Figure 3. Time series of surface chlorophyll (upper 15 m, green) and sea ice cover (violet)
at Palmer (a) and Rothera Stations (b). Sea ice cover is based on SMMR-SSM/I imagery
at Palmer (see Figure 2) and local observations of fast ice concentration at Rothera. The
darker green indicates chlorophyll under sea ice. Black bars indicate chlorophyll sampling
gaps > 21 d. Sampling at Palmer was weekly after 1996 when ice and wind conditions
permitted, with a gap for 2008–2009. Sampling at Rothera is weekly throughout
the record, when ice and wind conditions permit. Note that ice cover at Rothera still
reaches 100% in most years, at least briefly. In the Palmer Station region, the ice cover is
almost always < 70%.