This month’s newsletter is devoted to ocean indices aiming at a better understanding of the state of the ocean climate. Ocean climate indices can be linked to major patterns of climate variability and usually have a significant social impact. The estimation of the ocean climate indices along with their uncertainty is thus crucial: It gives an indication of our ability to measure the ocean. It is as well a useful tool for decision making. Ocean climate indices also provide an at-a-glance overview of the state of the ocean climate, and a way to talk to a wider audience about the ocean observing system. Several groups of experts are now working on various ocean indicators using ocean forecast models, satellite data and reanalysis models in observing system simulation experiments, among which the OOPC, NOAA and MERSEA/Boss4Gmes communities for example:

• http://ioc3.unesco.org/oopc/state_of_the_ocean/index.php
• http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/
• http://www.aoml.noaa.gov/phod/cyclone/data/method.html
• http://www.mersea.eu.org/Indicators-with-B4G.html

Scientific articles about Ocean indices in the present Newsletter are displayed as follows: The first article by Von Schuckmann et al. is dealing with the estimation of global ocean indicators from a gridded hydrographic field. Then, Crosnier et al. are describing the need to conduct intercomparison of model analyses and forecast in order for experts to provide a reliable scientific expertise on ocean climate indicators. The next article by Coppini et al. is telling us about ocean indices computed from the Mediterranean Forecasting System for the European Environment Agency and Boss4Gmes. Then Buarque et al. are revisiting the Tropical Cyclone Heat Potential Index in order to better represent the ocean heat content that interacts with Hurricane. The last article by Greiner et al. is dealing with the assessment of robust ocean indicators and gives an example with oceanic predictors for the Sahel precipitations.

• Estimating Global Ocean indicators from a gridded hydrographic field during 2003‐2008 By Karina von Schuckmann, Fabienne Gaillard and Pierre-Yves Le Traon
• Intercomparison of environmental Ocean indicators: a complementary step toward scientific expertise and decision making. By Laurence Crosnier, Marie Drévillon, Silvana Ramos Buarque, Jean-Michel Lellouche, Eric Chassignet, Ashwanth Srinivasan, Ole Martin Smedstad, Sanjay Rattan and Allan Wallcraft
• Mediterranean Marine environmental indicators from the Marine Core Service By Giovanni Coppini, Vladyslav Lyubartsev, Nadia Pinardi, Claudia Fratianni, Marina Tonani, Mario Adani, Paolo Oddo and Srdjan Dobricic, Rosalia Santoleri, Simone Colella and Gianluca Volpe
• Tropical Cyclone Heat Potential Index revisited By Silvana Ramos Buarque, Claude Vanroyen and Caroline Agier
• Assessment of robust Ocean indicators: an example with oceanic predictors for the Sahel precipitations. By Eric Greiner and Marie Drevillon