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.

The Date Of Snow Disappearance On The Arctic Tundra As Determined From Satellite, Meteorological Station And Radiometric In-situ Observations

Abstract: Satellite-derived snow cover maps for sites in Alaska, Canada, Scandinavia and Siberia were employed to assess the date when snow disappeared on the Arctic tundra and to determine whether the snow has been melting earlier in the spring in recent years. Results show that for three of the four sites there has been a tendency toward earlier snowmelt during the 1980s. In Alaska, the satellite-derived date of snowmelt was compared to the date of snowmelt as observed at the Barrow meteorological station and a site near Barrow where radiometric in situ measurements were made for the last 5 years. The three data sources complement each other even though the satellite site is located 150 km from Barrow. One mechanism which could cause a trend toward earlier snowmelt in Alaska is the deposition of soot and particulates on the snow surface as a result of Arctic haze. >

Deriving daily carbon fluxes from hourly CO2 mixing ratios measured on the WLEF tall tower: An upscaling methodology

Abstract: [1] The temporal variation of the CO 2 mixing ratio in the atmosphere at a given height results from several processes, including photosynthesis and respiration of the underlying ecosystems, the vertical mixing of the atmosphere near the surface and in the planetary boundary layer (PBL), and entrainment of the air above the PBL. Theoretically, if all atmospheric processes are modeled accurately, we can estimate the magnitude of ecosystem photosynthesis and respiration from the variations in the measured CO 2 mixing ratio. Through analyzing the CO 2 concentration measured at several heights (30 m, 122 m, and 396 m) on the Wisconsin tall tower, we demonstrate that it is possible to derive the daily carbon flux resulting from CO 2 uptake from hourly CO 2 mixing ratio data. At 30 m, the concentration-derived daily gross primary productivity (GPP) is well correlated with measured daily GPP derived from flux measurements (r 2 = 0.70), but the former was 20% larger than the latter. The correlation increased considerably for 10-day averages (r2 = 0.87). As the variations at lower heights have larger diurnal CO 2 amplitudes, the concentration-derived GPP is more accurate at lower heights. The footprint distance of CO 2 concentration during the daytime under the influence of the mixed layer is estimated to be of the order of 10 km, or a footprint area of 10 3 -10 4 km 2 , which is much larger than that of CO 2 fluxes measured using eddy covariance methods (typically 1 km 2 ). The difference in these footprint areas may partly explain the differences between these two flux estimates at the Wisconsin tower. These differences also signify the importance of retrieving flux information from the mixing ratio as it provides a means to upscale from local sites to a region.

Diagnosis of mixing between middle latitudes and the polar vortex from tracer‐tracer correlations

Abstract: [1] A method is introduced for diagnosing mixing between the polar vortex and midlatitudes from tracer data Tracers with different photochemical activities and lifetimes usually exhibit curved tracer-tracer correlation functions on an isentropic surface The effect of mixing events is to populate the inner side of such a curve Using simultaneous measurements of trace gases or model results, we exploit this process to calculate the distribution of recent origins in tracer space prior to such a mixing event The method relies on both hemispheric and local data and is applicable to situations where mixing is nonlocal in tracer space It is applied to measurements taken during the Stratospheric Aerosol and Gas Experiment (SAGE) III Ozone Loss and Validation Experiment/Third European Stratospheric Experiment on Ozone 2000 (SOLVE/THESEO 2000) winter campaign and to a chemical transport model simulation covering the same winter In one of the cases studied, a vortex breakup and subsequent remerger of the vortex fragments in March 2000 results in significant diagnosed mixing In a further example, an elongated filament shed off the polar vortex is characterized by anomalous composition For the two high-altitude aircraft flights of the SOLVE campaign that probe the vortex boundary, a correspondence is found for mixing diagnosed in the measurements and in the model Mixing timescales considered here are given by the life span of planetary waves, up to a few weeks

Longitudinal and vertical CO2 gradients over the subtropical/subantarctic oceanic sink

Abstract: The North-South gradient of atmospheric CO 2 is commonly used to infer the latitudinal distribution of sources and sinks at the earth surface. Here we analyze the East–West and vertical gradients occurring at regional scale over the subtropical/subantarctic ocean (around 30°S−45°S), which is known to be the major sink of the southern hemisphere. Using French and Australian inter calibrated datasets, we find a significant depletion of atmospheric CO 2 near Tasmania (Cape Grim, 40°41′S, 144°41′E, CGO) compared to the open Indian Ocean (Amsterdam Is., 37°48′S, 77°32′E, AMS). This depletion was about − 0.4 ± 0.2 ppmv for the 1988–1992 period. For the same period, CGO values were also depleted by − 0.85 ± 0.25 ppmv and − 1.1 ± 0.4 ppmv relative to the mid- and high-troposphere. Using a 3-D atmospheric transport model based on meteorological analysis, and a diagnostic CO 2 flux scenario updated for the year 1990, we investigate the respective role of industrial, oceanic and biospheric fluxes. The main component which can explain such longitudinal and vertical oceanic sink appears to be the subtropical/subantarctic oceanic sink and its regional patterns. Using the oceanographic datasets in the Atlantic, Pacific, and West Indian oceans, we can reconstruct more than half of vertical gradient observed over CGO, but not the CGO depletion relative to AMS. Finally, we discuss the hypothesis of an extra oceanic CO 2 sink south of the Australian mainland. DOI: 10.1034/j.1600-0889.1996.t01-3-00004.x

Record low ozone at Mauna Loa Observatory during winter 1994–1995: A consequence of chemical and dynamical synergism?

Abstract: During two days in late December 1994, total ozone measured at the Mauna Loa Observatory on the island of Hawaii, dropped below 200 Dobson Units (DU) for the first time since ozone measurements began at this site over 30 years ago. Total ozone values this low have not previously occurred over populated areas except on rare occasions when the edges of the springtime Antarctic ozone hole temporarily pass over the southern tip of Argentina. The monthly total ozone average for January 1995 was 216 DU, about 14% below the 1964–1981 baseline value. Ultraviolet radiation measured at Mauna Loa on clear days during this period increased inversely with ozone as expected, more than tripling in relative intensity at 295 nm. The normal annual minimum in total ozone occurs in winter at Mauna Loa; however, some winters experience considerably lower values than others. This was the case during the winter of 1994–1995. Although the general decline in global ozone, which began about 1980 and also appears in the Mauna Loa record, may be related to chemical ozone depletion, the unusually low values during some winters at Mauna Loa appear to be related to ozone transport from the tropics, and the timing of phase transitions of the QBO. This analysis provides an accurate method of forecasting low-ozone, high-UV winters in Hawaii.