Vicente B. Malano, Bernardo M. Soriano, Jr., Marino L. Mendoza
A numerical/spectral model is adapted over the eastern coast of Luzon and the Bicol Region to predict its state. The model is formulated based on the energy balance equation for deep water. The forcing function of the model consists of surface wind generated by the cyclone model of Holland with inflow angle of 25 degrees. The model domain is divided into 17 x 17 grids with 1 degree spacing. There are five typhoon cases that are investigated in this project. Validations of the model output are investigated using the TOPEX/Poseidon data.
Esperanza O. Cayanan, Bernardo M. Soriano, Jr.
Statistical rainfall forecasting models for the Visayas, Mindanao and Bicol Regions are developed using stepwise regression analysis. For Visayas and Mindanao, a set of 16-year rainfall observations, which are lagged for three hours, was utilized as developmental data and two to three-year independent data for testing. The predictors for the Visayas Region are weather parameters observed at Mactan, Iloilo and Tacloban. Results indicate appreciable performance of the January and February equations while further independent testing is recommended for the May, June and September equations.
For the Mindanao Region, the predictors are from Cagayan de Oro, Davao and Zamboanga. Evaluation of forecasts showed good performance for the June equation, but a longer period of test data is recommended to add more confidence in the forecast. More test data are also recommended for the December, January and February equations to check their real performance. Based on the observed rainfall pattern, it is suggested that Mindanao be divided into eastern and western forecast areas which means that two sets of forecast equations have to be developed.
In the Bicol Region, the predictor data, lagged for one day, from Daet, Legaspi and Virac were used in the regression. Insignificant correlation was obtained, hence a statistical model of shorter time lag and forecast range is proposed.
Julie M. Nimes, Fredolina D. Baldonado
Eleven occasions of tropical cyclone occurrences in three categories of depression (winds up to 64 kph), storm (winds > 64 < 119 kph) and typhoon (winds greater than or equal to 119 kph) that made landfall in Albay Gulf were studied including the water level responses due to associated cyclone surges. The time series of water level observations (observed, surge and astronomical tide levels) and the different cyclone parameters (wind and pressure) were examined and other parameters such as radius of maximum winds, landfall point and cyclone angle of approach were investigated. Other physical factors affecting surge levels such as the bathymetry, topography and coastal configuration of the Gulf were likewise described. Eventually, notable surges at the Gulf were compared with those at San Miguel Bay.
The study was supplemented by a statistical dynamical surge model, which gave considerable insight into the expected peak water level at cyclone landfall.
Results show that the different cyclone intensities induce different water level responses. Reasons are proposed for the observed differences.
Vicente P. Palcon, Jr.
The aim of this study is to assess the PAGASA Telecommunication Systems in the collection and dissemination of Meteorological Information. More specifically, this study answered the ff. questions: a.) How does the Telecommunication Systems perform in terms of collection and dissemination of Meteorological Information? b.) What is the status of the Telecommunication Systems in terms of equipment in place? The descriptive method of research was used in this study. A survey questionnaire was used with some unstructured follow-up interview. Documents and records of PAGASA was also utilized as secondary data. The study will attempted to determine the prevailing condition or situation of the meteorological telecommunication system in the country linked at PAGASA. Respondents of the study: The Chief Meteorological Officer of the 53 weather stations were the respondents of the study. The selection of the participating stations were taken from the records of the PAGASA wherein these stations are connected to Meteorological Telecommunication System as well as the Main Communication Center for a total of 54 stations. Instrumentation: The questionnaire was the main research instrument of the study which was divided into three parts, namely: 1. Collection of Meteorological Information, 2.) Dissemination of Meteorological Information and 3.) Equipment in Place. Data Gathering Procedure: The study made sure of both secondary and primary data as the source of information. The secondary data was taken from the records of the PAGASA on maintenance records submitted by the participating stations. While the primary data was gathered through the survey questionnaire floated to 53 weather stations and MCC. Statistical Treatment: The data collected were computed, tabulated, analyzed and interpreted using statistics like frequency counts and percentages to show the relationship of a part to the whole. Summary of findings: The collection of meteorological information by each collection centers when totalled came up with the equivalent of 93%. The 7% non-performance of the collection of meteorological information is mostly located in Tuguegarao Area. The dissemination of meteorological information performed by weather stations under each particular collection centers when totalled came up with the equivalent of 70%. The 30% non-performance of the dissemination of meteorological information was concentrated more in MCC where 37% of the stations under MCC were prominent. The equipment for the data exchange system of MTS were mostly functioning with the percentage of 91 to 100. The preference on using MTS system in sending and receiving meteorological information was more prominent with the equivalent of 76% who preferred to use it. Conclusions: Based on the findings in this study, the researcher came up with the ff. conclusions: 1.) As a whole, the 93% of collection of meteorological information is still efficient, although the target must be 100%. 2.) The performance of the PAGASA Telecommunication System in terms of dissemination of meteorological information is poor in terms of efficiency as shown by the percentage obtained. 3.) The status of the PAGASA Telecommunication System in terms of equipment in place were mostly functional although the preference in the use of MTS system in sending and receiving meteorological information was also poor due to the ff. reasons: a) Defective data exchange system equipment; b) Difficulty in establishing communication link due to interference; c) The attitude of the Observer on Duty to use or not to use MTS system Recommendations: Based on the conclusions reached, the ff. recommendations are hereby advanced: 1.) The dissemination of meteorological information has something to do with the time allotted, hence, a higher speed modem or protocol is required in order to surpass the noise and interference blocking the signal. 2.) Coordinate with some specialized Agencies of the DOST to develop a message handling system locally which include PC-based software to perform the same function of I/O terminal on which WMO format data can also be forwarded to Global Telecommunication System (GTS). 3. Implement a stringent policy regarding the dissemination of meteorological information to avoid the lack of apathy of the Observer on Duty in using the MTS system. 4.) Conduct an actual size observation and propagation of usable frequencies to determine the cause of the radio interference. 5.) Finally, there is a need to follow-up the present study utilizing a much more comprehensive survey on respondent's perception.
Edwin F. Manresa
This study aims to determine trends in key climatic elements in Laoag, Ilocos Norte, suggest possible causes and how these trends may relate to global warming. Time series of daytime and night time data of the principal climate elements (temperature, relative humidity, cloudiness and rainfall) were analyzed by means of a simple regression analysis and by computation of signal to noise ratio (S/N). The following periods and seasons were used: 30 year, decadal (1962-1971, 1972-1982 and 1983-1992), Non-El Nino years, El Nino years, northeast monsoon, southwest monsoon and north pacific trades. Based on regression analysis of the 30-year series, temperature and relative humidity trends increased by 0.55°C (daytime), 0.77°C (night time) and 4.58% (daytime), 3.50% (night time) while cloudiness and rainfall trends decreased by -0.41 okta (daytime), -0-61 okta (night time) and -0.24 mm, (daytime), -0.24mm (night time) respectively. The increase in temperature despite the decrease in cloudiness indicates that greenhouse gases may have increased. In addition, the relative increase in night time over daytime temperature further shows that greenhouse gases may have increased which effect is dominant during night time. In the decadal trends, the first decade gave positive trends in all the elements. The second decade showed negative trends for both cloudiness and rainfall, positive trend for relative humidity and varying trend for temperature. In the third decade, cloudiness and rainfall exhibited negative trend while temperature and relative humidity gave varying trends. The initial warming in the first decade is similar to the results of 2 X CO2 climate models of Manabe and Wetherald (1980), Hansen et al. (1984) and to the historical warm analogue model of Sellers (1986). In the second decade, daytime temperature decreased probably due to the series of volcanic eruptions from 1980 to 1982. In the third decade, although decreasing very slightly at -0.02°C, night time temperature is above normal. In general, temperature is increasing throughout the periods. The trends of the climatic elements could not be attributed to the recurring El Niño phenomenon as the same trends were also obtained when El Niño years were removed from the series (non-El Niño years), except for rainfall. Rainfall data showed increasing trend in the non-El Niño years opposite to that with El Niño years. This signifies that rainfall is related to the recurring El Niño phenomena. This result is supported by other climate studies in the tropics, which showed that rainfall and convection are related to the recurrence of the El Niño phenomenon (Chu et al. 1996). Signal to noise ratio gave values greater than one for all seasons except for rainfall during the north Pacific trades and northeast monsoon. This result is similar to the study of Hegerl et al. (1996). This is indicative of the changing external conditions. In general, the results of this study suggest that the trends in climate are indicative of a climate signal due to external forcing such as increase in greenhouse gas concentration. This suggests that the climatic trends in Laoag, Ilocos Norte may possibly be related to global warming.
Ninio A. Relox
Statement of the problem: the evaluation was able to resolve the following problems: (1) How does the forecast compare with the actual in terms of: wind and time frame? Geographical position? (2) How did the residents affected by the typhoon respond to PAGASA warning in terms of acceptability and action? Research Design - The study utilized a descriptive method of evaluation. The weather advisories and bulletins issued by PAGASA including weather observation reports from field stations during the passage of typhoon Gading were the bases of the evaluation of the forecast. The impact of which is assessed based on the human response interview result. Respondents of the study - Human response survey was conducted in the area affected by typhoon "Gading". Initially, a total of 90% respondents in the human response interview were targeted in the affected area. The final total number of response obtained was 113. Instrumentation - Human response questionnaire was the instrument used in this study. The investigation dealt with four main subjects namely; 1) Socio-economic information of the respondent, 2) Warning comprehension, 3) Warning acceptance, and 4) Action taken based on the warning received. For forecast evaluation, analysis of variance and streamline analysis were employed. Data Gathering Procedure - The study made use of all meteorological data obtained from the Weather Branch of PAGASA. In the case of human response, thirty respondents aging 12 years old and above regardless of social standing were interviewed in the area situated North of the "eye", thirty in the area where the "eye" crossed, and thirty in the area South of the "eye" track. Data Analysis - The forecast maximum sustained wind and positions were compared against the observed in the areas affected by the cyclone. Aside from geographical positions (latitude and longitude) of the cyclone, which were subjected to statistical analysis, other meteorological parameters were evaluated by using meteorologically accepted evaluation method. Human response on the other hand was assessed in terms of total response in relation to the warning level raised. Summary of findings - Forecast evaluation results show that prior to disaster impact, advance information about typhoon Gading was given out warning the public for possible typhoon danger. There were confusing statements indicated in the warning pertaining the validity of the information and the time of issuance for the next bulletin, and the predicted time of occurrence of maximum sustained wind in the warned areas and the meaning of the typhoon signals raised. Although these discrepancies can be considered minor problems in the warning statements, concerned institution should try to find ways for improvement. There were cases where intensification of the cyclone was observed and in fact tropical depression Gading was upgraded to tropical storm, but still the warning signal was not increased. The warning was upgraded only 3-hours before the typhoon unleased its fury in the forecast areas. Considering forecast accuracy of the predicted geographical position, statistical result shows that there was no evidence that the forecast and the observed have significant difference at 5% level of significance. When the observed data, however, was subjected to streamline analysis, a very large forecast position discrepancy was observed except when the cyclone was already overland. It is revealed by streamline analysis that beginning 2:00 am of September 18, the center of Gading was already in the vicinity of Lingayen Gulf that remained almost stationary until 2:00 pm of the same date after which, it healed in the East-Northeast direction toward the vicinity of Japan. This method, however, may not be possible during cyclone occurrence because data influx during bad weather is hampered by destruction of communication systems. Another significant fact unearth in the evaluation is the intensification of Gading during its landfall. Normally, tropical cyclone starts to weaken during landfall due to the effect of irregular terrain. This case is exceptional. Short term predictions, according to Hamilton (1998), cannot be done with any useful reliability or consistency due to the heterogeneous nature of the atmosphere and the uncertain stress with it. Typhoon hazards are fundamentally complex in nature due to the uncertain state of the forces that trigger the events. Generally, the forecast can be considered accurate and comparable with the works conducted in advanced countries especially for maximum sustained wind. In the United States, out of 480 tornado warnings released with the use of Doppler radar, only 237 of 0.49 were false alarm. In typhoon Gading case, out of 9 predictions, (excluding those that cannot be verified), 7 were correct for 6-hr forecast, 6 for 12-hr and 5 for 24-hr. In the case of human response, result showed that out of 113 respondents, 46 said that the forecast was accurate, 13 said it is partially correct, 39 said it is not, and 15 were not sure of its accuracy. As regard to warning comprehension, 84 respondents claimed full comprehension of the warning message, 19 claimed partial comprehension, and 10 did not understand. Verification, however, shows that nobody fully understood except for the 43 respondents who partially understood. Analyzing the influence of the three variables (perception about warning accuracy, warning comprehension and even the verified comprehension, these all have only minimal influence for positive response. Majority opted to have no response. It was found that increasing the signal level has great influence for positive response-the information that was not fully considered in the case of typhoon Gading. Conclusions - Based on the presented facts, it is concluded that: 1.) Timely and sufficient disaster information about typhoon Gading was given out by PAGASA. There were inconsistencies and in some occasion inaccuracies, but the forecast of geographical positions and wind in terms of time frame and intensity can still be considered correct and the primary purpose for issuing the warning was served. 2.) Forecast accuracy is not the only factor affecting mobilization of the people for the conduct of precautionary measures. Other variables may be considered like disaster education and human behavior or attitude toward the disaster information received. It is risk perception factor toward the issued warning that highly contributed to people's positive action. 3.) The success in the implementation of disaster mitigation plan is dependent on the concerted effort exerted by all concerned. Consequently, its failure may be the result of the negative attitude of just one component of the whole process. - Recommendations -Having been able to synthesize the weaknesses and strengths of the warning and human response, the ff. recommendations are hereby promulgated: 1.) The weather service should device means to simplify disaster warning that will be equally understandable to all users. This work may be possible by the collaborative work of the scientists, sociologists including verbal communication experts. 2.) Innovative disaster information education such as movie ads in movie houses, disaster education caravan in the rural areas, film showing using the developed typhoon disaster movie, etc. be conducted. 3.) Research aimed at reviewing typhoon disaster mitigation programs and program implementation such as typhoon disaster information dissemination should be conducted to ensure that all components (i.e. media, local government, non-government organizations, etc. role) have positively contributed to the efficiency in disaster information campaign. It is further recommended that the evaluation of disaster mitigation policies be conducted in order to obtain guidance in revising or developing appropriate disaster implements.