 provided further validation of the dataset. Important climatic features/indices such as the North Atlantic Oscillation, Arctic Oscillation, North Pacific index, Southern Oscillation index, Trans-Polar index, Antarctic Oscillation, Antarctic Circumpolar Wave, East Asian Summer Monsoon index, and the Siberian High index have all been resolved in HadSLP2, with extensions back to the mid-nineteenth century. [ABSTRACT FROM AUTHOR]

Recovers and examines atmospheric pressure data recorded at the Madras Observatory, and at other climate stations in India, focusing on their quality and veracity. In general, the Madras monthly mean sea-level pressure (MSLP) record is shown to be robust over time, and thus a useful long-term measure of fluctuations in the El Niño southern oscillation (ENSO) phenomenon across the Indian Ocean basin and of the Indian summer monsoon.

Global gridded data sets of observed extremes indices underpin assessments of changes in climate extremes. However, similar efforts to enable the assessment of indices relevant to different sectors of society have been missing. Here we present a data set of sector‐specific indices, based on daily station data, that extends the HadEX3 data set of climate extremes indices. These additional indices, which can be used singly or in combinations, have been recommended by the World Meteorological Organization and are intended to empower decision makers in different sectors with accurate historical information about how sector‐relevant measures of the climate are changing, especially in regions where in situ daily temperature and rainfall data are hard to come by. The annual and/or monthly indices have been interpolated on to a 1.875° × 1.25° longitude‐latitude grid for 1901–2018. We show changes in globally‐averaged time series of these indices in comparison with reanalysis products. Changes in temperature‐based indices are consistent with global scale warming, with days with Tmax > 30°C (TXge30) increasing virtually everywhere with potential impacts on crop fertility. At the other end of the scale, the number of days with Tmin < −2°C (TNltm2) are reducing, decreasing potential damage from frosts. Changes in heat wave characteristics show increases in the number, duration and intensity of these extreme events in most places. The gridded netCDF files and, where possible, the underlying station indices are available from https://www.metoffice.gov.uk/hadobs/hadex3 and https://www.climdex.org. Plain Language Summary: To be able to assess changes in extreme temperature and rainfall events across the globe, data sets which capture characteristics of these extreme events are required. The use of indices for these characteristics further enables both data sharing and the comparison of events across the world. Extreme events have impacts across human health, our infrastructure and the natural environment. So far there has not been a global product which presents indices which are relevant for different sectors of our society, including health, agriculture and water resources. In this work we present an extension to an existing data set of extremes indices, HadEX3, by including indices defined by the World Meteorological Organization which were developed with sector specific applications in mind. We have used the same approach and methodology, and where possible the same underlying daily temperature and rainfall observations. The temperature indices show changes consistent with global scale warming, with heat wave characteristics showing increases in the number, duration and intensity of these extreme events in most places. The data files are available for use by interested researchers in their work. Key Points: We present a sector specific extension to a data set of gridded temperature and precipitation extremesThis first quasi‐global product of these indices will support decision makers in a wide range of sectorsLong‐term changes show increases in intensity, frequency, and duration of warm extremes, and corresponding decreases in cool extremes [ABSTRACT FROM AUTHOR]

In this paper, we describe the results of a climate data rescue (DARE) activity conducted at the Ukrainian Hydrometeorological Institute (Kyiv, Ukraine) in cooperation with the Justus Liebig University Giessen (Giessen, Germany), the World Meteorological Organization (WMO) and Met Office Hadley Centre (Exeter, United Kingdom). The focus of our work is on pre‐1850 sub‐daily meteorological observations conducted on the territory of modern Ukraine. Data from eight stations (stored in special hard copy tables/books, with handwritten records) have been digitized during the DARE process, resulting in 291,103 rescued values in total. More than half of this number (165,980, ~57%) are related to air temperature data, 124,376 data values (~42.7%) concern atmospheric pressure records and 747 values (~0.3%) are precipitation data. Simple quality control of the digitized data has been conducted, including an intercomparison between stations as well as comparison with monthly temperature data previously digitized from other paper sources. The quality control procedures revealed fairly good agreement between rescued time series on the monthly time scale as well as with the monthly data from independent sources. However, several periods for a few stations should be used with caution due to relatively large discrepancies that were found. The rescued digital database can be used for extreme value analysis for the pre‐1850 period in comparison with today's climate, regional climatological studies and will be used for future Reanalysis. In addition, for the first time, we show that subdaily temperature from Kyiv during 'the year without summer' 1816 in Western and Central Europe were not anomalous in this part of Eastern Europe. [ABSTRACT FROM AUTHOR]

The article presents an update on efforts to rescue sources of historical climate information in Australia. Topics covered include the importance of Aboriginal environmental history to climate data rescue, the South Eastern Australian Recent Climate History (SEARCH) project and the climate citizen science project of the Australian Meteorological Association.

The Copernicus Climate Change Service (C3S) of the European Commission combinesobservations of the Earth System with state-of-the-art science to develop and make availableauthoritative and quality-assured data about the past, present and future climate, both inEurope and worldwide. The portfolio of service products includes the generation of ClimateData Records (CDRs) of Essential Climate Variables (ECVs) based on Earth Observation(EO) sensors and in-situ observations, reprocessing of Fundamental CDRs and data rescueactivities. Monitoring ECVs over long-term periods covering a minimum of several decades iscrucial, as they provide empirical evidence needed to understand the evolution of climate.C3S is currently producing global gridded CDRs of 22 ECVs divided in five themes:atmospheric physics, atmospheric composition, ocean, land hydrology and cryosphere andland biosphere. Several expert European consortia use advance methods to generate timely,consistent CDRs of ECVs with the satellite data record. Methodologies includeinter-sensor calibration, data harmonization and bias correction. This view of climateby remote observations is complemented with the generation of gridded CDRs ofECVs for the European domain, from 1950, based on surface in-situ data. Theseactivities support the work of international bodies such as the UNFCCC and theIPCC. Another activity for climate monitoring based on EO data is the comprehensivereprocessing of satellite data records from the satellite era (1979-). They can be used withclimate models or reanalysis to accurately describe the climate of the past. C3S supportsactivities encompassing the reprocessing of infrared and microwave sounding radiances;radio occultation and scatterometer data, as well as geostationary radiances and atmosphericmotion vectors derived from GEO and LEO satellites. In addition, C3S is engaged in therescue, assessment and characterisation of new data from the early satellite era (dating backto the late 1960s). This presentation will provide an overview and current status of the above activities, aswell as the main methodologies used in the service. [ABSTRACT FROM AUTHOR]

The El Niño event of 1877–1878 was one of the strongest during the last 150 years and had worldwide impacts, bringing widespread severe droughts, but also unusually wet conditions to some regions. We focus on the effects that this event had on precipitation in South Africa, taking advantage of newly rescued instrumental data, as well as documentary sources. Through the assimilation of the new data into an existing reanalysis, we could improve the synoptic reconstruction of specific weather events. However, much remains to be done in order to achieve a good and consistent reconstruction quality for the region. [ABSTRACT FROM AUTHOR]

The first daily mean sea‐level pressure (MSLP) series for the Southwestern Cape region of South Africa is presented for the 19th century, and is one of the longest and oldest for the Southern Hemisphere. Sub‐daily barometer readings from the South African Astronomical Observatory were digitized, together with temperature readings, and extend over the period 1834–1899. Pressure readings were recorded using mercury barometers and so needed to be corrected and reduced to standard conditions. Overall, austral winter (June, July, August) has the highest mean monthly MSLP values, symptomatic of the ridging anticyclones during this season. The year 1862 stands out with particularly low MSLP values and has 27 days during austral winter that were below the 10th percentile. This most likely indicates that the winter of 1862 experienced the highest number of passing cold fronts throughout the 66‐year study period. The first daily MSLP series for the Southwestern Cape region of South Africa is presented for the 19th century, and is one of the longest and oldest for the Southern Hemisphere. Sub‐daily barometer readings were digitized from the original hard copies. These barometer observations were corrected to modern‐day standard conditions, reduced to MSLP and an equivalent 24‐hr daily mean was calculated. The year 1862 stands out with particularly low MSLP values and has 27 days during austral winter that were below the 10th percentile, likely indicative of a high number of passing cold fronts. [ABSTRACT FROM AUTHOR]

Quantitative approaches to climate risk management such as mapping or impact modelling rely on past meteorological data with daily or sub‐daily resolution, a large fraction of which have not yet been digitized. Over the last decade or so, a number of projects have contributed to the rescue of some of these data. Here we provide a summary of a survey we have undertaken of several meteorological and climate data rescue projects, in order to identify the needs of climate data rescue services. To make these efforts more sustainable, additional integrated activities are needed. We argue that meteorological and climate data rescue must be seen as a continuous, coordinated long‐term effort. Technical developments (e.g. data assimilation), new scientific questions (e.g. process understanding of extreme events) and new social (e.g. risk assessment, health) or economic (e.g. new renewable energy sources, agriculture and forestry, tourism, infrastructure, etc.) services are highlighting the immense value of data previously neglected or never considered. This continuous effort is currently undertaken by projects of various sizes, structure, funding and staffing, as well as by dedicated programmes, ranging from those within many national weather services down to "grassroots" initiatives. These activities are often not sufficiently coordinated, staffed, or funded at an international level and will benefit considerably from climate data rescue services being established within the Copernicus Climate Change Service (C3S) (https://climate.copernicus.eu/). Open Practices: This article has earned an Open Data badge for making publicly available the digitally‐shareable data necessary to reproduce the reported results. Learn more about the Open Practices badges from the Center for Open Science: https://osf.io/tvyxz/wiki. [ABSTRACT FROM AUTHOR]

The sparse nature of observational records across the mid- to high latitudes of the Southern Hemisphere limits the ability to place late-twentieth-century environmental changes in the context of long-term (multidecadal and centennial) variability. Historical records from subantarctic islands offer considerable potential for developing highly resolved records of change. In 1905, a whaling and meteorological station was established at Grytviken on subantarctic South Georgia in the South Atlantic (54°S, 36°W), providing near-continuous daily observations through to present day. This paper reports a new, daily observational record of temperature and precipitation from Grytviken, which is compared to regional datasets and historical reanalysis. The authors find a shift toward increasingly warmer daytime extremes commencing from the mid-twentieth century and accompanied by warmer nighttime temperatures, with an average rate of temperature rise of 0.13°C decade-1 over the period 1907-2016 (p < 0.0001). Analysis of these data and reanalysis products suggest a change of pervasive synoptic conditions across the mid- to high latitudes since the mid-twentieth century, characterized by stronger westerly airflow and associated warm föhn winds across South Georgia. This rapid rate of warming and associated declining habitat suitability has important negative implications for biodiversity, including the survival of key marine biota in the region. [ABSTRACT FROM AUTHOR]

The article offers the author's view on the journal related to the study on geoscience. The author states that the journal is an online-only, open access journal which publishes short data papers related to the fields of Weather and Climate, Oceanography, and Atmospheric and Ocean Chemistry. The author mentions that the journal's Data Paper describes dataset, give details of collection, and file formats.

The article offers the author's view on the journal related to the study on geoscience. The author states that the journal is an online-only, open access journal which publishes short data papers related to the fields of Weather and Climate, Oceanography, and Atmospheric and Ocean Chemistry. The author mentions that the journal's data paper describes dataset, give details of collection, and file formats.

The article discusses a meeting of the World Meteorological Organization Commission for Climatology on September 7-9, 2010 sponsored by Great Britain's Meteorological Office. It states the meeting discussed the creation of a comprehensive, traceable data bank of global surface temperature and facilitate high-quality, robust data product creation to meet the needs of 21st century climate research. It commented on the need for increased openness and transparency in research data policy.

The authors present initial results of a new pan-European and international storminess since 1800 as interpreted from European and North Atlantic barometric pressure variability (SENABAR) project. This first stage analyzes results of a new daily pressure variability index, dp(abs)24, from long-running meteorological stations in Denmark, the Faroe Islands, Greenland, Iceland, the United Kingdom, and Ireland, some with data from as far back as the 1830s. It is shown that dp(abs)24 is significantly related to wind speed and is therefore a good measure of Atlantic and Northwest European storminess and climatic variations. The authors investigate the temporal and spatial consistency of dp(abs)24, the connection between annual and seasonal dp(abs)24 and the North Atlantic Oscillation Index (NAOI), as well as dp(abs)24 links with historical storm records. The results show periods of relatively high dp(abs)24 and enhanced storminess around 1900 and the early to mid-1990s, and a relatively quiescent period from about 1930 to the early 1960s, in keeping with earlier studies. There is little evidence that the mid- to late nineteenth century was less stormy than the present, and there is no sign of a sustained enhanced storminess signal associated with “global warming.” The results mark the first step of a project intending to improve on earlier work by linking barometric pressure data from a wide network of stations with new gridded pressure and reanalysis datasets, GCMs, and the NAOI. This work aims to provide much improved spatial and temporal coverage of changes in European, Atlantic, and global storminess. [ABSTRACT FROM AUTHOR]

El Niño‐Southern Oscillation (ENSO), the primary source of year‐to‐year climate variability on Earth, has profound impacts on the Indian Ocean dipole (IOD), another important climate pattern. Much attention has been paid to potentially increased ENSO predictability by utilizing IOD conditions, inferred from a statistically significant correlation with ENSO at a long lead time. However, the intrinsic dynamics for the causality of this IOD‐ENSO relationship remain largely elusive. Here, we demonstrate that the observed nonstationary IOD‐ENSO lead‐lag relationship is mainly ENSO‐driven and therefore adds no additional information for ENSO predictability. The nonstationarity of their correlation is a manifestation of ENSO cycle complexity. Multi‐climate model and theoretical results further demonstrate that ENSO pacing tightly controls the statistical IOD‐ENSO relationship via changes in ENSO periodicity and regularity. This highlights that ENSO dominates the inter‐basin Pacific‐Indian Ocean interactions, shedding light on the key predictors for interannual pantropical climate variability. Plain Language Summary: Mounting attention has been paid to finding potential predictability sources outside the tropical Pacific to extend the prediction horizon of the El Niño‐Southern Oscillation (ENSO). This study shows that the observed inter‐basin lead‐lag relationship in the Indo‐Pacific, that was previously invoked to identify the Indian Ocean dipole as an independent predictor of ENSO, is in fact a manifestation of ENSO cycle complexity. We demonstrate that ENSO pacing tightly controls the inter‐basin Pacific‐Indian Ocean interannual relationship via changes in fundamental ENSO properties. The causal relationship identified here regarding inter‐basin climate interactions is of crucial relevance for future studies investigating pantropical climate interactions. Key Points: The observed Indian Ocean dipole (IOD)‐El Niño‐Southern Oscillation (ENSO) lead‐lag relationship is primarily ENSO‐driven, which adds no additional information to ENSO predictabilityThe observed nonstationarity of inter‐basin Pacific‐Indian Ocean interannual connectivity is a manifestation of ENSO cycle complexityENSO pacing regulates the IOD‐ENSO relationship via changes in fundamental ENSO properties [ABSTRACT FROM AUTHOR]

El Niño‐Southern Oscillation (ENSO), the primary source of year‐to‐year climate variability on Earth, has profound impacts on the Indian Ocean dipole (IOD), another important climate pattern. Much attention has been paid to potentially increased ENSO predictability by utilizing IOD conditions, inferred from a statistically significant correlation with ENSO at a long lead time. However, the intrinsic dynamics for the causality of this IOD‐ENSO relationship remain largely elusive. Here, we demonstrate that the observed nonstationary IOD‐ENSO lead‐lag relationship is mainly ENSO‐driven and therefore adds no additional information for ENSO predictability. The nonstationarity of their correlation is a manifestation of ENSO cycle complexity. Multi‐climate model and theoretical results further demonstrate that ENSO pacing tightly controls the statistical IOD‐ENSO relationship via changes in ENSO periodicity and regularity. This highlights that ENSO dominates the inter‐basin Pacific‐Indian Ocean interactions, shedding light on the key predictors for interannual pantropical climate variability. Plain Language Summary: Mounting attention has been paid to finding potential predictability sources outside the tropical Pacific to extend the prediction horizon of the El Niño‐Southern Oscillation (ENSO). This study shows that the observed inter‐basin lead‐lag relationship in the Indo‐Pacific, that was previously invoked to identify the Indian Ocean dipole as an independent predictor of ENSO, is in fact a manifestation of ENSO cycle complexity. We demonstrate that ENSO pacing tightly controls the inter‐basin Pacific‐Indian Ocean interannual relationship via changes in fundamental ENSO properties. The causal relationship identified here regarding inter‐basin climate interactions is of crucial relevance for future studies investigating pantropical climate interactions. Key Points: The observed Indian Ocean dipole (IOD)‐El Niño‐Southern Oscillation (ENSO) lead‐lag relationship is primarily ENSO‐driven, which adds no additional information to ENSO predictabilityThe observed nonstationarity of inter‐basin Pacific‐Indian Ocean interannual connectivity is a manifestation of ENSO cycle complexityENSO pacing regulates the IOD‐ENSO relationship via changes in fundamental ENSO properties [ABSTRACT FROM AUTHOR]

We present results from the first 6 years of this major U.K. government funded project to accelerate and enhance collaborative research and development in climate science, forge a strong strategic partnership between U.K. and Chinese climate scientists, and demonstrate new climate services developed in partnership. The development of novel climate services is described in the context of new modeling and prediction capability, enhanced understanding of climate variability and change, and improved observational datasets. Selected highlights are presented from over 300 peer reviewed studies generated jointly by U.K. and Chinese scientists within this project. We illustrate new observational datasets for Asia and enhanced capability through training workshops on the attribution of climate extremes to anthropogenic forcing. Joint studies on the dynamics and predictability of climate have identified new opportunities for skillful predictions of important aspects of Chinese climate such as East Asian summer monsoon rainfall. In addition, the development of improved modeling capability has led to profound changes in model computer codes and climate model configurations, with demonstrable increases in performance. We also describe the successes and difficulties in bridging the gap between fundamental climate research and the development of novel real-time climate services. Participation of dozens of institutes through subprojects in this program, which is governed by the Met Office Hadley Centre, the China Meteorological Administration, and the Institute of Atmospheric Physics, is creating an important legacy for future collaboration in climate science and services. [ABSTRACT FROM AUTHOR]

Tropical cyclone (TC) activities over the western North Pacific (WNP) and TC landfall in Japan are investigated by collecting historical TC track data and meteorological observation data starting from the mid-nineteenth century. Historical TC track data and TC best track data are merged over the WNP from 1884 to 2018. The quality of historical TC data is not sufficient to count the TC numbers over the WNP due to the lack of spatial coverage and different TC criteria before the 1950s. We focus on TC landfall in Japan using a combination of TC track data and meteorological data observed at weather stations and lighthouses from 1877 to 2019. A unified TC definition is applied to obtain equivalent quality during the whole analysis period. We identify lower annual TC landfall numbers during the 1970s to the 2000s and find other periods have more TC landfall numbers including the nineteenth century. No trend in TC landfall number is detected. TC intensity is estimated by an annual power dissipation index (APDI). High APDI periods are found to be around 1900, in the 1910s, from the 1930s to 1960s, and after the 1990s. When we focus on the period from 1977 to 2019, a significant increasing trend of ADPI is seen, and significant northeastward shift of TC landfall location is detected. On the other hand, TC landfall location shifts northeastward and then southwestward in about 100-year interval. European and US ships sailed through East and Southeast Asian waters before the weather station network was established in the late nineteenth century. Then, we focus on TC events in July 1853 observed by the US Naval Japan Expedition of Perry’s fleet and August 1863 by a UK Navy ship that participated in two wars in Japan. A TC moved slowly westward over the East China Sea south of the Okinawa Islands from 21 to 25 July 1853. Another TC was detected in the East China Sea on 15–16 August 1863 during the bombardment of Kagoshima in southern Japan. Pressure data are evaluated by comparing the observations made by 10 naval ships in Yokohama, central Japan during 1863–1864. The deviation of each ship pressure data from the 10 ships mean is about 2.7–2.8 hPa. [ABSTRACT FROM AUTHOR]

Historical reanalyses that span more than a century are needed for a wide range of studies, from understanding large‐scale climate trends to diagnosing the impacts of individual historical extreme weather events. The Twentieth Century Reanalysis (20CR) Project is an effort to fill this need. It is supported by the National Oceanic and Atmospheric Administration (NOAA), the Cooperative Institute for Research in Environmental Sciences (CIRES), and the U.S. Department of Energy (DOE), and is facilitated by collaboration with the international Atmospheric Circulation Reconstructions over the Earth initiative. 20CR is the first ensemble of sub‐daily global atmospheric conditions spanning over 100 years. This provides a best estimate of the weather at any given place and time as well as an estimate of its confidence and uncertainty. While extremely useful, version 2c of this dataset (20CRv2c) has several significant issues, including inaccurate estimates of confidence and a global sea level pressure bias in the mid‐19th century. These and other issues can reduce its effectiveness for studies at many spatial and temporal scales. Therefore, the 20CR system underwent a series of developments to generate a significant new version of the reanalysis. The version 3 system (NOAA‐CIRES‐DOE 20CRv3) uses upgraded data assimilation methods including an adaptive inflation algorithm; has a newer, higher‐resolution forecast model that specifies dry air mass; and assimilates a larger set of pressure observations. These changes have improved the ensemble‐based estimates of confidence, removed spin‐up effects in the precipitation fields, and diminished the sea‐level pressure bias. Other improvements include more accurate representations of storm intensity, smaller errors, and large‐scale reductions in model bias. The 20CRv3 system is comprehensively reviewed, focusing on the aspects that have ameliorated issues in 20CRv2c. Despite the many improvements, some challenges remain, including a systematic bias in tropical precipitation and time‐varying biases in southern high‐latitude pressure fields. [ABSTRACT FROM AUTHOR]

Global dynamical reanalyses of the atmosphere and ocean fundamentally rely on observations, not just for the assimilation (i.e., for the definition of the state of the Earth system components) but also in many other steps along the production chain. Observations are used to constrain the model boundary conditions, for the calibration or uncertainty determination of other observations, and for the evaluation of data products. This requires major efforts, including data rescue (for historical observations), data management (including metadatabases), compilation and quality control, and error estimation. The work on observations ideally occurs one cycle ahead of the generation cycle of reanalyses, allowing the reanalyses to make full use of it. In this paper we describe the activities within ERA-CLIM2, which range from surface, upper-air, and Southern Ocean data rescue to satellite data recalibration and from the generation of snow-cover products to the development of a global station data metadatabase. The project has not produced new data collections. Rather, the data generated has fed into global repositories and will serve future reanalysis projects. The continuation of this effort is first contingent upon the organization of data rescue and also upon a series of targeted research activities to address newly identified in situ and satellite records. [ABSTRACT FROM AUTHOR]

ABSTRACT A World Meteorological Organization ( WMO) committee evaluated the record sea-level pressure ( SLP) measurement of 1089.4 hPa on 30 December 2004 in Tosontsengel, Mongolia (1724.6 m). Although instrumentation and data collection procedures were properly followed according to the assessment of the committee, concern was raised regarding the reliability of SLP adjustment from such a high-elevation station. This paper addresses this concern with a number of analyses that look at relationships between SLP extremes and corresponding station elevation and temperature. First, we selected data from stations extracted from the Integrated Surface Database ( ISD-Lite) of NOAA's National Climate Data Center. A spatial analysis indicates that elevation shows little to no association ( R2 values essentially zero) to extreme SLP. However, a second analysis between extreme SLP and air temperature indicates that high regionalism exists in spatial correlations (local R2) between those two variables. This relationship to temperature is likely the result of differences in SLP adjustment formulae used around the world. Based on this analysis, on the need to differentiate the SLP values adjusted using extremely cold temperatures (and generally high elevation), and following past WMO SLP guidelines, the WMO Rapporteurs for Climate and Weather Extremes therefore have created two distinct SLP records: (a) highest adjusted SLP (below 750 m), currently 1083.3 hPa recorded on 31 December 1968 at Agata, Evenhiyskiy, Russia; and (b) highest adjusted SLP (above 750 m), currently 1089.4 hPa (by Russian method; 1089.1 hPa by WMO formula) on 30 December 2004 in Tosontsengel, Mongolia. Future WMO guidance regarding SLP adjustment may lead to re-evaluation of this and other SLP records. [ABSTRACT FROM AUTHOR]

ABSTRACT Recent changes are found in the means and variability of the North Atlantic Oscillation ( NAO) index. There has been a sustained significant recent decrease in the summer NAO since the 1990s and, at the same time, a striking increase in variability of the winter - especially December - NAO that resulted in three of five (two of five) record high (record low) NAO Decembers occurring during 2004-2013 in the 115-year record. These NAO changes are related to an increasing trend in the Greenland Blocking Index ( GBI, high pressure over Greenland) in summer and a more variable GBI in December. The enhanced early winter NAO variability originates mainly at the southern node of the NAO but is also related to the more variable GBI in December. Transition seasons (spring and autumn) have remained relatively unchanged over the last 30 years. These results are corroborated using several NAO indices. The Arctic Oscillation ( AO) index, although strongly correlated with the NAO, does not show the recent sustained significant summer decrease, but it does show enhanced early winter variability. These recent observed changes are not present in the current generation of global climate models, although the latest process studies do offer insight into their causes. We invoke several plausible climate forcings and feedbacks to explain the recent NAO changes. [ABSTRACT FROM AUTHOR]