In an experiment conducted by Taguchi and Hartmann (2005), a sudden warming in the stratospheres was observed to double in El Nino during the months of January as compared to La Nina during winter. In experiments that mimic the occurrences of El Nino and La Nina, the two phenomenons were likely to result to “stratospheric day-to-day variability” that warms and weakens the pole and vortex. The planetary wave was affected by sudden warming in the stratosphere usually induced by the tropical SST. The affected wave shifts the heat influx in the lower atmosphere and forces the waves to enter the stratosphere.
Camp and Tung (2007) claimed that 10-50 hPa mean temperature is observable in the months of December to February. By using the coherent spatial structure, years with El Nino turn to be 4° K warmer than years with La Nina. The ENSO perturbation is equivalent to the magnitude of QBO perturbation as indicated by 3. 8° K difference in easterly QBO mean and the westerly QBO. The statistical significance reaches 95%. That was the first time that El Nino-Southern Oscillation (ENSO) ENSO attained such a high result on its influence in the polar stratosphere.
INCREASED OCCURRENCE OF STRATOSPHERIC WARMING DURING EL NINO
The aim of the study is to know the tools and methodology that is most reliable to use to come up with results that will prove or give answer to the identified problem, like the comparison of effect of El Nino and La Nina in the sudden warm up of the stratospheres. Different tools were used in the experiment to determine which is the most effective in getting the best results, would it be the statistical methods or the ones that uses models.
Subjects Two experiments were used in this study to compare the methodologies and results being used in the process. The study of Taguchi and Hartmann (2005) identified the variation of the Northern winter extra tropical stratosphere and troposphere in a yearly basis the WACCM model, while that of Camp and Tung (2007), usage of statistical materials or tools were used in predicting the cycle and effect of the phenomenon in the atmosphere. Apparatus or tools • LDA methodology for the collection of sample temperatures
• Cubic polynomials in getting the mean of temperature • Optimization algorithms • Cold Tongue Index (CTI) • WACCM model • Quasigeostrophic scaling Procedures Camp and Tung (2007) conducted the research by first considering the 10-50 hPa layers in a zonal, average and detrented means (see Figure 1). The possible effects of volcanoes were minimized by not including the year after Mt. Pinatubo and El Chicon had erupted. Data’s were divided into two categories, the cold and the warm.
Attempts to find the spatial pattern of the stratosphere of the warm and cold years were carried by maximizing the separation of two groups of variance represented by R; the variance in two groups and the variance inside the groups. The maximization of R resulted to minimization of QBO and also the solar variance in a group. The QBO and solar cycle were filtered using the spatial pattern. By using the optimization algorithms, each spatial location was determined as represented by the variable u (x). Then to obtain the canonical variate
Ct=Xu(x), X(t, x) is projected to u(x). For the recovery of the associated spatial pattern, regression input to C(t), i. e. X(t, x)=C(t)PT(x) +? (t, x). Taguchi and Hartmann (2005) used the models and experiment like the Whole Atmosphere Community Climate Model (WACCM) located in a 110 km altitude for the observation of the middle and upper atmosphere with horizontal resolutions of T63 and 66 vertical levels. The models were used to investigate the atmosphere within 9125 days to cover a 100 to 90-day winter.
A January experiment was conducted to gather data’s that will study such impact as external forcing on SSW frequency because of the interannual variability that usually occurs in midwinter. Short period experiments were also used by in the research. Biases Bias occurs only by chance at 22 of 10 000 trials frequency in two runs. RESULTS In the study of Camp and Tung (2007) there is only one spatial pattern determined in the experiment as compared to the QBO warming patterns. This pattern resulted to warming on the poles and cooling in the mid latitudes.
The warming in the poles resulted to ENSO pattern and the cooling in the tropics would have to result in QBO pattern. The two phenomenon displayed numeric values, as El Nino showed positive values which means warming in the poles and mid latitudes while that of La Nina years is a negative values that means cooling in the poles an mid latitudes. The values were explained by the temperature between 10 to 50 hPa. Polar warming occurs when QBO of 3. 8° K and by solar cycle of 4. 6° K. This also means that the value of ENSO is far higher than QBO.
In Taguchi and Hartmann’s (2005) study, the climate was said to be warmer in the run WARM compared to the run COLD, because the SSW occur frequently in the run WARM season or if the polar temperature reaches 235 K. The effect of wind was also being considered hence it affects the temperature with coefficients of -0. 75 and -0. 78 COLD run and WARM run within the 9125 day cycle. DISCUSSION Evaluation The two researches were able to support all the needed requirements for the success of the experiment.
Based on the results, ENSO provides core source of polar warming and the QBO is more on the tropical cooling. And also, a temperature of 235K would likely to result into a run WARM effect. Comparison of results with previous research In the experiment of Taguchi and Hartmann (2005), it was found out that the use of WACCM model is more reliable and accurate than any other methods used, like the statistical tools used by Camp and Tung (2007) in determining the hemispheric structures. Problems with the research. i. There is a limited observational data set. ii. The time of study is also limited.
iii. There is no enough tools that will measure the experiment accurately. CONCLUSION Based on the results of the experiments, the WACMM model used offered the most reliable results because most of experiments followed a monthly process. But the experiments of Camp and Tung (2007) also provided good outcome. In fact it uses a comprehensive means of analyzing data’s. Therefore if the two tools will be used in combination, there is a possibility that the weaknesses of the other research tool will be compensated with the other one thus, it will obtain a better results.
APPENDIx 1. Analysis of 10-50 hPa using LDA in getting the Mean of zonal temperature for the month of December-January-February (Camp and Tung, 2007).
Camp, C. D. and Tung, K. K. (2007). Stratospheric Polar Warming By ENSO In Winter, A Statistical Study. http://www. amath. washington. edu/people/faculty/tung/publications. html Taguchi, M. and Hartmann D. (2005). Increased Occurrence Of Stratospheric Sudden Warmings During El Nifio As Simulated. http://www. atmos. washington. edu/~dennis/Taguchi&Hartmann_JC06. pdf