Surge Profile Research Articles

SPECTRAL STUDY LOWER SOLAR ATMOSPHERE OF THE ACTIVE REGION SITE WITH THE ELLERMAN BOMB AND ACCOMPANYING Hα-EJECTIONS

The results of studying in details the features formation and development of the Ellerman bomb (EB) and accompanying Hα-ejections arose on the NOAA 11024 active region site, are presented. This site was in the region of emerging new magnetic flux. Spectral data with high spatial and temporal resolution were obtained with the French–Italian solar telescope THEMIS on July 4, 2009. Spectra with the Hα line and with the spectral region λλ ≈ 630 nm were used. Stokes I profiles were obtained with an interval corresponding to 160 km on the Sun surface. The Hα line profiles obtained for different periods of EB development were asymmetric with an excess of emission in the short-wavelength wing. The temporal variations of intensity in the Hα line wings at distances ±0.1 and ±0.16 nm from its center indicated that two periods can be distinguished in EB evolution: the preheating phase and the flaring phase, during which the gradual and pulse energy release occurred. Hα-ejections (surges) are small-scale eruptions of cold matter in the solar atmosphere. In all spectra they were visible in the absorption. The surge profiles were projected onto the blue or red Hα line wing. Its Doppler shifts were used to calculate the line-of-sight velocities (Vlos) of chromospheric matter in surges. The velocity distribution in the surges indicated their multi-flow structure. One of the surges showed signs of plasma vortex motions. Most surges occurred with a high velocity – Vlos up reached -110 km/s, and down to 90 km/s. We obtained temporal Vlos variations in a wide interval (140 ─ 490 km) of photospheric heights for the area of EB development and its immediate surroundings. At all photospheric levels predominantly upward motions were found. In the central part of the EB in the upper layer of the photosphere the Vlos varied between -0.5 ÷ 0.2 km/s, in the lower layer – -1.1 ÷ -0.1 km/s. An increase the core intensity of all photospheric lines was correlated in time with an increase of the emission intensity in the Hα line wings. The new observational data for the Ellerman bomb and accompanying Hα-ejections, which have been obtained and analyzed, can be used to verify existing and create new theoretical models.

0493 A new perspective on exploring the predictive factors of blood pressure reduction during CPAP treatment in OSA

Abstract Introduction The predictive factors of BP response to continuous positive airway pressure (CPAP) in obstructive sleep apnea (OSA) are still being explored. We aimed to assess the antihypertensive effect of CPAP considering the obstructive respiratory event-triggered BP surge profiles in 130 subjects with severe OSA and untreated hypertension. Methods Nocturnal BP was monitored continuously and synchronized with polysomnography. Event-triggered BP surge profiles were studied: BP surge as the value of event-related systolic BP elevation; BP index as the number of BP surge events of ≥10 mmHg per hour. Patients were then divided into two groups according to the median BP index (high and low BP surge groups) and assigned to 4 weeks of CPAP. Changes in BPs and plasma biomarkers were compared. After the initial evaluation, patients with a better BP response in the high BP surge group were then followed up for the second evaluation at 24 months. Results Overall, a modest decrease was observed in both office and asleep BPs at the 4-week follow-up; however, BPs dropped more markedly in patients in high BP surge group than those in low BP surge group, in both office systolic BP (SBP:5.3 mmHg vs.2.2 mmHg, P=.005) and diastolic (DBP:4.0mmHg vs.1.2 mmHg, P=.011), especially the asleep SBP (9.0mmHg vs.2.1 mmHg, P<.001). For 30 cases in the high BP surge group, optimal BP control was achieved in 60.0% of patients and BP < 140/90mmHg reached up to 83.3% after 24 months of CPAP. Linear regression revealed that BP index was significantly associated with BP decrease during CPAP treatment. Conclusion Our results suggest that high event-triggered BP surge was a sensitive predictor of BP response to CPAP in patients with severe OSA and hypertension. Support (if any)

New perspective on exploring the predictive factors of blood pressure reduction during CPAP treatment in people with severe OSA and hypertension: a prospective observational study

BackgroundThe predictive factors of blood pressure (BP) response to continuous positive airway pressure (CPAP) in obstructive sleep apnoea (OSA) are still being explored. We aimed to assess the antihypertensive effect...

Evaluation of Multivariate Adaptive Regression Splines and Artificial Neural Network for Prediction of Mean Sea Level Trend around Northern Australian Coastlines

Mean sea level rise is a significant emerging risk from climate change. This research paper is based on the use of artificial intelligence models to assess and predict the trend on mean sea level around northern Australian coastlines. The study uses sea-level times series from four sites (Broom, Darwin, Cape Ferguson, Rosslyn Bay) to make the prediction. Multivariate adaptive regression splines (MARS) and artificial neural network (ANN) algorithms have been implemented to build the prediction model. Both models show high accuracy (R2 > 0.98) and low error values (RMSE < 27%) overall. The ANN model showed slightly better performance compared to MARS over the selected sites. The ANN performance was further assessed for modelling storm surges associated with cyclones. The model reproduced the surge profile with the maximum correlation coefficients ~0.99 and minimum RMS errors ~4 cm at selected validating sites. In addition, the ANN model predicted the maximum surge at Rosslyn Bay for cyclone Marcia to within 2 cm of the measured peak and the maximum surge at Broome for cyclone Narelle to within 7 cm of the measured peak. The results are comparable with a MARS model previously used in this region; however, the ANN shows better agreement with the measured peak and arrival time, although it suffers from slightly higher predictions than the observed sea level by tide gauge station.

Reformulation of PULSAR for Analysis of Pulsatile LH Secretion and a Revised Model of Estrogen-Negative Feedback in Mice.

The recent use of the tail-tip bleeding approach in mice has enabled researchers to generate detailed pulse and surge profiles of luteinizing hormone (LH) secretion in mice. However, the analysis of pulsatile LH secretion is piecemeal across the field with each laboratory using their own methodology. We have reformulated the once-popular PULSAR algorithm of Merriam and Wachter to operate on contemporary computer systems and provide downloadable and online pulse analysis platforms. As it is now possible to record the activity of the gonadotropin-releasing hormone pulse generator in freely behaving mice, we have been able to unambiguously define LH pulses in intact and gonadectomized male and female mice. These data sets were used to determine the appropriate PULSAR parameter sets for analyzing pulsatile LH secretion in the mouse. This was then used to establish an accurate model of estrogen negative feedback in the mouse. Intact and ovariectomized mice given Silastic capsules containing 1, 2, and 4 μg 17-β-estradiol/20 g body weight were tail-tip bled at 6-min intervals, and the resultant LH profiles were analyzed with PULSAR. Only the 4 μg 17-β-estradiol capsule treatment was found to return LH pulse amplitude and frequency to that of intact diestrous mice. Ultrasensitive mass spectrometry analysis showed that the 4 μg 17-β-estradiol capsule generated circulating estradiol levels equivalent to that of diestrous mice. It is hoped that the reformulation of PULSAR and generation of a realistic model of estrogen-negative feedback will provide a platform for the more uniform assessment of pulsatile hormone secretion in mice.

Assessment of Catastrophic Failure for Phase Control Thyristors in AC Pulsed Applications

This article presents a theoretical development, supported by experimental results, which is useful for the evaluation of the ride through capability of phase control thyristors that should operate under high multicycle ac, power frequency current surges with different amplitudes between cycles. Despite being commonly found in the field of metals industry applications, this is not a standard data sheet test condition that can be readily used to predict if the device can handle a given surge profile. The present work is devoted to contributing to the fulfillment of this gap. A recursive, discrete-time method is used for the calculation of instantaneous virtual junction temperature of the devices tested. Such method is advantageous over the traditional equivalent power pulse technique since for any given time step only the immediately previous calculation is needed instead of the overall series. It is shown that the results obtained with these two methods are practically identical. Besides, a complete study based on a commercial power semiconductor device is given along with experimental results that support the application of the assessment method developed.

BREAKING AND WASH UP OF SOLITARY WAVES ON A COMPOSITE BEACH

Hazardous events, such as landslides, rock slides, rock falls or avalanches often generate extreme, impulsive waves when entering water bodies (Fuchs & Hager, 2015). These waves are approximated by solitary waves and researchers investigate their damage potential when inundating built environment. Deepening the understanding of solitary waves running up a uniform beach slope and propagating over a subsequent horizontal plane can help to reduce and mitigate damage and the number of casualties caused by such a hazardous event. So far, few authors addressed this specific setting near-shore (Fuchs & Hager, 2015; Zelt & Raichlen, 1991). In this study, large scale solitary waves propagate about 200 m in in the Large-Wave Flume (GWK, 307 m 5 m 7 m) at the Coastal Research Center in Hannover, Germany then they run up a beach slope and subsequently break, generating a bore which advances onto a subsequent, initially dry, horizontal surface. Unlike previous studies, the generated solitary waves broke close to the edge between the beach slope and the horizontal plane section. The overall aim of this study is to investigate the characteristics of the broken waves' dynamics. In addition, their surge profile and front celerity are compared to those of the non-breaking solitary waves. Subsequently, the differences between the velocity regimes along the bore propagation path are presented and linked to the fundamental physical processes behind.

Luteinising hormone profiles in conception and non-conception natural cycles

Objective: The aim of this study was to assess whether luteinising hormone (LH) surge characteristics influenced the likelihood of conceiving naturally. Methods: This was a single-cycle, home-based, observational, case-controlled study. Volunteers collected daily urine samples for one menstrual cycle. LH was measured and the basal levels, surge day, peak day, peak concentration and magnitude of LH surges were examined. Predictive models using sociodemographic data, LH surge characteristics, and sociodemographic data combined with LH profile properties, were evaluated. Results: The surge profile did not differ between cycles with early or late ovulation and was not affected by age or body mass index (BMI). The mean LH surge day was day 16 for both groups. Mean LH surge and concentrations did not differ between groups (surge concentration 54.8 IU/l vs. 58.2 IU/l and peak concentration 82.0 IU/l vs. 81.6 IU/l for pregnant vs. non-pregnant volunteers, respectively). Non-pregnant volunteers were more likely, however, to have a raised or a reduced basal LH on day 6 or have an atypical LH profile. Sociodemographic characteristics were significant predictors of pregnancy, and sociodemographic variable-based models had the greatest predictive ability for conception, providing up to 65% predictive accuracy. Conclusions: Sociodemographic variables can be used to predict the likelihood of a woman conceiving naturally. Provided an LH surge is present, its profile does not relate to the likelihood of spontaneous pregnancy. The conception rate was significantly lower, however, in women with elevated or reduced basal levels of LH, suggesting that follicular maturation needs an optimal basal level of LH in natural conception cycles. Trial registration: ClinicalTrials.gov identifier: NCT01577147.

The effect of circulating progesterone on magnitude of the GnRH-induced LH surge: Are there any differences between Bos indicus and Bos taurus heifers?

This study evaluated the effects of differing circulating progesterone (P4) levels on the luteinizing hormone (LH) surge profile following treatment with gonadotropin releasing hormone (GnRH) in B. indicus (Nelore, n = 13) and B. taurus (Holstein, n = 16) heifers. All heifers were synchronized with a hormonal protocol to induce either a Low or High circulating P4 environment at the time of GnRH treatment. Heifers were randomly assigned to a 2 × 2 factorial design composed by two genetic groups (B. indicus and B. taurus) and two levels of circulating P4 concentrations (Low or High). Blood samples were collected every 30 min from −30 to 210 min and at 270 min after GnRH treatment. As expected, mean P4 concentration was greater for cows in the High than in the Low P4 group (P = 0.0008) and in Bos indicus than in Bos taurus heifers (P = 0.06). Despite genetic group, the area under the curve of LH release was greater in the Low-P4 than in High-P4 concentration group (P < 0.0001). Interestingly, it appears that High P4 concentrations had a more pronounced effect on LH peak in B. indicus than in B. taurus heifers, as indicated by the interaction (P = 0.01) between genetic group and P4 levels. In conclusion, circulating P4 concentration have a great impact on the GnRH-induced LH surge of both B. indicus and B. taurus heifers, but it does not explain the much lower LH peak in B. indicus with low circulating P4. Thus, more studies are essential to uncover some of the underlying physiological factors other than circulating P4 that are limiting LH release following a GnRH treatment in B. indicus cattle.

Impact of phase of the estrous cycle and season on LH surge profile and fertility in dairy cows treated with different GnRH analogs (gonadorelin vs. buserelin)

Our aim was to assess the GnRH-induced LH surge profile in dairy cows receiving two GnRH products (gonadorelin vs buserelin) given at proestrus or diestrus phase and to investigate whether season could alter LH surge profile in dairy cows. In Experiment 1, dairy cows at 108.2 ± 2.3 DIM, producing 41.5 ± 0.3 kg/day were randomized to receive, during proestrus and diestrus: Ovarelin® i.m. (OVA; n = 56; 100 mg of gonadorelin diacetate tetrahydrate; Ceva Animal Health, France) or Receptal® i.m. (REC; n = 52; 10 mcg of buserelin diacetate; MSD, Germany). In Experiment 1, blood samples were collected at hour 0 (just before GnRH treatment) at 30min, 1 h and then hourly until 5 h post-GnRH. In Experiment 2, cows were synchronized with a modified G-6-G protocol and randomized to receive either OVA or REC throughout the synchronization program. In Experiment 1, peak LH concentrations (ng/mL) were not affected by type of GnRH (OVA = 6.2 ± 0.4 vs REC = 6.7 ± 0.4; P = 0.37) or season (Cool = 6.8 ± 0.4 vs Warm = 6.1 ± 0.4; P = 0.22), and there were no interactions between GnRH type and phase of the estrous cycle or season. Interestingly, the area under the curve (AUC) of LH release (ng/ml*time) was significantly lower during warmer months (Cool = 20.3 ± 1.2 vs Warm = 16.9 ± 1.1; P = 0.04). As expected, LH peak was affected by phase of the cycle (proestrus = 8.2 ± 0.4 vs diestrus = 4.7 ± 0.4; P < 0.01). Ovarelin caused LH concentrations to increase faster, reaching highest concentration sooner (h) than REC (1.5 ± 0.1 vs 2.3 ± 0.1; P < 0.01). As a result, cows receiving OVA had greater circulating LH concentrations (ng/mL) at 1 h after GnRH treatment than cows receiving REC (P < 0.01). In contrast, cows treated with REC had longer (P = 0.01) intervals from peak until return to nadir. In Experiment 2, pregnancy per AI (P/AI) was similar for cows receiving either GnRH product during the synchronization protocol, with no detectable interactions between GnRH type and season. In conclusion, phase of the estrous cycle had a great impact on the GnRH-induced LH surge profile and cows during warm season had reduced AUC. Additionally, type of GnRH did not influence LH surge profile and P/AI in synchronized cows. Regardless of GnRH type, strategies to avoid heat stress and excessively high levels of circulating P4 near the time of GnRH treatment might help improve LH release profile in dairy cows, and ultimately increase P/AI.

Numerical investigation of surge–tide interactions in the Bay of Bengal along the Bangladesh coast

The tidal amplitude at the Bay of Bengal along the Bangladesh coast varies from 2 to 7 m, whereas the tidal phase differs by more than 3 h from the outer part toward the inner part of the Meghna Estuary. At the time of cyclone landfall, the tidal phase has a significant impact on surge height, arrival time and duration. In this paper, the nature of surge–tide interactions at the Bay of Bengal along the Bangladesh coast has been investigated using a two-dimensional nonlinear shallow water model coupled with a storm surge model. Two previous major storm surge events along the Bangladesh coast have been analyzed for surge–tide interaction: Cyclone 1991 and Cyclone Sidr in 2007. To investigate the impact of the tidal phase on surge characteristics, in addition to the base cases, storm surges have been calculated at different phases of an entire tidal cycle at 1-h intervals. The results indicate that during the ebb tides the calculated total surge height of the surge–tide interaction model was higher compared to the total surge height obtained by superimposing surge height that is separately calculated with mean water level over the local tidal water level; the opposite occurs during high tide. The surge propagation time toward the inner part of the bay significantly varied depending on the tidal phases. When the tidal water level along the coast was low, the speed of surge propagation was much slower compared with when the tidal water level was high. The surge duration increases when the falling surge profile encounters an opposing strong tidal current at the landfall location.

Pulse and Surge Profiles of Luteinizing Hormone Secretion in the Mouse.

Using a new tail-tip bleeding procedure and a sensitive ELISA, we describe here the patterns of LH secretion throughout the mouse estrous cycle; in ovariectomized mice; in ovariectomized, estradiol-treated mice that model estrogen-negative and -positive feedback; and in transgenic GNR23 mice that exhibit allele-dependent reductions in GnRH neuron number. Pulsatile LH secretion was evident at all stages of the estrous cycle, with LH pulse frequency being approximately one pulse per hour in metestrous, diestrous, and proestrous mice but much less frequent at estrus (less than one pulse per 4 h). Ovariectomy resulted in substantial increases in basal and pulsatile LH secretion with pulses occurring approximately every 21 minutes. Chronic treatment with negative-feedback, estradiol-filled capsules returned LH pulse frequency to intact follicular phase levels, although pulse amplitude remained elevated. On the afternoon of proestrus, the LH surge was found to begin in a highly variable manner over a 4-hour range, lasting for more than 3 hours. In contrast, ovariectomized, estradiol-treated, positive-feedback mice exhibited a relatively uniform surge onset at approximately 0.5 hour prior to lights out. Gonadectomized wild-type and heterozygous GNR23 (∼200 GnRH neurons) male mice exhibited an LH pulse every 60 minutes. Homozygous GNR23 mice (∼80 GnRH neurons) had very low basal LH concentrations but continued to exhibit small amplitude LH pulses every 90 minutes. These studies provide the first characterization in mice of pulse and surge modes of LH secretion across the estrous cycle and demonstrate that very few GnRH neurons are required for pulsatile LH secretion.

Development of a New Tsunami Generator for Multiple Sources

The medium-sized experimental wave gengineer7snerator implemented at the Ujikawa Open Laboratory of Kyoto University’s Disaster Prevention Research Institute consists of a piston wave maker, a head storage tank and a current generator for reproducing long waves such as tsunamis and storm surges. The experimental series we discuss predicts the generator’s applicability in testing models. These three operating systems are controlled by a single operating system, and start time iscontrolled separately based on target tsunami and storm surge profiles. A sharp tsunami profile is reproduced when the start timing of the piston wave maker and tank gate opening is adjusted. The generator reproduces different types of tsunami wave, making it a strong tool in the research engineer’s arsenal for predicting the effectiveness of hardware “resiliency.”

Development of a New Tsunami Generator

A middle size experiental wave generator has been implemented is the Ujikawa Open Laboratory, Disaster Prevention Research Institute, Kyoto University. The generator is composed of a pistontype wave maker, a head strage water tank and a current generator to mainly reproduce long waves like tsunami and storm surge.The paper desribes severalexperimental series to predict the applicability of the generator to model tests. The three operating sysemes are capable to be controlled in one operating sysytem and start time is contorolled separately according with the target tsunami and storm surge profiles. A sharp tsunami profile is reproduced in adjusting the start timing of piston type wave maker and opening gates of head storage tunk. Any type of tsunami waves are reproduced in the generator and it becomes a strong tool to predict the effective of ”resiliency” of hardwares.

Experimental investigation of flow of fresh self-compacting concrete in improved L-box

To approach the rheological testing method based on L-box test for obtaining internal rheological parameters of fresh self-compacting concrete (SCC), an improved L-box without fiber bars and end wall is developed, and a flow investigation utilizing an image processing technique is operated. Specifically, the improved L-box test method is able to accurately reconstruct the process of free-surface evolution of fresh SCC when it is suddenly released in an open channel. The process involves the dam-break problem and open channel flow problem. In addition, by applying the image processing technique, the flow of fresh SCC in improved L-box (i.e. the front position of time-dependent and surge profile evolution), is easily observed and analyzed. By analyzing the experimental results, we conclude the time-dependent flow front position is governed by two regimes: an inertial regime and a pseudo-equilibrium regime. The flow surge plane is assumed to be divided into six flow zones (at the surge profile during the stable flow in pseudo-equilibrium regime). Simultaneously, a stable laminar flow zone is highlighted for further rheological solving. Additionally, by considering the fact of the most of the depth profiles in stable flow are convex curves in the experiment, a crude empirical fitting model is developed, and then the process of physical interpretation and verification is given. The comparison of results among improved L-box test and other tests shows that the improved L-box test is also available to test the workability parameters (i.e. penetrability, fillibility, et al.). Hence, this work is of significance for the further theoretical analysis and numerical simulation on the flow behaviors of the fresh SCC. The work may also interest the researchers who try to develop a convenient testing method in order to determine the rheological parameters of fresh SCC.

Local amplification of storm surge by Super Typhoon Haiyan in Leyte Gulf.

Typhoon Haiyan, which struck the Philippines in November 2013, was an extremely intense tropical cyclone that had a catastrophic impact. The minimum central pressure of Typhoon Haiyan was 895 hPa, making it the strongest typhoon to make landfall on a major island in the western North Pacific Ocean. The characteristics of Typhoon Haiyan and its related storm surge are estimated by numerical experiments using numerical weather prediction models and a storm surge model. Based on the analysis of best hindcast results, the storm surge level was 5–6 m and local amplification of water surface elevation due to seiche was found to be significant inside Leyte Gulf. The numerical experiments show the coherent structure of the storm surge profile due to the specific bathymetry of Leyte Gulf and the Philippines Trench as a major contributor to the disaster in Tacloban. The numerical results also indicated the sensitivity of storm surge forecast.

Follicular-phase ovarian follicular fluid and plasma cytokine profiling of natural cycle in vitro fertilization patients

To characterize follicular fluid (FF) and systemic cytokine profiles at various time points during the natural-cycle follicular and periovulatory phases. Observational clinical study across two consecutive cycles. Hospital-basedin vitro fertilization program. Ten women undergoing modified natural-cycle invitro fertilization (MNC-IVF). Plasma and follicular fluid (FF) collection. Forty FF cytokine concentrations from individual follicles and plasma from each patient were determined by fluid-phase multiplex immunoassay in two consecutive cycles: 1) tracking cycle-midfollicular or luteal surge; and 2) treatment cycle-periovulatory (at the time of MNC-IVF). Demographic, cycle, and cytokine data were compared with the use of chi-square, paired-scores t test, or Wilcoxon signed ranks tests. Fluctuations in various FF cytokines were evident during the follicular phase: Levels of interleukin (IL) 6 and IL-8 were higher in periovulatory samples, and IL-1 receptor antagonist and vascular endothelial growth factor were elevated earlier in the cycle. Luteal surge profiles were similar to those found in periovulatory samples. Conversely, circulatory cytokine concentrations were more stable during the follicular phase. These findings present an extensive physiologic reference profile of FF cytokines associated with antral folliculogenesis and highlight the compartmentalization of systemic and intraovarian cytokine networks in natural cycles.

2013年台風30号Haiyanによる高潮の予測可能性と再解析精度

Typhoon Haiyan, which struck the Philippines and nearby areas in November 2013, was an extremely intense tropical cyclone that had a catastrophic impact. A series of numerical analyses indicated that the maximum storm surge level was 5-6 m in Tacloban. The numerical experiments show the coherent structure of the storm surge profile due to the specific bathymetry of Leyte Gulf and the Philippines Trench as a major contributor to the storm surge disaster in Leyte Gulf. Based on the comparisons of forecasts and hindcasts, it was difficult to predict the storm surge a few days in advance, quantitatively.

New insights on modeling news dissemination on nuclear issues

Using a modified epidemiological model, the dissemination of news by media agents after the occurrence of large scale disasters was studied. A modified compartmented model was developed in a previous paper presented at INAC 2007 in which, the Chernobyl nuclear accident (1986) and the Concorde airplane crash (2000) were used as a base for the study. Now the model has been applied to a larger and more diverse group of events – nuclear, non-nuclear and naturally caused disasters. To be inclusive, old and recent events from various regions of the world were selected. A more robust news repository was used, and improved search techniques were developed to ensure that the scripts would not contain false positive news. The same model was used but with improved non-linear embedded simulation optimization algorithms to generate the parameters of interest for our model. Individual parameters and some specific combination of these allow a number of interesting perceptions on how the nature of the accident/disaster gives rise to different profiles of growth and decay of the news. In our studies, events involving nuclear causes generate news repercussion with more explosive/robust surge profiles and longer decaying tails than those of other nature. As a consequence of these differences, public opinion and policy makers are also much more sensitive to some issues than to others. The model, through its epidemiological parameters, shows in quantitative manner how “nervous” the media content generators are with respect to nuclear installations and how resilient this negative feelings toward nuclear can be.

Storm surge modelling with geographic information systems: estimating areas and population affected by cyclone Nargis

AbstractA methodology has been developed to model storm surges during cyclones, and to estimate affected areas and population with Geographical Information System (GIS). Surge profiles were derived from the calibrated wind velocity distribution by using regional regressive relationships between the wind velocities and surge heights. Discretised forms of the calculated surge profiles were entered in GIS analysis to estimate affected area and population. This approach was compared with a simple and more common GIS approach that uses a constant storm surge height. The study also considers the effects of different time advisories on the estimation of affected population and areas. It was found that for the cyclone ‘Nargis’, the affected area and population could be estimated with accuracies of 60 and 20%, respectively, for advisories issued when the cyclone centre was more than 600 km from the landing point. These accuracies were 80 and 60%, respectively, when the cyclone centre was within 200 km of landfall. The proposed methodology can be helpful for early warning systems and disaster risk management due to its simplicity and speed as well as in cases where minimal information on the affected areas and population is available such as in the case of cyclone Nargis in Myanmar. Copyright © 2010 Royal Meteorological Society