Fig. 2From: Tropical cyclone influence on the long-term variability of Philippine summer monsoon onsetAvailability of upper-air observations. More than half of the period of May to July, upper-air observation is conducted at 00Z or at both 00Z and 12Z—i.e., once or twice a day, are colored in blue and red respectively. The measurement stations Laoag (Lao), Clark air base (Cla), Subic (Sub), Tanay (Tan), Legaspi (Leg), Puerto Princesa (Pue), Cebu (Ceb), Davao (Dav), and Zamboanga (Zam) are shown along the x-axisBack to article page