Abstract: Devices and methods are disclosed for remote measurment of temperature (and velocity) profiles in a fluid medium (i.e., the atmosphere and/or oceans). Each device, herein called an echometer, and method are capable of providing remote measurements of temperature through the use of propagated waves (i.e., acoustic or electromagnetic waves) and interferometric principles. By use of Doppler processing, simultaneous measurement can be made of three-dimensional velocities at the same points in space to enable remote measurement of heat fluxes in the atmosphere or ocean.