Climate Monitoring and Diagnostics Laboratory

About: Climate Monitoring and Diagnostics Laboratory is a based out in . It is known for research contribution in the topics: Aerosol & Stratosphere. The organization has 107 authors who have published 263 publications receiving 26434 citations.

A comparison of modeled and measured surface shortwave irradiance for a molecular atmosphere

Abstract: We compare the downward diffuse and direct normal irradiance computed by a two-stream model with measurements taken at the Mauna Loa Observatory when the atmosphere was close to a molecular atmosphere. The modeled downward diffuse irradiance agrees with measurements taken by a shaded pyranometer within the uncertainty of the measurement. Therefore, the two-stream approximation is adequate for computing the downward diffuse irradiance in a molecular atmosphere. This result also indicates that neglecting the state of polarization introduces a negligible error in the irradiance computation.

Comparisons of aerosol optical depth and surface shortwave irradiance and their effect on the aerosol surface radiative forcing estimation

Abstract: [1] Column aerosol optical depth (AOD) and surface shortwave irradiance (SSI) measurements relevant to computation of the aerosol surface radiative forcing (ΔF) and forcing efficiency (β) were taken as part of Aerosol Characterization Experiment-Asia (ACE-Asia) at the Gosan surface site in Korea in April 2001. We compare the AOD and SSI derived from three different types of Sun photometers and three sets of radiometers. We also estimate the ΔF and β using two methods and quantify the observational uncertainties of these parameters. A comparison of the AOD at 500 nm shows that the three Sun photometers generally agreed within 0.014 (mean), 0.0142 (bias), and 0.0298 (root mean square) for coincident observations. Over the course of the comparison, the mean differences between the SSI measurements were 1.6, 11.7, and 10.1 Wm−2 for direct, diffuse and global irradiances, respectively. However, for both the AOD and the SSI comparisons, relatively high instantaneous differences between the instruments were apparent on days with heavy dust at the surface. The mean β and associated deviations, which were estimated by the combinations of different instrument-derived AODs and SSIs, for simultaneous observation data at a 60° solar zenith angle are −79.50 ± 3.92 and −82.57 ± 5.70 Wm−2/τ500 for globalshaded (sum of direct and diffuse irradiances) and globalunshaded (measured by the unshaded pyranometer) irradiances, respectively. The uncertainties in β associated with uncertainties in the AOD and SSI (in parentheses) for globalshaded and globalunshaded irradiance are about 8.6% and 3.2% (10.7%), respectively. A 2% difference between the measured global irradiances for a given 9 days was translated into an uncertainty of 19% in ΔF. This difference in ΔF between instruments caused a 14% deviation in β.

In situ observations of dehydrated air parcels advected horizontally in the Tropical Tropopause Layer of the western Pacific

Abstract: Water vapor observations by chilled-mirror hygrometers were conducted at Bandung, Indonesia (6.90° S, 107.60° E) and Tarawa, Kiribati (1.35° N, 172.91° E) in December 2003 to examine the efficiency of dehydration during horizontal advection in the tropical tropopause layer (TTL). Trajectory analyses based on bundles of isentropic trajectories suggest that the modification of air parcels' identity due to irreversible mixing by the branching-out and merging-in of nearby trajectories is found to be an important factor, in addition to the routes air parcels follow, for interpreting the water vapor concentrations observed by chilled-mirror frostpoint hygrometers in the TTL. Clear correspondence between the observed water vapor concentration and the estimated temperature history of air parcels is found showing that drier air parcels were exposed to lower temperatures than were more humid ones during advection. Although the number of observations is quite limited, the water content in the observed air parcels on many occasions was more than that expected from the minimum saturation mixing ratio during horizontal advection prior to sonde observations.