Climatological Changes Research Articles

Depositional evidence for the Kamikaze typhoons and links to changes in typhoon climatology

In the late 13 th century, Kublai Khan, ruler of the Mongol Empire, launched one of the world’s largest armadas of its time in an attempt to conquer Japan. Early narratives described the decimation and dispersal of these fleets by the “Kamikaze” of 1274 CE and 1281 CE, a pair of intense typhoons “divinely” sent to protect Japan from invasion. These historical accounts are prone to exaggeration, and significant questions remain regarding the occurrence and true intensity of these legendary typhoons. To provide independent insight, we present a new 2000 yr sedimentary reconstruction of extreme coastal flooding from a coastal lake near the location of the Mongol invasions. Two marine-sourced flood deposits date to the Kamikaze typhoons and are the events of record in the reconstruction. The complete reconstruction indicates periods of greater flood activity relative to modern beginning ca. 250 CE and extending past the timing of the Kamikaze events to 1600 CE. Comparisons with additional reconstructions are consistent with greater regional typhoon activity during the Mongol invasions due to the preferential steering of storms toward Japan, and driven by greater El Nino activity relative to modern. Results are consistent with the paired Kamikaze typhoons being of significant intensity, and support accounts of them playing an important role in preventing the conquering of Japan by Mongol fleets. The Kamikaze typhoons may therefore serve as a prominent example for how past increases in severe weather associated with changing climate have had significant geopolitical impacts.

First results from a rotational Raman scattering cloud algorithm applied to the Suomi National Polar-orbiting Partnership (NPP) Ozone Mapping and Profiler Suite (OMPS) Nadir Mapper

Abstract. This paper reports initial results from an Ozone Mapping and Profiler Suite (OMPS) Nadir Mapper cloud pressure and cloud fraction algorithm. The OMPS cloud products are intended for use in OMPS ozone or other trace-gas algorithms. We developed the OMPS cloud products using a heritage algorithm developed for the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite. The cloud pressure algorithm utilizes the filling-in of ultraviolet solar Fraunhofer lines by rotational Raman scattering. The OMPS cloud products are evaluated by comparison with OMI cloud products that have been compared in turn with other collocated satellite data including cloud optical thickness profiles derived from a combination of measurements from the CloudSat radar and MODerate-resolution Imaging Spectroradiometer (MODIS). We find that the probability density functions (PDFs) of effective cloud fraction retrieved from OMPS and OMI measurements are very similar. The PDFs of the OMPS and OMI cloud pressures are comparable. However, OMPS retrieves somewhat higher pressures on average. The current NASA total ozone retrieval algorithm makes use of a monthly gridded cloud pressure climatology developed from OMI. This climatology captures much of the variability associated with the relevant cloud pressures. However, the use of actual cloud pressures retrieved with OMPS in place of the OMI climatology changes OMPS total column ozone estimates locally (presumably in the correct direction) only in areas with large differences between climatological and actual cloud pressures. The ozone differences can be up to 5% in such areas.

Characteristics and sources of atmospheric mercury speciation in a coastal city, Xiamen, China

Semi-continental monitoring of gaseous elemental mercury (GEM), particulate mercury (Hgp), and reactive gaseous mercury (RGM) was conducted in the Institute of Urban Environment, CAS in Xiamen, China from March 2012 to February 2013. The average concentrations and relative standard deviations (RSD) were 3.50 (34.6%) ngm−3, 174.41 (160.9%) pgm−3, and 61.05 (113.7%) pgm−3 for GEM, Hgp, and RGM, respectively. The higher concentrations of GEM and Hgp were observed in spring and winter months, indicating the combustion source, while RGM showed the different seasonal variation with highest concentration in spring and the minimum value in winter. The concentrations of Hg species were generally elevated in nighttime and low in daytime to reflect the diurnal changes in meteorology, especially the mixing condition of the air masses. The high Hg concentrations were observed in SWW–NW sectors due to calm wind while the low levels in NE–SE due to high speed wind, and the amplitude was much larger for Hgp and RGM. Backward trajectories calculation indicated that summer air masses were much more from ocean with lower Hg while the air masses were mainly from inland area in other seasons. Principal component analysis suggested that combustion and road traffic emissions were the dominant anthropogenic mercury sources for the study area, and the temporal distribution of atmospheric mercury was mainly the result of climatological change.

The increasing efficiency of tornado days in the United States

The authors analyze the historical record of tornado reports in the United States and find evidence for changes in tornado climatology possibly related to global warming. They do this by examining the annual number of days with many tornadoes and the ratio of these days to days with at least one tornado and by examining the annual proportion of tornadoes occurring on days with many tornadoes. Additional evidence of a changing tornado climate is presented by considering tornadoes in geographic clusters and by analyzing the density of tornadoes within the clusters. There is a consistent decrease in the number of days with at least one tornado at the same time as an increase in the number of days with many tornadoes. These changes are interpreted as an increasing proportion of tornadoes occurring on days with many tornadoes. Coincident with these temporal changes are increases in tornado density as defined by the number of tornadoes per area. Trends are insensitive to the begin year of the analysis. The bottom line is that the risk of big tornado days featuring densely concentrated tornado outbreaks is on the rise. The results are broadly consistent with numerical modeling studies that project increases in convective energy within the tornado environment.

Probabilistic reconstructions of local temperature and soil moisture from tree-ring data with potentially time-varying climatic response

We explore a probabilistic, hierarchical Bayesian approach to the simultaneous reconstruction of local temperature and soil moisture from tree-ring width observations. The model explicitly allows for differing calibration and reconstruction interval responses of the ring-width series to climate due to slow changes in climatology coupled with the biological climate thresholds underlying tree-ring growth. A numerical experiment performed using synthetically generated data demonstrates that bimodality can occur in posterior estimates of past climate when the data do not contain enough information to determine whether temperature or moisture limitation controlled reconstruction-interval tree-ring variability. This manifestation of nonidentifiability is a result of the many-to-one mapping from bivariate climate to time series of tree-ring widths. The methodology is applied to reconstruct temperature and soil moisture conditions over the 1080–1129 C.E. interval at Methusalah Walk in the White Mountains of California, where co-located isotopic dendrochronologies suggest that observed moisture limitations on tree growth may have been alleviated. Our model allows for assimilation of both data sources, and computation of the probability of a change in the climatic controls on ring-width relative to those observed in the calibration period. While the probability of a change in control is sensitive to the choice of prior distribution, the inference that conditions were moist and cool at Methuselah Walk during the 1080–1129 C.E. interval is robust. Results also illustrate the power of combining multiple proxy data sets to reduce uncertainty in reconstructions of paleoclimate.

Long‐term changes in Australian tropical cyclone numbers

AbstractTropical cyclone (TC) observations are used to examine changes in the TC climatology of the Australian region. The ability to investigate long‐term changes in TC numbers improves when the El Niño‐Southern Oscillation (ENSO) is considered. Removing variability in TC numbers associated with ENSO shows a significant decreasing trend in TC numbers at the 93–98% confidence level. Additionally, there is some indication of a temporal change in the relationship between ENSO and TC numbers, with ENSO accounting for about 35–50% of the variance in TC numbers during the first half of the study period, but only 10% during the second half.

Effects of localized temperature and precipitation on historic Walleye recruitment in Wisconsin, USA with implications for climate change

Walleye (Sander vitreus) populations in Wisconsin are near the center of their geographical range and support valuable fisheries. The role of seasonal temperature and precipitation in Walleye recruitment was examined using regression tree analysis. Climatological variables were estimated at the 8 km2 scale and Walleye recruitment was estimated based on 298 individual electrofishing surveys. Estimated changes in Walleye recruitment between 1950 and 2006 were examined based on changes in explanatory climatological variables. Spring precipitation and summer maximum temperature were significant predictors of age-0 Walleye density and mean estimated changes in these variables between 1950 and 2006 were used to estimate changes in Walleye recruitment. The model predicted a small overall increase in Walleye recruitment and provides insight into the direct role of climatological variables in Walleye recruitment. However, given the low explanatory power (R2 = 0.103), it is likely that historic climatological changes have had a limited effect on recruitment levels.

Revised solar maps of Algeria based on sunshine duration

Solar irradiation data is generally required in modelling a system’s thermal performance, and evaluation of long-term effects of climatological changes. In Algeria, measurements of solar irradiation have been carried out for a few locations because the measuring instruments are expensive to purchase and install. The only alternative to obtain solar irradiation data is to estimate it by use of an appropriate solar irradiation model.The present study attempted to draw global solar irradiation maps for Algeria, witch are generated for all types of sky. The incident solar radiation on a horizontal surface, on a surface tilted at the latitude angle and for a vertical plane facing east, south, west, south-east, south-west was determined using numerical models. To obtain a solar radiation map of a certain zone it is necessary to know the solar radiation of a huge number of sites spread wide across the zone.The comparison between the measured and the computed values is satisfactory; the relative error is less than 7%. The results allow to view information about 48 provinces of Algeria, and are presented in the form of an annual solar radiation map. The solar maps developed in this paper provide information about the levels of total solar radiation which can be used as a database for future investments in the solar sector in Algeria.

Predicting Dynamic Trends of the Atlantic Meridional Overturning Circulation for Transient and Stochastic Forcing Effects

The Atlantic meridional overturning circulation (AMOC) plays a central role in regulating the climatic conditions of the North Atlantic regions. The AMOC exhibits two stable equilibrium states, one strong as in the present-day and one weak which under certain conditions ceases to exist. These states and possible transitions between them are strongly influenced by climatological changes, as past history has shown [P. U. Clark et al., Nature, 415 (2002), pp. 863--869]. Our work investigates two important factors that can alter AMOC dynamics: temperature variability and stochastic freshwater variations. These two factors in combination can lead to undesired transitions to the weak state, resulting in abrupt cooling and a reduction in precipitation in the North Atlantic and Europe [S. Rahmstorf and A. Ganopolski, Climatic Change, 43 (1999), pp. 353--367]. Our analysis is performed by implementing a two-box single-hemispheric model within which the effects of slowly varying restoring temperature conditions and stochastic freshwater forcing are analyzed numerically, as well as by use of multiple-scales approximations, given the different time scales involved. Our findings suggest that stochastic and large deterministic freshwater forcings can cause the AMOC to transition between strong and weak states under a constant temperature forcing, but large temperature gradients between boxes generally favor a strong AMOC. While there has been some concern over increased freshwater input into the Atlantic causing a weakening of the AMOC, our results suggest that if the system is forced into the weak state by large freshwater perturbations, a subsequent increase in temperature gradient can counteract this and return the system to the strong state once again.

Isotope Analysis of Air Moisture and its Applications in Hydrology

New scientific knowledge of the modern tools and techniques, including isotope applications is required: (i) to improve the growing scenario of increased water stress and (ii) to resolve resulting conflicts for water for sustainable development. The isotope analysis of air moisture can greatly support in tracking the hydrological cycle through fingerprinting the source of water vapor, its transport and its condensation through direct analysis. This can be further used to understand factors controlling the water and energy balance of the atmosphere and guide new studies of clouds and the atmospheric hydrology. This paper presents the work carried out by National Institute of Hydrology, Roorkee to understand the role of water vapor isotopes in climate studies , vapor source identification and in understanding southwest monsoon dynamics. It has been found that air moisture isotope analysis can be used (i) for studying the climatological changes (ii) to identify the source of air moisture and (iii) for southwest monsoon studies.

High‐resolution model captures global atmospheric deep convection

When moist air is mixed high into the atmosphere, a process known as deep convection, the motion can give rise to towering storm clouds. Deep convection is also an important process for balancing momentum and energy within the atmosphere. Atmospheric deep convection is a relatively small‐scale physical process, with the motion spanning anywhere from 1 to 10 kilometers. Its effects, though, are globally relevant, dictating storm patterns and climatological changes. Modeling deep convection in a global simulation, then, is challenging because these small‐scale processes need to be represented and tracked across the whole planet.

Climatic Variation at Thumba Equatorial Rocket Launching Station, India

Long-term (45 years) diversified surface meteorological records from Thumba Equatorial Rocket Launching Station (TERLS), India, were collected and analysed to study the long-term changes in the overall climatology, climatology pertained to a particular observational time, mean daily climatology in temperature, inter-annual variability in temperature, interannual variability in surface pressure, and rainfall for the main Indian seasons—South West and North East monsoons and inter-annual mean monthly anomaly structure in temperature. Results on various analyses show strong and vivid features contributed by climate change for this South Peninsular Indian Arabian Sea Coastal Station, and this paper may be a first time venture which discusses climate change imparted perturbations in several meteorological parameters in different time domains, like a specific time, daily, monthly, and interannually over a station. Being a coastal rocket launching station, climatic change information is crucial for long-term planning of its facilities as well as for various rocket range operational demands.

A long‐term perspective on woody plant encroachment in the desert southwest, New Mexico, USA

AbstractObjectiveTo assess potential causes of woody plant encroachment into desert grassland systems using a 5500‐yr‐old sediment record from a ciénega in New Mexico.LocationCloverdale Ciénega, southwestern New Mexico.MethodsUtilizing fossil pollen and charcoal preserved in wetland sediments, a long‐term record of variations in vegetation composition and fire activity was generated. The record was compared to published data on drought, the El Niño/Southern Oscillation (ENSO), carbon dioxide concentrations and known dates of grazing impacts to evaluate various hypotheses regarding the timing and causes of woody plant encroachment in desert grasslands.ResultsThe woody plant encroachment observed in the past 200 yrs is unprecedented in the context of the previous 5500 yrs of vegetation history. The observed increase in woody plant abundance was not related to droughts or changes in ENSO event frequency, and was contemporaneous with the rise in atmospheric CO2 and known grazing impacts. Charcoal influx increased in conjunction with historic woody plant pollen abundance and therefore the encroachment was not related to fire exclusion.ConclusionsThe long‐term sediment record from Cloverdale Ciénega provides the context for evaluation of the various hypotheses for woody plant encroachment. At Cloverdale Ciénega we demonstrate that woody plant encroachment of the last 200 yrs is unprecedented and outside of the historic natural range of variability of the previous five millennia. We also demonstrate that woody plant encroachment is not related to climatological changes such as drought or increases in ENSO frequency. Increases in woody plant pollen are associated with increases in carbon dioxide, and high‐intensity grazing during the late 19th and early 20th centuries.

Climate, conflict, and social stability: what does the evidence say?

Are violent conflict and socio-political stability associated with changes in climatological variables? We examine 50 rigorous quantitative studies on this question and find consistent support for a causal association between climatological changes and various conflict outcomes, at spatial scales ranging from individual buildings to the entire globe and at temporal scales ranging from an anomalous hour to an anomalous millennium. Multiple mechanisms that could explain this association have been proposed and are sometimes supported by findings, but the literature is currently unable to decisively exclude any proposed pathway. Several mechanisms likely contribute to the outcomes that we observe.

Attribution of changes in precipitation patterns in African rainforests

Tropical rainforests in Africa are one of the most under-researched regions in the world, but research in the Amazonian rainforest suggests potential vulnerability to climate change. Using the large ensemble of Atmosphere-only general circulation model (AGCM) simulations within the weather@home project, statistics of precipitation in the dry season of the Congo Basin rainforest are analysed. By validating the model simulation against observations, we could identify a good model performance for the June, July, August (JJA) dry season, but this result does need to be taken with caution as observed data are of poor quality. Additional validation methods have been used to investigate the applicability of probabilistic event attribution analysis from large model ensembles to a tropical region, in this case the Congo Basin. These methods corroborate the confidence in the model, leading us to believe the attribution result to be robust. That is, that there are no significant changes in the risk of low precipitation extremes during this dry season (JJA) precipitation in the Congo Basin. Results for the December, January, February dry season are less clear. The study highlights that attribution analysis has the potential to provide valuable scientific evidence of recent or anticipated climatological changes, especially in regions with sparse observational data and unclear projections of future changes. However, the strong influence of sea surface temperature teleconnection patterns on tropical precipitation provides more challenges in the set up of attribution studies than midlatitude rainfall.

Climate, Conflict, and Social Stability: What Does the Evidence Say?

Are violent conflict and socio-political stability associated with changes in climatological variables? We examine 50 rigorous quantitative studies on this question and find consistent support for a causal association between climatological changes and various conflict outcomes, at spatial scales ranging from individual buildings to the entire globe and at temporal scales ranging from an anomalous hour to an anomalous millennium. Multiple mechanisms that could explain this association have been proposed and are sometimes supported by findings, but the literature is currently unable to decisively exclude any proposed pathway. Several mechanisms likely contribute to the outcomes that we observe.

Intersatellite calibration of NOAA HIRS CO2 channels for climate studies

AbstractThe 30 years of observations from the High‐Resolution Infrared Radiation Sounder (HIRS) longwave CO2 channels aboard the NOAA series of satellites are being used to detect climatological changes of cloud. However, the intersatellite radiance discrepancies in the channels need to be removed for the development of a consistent cloud series using HIRS data. By analyzing the intersatellite radiance comparisons at simultaneous‐nadir‐overpass locations for HIRS longwave CO2 channels onboard the NOAA and MetOp series of satellites, this study optimizes the spectral response functions (SRF) for each HIRS to generate a more consistent long‐term set of observations. Intersatellite radiance biases as large as 5% are found for these channels; the spectral differences and spectral uncertainties are shown to be the main causes. To estimate the radiance change for a specific channel due to SRF difference and uncertainty, a linear model is developed to correlate the radiance change for the channel being analyzed with the spectral radiances in the eight selected HIRS channels. The hyperspectral measurements from the Infrared Atmospheric Sounding Interferometer on the MetOp satellite are used to simulate HIRS observations and estimate the parameters of the linear models. The linear models are applied to the NOAA and MetOp HIRS data at simultaneous‐nadir‐overpass locations to estimate the intersatellite radiance differences due to the SRF differences and uncertainties. The intersatellite mean radiance biases are minimized toward zero with residual maximum uncertainty less than 1% after the SRF differences and uncertainties are mitigated. Using the MetOp Infrared Atmospheric Sounding Interferometer as a reference, the optimized SRFs for every NOAA HIRS are found by effectively minimizing the root‐mean‐square values of the intersatellite radiance differences. The optimized shifts of the SRF can be as large as 3 cm−1.

Projected change in East Asian summer monsoon precipitation under RCP scenario

Future changes in East Asian summer monsoon precipitation climatology, frequency, and intensity are analyzed using historical climate simulations and future climate simulations under the RCP4.5 scenario using the World Climate Research Programme’s (WCRP) Coupled Model Intercomparison Project 5 (CMIP5) multi-model dataset. The model reproducibility is evaluated, and well performance in the present-day climate simulation can be obtained by most of the studied models. However, underestimation is obvious over the East Asian region for precipitation climatology and precipitation intensity, and overestimation is observed for precipitation frequency. The overestimation of precipitation frequency is mainly due to the large positive bias of the light precipitation (precipitation 10 mm/day) intensity. For the future climate simulations, simple multi-model ensemble (MME) averages using all of the models show increases in precipitation and its intensity over almost all of East Asia, while the precipitation frequency is projected to decrease over eastern China and around Japan and increase in other regions. When the weighted MME is considered, no large difference can be observed compared with the simple MME. For the MME using the six best models that have good performance in simulating the present-day climate, the future climate changes over East Asia are very similar to those predicted using all of the models. Further analysis shows that the frequency and intensity of intense precipitation events are also projected to significantly increase over East Asia. Increases in precipitation frequency and intensity are the main contributors to increases in precipitation, and the contribution of frequency increases (contributed by 40.8 % in the near future and by 58.9 % by the end of the twenty-first century) is much larger than that of intensity increases (contributed by 29.9 % in the near future and by 30.1 % by the end of the twenty-first century). This finding also implies an increased risk of intense precipitation events over the East Asian region under global warming scenario. These results regarding future climate simulations show much greater reliability than those using CMIP3 simulations.

Seasonal variations in aridity and temperature characterize changing climate during the last deglaciation in New Zealand

New multiproxy records of aridity from northern New Zealand assess the seasonality and overall pattern of wetness through the Last Glacial Coldest Period (LGCP) to the early Holocene in the subtropical Southwest Pacific. Biomass burning indicators based on terrestrial biomarkers and δ13C of individual plant leaf wax carbon compounds (n-alkanoic acids) from a maar lake were used to track aridity. In combination with published sea surface temperatures and new pollen-based temperature estimates from the same core, seasonal climatological changes in the Auckland area were determined from 27 to 9 cal. ka BP. These proxies document a shift from cold and dry conditions in the Last Glacial Maximum to seasonally wetter conditions through the deglaciation. Spring became warmer first and possibly wetter while summers remained drier and initially cooler. The progression from cold-dry to warm-wet was punctuated by the Antarctic Cold Reversal (ACR) which stands out as having wetter conditions in both spring and summer and mild cooling largely concentrated in spring. The seasonal climate trends observed here can be plausibly explained by a rapid change from a subpolar climate to one with subtropical control in this region of the southwest Pacific across the Last Glacial to Interglacial transition. A southerly shift and decreasing intensity of the westerly wind belt after the LGCP is considered to have driven the early deglacial warming and pulse of wetness whereas a northward shift without a commensurate increase in intensity of the westerlies may explain conditions in the ACR.

The “New Urban Europe”: Global Challenges and Local Responses in the Urban Century

Modern cities in the open European space-economy are powerhouses of creative ideas, smart technologies, sustainable developments and socio-economic wealth. They play a pivotal role in the future of an urbanized Europe, but they are also confronted with grand challenges, notably far-reaching demographic transformations, environmental decay and climatological change, unequal social participation and ever-rising mobility trends. The challenges for urban environments may be turned into new opportunities, in particular, in such domains as advanced infrastructure and logistic systems, environmental and climate-neutral facilities, creative and knowledge-intensive strategies for socio-economic prosperity and well-being. Cities—and in particular metropolitan areas—may thus act as spearheads of sustainable economic growth for European countries. These observations call for appropriate long-range policy strategies for metropolitan areas—and networks of cities—in the highly diversified European space-economy. Such policy actions would need to be supported by solid, multidisciplinary and evidence-based research on the challenges and opportunities of urban environments in Europe. The main contribution of this paper lies in the systematic strategic approach to transform urban megatrends and challenges into research and policy concerns for Europe. The analytical framework employed to highlight and better understand such research and policy response in Europe from a typological perspective is built around four interconnected pillars (cornerstones) that form the focal points for identifying strategic future images that may be instrumental in mapping out the research and policy challenges for the “New Urban Europe”.