Examining rainfall records : a study into possible scaling relations
Ang, Sean Hong Da
Date of Issue2015
School of Physical and Mathematical Sciences
This study examines and analyses 15 years of data from the Tropical Rainfall Measuring Mission (TRMM), a mission which is currently at the end of its lifespan, and due to be superseded by the Global Precipitation Measurement (GPM). The TRMM provisions quality data around a wide band of the tropics at 0.25 deg by 0.25 deg spatial resolution, and at 3 hour temporal resolution, which was ahead of its time when it was launched. This study is conducted on cropped regions spanning 30 deg by 30 deg over four speci c locations in oceans: Atlantic Ocean, Indian Ocean, East Paci c Ocean, and West Paci c Ocean. The choice of locations places the regions along the equator, enabling us to focus on climatological objects of interest: Deep Convective Clouds. Along the tropics, the Intertropical Convergence Zone (ITCZ) is home to the largest clouds formations known to scientists. This is where clouds formations, which are drivers of the global climate, are a key focus of study. Statistical rigor is a principal aspect of this project, employing Maximum Likelihood Estimator (MLE) methods and Kolmogorov-Smirnov (KS) statistic goodness-of-fi t tests in the analysis of whether the data shows Finite-Size Scaling (FSS) relations. There are two sets of results, fitting for cluster durations and cluster amounts. Both sets of results indicate that the East Paci c Ocean region is an outlier, prompting speculation of explanations for the marked di fference.The cluster amounts pass the goodness-of-fi t test, while the cluster durations do not. A possible explanation could be that the orders of magnitude are not large enough (10^6 vs 10^2), leading to the guess that a higher time-resolution of data by around 10^2 is necessary for progress in uncovering the scaling exponent of cluster durations (\sim15 min intervals). Finally, the fit of the cluster amounts show that three out of four regions (Atlantic Ocean, Indian Ocean and West Pacific Ocean) follow a similar scaling exponent \tau_A \sim 1.2, indicating that their underlying distributions hint at some form of universality, the veri cation of which remains as future work. For the East Paci fic Ocean, its exponent is \tau_A \sim 1.4 which is an outlier value in relation to other regions. This work places the Madden-Julian Oscillation as the prime suspect for the anomaly.
DRNTU::Science::Physics::Meteorology and climatology
Final Year Project (FYP)