Climatological Approach Research Articles

A Statistical Forecast Model of Weather-Related Damage to a Major Electric Utility

AbstractA generalized linear model (GLM) has been developed to relate meteorological conditions to damages incurred by the outdoor electrical equipment of Public Service Electric and Gas, the largest public utility in New Jersey. Utilizing a perfect-prognosis approach, the model consists of equations derived from a backward-eliminated multiple-linear-regression analysis of observed electrical equipment damage as the predictand and corresponding surface observations from a variety of sources including local storm reports as the predictors. Weather modes, defined objectively by surface observations, provided stratification of the data and served to increase correlations between the predictand and predictors. The resulting regression equations produced coefficients of determination up to 0.855, with the lowest values for the heat and cold modes, and the highest values for the thunderstorm and mix modes. The appropriate GLM equations were applied to an independent dataset for model validation, and the GLM shows skill [i.e., Heidke skill score (HSS) values greater than 0] at predicting various thresholds of total accumulated equipment damage. The GLM shows higher HSS values relative to a climatological approach and a baseline regression model. Two case studies analyzed to critique model performance yielded insight into GLM shortcomings, with lightning information and wind duration being found to be important missing predictors under certain circumstances.

Prospects of growing yellow sarson under rainfed condition in the new alluvial agroclimatic zone of West Bengal

Using 100 years of weekly rainfall data for Baharampur, profile moisture at sowing were simulated for coarse, medium and fine textured soils for six different sowing weeks starting from 38th (Sep 17 – 23) standard meteorological week (SMW) at two weeks interval and associated climatic risk was quantified using climatological water balance approach for yellow sarson, an important rainfed rabi crop of West Bengal. Same database was also used to run a FAO crop specific water balance model at weekly time steps to assess model outputs for Binoy variety. Yield prospects were estimated from water requirement satisfaction index (WRSI). At least 100 mm moisture is present to start sowing upto 42nd and 46th SMW in medium and fine textured soil respectively, at 75 percent probability level, for good initial growth of the plant. At least mediocre crop yield, in every alternate year, is possible when sown upto 40th SMW in medium and upto 44th SMW in fine textured soil. Prospect of getting good yield exist in more than 20 percent of the year if sown within 7th October in fine textured soil.

Relationships of surface bromoform concentrations with mixed layer depth and salinity in the tropical oceans

Bromoform is ubiquitously present in the surface ocean because of its release from algae. Bromoform initiates catalytic ozone destruction in both the troposphere and stratosphere and may act as biogenic feedback in a changing climate. Thus, the temporal and spatial variation in the sea‐air flux of bromoform is of great interest to atmospheric chemists. However, this is poorly characterized. Here we present a climatological approach to the sea surface bromoform concentration based on parameterizing remotely sensed variables. Significant parameters in capturing the variability were found to be chlorophyll‐a concentrations, the mixed layer depth (with which bromoform is positively correlated), and salinity (negatively correlated). Climatology surface concentrations ranged from 4 to 90 ppt (∼200–4500 pmol dm−3), and average seasonal sea‐air flux ranged from 10 to 100 nmol m−2 h−1. Using these fluxes, we obtained the total contribution of the tropical oceans to the global sea‐air flux of bromoform to be 1.45 ± 0.9 Gmol a−1, representing about 75% of current global estimates.

Global Environmental Issues: A Climatological Approach by David D. Kemp, Routledge (London) 1990. No. of pages: 220 + xv, Price: £35.00 (hardback), £9.99 (paperback)

Global Environmental Issues: A Climatological Approach by David D. Kemp, Routledge (London) 1990. No. of pages: 220 + xv, Price: £35.00 (hardback), £9.99 (paperback)

A Synoptic Climatological Approach to Assess Climatic Impact on Air Quality in South-central Canada. Part I: Historical Analysis

Automated synoptic weather typing and robust orthogonal stepwise regression analysis (via principal components analysis) were applied together to develop within-weather-type air pollution prediction models for a variety of pollutants (specifically, carbon monoxide – CO, nitrogen dioxide – NO2, ozone – O3, sulphur dioxide – SO2, and suspended particles – SP) for the period 1974–2000 in south-central Canada. The SAS robust regression procedure was used to limit the influence of outliers on air pollution prediction algorithms. Six-hourly Environment Canada surface observed meteorological data and 6-hourly US National Centers for Environmental Prediction (NCEP) reanalysis data of various weather elements were used in the analysis. The models were developed using two-thirds of the total years for meteorological and air pollution data; the remaining one-third (randomly selected) was used for model validation. Robust stepwise regression analysis was performed to analytically determine the meteorological variables that might be used to predict air pollution concentrations. There was a significant correlation between observed daily mean air pollution concentrations and model predictions. About 20, 50, and 80% of the 80 prediction models across the study area possessed R 2 values ≥ 0.7, 0.6, and 0.5, respectively. The results of model validation were similar to those of model development, with slightly smaller model R 2 values.

A Synoptic Climatological Approach to Assess Climatic Impact on Air Quality in South-central Canada. Part II: Future Estimates

Using within-weather-group air pollution prediction models developed in Part I of this research, this study estimates future air pollution levels for a variety of pollutants (specifically, carbon monoxide – CO, nitrogen dioxide – NO2, ozone – O3, sulphur dioxide – SO2, and suspended particles – SP) under future climate scenarios for four cities in south-central Canada. A statistical downscaling method was used to downscale five general circulation model (GCM) scenarios to selected weather stations. Downscaled GCM scenarios were used to compare respective characteristics of the weather groups developed in Part I; discriminant function analysis was used to allocate future days from two windows of time (2040–2059 and 2070–2089) into one of four weather groups. In Part I, the four weather groups were characterised as hot, cold, air pollution-related, and other (defined as relatively good air quality and comfortable weather conditions). In estimating future daily air pollution concentrations, three future pollutant emission scenarios were considered: Scenario I – emissions decreasing 20% by 2050, Scenario II – future emissions remaining at the same level as at the end of the twentieth century, and Scenario III – emissions increasing 20% by 2050. The results showed that, due to increased temperatures, the average annual number of days with high O3 levels in the four selected cities could increase by more than 40–100% by the 2050s and 70–200% by the 2080s (from the current areal average of 8 days) under the three pollutant emission scenarios. The corresponding number of low O3 days could decrease by 4–10% and 5–15% (from the current areal average of 312 days). For the rest of the pollutants, future air pollution levels will depend on future pollutant emission levels. Under emission Scenarios II and III, the average annual number of high pollution days could increase 20–40% and 80–180%, respectively, by the middle and late part of this century. In contrast, under Scenario I, the average annual number of high pollution days could decrease by 10–65%.

Mapping “At Risk” Snow in the Pacific Northwest

Abstract One of the most visible and widely felt impacts of climate warming is the change (mostly loss) of low-elevation snow cover in the midlatitudes. Snow cover that accumulates at temperatures close to the ice-water phase transition is at greater risk to climate warming than cold climate snowpacks because it affects both precipitation phase and ablation rates. This study maps areas in the Pacific Northwest region of the United States that are potentially at risk of converting from a snow-dominated to a rain-dominated winter precipitation regime, under a climate-warming scenario. A data-driven, climatological approach of snow cover classification is used to reveal these “at risk” snow zones and also to examine the relative frequency of warm winters for the region. For a rain versus snow temperature threshold of 0°C the at-risk snow class covers an area of about 9200 km2 in the Pacific Northwest region and represents approximately 6.5 km3 of water. Many areas of the Pacific Northwest would see an increase in the number of warm winters, but the impacts would likely be concentrated in the Cascade and Olympic Ranges. A number of lower-elevation ski areas could experience negative impacts because of the shift from winter snows to winter rains. The results of this study point to the potential for using existing datasets to better understand the potential impacts of climate warming.

Winter air -mass-based synoptic climatological approach and hospital admissions for myocardial infarction in Florence, Italy

The aim of this study was to evaluate the relationship between the risk of hospital admission for myocardial infarction (MI) and the daily weather conditions during the winters of 1998–2003, according to an air-mass-based synoptic climatological approach. The effects of time lag and 2-day sequences with specific air mass types were also investigated. Studies concerning the relationship between atmospheric conditions and human health need to take into consideration simultaneous effects of many weather variables. At the moment few studies have surveyed these effects on hospitalizations for MI. Analyses were concentrated on winter, when the maximum peak of hospitalization occurred. An objective daily air mass classification by means of statistical analyses based on ground meteorological data was carried out. A comparison between air mass classification and hospital admissions was made by the calculation of a MI admission index, and to detect significant relationships the Mann–Whitney U test, the analysis of variance, and the Bonferroni test were used. Significant increases in hospital admissions for MI were evident 24 h after a day characterized by an anticyclonic continental air mass and 6 days after a day characterized by a cyclonic air mass. Increased risk of hospitalization was found even when specific 2-day air mass sequences occurred. These results represent an important step in identifying reliable linkages between weather and health.

Synoptic climatology of extreme fire-weather conditions across the southwest United States

Extreme fire-weather conditions are usually thought of as discrete events rather than part of a continuum of meteorological and climatological variability. This study uses a synoptic climatological approach (weather typing) to examine the seasonal climatology of extreme fire-weather conditions across the southwest United States (Arizona and New Mexico) during the period of 1988–2003. Three key circulation patterns representing broad southwesterly flow and large geopotential height gradients are associated with over 80% of the extreme fire-weather days identified in this study. Seasonal changes in relative humidity levels, strength of height gradient, and geopotential heights all modulate the relationship between these key circulation patterns and extreme fire-weather days. Examination of daily incident summaries for three recent wildfires (May 2000, June 2002 and June 2003) shows that wildfire activity can be strongly regulated by these critical fire-weather circulation patterns. Copyright © 2006 Royal Meteorological Society.

Trends in aerosol optical depth in the Russian Arctic and their links with synoptic climatology

Temporal and spatial variability of aerosol optical depth (AOD) are examined using observations of direct solar radiation in the Eurasian Arctic for 1940–1990. AOD is estimated using empirical methods for 14 stations located between 66.2°N and 80.6°N, from the Kara Sea to the Chukchi Sea. While AOD exhibits a well-known springtime maximum and summertime minimum at all stations, atmospheric turbidity is higher in spring in the western (Kara–Laptev) part of the Eurasian Arctic. Between June and August, the eastern (East Siberian–Chukchi) sector experiences higher transparency than the western part. A statistically significant positive trend in AOD was observed in the Kara–Laptev sector between the late 1950s and the early 1980s predominantly in spring when pollution-derived aerosol dominates the Arctic atmosphere but not in the eastern sector. Although all stations are remote, those with positive trends are located closer to the anthropogenic sources of air pollution. By contrast, a widespread decline in AOD was observed between 1982 and 1990 in the eastern Arctic in spring but was limited to two sites in the western Arctic. These results suggest that the post-1982 decline in anthropogenic emissions in Europe and the former Soviet Union has had a limited effect on aerosol load in the Arctic. The post-1982 negative trends in AOD in summer, when marine aerosol is present in the atmosphere, were more common in the west. The relationships between AOD and atmospheric circulation are examined using a synoptic climatology approach. In spring, AOD depends primarily on the strength and direction of air flow. Thus strong westerly and northerly flows result in low AOD values in the East Siberian–Chukchi sector. By contrast, strong southerly flow associated with the passage of depressions results in high AOD in the Kara–Laptev sector and trajectory analysis points to the contribution of industrial regions of the sub-Arctic. In summer, low pressure gradient or anticyclonic conditions result in high atmospheric turbidity. The frequency of this weather type has declined significantly since the early 1980s in the Kara–Laptev sector, which partly explains the decline in summer AOD values.

A SYNOPTIC CLIMATOLOGICAL APPROACH TO SEPARATE WEATHER- AND POLLUTION-INDUCED IMPACTS ON HUMAN MORTALITY

ISEE-67 Abstract: Considerable research indicates that human mortality is significantly affected by both ambient meteorological conditions on a particular day, as well as atmospheric pollutant levels. However, it is difficult to segregate the impact of each of these factors, and to identify any possible synergistic effects. The goal of this study is to describe a climatological procedure that facilitates the separation of pollution and meteorological effects on human mortality. Our research into the segregation of these impacts involves use of the synoptic climatological approach. Each day at a particular location is classified into one of several air masses, or weather types, based on ambient meteorological conditions. In this study, the Spatial Synoptic Classification (SSC) has been utilized, and a number of air mass types and transitional situations can then be ascribed to each day. When analyzed synoptically, the heat-mortality relationship usually identifies one or two air masses that are associated with mean mortality statistically significantly greater than the mean. It is these oppressive air masses that serve as the basis for our division into “offensive” days and “non-offensive” days, based on meteorological conditions. Once divided, the pollutant-mortality relationship is then evaluated within each of these groups. Days are then classified by quintiles of suspended particulates (PM10, PM2.5, TSP) and ozone (O3) within each of these two groups. Results vary across the several cities analyzed. In some cases, important differentials are noted. For example, on “oppressive” days, there is no correlation between pollutant levels and mortality; mortality remains high irrespective of pollution concentration. It is only during “non-oppressive” conditions that mean mortality increases along with pollution levels. In other locales, pollution seems to play some role during oppressive meteorological conditions. This suggests that, while there is considerable interurban variability, in some cases the meteorological impact seems to overwhelm any pollution signal. These responses seem to be robust on an intraregional level.

An assessment of microwave absorption models and retrievals of cloud liquid water using clear‐sky data

Passive microwave radiometers have a long history in the remote sensing of atmospheric liquid and water vapor. Retrievals of these quantities are sensitive to variations in pressure and temperature of the liquid and water vapor. Rather than use a statistical or climatological approach to account for the natural variability in atmospheric pressure and temperature, additional information on the atmospheric profile at the time of the radiometer measurements can be directly incorporated into the retrieval process. Such an approach has been referred to in the literature as a “physical‐iterative” solution. This paper presents an assessment of the accuracy of the column liquid water path that can be expected using such an iterative technique as a result of uncertainties in the microwave emissions from oxygen and water vapor. It is shown that the retrieval accuracy is influenced by the accuracy of the instrument measurements and the quality of the atmospheric profiles of temperature and pressure, as one would expect. However, also critical is the uncertainty in the absorption coefficients used in the underlying microwave radiative transfer model. The uncertainty in the absorption coefficients is particularly problematic in that it may well bias the liquid water retrieval. The differences between three absorption models examined in this paper are equivalent to a bias of 15 to 30 g/m2, depending on the total column water vapor. An examination of typical liquid water paths from the Southern Great Plains region of the United States shows that errors of this magnitude have significant implications for shortwave radiation and retrievals of cloud effective particle size.

Global circulation of atmospheric mercury: a modelling study

This paper presents a comprehensive atmospheric global and regional mercury model and its capability in describing the atmospheric cycling of mercury. This is an on-line model (integrated within the Canadian operational environmental forecasting and data assimilation system) which can be used to understand the role of meteorology in mercury cycling (atmospheric pathways), the inter-annual variability of mercury and can be evaluated against observations on global scales. This is due to the fact that the model uses a combination of actual observed and predicted meteorological state of the atmosphere at high resolution to integrate the model as opposed to the climatological approach used in existing global mercury models. The model was integrated and evaluated on global scale using only anthropogenic emissions. North to south gradients in mercury concentrations, seasonal variability, dry and wet deposition and vertical structure are well simulated by the model. The model was used to explain the observed seasonal variations in atmospheric mercury circulation. The results from this study include a global animation of surface air concentrations of total gaseous mercury for 1997.

Response of nine forage grasses to saline irrigation and its schedules in a semi-arid climate of north-west India

Traditionally, the degraded lands in arid and semi-arid regions are left for pastures but their forage productivity is low, unstable and unremunerative. Often this results in acute shortages of fodder during the post-monsoon period that can perhaps be partly overcome if the limited saline ground-water resources are effectively utilized to supplement water supplies. Thus, a field experiment was conducted during 1993–1997 on a calcareous soil in a semi-arid part of north-west India (average rainfall 350 mm/annum) to evaluate the suitability of forage grasses to saline irrigation (ECiw 8.5–10.0 dS/m) and optimize its schedule. Grass species included in this experiment were Brachiaria mutica Stapf. Cenchrus setigerus Vahl. Chloris gayana Kunth, Cymbopogon flexuosus, Cynodon dactylon Pers. Echinochloa colonum Link. Panicum antidotale Retz., P. coloratum Linn., P. laevifolium Hack., P. maximum Jacq. (Local wild), P. maximum Jacq. (Cultivated) and P. virgatum. Species those were identified to be the most promising included Panicum laevifolium and P. maximum (both local wild and cultivated) with an annual forage production of 3.43–4.23 Mg/ha. The overall reduction in forage yield with saline irrigation equalled 29 per cent when compared with canal water (ECiw 0.4 dS/m). Scheduling saline irrigation based on climatological approach, i.e. when the ratio of depth of irrigation water (Diw) and cumulative open pan evaporation (CPE) equalled 0.4, was observed to be optimal whereas increased salt accumulation nullified the benefits of enhanced water supplies (Diw/CPE=0.8). Two of the definite advantages of irrigated forages were about three–four-fold increase in productivity as compared with natural/seeded pastures and extension of production period to those of conventional shortages, i.e. during summer months (April–June) when the most nomad populations are forced to migrate to traditionally irrigated areas. Thus, it was concluded that saline water use strategies for rehabilitating arid lands with above grass species would not only render these degraded lands be more productive but also ensure conservation and improvement for long-range ecological security of these lands.

Airflow Configurations of Warm Season Southerly Low-Level Wind Maxima in the Great Plains. Part I: Spatial and Temporal Characteristics and Relationship to Convection

Abstract A synoptic climatological approach was used to investigate 1) the airflow characteristics of southerly low-level wind maxima in the Great Plains, 2) the typical thermodynamic environments in which low-level wind maxima form, 3) the convergence fields accompanying the wind maxima, and 4) the associated patterns of cloud-to-ground lightning activity. A total of 260 low-level jet events that occurred at either 0000 or 1200 UTC during the warm seasons (Apr–Sep) of 1991–92 were employed in the analysis. The spatial configuration of southerly low-level jets was shown to be considerably more complex than previously portrayed. A subjective classification of the jet events—based on streamline curvature, latitudinal extent, and the orientation of confluence and deformation zones—resulted in 12 distinct configuration types. Only 37% of the events were broadly classified as anticyclonically curving jets, even though the majority of previous case studies focused on this type of wind maximum. Another unanticip...

Regional Diurnal Albedo Climatology and Diurnal Time Extrapolation of Reflected Solar Flux Observations: Application to the ScaRaB Record

Abstract A regional (2.5° × 2.5° resolved) diurnal (hourly) albedo climatology for low and midlatitudes is derived for each month from the 5⅓-yr narrow-field-of-view data record obtained from the Earth Radiation Budget Satellite (ERBS). It is used in a quasi-operational diurnal interpolation/extrapolation procedure (DIEP) to calculate regional monthly means of the reflected shortwave radiation flux (RSR) from instantaneous albedo observations. This climatological approach (CDIEP) replaces the questionable assumption of diurnally constant cloud conditions made in the conventional DIEP by assuming a diurnal variation of cloudiness corresponding to the mean long-term diurnal variation of the planetary albedo. Validation of CDIEP, using the three-satellite Earth Radiation Budget Experiment (ERBE) data for December of 1986, indicates that on regional scales monthly time sampling errors for single satellite products are generally reduced but not completely removed in comparison with the currently applied diurna...

Forecasting Air Pollution Potential: A Synoptic Climatological Approach

ABSTRACT This paper describes the development and application of an air pollution potential (APP) forecast model based on a synoptic climatological approach in a heavily industrialized area in Durban, South Africa. The aim of the forecasting procedure, based on a system of orange, red, and all-clear alerts, was to give industry advance warning of periods of poor atmospheric dispersion so that it could take action to reduce emissions. The key meteorological parameter in accurately identifying the commencement of an APP episode was found to be negative surface pressure tendency. Wind direction was the most useful parameter in estimating the end point of an APP episode. The model was very successful in identifying periods of elevated SO2, but there is a need for further refinement in forecasting the end point of an episode.

Using a synoptic climatological approach to understand climate-viticulture relationships

Regional circulation and local air mass synoptic climatologies are developed for Bordeaux, France, to examine the relationship between climate and viticulture. Using a variation of the temporal synoptic index, days with similar weather (both throughout Western Europe and at Bordeaux) are grouped together. The annual relative frequencies of these groups are used as independent variables to investigate climate–viticulture relationships for the region. The viticulture data are divided annually into stages based on the region-wide mean phenology of the grapevines. Synoptic climate–phenology models are then developed using multiple linear regression analysis. A high degree of spatial and temporal cohesiveness is found between the regional and the local synoptic climatologies. Circulation patterns identified in the regional circulation analyses are linked in a consistent fashion with corresponding thermal, moisture, wind and cloud cover conditions at the Bordeaux site. A small number of synoptic clusters greatly affect viticultural potential throughout the year. In general, vintage quality and production are reduced by (i) increased frequencies of cold- and moisture-producing events that delay the plant's physiology, and (ii) increases in frontal incursions and the associated winds and rain that affect flowering and the setting of berries. Conversely, the relative occurrence of warm, stable events during maturation lead to full ripeness and higher vintage quality. Copyright © 2000 Royal Meteorological Society

Computation of crop evapotranspiration for scheduling irrigation in surgarcane

Field experiments were carried out to investigate the suitability of empirical formulae of climatological approach for irrigation scheduling, improving the water use efficiency in early maturing sugarcane during main and special seasons (1993-95) at Tamil Nadu Agricultural University, Coimbatore. For scheduling irrigation based on Blaney - Criddle method, ETC was worked out with thirty years mean climatic data. For evaluating various empirical methods including Blaney Criddle methods, the actual weather parameters that prevailed during the cropping period alone were considered. The estimated ETC was 1223 and 1345 mm for main and special seasons respectively. Blaney Criddle empirical method of climatological approach promises to be suitable for irrigation scheduling in early maturing sugarcane. For high WUE scheduling irrigation at 100 per cent ETC during germination and early tillering followed by at 75 per cent ETC during subsequent growth phases of cane could be adopted. Climatological methods of predicting ETC and scheduling irrigation for sugarcane could be exploited for various agro climatic zones of Tamil Nadu for efficient water budgeting.

Reconstructing holocene palaeorunoff regimes from palaeoclimate: An initial attempt to apply a climatological approach to palaeohydrology for the north China plain

Employing the regression equations relating mean annual runoff to mean annual temperature and mean annual precipitation derived with modern data, palaeorunoff values were calculated from palaeoclimatic information for three localities in the eastern part of the North China Plain (37 – 41°N, 115 – 120°E) during the last 12 000 years. These results present a general pattern of temporal and spatial variations of the Holocene palaeorunoff occurring in this region. The annual runoff was the highest during 8000 – 3000 a B.P., the second high during 12 000 – 8000 a B.P., and the lowest during 3000 – 0 a B.P. Spatially the annual runoff was the highest at the downstream area of the Luanhe River in the north, the second highest at the area around Beijing in the middle, and the lowest at the area around Xingtai in the southwest. These results were further compared to other palaeohydrological reconstruction achieved by other researchers or with other methods, which usually indicates the similar trend of hydrological changes for this region.