Air temperature profile and air/sea temperature difference measurements by infrared and microwave scanning radiometers

[1] A system of two scanning radiometers has been developed by the National Oceanic and Atmospheric Administration/Environmental Technology Laboratory and deployed on the NOAA R/V Ronald H. Brown during the Nauru99 cruise in the tropical western Pacific in June and July 1999. The system is composed of a high-quality temperature sensor and two independent, vertically scanning radiometers, measuring atmospheric and oceanic emission in the microwave (MW), and infrared (IR) regions. Both radiometers measure emission from a uniformly mixed atmospheric gas: oxygen for MW (60 GHz) and carbon dioxide for IR (14.2 μm). The high atmospheric absorption at these frequencies allows one calibration point from the horizontal atmospheric view using the in situ temperature sensor measurements as a reference. The signal at all other scan angles is scaled relative to that at the horizontal, resulting in a differential technique that is independent of calibration offset. This technique provides continuous and accurate estimates of boundary layer air temperature profile and air/sea temperature difference. The main advantage of this technique is that the water skin temperature can be measured at different optical depths without disturbing the skin layer (magnitude order of microns). We first compare radiometric data collected during the experiment with simulations obtained by atmospheric and oceanic radiative transfer models. We then use statistical inversion techniques to estimate air temperature profiles from upward looking measurements, based on an a priori data set of about 1500 ship-based radiosonde observations. For the “well-posed” problem of air/sea temperature difference estimation, we apply a physical retrieval algorithm to the downward looking measurements, accounting for air attenuation and sea surface roughness. Then we show retrieval results and evaluate the achieved accuracy. Finally, we compare radiometric estimates with in situ measurements, discussing similarities and discrepancies.

[1]  E. F. Bradley,et al.  Cool‐skin and warm‐layer effects on sea surface temperature , 1996 .

[2]  Yuri G. Trokhimovski,et al.  Sea‐air and boundary layer temperatures measured by a scanning 5‐mm‐wavelength radiometer: Recent results , 1998 .

[3]  P. Webster,et al.  TOGA COARE: The Coupled Ocean-Atmosphere Response Experiment. , 1992 .

[4]  Lawrence S. Bernstein,et al.  Very Narrow Band Model Calculations of Atmospheric Fluxes and Cooling Rates , 1996 .

[5]  R. A. Elliot,et al.  Optical remote sensing of the atmosphere. , 1985, Applied optics.

[6]  G. Ewing,et al.  On the Thermal Boundary Layer of the Ocean , 1960, Science.

[7]  Scanning infrared radiometer for measuring the air-sea temperature difference. , 2001, Applied optics.

[8]  J H Churnside,et al.  Scanning-laser glint measurements of sea-surface slope statistics. , 1997, Applied optics.

[9]  William J. Emery,et al.  The Behavior of the Bulk – Skin Sea Surface Temperature Difference under Varying Wind Speed and Heat Flux , 1996 .

[10]  E. Westwater,et al.  REMOTE SENSING OF BOUNDARY LAYER TEMPERATURE PROFILES BY A SCANNING 5-MM MICROWAVE RADIOMETER AND RASS : COMPARISON EXPERIMENTS , 1999 .

[11]  M. Iacono,et al.  Line-by-Line Calculations of Atmospheric Fluxes and Cooling Rates: Application to Water Vapor , 1992 .

[12]  Russell L Jaycock.  The Coupled Ocean-atmosphere Response Experiment (TOGA COARE) , 1993 .

[13]  Hans J. Liebe,et al.  Millimeter-wave properties of the atmosphere: Laboratory studies and propagation modeling , 1987 .

[14]  W. Mcleish,et al.  Airborne measurements of the total heat flux from the sea during Bomex , 1971 .

[15]  I. M. Fuks,et al.  Emissivity of a statistically rough surface including multiple reflections , 1993 .

[16]  X. Wu,et al.  Emissivity of rough sea surface for 8-13 num: modeling and verification. , 1997, Applied optics.

[17]  N. Nalli,et al.  Quasi-specular model for calculating the reflection of atmospheric-emitted infrared radiation from a rough water surface. , 2001, Applied optics.

[18]  P. Rosenkranz.  Water vapor microwave continuum absorption: A comparison of measurements and models , 1998 .

[19]  Stuart D. Smith.  Coefficients for sea surface wind stress, heat flux, and wind profiles as a function of wind speed and temperature , 1988 .

[20]  Airborne measurements of the sea-air temperature difference by a scanning 5-mm wavelength radiometer , 2000, IGARSS 2000. IEEE 2000 International Geoscience and Remote Sensing Symposium. Taking the Pulse of the Planet: The Role of Remote Sensing in Managing the Environment. Proceedings (Cat. No.00CH37120).

[21]  A. V. Smirnov,et al.  Polarimetric radar imagery of the ocean at low grazing angles under atmospheric conditions of variable stability , 1994, Proceedings of IGARSS '94 - 1994 IEEE International Geoscience and Remote Sensing Symposium.

[22]  Paul A. Hwang,et al.  The dependence of sea surface slope on atmospheric stability and swell conditions , 1988 .

[23]  P. Minnett,et al.  The Marine-Atmospheric Emitted Radiance Interferometer: A High-Accuracy, Seagoing Infrared Spectroradiometer , 2001 .

[24]  Shepard A. Clough,et al.  Infrared spectral radiance measurements in the tropical Pacific atmosphere , 1997 .

[25]  William J. Emery,et al.  On the bulk‐skin temperature difference and its impact on satellite remote sensing of sea surface temperature , 1990 .

[26]  W. Munk,et al.  Measurement of the Roughness of the Sea Surface from Photographs of the Sun’s Glitter , 1954 .

[27]  M. N. Pospelov.  Surface wind speed retrieval using passive microwave polarimetry: the dependence on atmospheric stability , 1995, 1995 International Geoscience and Remote Sensing Symposium, IGARSS '95. Quantitative Remote Sensing for Science and Applications.

[28]  J. Hadamard,et al.  Le problème de Cauchy et les équations aux dérivées partielles linéaires hyperboliques : leçons professées à l'Université Yale , 1932 .

[29]  C. Swift,et al.  An improved model for the dielectric constant of sea water at microwave frequencies , 1977, IEEE Journal of Oceanic Engineering.

[30]  John F. Vesecky,et al.  Water surface temperature estimates using active and passive microwave remote sensing: preliminary results from an outdoor wind-wave tank , 1994, Proceedings of IGARSS '94 - 1994 IEEE International Geoscience and Remote Sensing Symposium.

[31]  D. C. Robertson,et al.  MODTRAN cloud and multiple scattering upgrades with application to AVIRIS , 1998 .

[32]  William L. Smith,et al.  Sounding the Skin of Water: Sensing Air–Water Interface Temperature Gradients with Interferometry , 1995 .

[33]  Yuri G. Trokhimovski,et al.  Air and sea surface temperature measurements using a 60-GHz microwave rotating radiometer , 1998, IEEE Trans. Geosci. Remote. Sens..