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Surface Air Temperature (surface + air_temperature)
Selected AbstractsSpatial and temporal variability of the Aleutian climateFISHERIES OCEANOGRAPHY, Issue 2005SERGEI N. RODIONOV Abstract The objective of this paper is to highlight those characteristics of climate variability that may pertain to the climate hypothesis regarding the long-term population decline of Steller sea lions (Eumetopias jubatus). The seasonal changes in surface air temperature (SAT) across the Aleutian Islands are relatively uniform, from 5 to 10°C in summer to near freezing temperatures in winter. The interannual and interdecadal variations in SAT, however, are substantially different for the eastern and western Aleutians, with the transition found at about 170°W. The eastern Aleutians experienced a regime shift toward a warmer climate in 1977, simultaneously with the basin-wide shift in the Pacific Decadal Oscillation (PDO). In contrast, the western Aleutians show a steady decline in winter SATs that started in the 1950s. This cooling trend was accompanied by a trend toward more variable SAT, both on the inter- and intra-annual time scale. During 1986,2002, the variance of winter SATs more than doubled compared to 1965,1985. At the same time in Southeast Alaska, the SAT variance diminished by half. Much of the increase in the intra-seasonal variability for the western Aleutians is associated with a warming trend in November and a cooling trend in January. As a result, the rate of seasonal cooling from November to January has doubled since the late 1950s. We hypothesize that this trend in SAT variability may have increased the environmental stress on the western stock of Steller sea lions and hence contributed to its decline. [source] Early 20th century Arctic warming in retrospectINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2010Kevin R. Wood Abstract The major early 20th century climatic fluctuation (,1920,1940) has been the subject of scientific enquiry from the time it was detected in the 1920s. The papers of scientists who studied the event first-hand have faded into obscurity but their insights are relevant today. We review this event through a rediscovery of early research and new assessments of the instrumental record. Much of the inter-annual to decadal scale variability in surface air temperature (SAT) anomaly patterns and related ecosystem effects in the Arctic and elsewhere can be attributed to the superposition of leading modes of variability in the atmospheric circulation. Meridional circulation patterns were an important factor in the high latitudes of the North Atlantic during the early climatic fluctuation. Sea surface temperature (SST) anomalies that appeared during this period were congruent with low-frequency variability in the climate system but were themselves most likely the result of anomalous forcing by the atmosphere. The high-resolution data necessary to verify this hypothesis are lacking, but the consistency of multiple lines of evidence provides strong support. Our findings indicate that early climatic fluctuation is best interpreted as a large but random climate excursion imposed on top of the steadily rising global mean temperature associated with anthropogenic forcing. Copyright © 2009 Royal Meteorological Society [source] Predictions of future climate change in the caribbean region using global general circulation modelsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 5 2007Moises E. Angeles Abstract Since the 1800s the global average CO2 mixing ratio has increased and has been related to increases in surface air temperature (0.6 ± 0.2 °C) and variations in precipitation patterns among other weather and climatic variables. The Small Island Developing States (SIDS), according to the 2001 report of the Intergovernmental Panel on Climate Change (IPCC), are likely to be among the most seriously impacted regions on Earth by global climate changes. In this work, three climate change scenarios are investigated using the Parallel Climate Model (PCM) to study the impact of the global anthropogenic CO2 concentration increases on the Caribbean climate. A climatological analysis of the Caribbean seasonal climate variation was conducted employing the National Center for Environmental Prediction (NCEP) reanalysis data, the Xie,Arkin precipitation and the Reynolds,Smith Sea Surface Temperature (SST) observed data. The PCM is first evaluated to determine its ability to predict the present time Caribbean climatology. The PCM tends to under predict the SSTs, which along with the cold advection controls the rainfall variability. This seems to be a main source of bias considering the low model performance to predict rainfall activity over the Central and southern Caribbean. Future predictions indicate that feedback processes involving evolution of SST, cloud formation, and solar radiative interactions affect the rainfall annual variability simulated by PCM from 1996 to 2098. At the same time two large-scale indices, the Southern Oscillation Index (SOI) and the North Atlantic Oscillation (NAO) are strongly related with this rainfall annual variability. A future climatology from 2041 to 2058 is selected to observe the future Caribbean condition simulated by the PCM. It shows, during this climatology range, a future warming of approximately 1 °C (SSTs) along with an increase in the rain production during the Caribbean wet seasons (early and late rainfall seasons). Although the vertical wind shear is strengthened, it typically remains lower than 8 m/s, which along with SST > 26.5 °C provides favorable conditions for possible future increases in tropical storm frequency. Copyright © 2006 Royal Meteorological Society [source] Covariabilities of spring soil moisture and summertime United States precipitation in a climate simulationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 4 2007Wanru Wu Abstract This paper explores the space-time connections between springtime soil moisture and summer precipitation over the continental United States by applying a singular value decomposition (SVD) method to a 50-year climate simulation. The first two SVD modes were analyzed. The two leading SVD modes account for 43% of the squared covariance between spring soil moisture and summer precipitation. Their corresponding components explain 14% of the soil moisture variance and 19% of the precipitation variance, respectively, which is larger than that contributed by tropical Pacific sea-surface temperatures (SSTs). The temporal correlations between the two expansion coefficients of each SVD mode are 0.83 and 0.88, respectively, indicating a significant association between spring soil moisture variation and summer precipitation variability. Both positive and negative cross-correlations exist over different regions of the United States in the two modes. Linear regression relates surface relative humidity and surface air temperature to the soil moisture SVD time series. The patterns revealed by the SVD analysis show where the local soil moisture-precipitation coupling contributes to the model's simulation of precipitation. Copyright © 2006 Royal Meteorological Society [source] The behavior of extreme cold air outbreaks under greenhouse warmingINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2006S. Vavrus Abstract Climate model output is used to analyze the behavior of extreme cold-air outbreaks (CAOs) under recent and future climatic conditions. The study uses daily output from seven GCMs run under late-twentieth century and projected twenty-first century radiative conditions (SRES A1B greenhouse gas emission scenario). We define a CAO as an occurrence of two or more consecutive days during which the local mean daily surface air temperature is at least two standard deviations below the local wintertime mean temperature. In agreement with observations, the models generally simulate modern CAOs most frequently over western North America and Europe and least commonly over the Arctic. These favored regions for CAOs are located downstream from preferred locations of atmospheric blocking. Future projections indicate that CAOs,defined with respect to late-twentieth century climatic conditions,will decline in frequency by 50 to 100% in most of the Northern Hemisphere during the twenty-first century. Certain regions, however, show relatively small changes and others actually experience more CAOs in the future, due to atmospheric circulation changes and internal variability that counter the thermodynamic tendency from greenhouse forcing. These areas generally experience greater near-surface wind flow from the north or the continent during the twenty-first century and/or are especially prone to atmospheric blocking events. Simulated reductions in CAOs are smallest in western North America, the North Atlantic, and in southern regions of Europe and Asia. The Eurasian pattern is driven by a strong tendency for the models to produce sea-level pressure (SLP) increases in the vicinity of the Mediterranean Sea (intermodel mean of 3 hPa), causing greater advection of continental air from northern and central Asia, while the muted change over western North America is due to enhanced ridging along the west coast and the increased frequency of blocking events. The North Atlantic response is consistent with a slowdown of the thermohaline circulation, which either damps the warming regionally or results in a cooler mean climate in the vicinity of Greenland. Copyright © 2006 Royal Meteorological Society. [source] Ten-year climatology of summer monsoon over South China and its surroundings simulated from a regional climate modelINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2006Yiming Liu Abstract In a previous study by the authors, a regional climate model (hereafter the RCM) developed to study the summer monsoon over South China (SC) and the South China Sea (SCS) has been tested and found to be able to simulate to a large extent the precipitation over this region for the months of May and June. To examine the interannual variability of the summer monsoon here, it is necessary to establish a model climatology to serve as a comparison and to reduce or even remove any systematic model biases. This paper presents the analyses of such a 10-year climatology (1991,2000). The model was initialized on 1 April and integrated up to the end of June for the ten years. The initial atmospheric conditions and lateral boundary data used in this study are from the European Centre for Medium-range Weather Forecasts ,40-year' reanalyses. The RCM can reproduce well the main features of the monsoon circulation and vertical structure of the atmosphere. The RCM can simulate the intensification and northwestward displacement of the south Asian upper anticyclones from May to June, as well as the low-level moisture transport from the Bay of Bengal to SC. In the simulation, the average SCS summer monsoon onset occurs in the fourth pentad of May, which is consistent with the results from previous observational research. In addition, the RCM can reproduce the main characteristics of the onset such as the change of the low-level zonal flow from easterly to westerly as well as the rapid increase in daily precipitation. The SC and SCS precipitation anomalies have the correct sign in almost all the years. The shortcomings of the model simulation include an under-prediction of the strength of the subtropical high over the Northwest Pacific and the moisture transport from the Bay of Bengal to the Indochina Peninsula (IC) and SCS. A cold bias in surface air temperature is also observed, with the 10-year mean biases of the simulated surface air temperature over SC, SCS and IC in May and June being about ,2.1 °C, ,2.4 °C and ,1.4 °C respectively. The 10-year mean biases of the simulated daily precipitation rate over SC, SCS and IC are about 2.0, ,3.8 and 3.5 mm d,1 respectively. Copyright © 2005 Royal Meteorological Society. [source] Sensitivity of an Arctic regional climate model to the horizontal resolution during winter: implications for aerosol simulationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2005Eric Girard Abstract Our ability to properly simulate current climate and its future change depends upon the exactitude of the physical processes that are parameterized on the one hand, and on model configuration on the other hand. In this paper, we focus on the latter and investigate the effect of the horizontal grid resolution on the simulation of a month of January over the Arctic. A limited-area numerical climate model is used to simulate the month of January 1990 over a grid that includes the Arctic and sub-Arctic regions. Two grid resolutions are used: 50 km and 100 km. Results show that finer details appear for regional circulation, temperature, and humidity when increasing horizontal resolution. This is particularly true for continental and sea ice boundaries, which are much better resolved by high-resolution model simulations. The Canadian Archipelago and rivers in northern Russia appear to benefit the most from higher horizontal resolution. High-resolution simulations capture some frozen rivers and narrow straits between islands. Therefore, much colder surface air temperature is simulated over these areas. Precipitation is generally increased in those areas and over topography due to a better representation of surface heterogeneities when increasing resolution. Large-scale atmospheric circulation is substantially changed when horizontal resolution is increased. Feedback processes occur between surface air temperature change over heterogeneous surfaces and atmospheric circulation. High-resolution simulations develop a stronger polar vortex. The mean sea-level pressure increases over the western Arctic and Iceland and decreases over the eastern Arctic. This circulation leads to a substantial cooling of the eastern Arctic and enhanced synoptic activity over the Arctic associated with an intensification of the baroclinic zone. Aerosol mass loading, which is simulated explicitly in this model, is significantly altered by the grid resolution change with the largest differences in aerosol concentration over areas where precipitation and atmospheric circulation are the most affected. The implications of this sensitivity study to the evaluation of indirect radiative effects of anthropogenic aerosols are discussed. Copyright © 2005 Royal Meteorological Society. [source] Characterizing regional-scale variations in monthly and seasonal surface air temperature over MexicoINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 15 2004Phil J. Englehart Abstract Monthly and seasonal variations in surface air temperature (SAT) over Mexico have not received much research attention, a situation partly reflecting the lack of a coherent historical data set. As a step toward rectifying the data gap, this study outlines the development of a gridded monthly (2.5° × 2.5°lat.,long.) SAT data set (1940,2001) for Mexico. Using the data set, we investigate several basic dimensions of SAT variability. Our analysis demonstrates that much of the variability can be compactly expressed in terms of four regions which are physically plausible with respect to the country's climatology. Not surprisingly, persistence is an important component of regional SAT variability. Evaluated month to month, persistence tends to be greatest during the warm season, whereas across seasons there is evidence for persistence of warm season anomalies into the following cool season, behaviour that is consistent with positive feedback relationships between SAT, rainfall and land surface conditions. The regional time series display longer period variability that is partially linked to the state of the large-scale, slowly evolving climate modes of the Atlantic multidecadal oscillation and the Pacific decadal oscillation. Analyses are also presented to describe teleconnections between SAT and the El Niño,southern oscillation phenomena, and SAT and other large-scale atmospheric modes, such as the Pacific North American pattern and the North Atlantic oscillation. Copyright © 2004 Royal Meteorological Society [source] Characteristics of wintertime daily and extreme minimum temperature over South KoreaINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2004Sang-Boom Ryoo Abstract In South Korea, consecutive positive temperature anomalies have been observed since the mid-1980s. The objective of this study is to assess the recent trends in, and variability of, daily minimum temperature over South Korea with particular emphasis on its extremes. Temporal characteristics of wintertime daily and extreme minimum temperature-related variables were analysed on a seasonal basis for the period of 1958,59 to 2000,01. The results show continually fewer days with extreme low minimum temperature since the mid-1980s. However, no significant change in the 1 day temperature difference was observed during the same period, indicating little change in the frequency of cold surges. Also, during the period analysed, there is a significant positive trend in the seasonal mean temperature, a negative trend in the frequency of the extreme cold days, and no significant trend in the seasonal occurrence of cold surges. Northern Hemisphere geopotential height fields before and after 1986,87, i.e. the start of successive positive anomalies in the winter surface air temperature over South Korea, showed a substantial decrease throughout the troposphere over the polar region. In the upper levels the overall pattern becomes more wavelike, with eddies embedded between meanders. The differences in the lower troposphere are remarkably similar to the Arctic oscillation, although the centre in the North Atlantic is shifted toward western Europe and differences in the North Pacific are relatively weaker than those in the polar region. The recent positive phase of the Arctic oscillation may contribute to these abrupt changes in wintertime daily minimum temperatures over South Korea. El Niño,southern oscillation phenomena appear to contribute to the interannual variation of cold surge days in South Korea. Years with no cold surges were experienced during La Niña episodes. On the other hand, all years with more than four cases of cold surges were during El Niño episodes. Copyright © 2004 Royal Meteorological Society [source] Spring northward retreat of Eurasian snow cover relevant to seasonal and interannual variations of atmospheric circulationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2003Hiroaki Ueda Abstract An observational study is made of the seasonal and interannual variations of spring snow-disappearance over the Eurasian continent and the circulation mechanisms causing those variations. The spring northward retreat of the snow boundary over the East European Plain (EEP) between 30 and 60° E is faster (0.4° per day) than to the east of the Ural Mountain range (0.3° per day). These migrations of the snow boundary lag behind the appearance of the surface air temperature 0 °C by about 1 to 5 pentads. The analyses of the atmospheric heat and moisture budgets showed that the seasonal intrusion of warm air associated with southwesterly winds is primarily responsible for the rapid snowmelt in March and April over the EEP. In addition, the adiabatic heating of descending air plays a secondary role in the snowmelt in mid-March. On an interannual time scale, horizontal warm advection also plays an essential role in the spring northward retreat of snow cover extent. The present study confirms the previous finding that the surface air temperature anomalies, produced during the seasonal snow-disappearance period, diminished in May, suggesting a weak dynamical linkage between the EEP snow cover and Asian summer monsoon. Copyright © 2003 Royal Meteorological Society [source] Daily dataset of 20th-century surface air temperature and precipitation series for the European Climate AssessmentINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 12 2002A. M. G. Klein Tank Abstract We present a dataset of daily resolution climatic time series that has been compiled for the European Climate Assessment (ECA). As of December 2001, this ECA dataset comprises 199 series of minimum, maximum and/or daily mean temperature and 195 series of daily precipitation amount observed at meteorological stations in Europe and the Middle East. Almost all series cover the standard normal period 1961,90, and about 50% extends back to at least 1925. Part of the dataset (90%) is made available for climate research on CDROM and through the Internet (at http://www.knmi.nl/samenw/eca). A comparison of the ECA dataset with existing gridded datasets, having monthly resolution, shows that correlation coefficients between ECA stations and nearest land grid boxes between 1946 and 1999 are higher than 0.8 for 93% of the temperature series and for 51% of the precipitation series. The overall trends in the ECA dataset are of comparable magnitude to those in the gridded datasets. The potential of the ECA dataset for climate studies is demonstrated in two examples. In the first example, it is shown that the winter (October,March) warming in Europe in the 1976,99 period is accompanied by a positive trend in the number of warm-spell days at most stations, but not by a negative trend in the number of cold-spell days. Instead, the number of cold-spell days increases over Europe. In the second example, it is shown for winter precipitation between 1946 and 1999 that positive trends in the mean amount per wet day prevail in areas that are getting drier and wetter. Because of its daily resolution, the ECA dataset enables a variety of empirical climate studies, including detailed analyses of changes in the occurrence of extremes in relation to changes in mean temperature and total precipitation. Copyright © 2002 Royal Meteorological Society. [source] Evaluating Antarctic sea ice variability and its teleconnections in global climate modelsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2002Jiping Liu Abstract This study evaluates simulated Antarctic sea ice edge (SIE) variability and its teleconnections in three global coupled climate models (GISS, NCAR and GFDL) against the observations. All models do a reasonable job in simulating the seasonal advance and retreat of the Antarctic sea ice fields. The simulated GISS and NCAR SIE distributions are in agreement with observations in summer and autumn, whereas the GFDL model does best in spring and winter. A common problem is the poor simulation of the observed SIE in the Weddell Sea. All models are not particularly good at simulating the observed regionally varying SIE trends. A comparison of dominant empirical orthogonal function modes of surface air temperature (SAT) variability in each model associated with observed modes show that the models generally capture features of the more prominent covarying spatial patterns such as an El Niño,southern oscillation (ENSO)-like pattern in the tropical Pacific. The simulated teleconnection patterns between detrended Antarctic SIE anomalies and detrended global SAT anomalies in each model are evaluated for comparison with observed teleconnection patterns. All models capture the ENSO-like phenomenon to some degree. Also, the GISS and NCAR models capture the Antarctic dipole pattern and meridional banding structure through the Pacific. The Antarctic SIE regions showing the strongest extrapolar teleconnections differ among the models and between the models and observations. Almost all models miss the observed polar,extrapolar teleconnections in the central Indian, western extreme of the tropical and southern Pacific, and over the tropical continents. Copyright © 2002 Royal Meteorological Society. [source] The influence of the winter Arctic oscillation on the northern Russia spring temperatureINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2002Vladimir N. Kryjov Abstract Correlation and trend analyses are applied to examine relationships between the northern Russia snow/ice season surface air temperature (SAT) and winter circulation, represented by the January,March Arctic oscillation (AO) index. The 1935,99 series of winter and spring monthly SAT from five stations are used, with the winter season being defined as January,March and the spring season being defined specifically for each station in accordance with local snow/ice season duration from April,May through April,July. It is shown that the influence of the winter circulation on SAT is evident at least until the end of snow/ice season, which suggests that this influence is implemented via feedbacks provided by snow and sea ice. The winter AO accounts for some 25,50% (15,20%) of the winter (spring) SAT variance. More than 50% of the 30 year (1968,97) trends in both winter and spring SAT for northwestern Russia and more than 40% for northwestern Siberia are linearly correlated with the winter AO. It is proposed that in the Arctic Ocean regions, where snow and ice do not melt completely, the winter AO influence on SAT is likely to be evident at least until the next year's winter. Copyright © 2002 Royal Meteorological Society [source] Downscaling temperature and precipitation: a comparison of regression-based methods and artificial neural networksINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2001J.T. Schoof Abstract A comparison of two statistical downscaling methods for daily maximum and minimum surface air temperature, total daily precipitation and total monthly precipitation at Indianapolis, IN, USA, is presented. The analysis is conducted for two seasons, the growing season and the non-growing season, defined based on variability of surface air temperature. The predictors used in the downscaling are indices of the synoptic scale circulation derived from rotated principal components analysis (PCA) and cluster analysis of variables extracted from an 18-year record from seven rawinsonde stations in the Midwest region of the United States. PCA yielded seven significant components for the growing season and five significant components for the non-growing season. These PCs explained 86% and 83% of the original rawinsonde data for the growing and non-growing seasons, respectively. Cluster analysis of the PC scores using the average linkage method resulted in eight growing season synoptic types and twelve non-growing synoptic types. The downscaling of temperature and precipitation is conducted using PC scores and cluster frequencies in regression models and artificial neural networks (ANNs). Regression models and ANNs yielded similar results, but the data for each regression model violated at least one of the assumptions of regression analysis. As expected, the accuracy of the downscaling models for temperature was superior to that for precipitation. The accuracy of all temperature models was improved by adding an autoregressive term, which also changed the relative importance of the dominant anomaly patterns as manifest in the PC scores. Application of the transfer functions to model daily maximum and minimum temperature data from an independent time series resulted in correlation coefficients of 0.34,0.89. In accord with previous studies, the precipitation models exhibited lesser predictive capabilities. The correlation coefficient for predicted versus observed daily precipitation totals was less than 0.5 for both seasons, while that for monthly total precipitation was below 0.65. The downscaling techniques are discussed in terms of model performance, comparison of techniques and possible model improvements. Copyright © 2001 Royal Meteorological Society [source] Downscaling daily maximum and minimum temperatures in the midwestern USA: a hybrid empirical approachINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 4 2007J. T. Schoof Abstract A new hybrid empirical downscaling technique is presented and applied to assess 21st century projections of maximum and minimum daily surface air temperatures (Tmax, Tmin) over the Midwestern USA. Our approach uses multiple linear regression to downscale the seasonal variations of the mean and standard deviation of daily Tmax and Tmin and the lag-0 and lag-1 correlations between daily Tmax and Tmin based on GCM simulation of the large-scale climate. These downscaled parameters are then used as inputs to a stochastic weather generator to produce time series of the daily Tmax and Tmin at 26 surface stations, in three time periods (1990,2001, 2020,2029, and 2050,2059) based on output from two coupled GCMs (HadCM3 and CGCM2). The new technique is demonstrated to exhibit better agreement with surface observations than a transfer-function approach, particularly with respect to temperature variability. Relative to 1990,2001 values, downscaled temperature projections for 2020,2029 indicate increases that range (across stations) from 0.0 K to 1.7 K (Tmax) and 0.0 K to 1.5 K (Tmin), while increases for 2050,2059 relative to 1990,2001 range from 1.4 K to 2.4 K (Tmax) and 0.8 to 2.2K (Tmin). Although the differences between GCMs demonstrate the continuing uncertainty of GCM-based regional climate downscaling, the inclusion of weather-generator parameters represents an advancement in downscaling methodology. Copyright © 2006 Royal Meteorological Society [source] Wintertime temperature anomalies in Alaska correlated with ENSO and PDOINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2001John M. Papineau Abstract Wintertime (November,March) surface air temperatures at 14 stations throughout the state of Alaska are correlated with the Southern Oscillation Index and the Pacific Decadal Oscillation index, for the years 1954,2000. On the seasonal and monthly timescales, the principal results are: (i) During El Niño winters, temperatures are near normal in western Alaska but significantly warmer than normal for the eastern two-thirds of the state. (ii) La Niña winters produce significant below normal temperatures statewide. (iii) Temperature patterns produced during El Niño, La Niña, and neutral winters are modified by the concurrent state of the North Pacific sea-surface temperature anomalies, as indicated by the Pacific Decadal Oscillation index. On the sub-monthly timescale, temperatures across Alaska are to the first order correlated with the alternating zonal to meridional Pacific/North American pattern. Analysis of daily winter temperatures at Fairbanks indicates that cold anomalies are more frequent and are longer in duration than warm anomalies, primarily due to radiational cooling of the boundary layer and the subsequent formation of deep temperature inversions. The development of strong inversions over the interior of Alaska limits the response of temperatures to changes in the synoptic-scale flow pattern. Warm anomalies in contrast to cold anomalies, are primarily a function of warm air advection, therefore temperatures during warm anomalies fluctuate in phase with changes in the synoptic-scale flow. Ultimately, air temperatures across Alaska are a function of: synoptic-scale forcings, radiative cooling of the boundary layer as well as local and regional effects such as downslope and drainage winds. Copyright © 2001 Royal Meteorological Society [source] | ||||||||||