Monthly Observations of Cold-point Tropopause Temperature and Height for 2008 in the Philippines Using COSMIC GPS Radio Occultations

Abstract

The cold-point tropopause (CPT) is the thermal boundary between the troposphere and stratosphere defined by a temperature profile’s coldest level. In this paper, the CPT is examined using temperature profiles from Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) GPS radio occultation measurements during 2008 inside the Tropical Cyclone Advisory Domain (TCAD) in the Philippines. The monthly and spatial variability is examined using two CPT properties: CPT temperature (CPT-T) and CPT height (CPT-H). Generally, the coldest CPT temperatures are in the months of December-January-February, which lie within the cool dry season. CPT-T is at its hottest in July-August-September, within the rainy season. CPT-H is observed to decrease (increase) as CPT-T increases (decreases), suggesting an inverse relationship between the two properties. CPT-T is also observed to rise in the upper latitudes, while no discernible spatial pattern can be seen for CPT-H over this domain expect for that the start increase and decrease of CPT-H appear to occur over the Pacific first.