Modern Climatology - Full Text

Climatology, the study of climate, is no longer regarded as a single discipline that treats climate as something that fluctuates only within the unchanging boundaries described by historical statistics. The field has recognized that climate is something that changes continually under the influence of physical and biological forces and so, cannot be understood in isolation but rather, is one that includes diverse scientific disciplines that play their role in understanding a highly complex coupled “whole system” that is the Earth’s climate. The modern era of climatology is echoed in this book. On the one hand it offers a broad synoptic perspective but also considers the regional standpoint as it is this that affects what people need from climatology, albeit water resource managers or engineers etc. Aspects on the topic of climate change – what is often considered a contradiction in terms – is also addressed. It is all too evident these days that what recent work in climatology has revealed carries profound implications for economic and social policy; it is with these in mind that the final chapters consider acumens as to the application of what has been learned to date. This book is divided into four sections that cover sub-disciplines in climatology. The first section contains four chapters that pertain to synoptic climatology, i.e., the study of weather disturbances including hurricanes, monsoon depressions, synoptic waves, and severe thunderstorms; these weather systems directly impact humanity. The second section on regional climatology has four chapters that describe the climate features within physiographically defined areas. The third section is on climate change which involves both past (paleoclimate) and future climate: The first two chapters cover certain facets of paleoclimate while the third is centered towards the signals (observed or otherwise) of climate change. The fourth and final section broaches the sub-discipline that is often referred to as applied climatology; this represents the important goal of all studies in climatology–one that affects modes of living. Here, three chapters are devoted towards the application of climatological research that might have useful application for operational purposes in industrial, manufacturing, agricultural, technological and environmental affairs. Please click here to explore the components of this work.https://digitalcommons.usu.edu/modern_climatology/1014/thumbnail.jp

Observed change in Sahel rainfall, circulations, African easterly waves, and Atlantic hurricanes since 1979

Here, we examine the dynamic properties associated with the recent increase in the Sahel rainfall using an ensemble of five global reanalysis datasets (1979–2010). The rainfall that has been observed to be increasing over the Sahel is accounted for by enhancements in both the tropical easterly jet and the African easterly jet, both of which are known to induce wet anomalies. Moreover, positional shifts in the African easterly jet and African easterly waves (AEWs) accompanied the northward migration of the Sahel rainband. Change in the African easterly jet and AEWs are coupled to a northward shift and amplification of convective activity; this signals an increased potential for the occurrence of flash floods along the northern Sahel. In addition, the result from a wave tracking analysis suggests that the change in AEWs is closely linked to increased activity of intense hurricanes in the North Atlantic. The synoptic concurrence of AEWs in driving the dynamics of the Sahel greening and the increase in tropical cyclogeneses over the North Atlantic is an important aspect in the evaluation of climate model projections

Climatology of the U.S. Inter-Mountain West

The Inter-Mountain West (IMW) of North America is a region that lies between the Rocky Mountains to the east and the Cascades and Sierra Nevada to the west (Fig. 1). The climate of the IMW is generally semi-arid but this varies by location and elevation. An estimated 50- 80% of the IMW’s streams and rivers are fed by mountain snowpack (Marks and Winstral 2001), while the majority of the streams and rivers flow into desert sinks or closed-basin lakes such as the Great Salt Lake (Fig. 1). These streams and rivers create some agriculturally productive areas in the otherwise dry basins and mountain valleys. In particular, the Colorado River supplies water to the population-booming southwestern states and cities. Climate in the Colorado River Basin has been a subject of intense research due to its projected drying trend (Barnett and Pierce 2008). Change in winter precipitation regime (i.e. ratio between rainfall and snowfall) is also a subject of interest not only because its role in water resource but also its impact on recreational (ski) industry in the IMW.https://digitalcommons.usu.edu/modern_climatology/1005/thumbnail.jp

A remotely sensed index of deforestation/urbanization for use in climate models

The object of this research is to use indirect measurements, notably thermal infrared, to describe urbanization and deforestation with parameters that can be used to assess, as well as predict, the effects of land use changes on local microclimate. More specifically, we use a new approach for the treatment of remotely sensed data; this is referred to as the 'triangle' method. The name triangle is given because the envelope of data points, when plotted as a function of surface radiant temperature versus vegetation index or fractional vegetation cover, exhibits the shape of a triangle. From the information contained on these 'scatter plots', land use changes can be related to two intrinsic surface variables, the surface moisture availability (M(sub 0))(sup 1) and fractional vegetation cover. Recent work by Carlson et al. indicate that the triangle shape on the scatter plots may be scale similar, suggesting that these two parameters are subject to the same interpretation on differing scales. A second objective in this research is to determine if historical data for Advanced Very High Resolution Radiometer (AVHRR) (NOAA satellite; 1.1 km resolution at nadir) can be used to assess changes in regional land use over time. To this end, two target areas were chosen for the investigation of urbanization and two for deforestation. The former comprise tow areas in Pennsylvania, one a small but rapidly growing population center (State College) and the other a medium-sized urban area which continues to undergo development (Chester County). The two deforestation sites consist of rain forest areas in western and central Costa Rica and a region in the Brazilian Amazon

Graphical surface-vegetation-atmosphere transfer (SVAT) model as a pedagogical and research tool

This paper considers, by example, the use of a Surface-Atmosphere-Vegetation-Transfer (SVAT), Atmospheric Boundary Layer (ABL) model designed as a pedagogical tool. The goal of the computer software and the approach is to improve the efficiency and effectiveness of communicating often complex and mathematical based disciplines (e.g., micrometeorology, land surface processes) to the non-specialist interested in studying problems involving interactions between vegetation and the atmosphere and, in the nature of interactions rather than a description of the components. Topics are addressed within a Socratic framework using a scenario system based approach: As an example of this, the interactions between a vegetation canopy and a carbon dioxide rich (2 times ambient CO2) atmosphere, are presented. This will illustrate obvious to the student or, would be to complicated to be insightful. This type of approach is another careful, critical way of thinking fostered by interactions with a computer model. The student instead of taking things apart, is looking at them as wholes and is encouraged to make new and important distinctions

Pakistan’s two-stage monsoon and links with the recent climate change

Meteorological conditions related to the Pakistan floods of 2010 were examined in the context of monsoon dynamics and large‐scale circulations. Case and climatological analyses suggest that summer precipitation in northern Pakistan comprises two distinct phases: (1) a premonsoon trough phase (July) whose rainfall is more episodic and intense, occurring prior to arrival of the monsoon trough, and (2) a monsoon trough phase (August) whose rainfall is persistent, yet less episodic, driven by northward migration of the monsoon trough. Analyses of conditional instability, moisture flux, and circulation features support a persistent increase in conditional instability during the July premonsoon trough phase, accompanied by increased frequency of heavy rainfall events. Conversely, evidence does not support intensification of the August monsoon trough phase. The increased convective activity during the premonsoon trough phase agrees with the projected increase in the intensity of heavy rainfall events over northern Pakistan. Largescale circulation analysis reveals an upper‐level cyclonic anomaly over and to the west of Pakistan–a feature empirically associated with weak monsoon. The analysis also suggests that the anomalous circulation in 2010 is not sporadic but rather is part of a long‐term trend that defies the typical linkage of strong monsoons with an anomalous anticyclone in the upper troposphere

Simulating the Storm Environment Responsible for Nepal\u27s First Observed Tornado

A high-resolution numerical forecast model was used to simulate the meteorological conditions leading up to the March 31st, 2019 severe weather event that produced Nepal\u27s first-ever observed tornado. The sparse meteorologic observations in the region capturing the storm environment limit the ability to anticipate another similar situation should the particular set of conditions present themselves again. This study presents a multifaced view of the storm environment through 1) a synoptic perspective provided by the Global Data Assimilation System (GDAS) reanalysis dataset and 2) a trio of progressively higher resolution one-way nested simulations (12 km–4km–1km) driven by GDAS boundary conditions to more closely examine the storm-scale environment. GDAS data and numerical simulations revealed moderately strong instability throughout the region with CAPE values between 1000 and 2000 J kg−1 K−1 and lifted index values between −4 and −7. Vertical wind profiles featuring little directional shear and moderate velocity shear yielded shear-based convective indices that suggested slight potential for rotating supercell thunderstorms. Within this environment, the 1-km simulation produced strong, rotating convection in nearly the same location and at nearly the same time as the observed tornadic storm. Lastly, an assessment of the limited number of observed historical tornadic events in the region showed that with amply convective available potential energy, the 2019 Nepal tornado environment stood out for the limited vertical directional wind shear present

Connecting Subseasonal Movements of the Winter Mean Ridge in Western North America to Inversion Climatology in Cache Valley, Utah

A 10-yr record of PM2.5 (particulate matter of aerodynamic diameter ≤ 2.5 μm), collected in Cache Valley near downtown Logan, Utah, reveals a strong peak in the PM2.5 concentration climatology that is tightly localized in mid-January. The cause of this subseasonal variation in the PM2.5 climatology is investigated through dynamical downscaling and large-scale diagnostics. Climatological analysis of the U.S. winter mean ridge reveals a mid-January subseasonal shift in the zonal direction, likely in response to variations in the Rossby wave source over the central North Pacific Ocean. This displacement of the winter mean ridge, in turn, has an impact on regional-scale atmospheric conditions—specifically, subsidence with local leeside enhancements and midlevel warming over Cache Valley. The analyses of this study indicate that the subseasonal peak of long-term mean PM2.5 concentrations in Cache Valley is linked to the large-scale circulations’ subseasonal evolution, which involves remote forcing in the circumpolar circulations as well as possible tropical–midlatitude interactions. This subseasonal evolution of the winter mean circulation also affects precipitation along the West Coast

Endogenous Skin Fluorescence Includes Bands that may Serve as Quantitative Markers of Aging and Photoaging

Aging and photoaging cause distinct changes in skin cells and extracellular matrix. Changes in hairless mouse skin as a function of age and chronic UVB exposure were investigated by fluorescence excitation spectroscopy. Fluorescence excitation spectra were measured in vivo, on heat-separated epidermis and dermis, and on extracts of mouse skin to characterize the absorption spectra of the emitting chromophores. Fluorescence excitation spectra obtained in vivo on 6 wk old mouse skin had maxima at 295, 340, and 360 nm; the 295 nm band was the dominant band. Using heat separated tissue, the 295 nm band predominantly originated in the epidermis and the bands at 340 and 360 nm originated in the dermis. The 295 nm band was assigned to tryptophan fluorescence, the 340 nm band to pepsin digestable collagen cross-links fluorescence and the 360 nm band to collagenase digestable collagen cross-links fluorescence. Fluorescence excitation maxima remained unchanged in chronologically aged mice (34–38 wk old), whereas the 295 nm band decreased in intensity with age and the 340 nm band increased in intensity with age. In contrast, fluorescence excitation spectra of chronically UVB exposed mice showed a large increase in the 295 nm band compared with age-matched controls and the bands at 340 and 350 nm were no longer distinct. Two new bands appeared in the chronically exposed mice at 270 nm and at 305 nm. These reproducible changes in skin autofluorescence suggest that aging causes predictable alterations in both epidermal and dermal fluorescence, whereas chronic UV exposure induces the appearance of new fluorphores