Philippine Atmospheric

Quezon City, Philippines

Philippine Atmospheric

Quezon City, Philippines
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Manzanas R.,University of Cantabria | Lucero A.,Philippine Atmospheric | Weisheimer A.,University of Oxford | Weisheimer A.,ECMWF | Gutierrez J.M.,University of Cantabria
Climate Dynamics | Year: 2017

Statistical downscaling methods are popular post-processing tools which are widely used in many sectors to adapt the coarse-resolution biased outputs from global climate simulations to the regional-to-local scale typically required by users. They range from simple and pragmatic Bias Correction (BC) methods, which directly adjust the model outputs of interest (e.g. precipitation) according to the available local observations, to more complex Perfect Prognosis (PP) ones, which indirectly derive local predictions (e.g. precipitation) from appropriate upper-air large-scale model variables (predictors). Statistical downscaling methods have been extensively used and critically assessed in climate change applications; however, their advantages and limitations in seasonal forecasting are not well understood yet. In particular, a key problem in this context is whether they serve to improve the forecast quality/skill of raw model outputs beyond the adjustment of their systematic biases. In this paper we analyze this issue by applying two state-of-the-art BC and two PP methods to downscale precipitation from a multimodel seasonal hindcast in a challenging tropical region, the Philippines. To properly assess the potential added value beyond the reduction of model biases, we consider two validation scores which are not sensitive to changes in the mean (correlation and reliability categories). Our results show that, whereas BC methods maintain or worsen the skill of the raw model forecasts, PP methods can yield significant skill improvement (worsening) in cases for which the large-scale predictor variables considered are better (worse) predicted by the model than precipitation. For instance, PP methods are found to increase (decrease) model reliability in nearly 40% of the stations considered in boreal summer (autumn). Therefore, the choice of a convenient downscaling approach (either BC or PP) depends on the region and the season. © 2017 Springer-Verlag Berlin Heidelberg

Yumul Jr. G.P.,University of the Philippines at Diliman | Cruz N.A.,Philippine Atmospheric | Dimalanta C.B.,University of the Philippines at Diliman | Servando N.T.,Philippine Atmospheric | Hilario F.D.,Philippine Atmospheric
Climatic Change | Year: 2010

Climate change, involving both human-induced global warming and natural climate variability, has been called upon to explain the occurrences of weather extremes with their associated natural hazards. The Philippines experienced a dry spell in 2007 specifically in parts of Luzon which occurred during the rainy season. On the other hand, areas in Mindanao, southern Philippines which were supposed to be dry, were wet due to the non-migration of the inter-tropical convergence zone northward. The 2007 dry spell in Luzon, northern Philippines affected the agricultural, power, water and health sectors. The local effects of this weather extreme have to be documented and studied to ensure that the appropriate response measures are adopted should there be a recurrence. The building up of the database on this weather extreme and related natural hazards will definitely help the country cope with future similar events. © 2009 Springer Science+Business Media B.V.

Cinco T.A.,Philippine Atmospheric | de Guzman R.G.,Philippine Atmospheric | Hilario F.D.,Philippine Atmospheric | Wilson D.M.,University of the Philippines at Los Baños | And 2 more authors.
Atmospheric Research | Year: 2014

Observed daily precipitation and near surface air temperature data from 34 synoptic weather stations in the Philippines for the period 1951-2010 were subjected to trend analysis which revealed an overall warming tendency compared to the normal mean values for the period 1961-1990. This warming trend can be observed in the annual mean temperatures, daily minimum mean temperatures and to a lesser extent, daily maximum mean temperatures. Precipitation and temperature extremes for the period 1951-2010 were also analysed relative to the mean 1961-1990 baseline values. Some stations (Cotabato, Iloilo, Laoag and Tacloban,) show increases in both frequency and intensity of extreme daily rainfall events which are significant at the 95% level with none of the stations showing decreasing trends. The frequency of daily temperature maximum above the 99th percentile (hot days) and nights at the 1st percentile (cold nights) suggests that both days and nights in particular are becoming warmer. Such indicators of a warming trend and increase in extreme events in the Philippines are discussed in the context of similar national, regional (Asia Pacific) and global studies. The relevance of such empirically based climatology studies, particularly for nations such as the Philippines which are increasingly vulnerable to the multiple impacts of global climate change, is also considered. © 2014 .

Chen T.-C.,Iowa State University | Tsay J.-D.,Iowa State University | Yen M.-C.,National Central University | Cayanan E.O.,Philippine Atmospheric
Weather and Forecasting | Year: 2010

Stretched from Indochina, across the South China Sea, to the Philippine Sea, a monsoon cyclonic shear flow was formed by easterlies of the cold surge-like flow in the north and monsoon westerlies in the south before the onset of the tropical Southeast Asian monsoon on 12 May 2008. On this date, two named tropical cyclones (Halong and Matmo) evolved with a 12-h lag from a closed vortex adjacent to the coast of central Vietnam and another closed vortex near Palawan Island (Philippines) within this shear flow. These two cyclones, named the twin Philippine tropical cyclones, moved almost on the same track, along the anomalous shear line (departure from the climatological one) across the Philippines, and turned northeastward to the ocean south of Japan. It was revealed from synoptic analysis that the cold surge-like flow was coupled with the midlatitude eastward-propagating short wave in northeast Asia, and part of the monsoon westerlies were fed by the cross-equatorial flow, the downstream flow of easterlies around the northern rim of the Southern Hemisphere subtropical high. The environment favorable for the formation of the twin cyclones was developed from the tropics-midlatitude interaction between synoptic systems in these two latitudinal zones. Formations of these cyclones were a result of drastic spinups of the two closed vortices (within the monsoon shear flow) following the surge of monsoon westerlies, which coincided with those of easterlies of the cold surge-like flow, and the cross-equatorial flow originating from easterlies between the Southern Hemisphere subtropical high and the Southern Hemisphere shear flow. © 2010 American Meteorological Society.

Cayanan E.O.,Philippine Atmospheric | Chen T.-C.,Iowa State University | Argete J.C.,University of the Philippines | Yen M.-C.,National Central University | Nilo P.D.,Philippine Atmospheric
Journal of the Meteorological Society of Japan | Year: 2011

Intense southwest monsoon (SWM) rainfall events causing massive landslides and flash floods along the western sections of the Philippines were studied. These rainfall events, are not directly coming from the tropical cyclones (TCs) for they are situated far north to northeast of Luzon Island. The heavy rainfall is hypothesized as caused by the interaction of strong westerlies with the mountain ranges along the west coast of Luzon that produces strong vertical motion and consequently generates heavy rainfall. Four of heavy SWM rainfall cases were examined to determine how the presence and position of tropical cyclones in the Philippine vicinity affect these SWM rainfall events; three cases with TC of varying positions within the Philippine area of responsibility (PAR) and the fourth case without TC. Using a spatial Fourier decomposition approach, the total streamfunction is decomposed into two flow regimes: monsoon basic flow (Waves 0-1) and tropical cyclone perturbation flow (Waves 2-23) over a domain of (20°E-140°W, 5°S-35°N). The purpose of this flow decomposition is to determine the latter's effect on or contribution to the monsoon activity. The analysis utilized the NCEP Final (FNL) data with 1° long. x 1° lat. resolution. Results show that the tropical cyclones over the Pacific Ocean located northeast of Luzon generate strong southwesterly winds over the west coast of Luzon. These in addition to the southwesterlies from the basic flow strengthened the southwest winds that interact with the high Cordillera Mountain ranges. © 2011, Meteorological Society of Japan.

Yumul Jr. G.P.,University of the Philippines at Diliman | Yumul Jr. G.P.,Monte Oro Resources and Energy Inc. | Dimalanta C.B.,University of the Philippines at Diliman | Servando N.T.,Philippine Atmospheric | Cruz N.A.,Philippine Atmospheric
Climatic Change | Year: 2013

The Philippines has recently experienced distinct changes in the weather patterns with disastrous results. These changes which were distinctly felt in 2009 included: 1. too much precipitation throughout the year; 2. some areas received a lot of rain while other parts of the country went through dry spell and drought conditions; and 3. abnormalities and variance in weather patterns (e.g. multiple entry of a tropical cyclone during an El Niño event; longer duration of tropical cyclone; deviations from the normal tropical cyclone path). The country, with its disaster risk management program in place, has managed to bring down the cost of damage and number of casualties due to weather-related disasters. However, in some instances, disaster risk response was made difficult due to other factors (e.g. degraded ecosystem, ill-managed land use and risk denial by people and communities). In general though, the resiliency and ability to recover by the people devastated by these disasters and the availability of community-based support systems provided the best means of coping with these catastrophic events. This is important as climate change is projected to bring more variations in the country's weather and climate patterns which, as of now, are already adversely affecting the people. © 2013 Springer Science+Business Media Dordrecht.

Yumul G.P.,University of the Philippines | Cruz N.A.,Philippine Atmospheric | Servando N.T.,Philippine Atmospheric | Dimalanta C.B.,University of the Philippines
Disasters | Year: 2011

Being an archipelagic nation, the Philippines is susceptible and vulnerable to the ill-effects of weather-related hazards. Extreme weather events, which include tropical cyclones, monsoon rains and dry spells, have triggered hazards (such as floods and landslides) that have turned into disasters. Financial resources that were meant for development and social services have had to be diverted in response, addressing the destruction caused by calamities that beset different regions of the country. Changing climatic patterns and weather-related occurrences over the past five years (2004-08) may serve as an indicator of what climate change will mean for the country. Early recognition of this possibility and the implementation of appropriate action and measures, through disaster risk management, are important if loss of life and property is to be minimised, if not totally eradicated. This is a matter of urgent concern given the geographical location and geological characteristics of the Philippines. © 2011 The Author(s). Disasters © Overseas Development Institute, 2011.

Manzanas R.,University of Cantabria | Brands S.,University of Cantabria | San-Martin D.,Predictia Intelligent Data Solutions | Lucero A.,Philippine Atmospheric | And 2 more authors.
Journal of Climate | Year: 2015

This work shows that local-scale climate projectionsobtainedbymeans of statisticaldownscaling are sensitive to the choice of reanalysis used for calibration. To this aim, a generalized linear model (GLM) approach is applied to downscale daily precipitation in the Philippines. First, theGLMs are trainedandtestedseparatelywithtwodistinct reanalyses (ERA-Interim and JRA-25) using a cross-validation scheme over the period 1981-2000. When the observed and downscaled time series are compared, the attained performance is found to be sensitive to the reanalysis considered if climate change signal-bearing variables (temperature and/or specific humidity) are included in the predictor field. Moreover, performance differences are shown to be in correspondence with the disagreement found between the raw predictors from the two reanalyses. Second, the regression coefficients calibrated either with ERA-Interim or JRA-25 are subsequently applied to the output of a global climate model (MPI-ECHAM5) in order to assess the sensitivity of local-scale climate change projections (up to 2100) to reanalysis choice. In this case, the differences detected in present climate conditions are considerably amplified, leading to ''delta-change'' estimates differing by up to 35%(on average for the entire country) depending on the reanalysis used for calibration. Therefore, reanalysis choice is an important contributor to the uncertainty of localscale climate change projections and, consequently, should be treated with as much care as other better-known sources of uncertainty (e.g., the choice of theGCMand/or downscalingmethod). Implications of the results for the entire tropics, as well as for the model output statistics downscaling approach are also briefly discussed. ©2015 American Meteorological Society.

Faustino-Eslava D.V.,University of the Philippines at Diliman | Yumul G.P.,University of the Philippines at Diliman | Servando N.T.,Philippine Atmospheric | Dimalanta C.B.,University of the Philippines at Diliman
Global and Planetary Change | Year: 2011

In the first half of January 2009, the southern Philippine island of Mindanao was overwhelmed by numerous natural disasters caused by the passage of the tail-end of the cold front. This otherwise ordinary weather condition was accompanied by unusually heavy precipitation sustained over a period of several days. This triggered numerous landslides and caused many drainage systems to swell, flooding huge tracts of low lying areas that have not experienced similar events in the recent past. Many communities were caught unprepared for the calamity. The amount and extent of damage reflect both the magnitude of the natural disaster itself and the community's nominal level of disaster-preparedness. In view of the increasing atmospheric moisture levels and the likelihood that global warming will affect the weather patterns, there is a possibility that similar weather disturbances can become more frequent. Therefore, there is an urgent need for disaster risk management programs to be developed or enhanced at the local community level especially in areas most vulnerable to weather-related natural hazards, in light of changing global climatic patterns. © 2010 Elsevier B.V.

News Article | December 23, 2016

NASA-NOAA's Suomi NPP satellite captured a visible image of Tropical Storm Nock-ten as it continued to move west toward the Philippines where it is locally called "Nina." On Dec. 23 at 12:13 a.m. EST (5:13 UTC) the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NASA-NOAA's Suomi NPP satellite provided a visible-light image of the Tropical Storm Nock-ten moving through the Northwestern Pacific Ocean. The VIIRS image showed strong thunderstorms around the center of circulation and a large thick band of thunderstorms to the north of the center. On Dec. 23, the Philippine Atmospheric, Geophysical and Astronomical Services Administration or PAGASA issued the following bulletin about Nock-ten (Nina): "Estimated rainfall amount is from moderate to heavy rains within its 400 km diameter of the severe tropical storm. "Nina" is expected to intensify further before making landfall. It is expected to make landfall over Catanduanes by Sunday (Dec. 25) afternoon or evening (local time). Sea travel is risky over the Seaboards of Northern Luzon. At 4 a.m. EST (0900 UTC) Tropical Storm Nock-ten's maximum sustained winds had increased to 69 mph (60 knots /111 kph). Nock-ten is expected to continue intensifying and reach typhoon strength by Dec. 24. It was centered near 12.2 degrees north latitude and 132.2 degrees east longitude, about 669 miles east of Manila, Philippines. Nock-ten is moving to the west-northwest at 14 mph (12 knots/22 kph). Nock-ten is forecast to intensify to 105 knots on approach to the Philippines. After passing through the central and northern Philippines during Christmas weekend, the storm will weaken over the South China Sea.

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