(1/🧵) How much of Earth's phytoplankton do space satellites not "see"? Can chlorophyll from satellites reliably describe phytoplankton biomass? 🛰️🦠. In our new paper in @PNAS, we answer these questions with a fleet of undersea Argo robots 🤖🌊:.

Thank you Paula Gale for having me on the CBC's The Broadcast to talk about our latest research on estimating Earth's phytoplankton biomass with Biogeochemical-Argo floats!.

RT @PNASNews: Using data from @bgc_argo—a network of autonomous floating units—researchers estimate the global stock of phytoplankton carbo….

(10/🧵) Take-aways from this paper:.1. @bgc_argo robots are needed to properly monitor Earth's phytoplankton since they detect these organisms where satellites can't. 2. Satellite chlorophyll should not be used to describe phytoplankton blooms: it is a poor stand-in for biomass.

(9/🧵) This means that when we see a jump in chlorophyll in a satellite image, it is likely not associated with an increase in biomass. Rather, it is more likely that physiological mechanisms are at play, which is especially true in sub-tropical and tropical regions.

(8/🧵) For example, the annual peak in chlorophyll at the surface is not associated with the peak in the water's total phytoplankton biomass in two-thirds of the ocean! And that two-thirds contains half of Earth's phytoplankton biomass.

(7/🧵) Q: Can chlorophyll from satellites reliably describe phytoplankton biomass? A: The short answer is no. With Argo floats again, we show how using chlorophyll at the surface as a stand-in for biomass leads to biases in how we describe phytoplankton blooms.

(6/🧵) Q: How much of Earth's phytoplankton do space satellites not "see"? A: Using Argo robots, we find the ocean’s phytoplankton biomass is ~343 million tonnes of carbon, equal to the carbon found in ~250 million elephants. At least half of that is not detected by satellites!.

(5/🧵) Fortunately, floats can tackle both these problems because they can detect phytoplankton biomass and do so throughout the whole water column! In other words, Argo robots can give us a much more complete picture of what phytoplankton are doing out there!.

(4/🧵) Secondly, satellite observations of chlorophyll are often used as an indicator of phytoplankton biomass. However, due to physiological mechanisms responding to growing conditions (like sunlight availability), chlorophyll ends up being a poor stand-in for biomass.

(3/🧵) Why does this matter when we have space satellites? Well, satellites only observe the surface of the ocean, meaning that phytoplankton deeper below are not well monitored (think 20 to 200 m deep).

(2/🧵) In the study, we use the global fleet of @bgc_argo floats to detect the phytoplankton otherwise "hidden" below the sea surface. These robots drift in the ocean for several years, all while collecting data on phytoplankton biomass throughout the water column.

RT @US_OCB: Register now - October 16 BGC Argo webinar: Comparing BGC-Argo observations with models-

RT @US_OCB: Get ready for @bgc_argo @GO_BGC Webinar #8: Comparing BGC-Argo observations with models.October 16, 11 PT/2 ET, more info her….

I'm very excited for this!.

RT @US_OCB: Countdown to the next @GO_BGC webinar! Jan. 31 on carbon export dynamics with Ellen Park (@WHOI) and Adam Stoer (@DalhousieU) -….

RT @FrontMarineSci: New Research: A census of quality-controlled Biogeochemical-Argo float measurements: Biogeochemical- (BGC-) Argo aims t….

A closer-up variation

DALL-E image using the prompt: "A satellite image of Mars with an ocean"

RT @KatjaFennel: Can we create diurnal cycles of carbon biomass in the ocean from composite BGC Argo profiles of backscatter?✅.Can we use t….