Thomas Mote

University of Georgia | UGA · Department of Geography

Arctic observations in 2023 provided clear evidence of rapid and pronounced climate and environmental change, shaped by past and ongoing human activities that release greenhouse gases into the atmosphere and push the broader Earth system into uncharted territory. This chapter provides a snapshot of 2023 and summarizes decades-long trends observed a...

Rapid warming due to human-caused climate change is reshaping the Arctic, enhanced by physical processes that cause the Arctic to warm more quickly than the global average, collectively called Arctic amplification. Observations over the past 40+ years show a transition to a wetter Arctic, with seasonal shifts and widespread disturbances influencing...

The exceptional atmospheric conditions that have accelerated Greenland Ice Sheet mass loss in recent decades have been repeatedly recognized as a possible dynamical response to Arctic amplification. Here, we present evidence of two potentially synergistic mechanisms linking high-latitude warming to the observed increase in Greenland blocking. Consi...

What: Participants of the Caribbean Drought Learning Network’s first annual meeting discussed issues surrounding droughts in this region, including the need to increase awareness of drought-related initiatives in Puerto Rico and the U.S. Virgin Islands and the promotion of peer-to-peer learning pertaining to the latest in drought research and commu...

Study region: Puerto Rico, a tropical island in the Caribbean Sea. Study focus: This study examines how water stress in Puerto Rico is influenced by its physical geography using a new USGS Soil-Water-Balance Model (Version 2.0) applied to three periods: a baseline climatology (1981-2010), a recent decade (2010-2019), and multiple drought years (19...

The Greenland Ice Sheet has been losing mass at an increased rate in recent decades. In northeast Greenland, increasing surface melt has accompanied speed-ups in the outlet glaciers of the Northeast Greenland Ice Stream, which contain over one meter of sea level rise potential. Here we show that the most intense northeast Greenland melt events are...

General circulation model (GCM) outputs are a primary source of information for climate change impact assessments. However, raw GCM data rarely are used directly for regional-scale impact assessments as they frequently contain systematic error or bias. In this article, we propose a novel extension to standard quantile mapping that allows for a cont...

* The Greenland Ice Sheet total mass change for 1 September 2021 through mid-August 2022 was -146 ± 64 Gt, equivalent to ~0.4 mm of sea level rise and representing the 25th consecutive year of ice loss. * Cold temperatures delayed summer ice loss, yet the ice sheet still experienced unprecedented melt events during 2022. * During September 2022, th...

The increase in Greenland Ice Sheet (GrIS) surface runoff since the turn of the century has been linked to a rise in Greenland blocking frequency. However, a range of synoptic patterns can be considered blocked flow and efforts that summarize all blocking types indiscriminately likely fail to capture consequential differences in GrIS response. To a...

The insular Caribbean experiences numerous climate and environmental hazards, including but not limited to hurricanes, floods, earthquakes, and drought. While some hazards are well explored in scientific literature, drought is considered one of the neglected hazards because of the lack of studies focusing on its causes and effects. This study ident...

* Greenland ice sheet total mass change for 1 September 2020 to 31 August 2021 was -85 ± 16 Gt, 179 Gt less than the 2002-21 average of -264 ± 12 Gt yr –1. * High variability characterized 2021 surface melting with a two-week long August period of increased melt and bare ice exposure contrasting with low June and July melt conditions. An overall a...

Arctic Amplification is a fundamental feature of past, present, and modelled future climate. However, the causes of this “amplification” within Earth’s climate system are not fully understood. To date, warming in the Arctic has been most pronounced in autumn and winter seasons, with this trend predicted to continue based on model projections of fut...

At a continental scale, trends in aggregate ablation frequency inform changes in snow cover extent, however the variability and trends in the frequency and magnitude of snow ablation events at regional scales are less well understood. Determining such variability is critical in describing regional hydroclimate, where snow ablation can influence str...

Long‐range aerosol transport is an important physical mechanism for ecological, biological, and hydrological elements of the earth system. Regarding the latter, regional climate models have no way of assimilating future aerosol concentrations, so dust aerosol emissions must be parameterized using local landscape and meteorological conditions. The p...

As the Arctic continues to warm, a weakening of upper‐tropospheric westerly winds is hypothesized to induce a meandering jet stream and slower propagation of Rossby waves. As such, current hypotheses suggest an increase in Greenland blocking due to increased stationarity of the high amplitude waves. These hypotheses have been supported observationa...

We provide an updated analysis of instrumental Greenland monthly temperature data to 2019, focusing mainly on coastal stations but also analysing ice‐sheet records from Swiss Camp and Summit. Significant summer (winter) coastal warming of ~1.7 (4.4)°C occurred from 1991–2019, but since 2001 overall temperature trends are generally flat and insignif...

Blocked atmospheric flows over Greenland and the North Atlantic Arctic (NAA) can be defined by the appearance of an anomalous ridge, many times off the western margin of continents, that deflects traveling cyclones from their usual storm tracks. Atmospheric blocking often produces a strong equatorward deflection of polar air on the eastern flank of...

Mass loss from the Greenland Ice Sheet (GrIS) has accelerated over the past two decades, coincident with rapid Arctic warming and increasing moisture transport over Greenland by atmospheric rivers (ARs). Summer ARs affecting western Greenland trigger GrIS melt events, but the physical mechanisms through which ARs induce melt are not well understood...

Mesoscale convective complexes (MCCs) are meteorological events that result in severe storms, hail, flood, and tornadoes, but they are difficult to forecast. In South America (SA), MCCs are usually larger and last longer than those in the USA. Southern Brazil (SB) is one of their preferred regions of occurrence. This study’s objective was to contri...

The 2017 and 2018 Atlantic hurricane seasons poignantly illustrated the dangers tropical cyclones pose to US, Central American, and Caribbean coastlines. In particular, Hurricane Maria inflicted widespread damage, including catastrophic defoliation, to Puerto Rico, altering surface heat fluxes and possibly modifying precipitation patterns. This stu...

A meandering polar jet was discovered as responsible for the emission and transport of dust from Northwest Africa to the Arctic. Poleward transport of warm, moist, and dust-laden air masses from the Sahara Desert results in ice melting in southeast Greenland.

One consequence of recent Arctic warming is an increased occurrence and longer seasonality of above-freezing air temperature episodes. There is significant disagreement in the literature concerning potential physical connectivity between high-latitude open water duration proximate to the Greenland Ice Sheet (GrIS) and late-season (i.e., end-of-summ...

Rain-on-snow (ROS) has the potential to produce devastating floods by enhancing runoff from snowmelt. Although a common phenomenon across the eastern United States, little research has focused on ROS in this region. This study used a gridded observational snow dataset from 1960–2009 to establish a comprehensive seasonal climatology of ROS for this...

Coastal waters in the Labrador Sea are influenced by the seasonal input of meltwater from the Greenland ice sheet, which is predicted to more than double by the end of the century. Mechanisms controlling the offshore export of meltwater can have a significant effect on stratification and vertical stability in the Labrador Sea, being particularly im...

El Yunque National Forest, situated in the Luquillo Mountains of northeast Puerto Rico, is home to a wide range of climate-sensitive ecosystems and forest types. In particular, these ecosystems are highly sensitive to changes in the hydroclimate, even on short time scales. Current global climate models (GCMs) predict coarse-scale reductions in prec...

In this study, we identify a new mechanism by which dust aerosols travel over long distances across the eastern side of the North Atlantic Ocean toward the Arctic. The meandering polar jet was at the origin of both dust emission through cyclogenesis over Northwest Africa and poleward transport of the uplifted dust towards the Arctic, through cut-of...

In this study, we identify a new mechanism by which dust aerosols travel over long distances across the eastern side of the North Atlantic Ocean toward the Arctic. The meandering polar jet was at the origin of both dust emission through cyclogenesis over Northwest Africa and poleward transport of the uplifted dust towards the Arctic, through cut-of...

In September 2017, Hurricane Maria severely defoliated Puerto Rico's landscape, coinciding with a series of persistent hydrological consequences involving the atmospheric, terrestrial, and marine components of the water cycle. During the defoliated period, the atmosphere's thermodynamic structure more strongly explained daily cloud activity (R ²PRE...

With limited ground water reserves and few reservoirs, Caribbean islands such as Puerto Rico are largely dependent on regular rainfall to meet societal and ecological water needs. Thus, the ability to anticipate seasonal rainfall shortages, such as the 2015 drought, is particularly important, yet few reliable tools exist for this purpose. Consequen...

One consequence of recent Arctic warming is an increased occurrence and longer seasonality of above-freezing air temperature episodes. There is significant disagreement in the literature concerning potential physical connectivity between high-latitude open water duration proximate to the Greenland Ice Sheet (GrIS) and unseasonal (i.e. late summer a...

A number of insitu and passive microwave satellite sensors have observed Arctic sea ice and Greenland Ice Sheet (GrIS) mass loss trends over recent decades. Along with sea and land ice declines, above-freezing, near-surface air temperatures are observed earlier in boreal spring and later in autumn thus extending periods of melt beyond the core of s...

This study highlights the role that the polar jet and associated atmospheric circulation plays in the transport of mineral dust from the Sahara desert to the Arctic across eastern side of the North Atlantic Ocean. The poleward transport of dust following this newly identified path was caused by a meandering polar jet stream that was at the origin o...

The Luquillo Mountains of eastern Puerto Rico are home to the only tropical rainforest managed by the United States Forest Service, with cloud-immersed forests historically occupying the highest elevations. However, within the past 50 years, studies of the Luquillo cloud forest have suggested an increase in cloud base heights (CBH), although CBH in...

The accurate differentiation of pulse thunderstorms from benign weakly forced thunderstorms (WFTs) is both a historical and contemporary forecasting challenge. Little research has been directed toward WFTs, and the few existing efforts are characterized by small sample sizes and inflated proportions of pulse thunderstorms. The purpose of this study...

In 2017, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-reached new record highs. The annual global average carbon dioxide concentration at Earth's surface for 2017 was 405.0 ± 0.1 ppm, 2.2 ppm greater than for 2016 and the highest in the modern atmospheric measurement record and in ice cor...

Greenland Ice Sheet (GrIS) mass loss has accelerated since the turn of the 21st century. Several recent episodes of rapid GrIS ablation coincided with intense moisture transport over Greenland by atmospheric rivers (ARs), suggesting that these events influence the evolution of GrIS surface mass balance (SMB). ARs likely provide melt energy through...

Mineral dust aerosols play an important role in the climate system of polar regions. Dust emitted from source areas in the tropics can reach the poles by different mechanisms and be deposited on ice where it reduces its capacity in reflecting the solar radiation and contributes to the melting processes. This study identifies a new mechanism by whic...

Oceanic and atmospheric warming of Greenland and surrounding areas has led to increased ice sheet spatial melt extent and decreased sea ice coverage during the summer months. The last two decades have witnessed increased warm air and moisture advection into the region from Greenland blocks and transient synoptic patterns that have exasperated the b...

This data set provides daily snow depth, snowfall, surface air temperature, and precipitation for North America on a 1-degree by 1-degree grid from 1959 to 2009. The data were obtained from U.S. National Weather Service Cooperative Observer Program (COOP) ground station network and daily surface observations from the Meteorological Service of Canad...

Weakly forced thunderstorms (WFTs), short-lived convection forming in synoptically quiescent regimes, are a contemporary forecasting challenge. The convective environments that support severe WFTs are often similar to those that yield only non-severe WFTs and, additionally, only a small proportion of individual WFTs will ultimately produce severe w...

https://aag.secure-abstracts.com/AAG%20Annual%20Meeting%202018/abstracts-gallery/16601

We present a homogenized Greenland blocking index (GBI) daily record from 1851 to 2015, therefore significantly extending our previously published monthly/seasonal GBI analysis. This new time series is analysed for evidence of changes in extreme events, and we investigate the underlying thermodynamic and dynamic precursors. We compare occurrences a...

In July 2012, the surface of the Greenland Ice Sheet (GrIS) melted to an extent unprecedented over the last 100 years; we questioned the potential for such an extreme melt event to impact marine phytoplankton offshore. We hypothesized that stratification from meltwater could reduce light limitation for phytoplankton, and used a suite of numerical m...

In the western United States, meltwater from mountain snowpacks serves as the dominant water supply for many communities. Efficient distribution and use of this renewable, yet temporally and spatially variable resource relies critically on accurate forecasting of future water availability. Here we report on initial efforts to use Interactive Multis...

Greenland's largest precipitation flux occurs in its southeast (SE) region during the winter, controlled primarily by easterly winds and frequent cyclogenesis in the North Atlantic. Several studies have attempted to link SE Greenland precipitation to the North Atlantic Oscillation (NAO) but results are inconsistent. This work uses reanalysis, autom...

Ongoing climatic and cryospheric changes observed throughout the greater Alaska region are interconnected and often linked to oceanic and atmospheric patterns and processes that operate on varying spatiotemporal scales. To evaluate the long-term, mid-tropospheric circulation field across Alaska, and possible connections to climate and environmental...

The tropical forests of northeast Puerto Rico (NE PR) and the Luquillo Mountains (LM) are a large repository for biodiversity and have an important role in regional biogeochemical processes. Precipitation is a key driver of the productivity of these sensitive ecosystems. This study analyses historical precipitation variability from 1985 to 2014 at...

Eastern Puerto Rico and the surrounding Caribbean experienced a severe drought in 2015 that resulted in record low reservoir and river levels. Rainfall deficits in April and May, which represent the period when the drought began, were more severe in 2015 than recent droughts of record. While El Niño has been associated with drought in the Caribbean...

Weakly forced thunderstorms (WFTs), short-lived convection forming in synoptically quiescent regimes, are a contemporary forecasting challenge. The convective environments that support severe WFTs are often similar to those that yield only nonsevere WFTs, and additionally, only a small proportion individual WFTs will ultimately produce severe weath...

Weakly forced thunderstorms (WFTs), convection forming in the absence of a synoptic forcing mechanism and its associated shear regime, are the dominant convective mode during the warm season in the southeast United States. This study uses 15 yr (2001-15) of warm-season (May-September) composite reflectivity images from 30 WSR-88D sites in the south...

Ch 7. Regional Climates: f. Europe and the Middle East

Each summer, large quantities of freshwater and associated dissolved and particulate material are released from the Greenland Ice Sheet (GrIS) into local fjords where they promote local phytoplankton growth. Whether the influx of freshwater and associated micronutrients in glacial meltwater is able to stimulate phytoplankton growth beyond the fjord...

Atmospheric rivers (ARs) are narrow and elongated bands of anomalous water vapour transport that have been widely studied due to their notable influence on regional weather patterns, surface hydrology, and the global water cycle. Although ARs produce a relatively large proportion of the annual precipitation in the southeastern quadrant of the Unite...

Warm-season precipitation variability over subtropical South America is characterized by an inverse relationship between the South Atlantic convergence zone (SACZ) and precipitation over the central and western La Plata basin of southeastern South America. This study extends the analysis of this “South American Seesaw” precipitation dipole to relat...

The growing need for local climate change scenarios has given rise to a wide range of empirical climate downscaling techniques. One of the most critical decisions in these methodologies is the selection of appropriate predictor variables for the downscaled surface predictand. A systematic approach to selecting predictor variables should be employed...

Rainfall is one of many types of weather hazard that can lead to motor vehicle crashes. To better understand the link between rainfall and crash rates, daily gridded precipitation data and automobile crash data are gathered for six U.S. states (Arkansas, Georgia, Illinois, Maryland, Minnesota, Ohio) for the period 1996–2010. A matched pair analysis...

Isolated, short-lived thunderstorms forming in weakly forced environments are referenced through a surplus of terminology. Further, the language used to describe the strongest, severe-weather-producing subset of these storms is applied inconsistently, posing a communication hurdle for the effective dissemination of hazardous weather risks. The term...

The Greenland Ice Sheet (GrIS) has been losing mass in recent decades, with an acceleration in mass loss since 2000. In this study, we apply a self-organizing map (SOM) classification to integrated vapor transport (IVT) data from the ERA-Interim reanalysis to determine if these GrIS mass loss trends are linked to increases in moisture transport to...

Large-scale atmospheric circulation controls the mass and energy balance of the Greenland ice sheet through its impact on radiative budget, runoff and accumulation. Here, using reanalysis data and the outputs of a regional climate model, we show that the persistence of an exceptional atmospheric ridge, centred over the Arctic Ocean, was responsible...