Measurements made from R/P Flip using rapid profiling conductivity, temperature, and depth probes and vector-measuring current meters provide a new and detailed look at the diurnal cycle of the upper ocean. A diurnal cycle occurs when solar heating warms and stabilizes the upper ocean. This limits the downward penetration of turbulent wind mixing so that air-sea fluxes of heat and momentum are surface trapped during midday. The central problem is to learn how the trapping depth D T (mean depth value of the diurnal temperature and velocity response) is set by the competi_ng effects of wind mixing and surface heating. In this data set the diurnal range of surface temperature T s was observed to vary from 0.05 < •s < 0.4øC, with most of the day-to-day variability attributable to variations of wind stress r. Wind mixing causes a pronounced asymmetry of the T s response by limiting the warming phase to only about half of the period that the surface heat flux Q is positive. The associated wind-driven current, the diurnal jet, has an amplitude of typically •s • 0.1 m s-x, with no obvious dependence upon r. The diurnal jet accelerates downwind during the morning and midday. It is turned into the wind by the Coriolis force during early evening and is often erased by the following morning. Under the assumption that wind mixing occurs as an adjustment to shear flow stability, a scaling analysis and a numerical model study show that the daily minimum trapping depth /•T goes like •/Qx/2. It follows that •s goes like Q3/2/• and that • goes like Q•/2. These results, as well as the simulated time dependence of the diurnal cycle, are at least roughly consistent with the observations. The observed time-averaged velocity profile has a spiral shape reminiscent of the classical Ekman spiral. However, its structure is a consequence of diurnal cycling, and its parameter dependence is in some ways just opposite that of the Ekman model' e.g., increased wind stress may cause decreased vertical shear between fixed levels in the upper ocean. Paper number 6C0214 0148-0227/86/006C-0214505.00 to heating and wind mixing which can simulate the diurnal cycle (sections 4 and 7); (3) to determine the explicit parameter dependence of the diurnal cycle upon the heating rate, the wind stress, and other external variables (sections 5 and 7), and lastly (4) to show how the process of diurnal cycling acts to shape the longer term response of the upper ocean to atmospheric forcing (section 8). 2. FIELD OBSERVATIONS The field data reported here were taken in spring 1980 from R/P Flip. Measurements were begun on April 28 at 30.9øN, 123.5øW, about 400 km west of San Diego, California. Flip drifted southward with the prevailing wind, and the measurement program ended on May 24 when Flip was at 28.7øN, 124.0øW. 2.1. Data Types Precision Comments profiling CTD; T, C, P profiling VMCM; V, T, P Fixed level VMCM' V, T Wind speed U Eppley pyranometer, I 0 Air temperatures, cloud cover, pressure 128.4 < t < 145.3 days* At = 2 min T _ 0.002øC 2

Synthesizing surface meteorology obtained from satellite remote sensing and atmospheric model reanalyses leads to improved estimates of global latent and sensible heat fluxes.T he ocean and the atmosphere exchange heat at their interface via a number of processes-solar radiation, longwave radiation, sensible heat transfer by conduction and convection, and latent heat transfer by evaporation of sea surface water. The amount of heat being exchanged is called heat flux, and its distribution over the global oceans is required virtually for every aspect of climate studies (WGASF 2000). However, direct flux measurements are sparse. Our present knowledge of the global air-sea heat flux distribution stems primarily from the bulk parameterizations of air-sea fluxes as functions of surface meteorological variables (e.g., wind speed, temperature, humidity, cloud cover, etc.). The sources of

This study investigates the exchange of momentum between the atmosphere and ocean using data collected from four oceanic field experiments. Direct covariance estimates of momentum fluxes were collected in all four experiments and wind profiles were collected during three of them. The objective of the investigation is to improve parameterizations of the surface roughness and drag coefficient used to estimate the surface stress from bulk formulas. Specifically, the Coupled Ocean-Atmosphere Response Experiment (COARE) 3.0 bulk flux algorithm is refined to create COARE 3.5. Oversea measurements of dimensionless shear are used to investigate the stability function under stable and convective conditions. The behavior of surface roughness is then investigated over a wider range of wind speeds (up to 25 m s 21 ) and wave conditions than have been available from previous oversea field studies. The wind speed dependence of the Charnock coefficient a in the COARE algorithm is modified to a 5 mU 10N 1 b, where m 5 0.017 m 21 s and b 5 20.005. When combined with a parameterization for smooth flow, this formulation gives better agreement with the stress estimates from all of the field programs at all winds speeds with significant improvement for wind speeds over 13 m s 21. Wave age-and wave slope-dependent parameterizations of the surface roughness are also investigated, but the COARE 3.5 wind speed-dependent formulation matches the observations well without any wave information. The available data provide a simple reason for why wind speed-, wave age-, and wave slopedependent formulations give similar results-the inverse wave age varies nearly linearly with wind speed in long-fetch conditions for wind speeds up to 25 m s 21.

The estimate of surface irradiance on a global scale is possible through radiative transfer calculations using satellite-retrieved surface, cloud, and aerosol properties as input. Computed top-of-atmosphere (TOA) irradiances, however, do not necessarily agree with observation-based values, for example, from the Clouds and the Earth's Radiant Energy System (CERES). This paper presents a method to determine surface irradiances using observational constraints of TOA irradiance from CERES. A Lagrange multiplier procedure is used to objectively adjust inputs based on their uncertainties such that the computed TOA irradiance is consistent with CERES-derived irradiance to within the uncertainty. These input adjustments are then used to determine surface irradiance adjustments. Observations by the Atmospheric Infrared Sounder (AIRS), Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), CloudSat, and Moderate Resolution Imaging Spectroradiometer (MODIS) that are a part of the NASA A-Train constellation provide the uncertainty estimates. A comparison with surface observations from a number of sites shows that the bias [root-mean-square (RMS) difference] between computed and observed monthly mean irradiances calculated with 10 years of data is 4.7 (13.3) W m 22 for downward shortwave and 22.5 (7.1) W m 22 for downward longwave irradiances over ocean and 21.7 (7.8) W m 22 for downward shortwave and 21.0 (7.6) W m 22 for downward longwave irradiances over land. The bias and RMS error for the downward longwave and shortwave irradiances over ocean are decreased from those without constraint. Similarly, the bias and RMS error for downward longwave over land improves, although the constraint does not improve downward shortwave over land. This study demonstrates how synergetic use of multiple instruments (CERES, MODIS, CALIPSO, CloudSat, AIRS, and geostationary satellites) improves the accuracy of surface irradiance computations.

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