Cooperative Institute for Research in the Atmosphere

About: Cooperative Institute for Research in the Atmosphere is a based out in . It is known for research contribution in the topics: Snow & Data assimilation. The organization has 332 authors who have published 997 publications receiving 38835 citations. The organization is also known as: CIRA.

Optical measurements of aerosol size distributions in Great Smoky Mountains National Park: dry aerosol characterization.

Abstract: Aerosol size distributions were measured during the summertime 1995 Southeastern Aerosol and Visibility Study (SEAVS) in Great Smoky Mountains National Park using an Active Scattering Aerosol Spectrometer (ASASP-X) optical particle counter. We present an overview of the experimental method, our data inversion technique, timelines of the size distribution parameters, and calculations of dry accumulation mode aerosol density and refractive index. Aerosol size distributions were recorded during daylight hours for aerosol in the size range 0.1 < Dp < 2.5 u,m. The particle refractive index used for the data inversion was calculated with the partial molar refractive index approach using 12-hr measured aerosol chemical composition. Aerosol accumulation mode volume concentrations ranging from 1 to 26 u,m3 cm-3 were observed, with an average of 7 ± 5 u,m3 cm-3. The study average dry accumulation mode geometric volume median diameter was 0.27 ± 0.03 u,m, and the mean geometric standard deviation was 1.45 ±...

Using airborne HIAPER Pole-to-Pole Observations (HIPPO) to evaluate model and remote sensing estimates of atmospheric carbon dioxide

Abstract: . In recent years, space-borne observations of atmospheric carbon dioxide (CO2) have been increasingly used in global carbon-cycle studies. In order to obtain added value from space-borne measurements, they have to suffice stringent accuracy and precision requirements, with the latter being less crucial as it can be reduced by just enhanced sample size. Validation of CO2 column-averaged dry air mole fractions (XCO2) heavily relies on measurements of the Total Carbon Column Observing Network (TCCON). Owing to the sparseness of the network and the requirements imposed on space-based measurements, independent additional validation is highly valuable. Here, we use observations from the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations (HIPPO) flights from 01/2009 through 09/2011 to validate CO2 measurements from satellites (Greenhouse Gases Observing Satellite – GOSAT, Thermal Emission Sounder – TES, Atmospheric Infrared Sounder – AIRS) and atmospheric inversion models (CarbonTracker CT2013B, Monitoring Atmospheric Composition and Climate (MACC) v13r1). We find that the atmospheric models capture the XCO2 variability observed in HIPPO flights very well, with correlation coefficients (r2) of 0.93 and 0.95 for CT2013B and MACC, respectively. Some larger discrepancies can be observed in profile comparisons at higher latitudes, in particular at 300 hPa during the peaks of either carbon uptake or release. These deviations can be up to 4 ppm and hint at misrepresentation of vertical transport. Comparisons with the GOSAT satellite are of comparable quality, with an r2 of 0.85, a mean bias μ of −0.06 ppm, and a standard deviation σ of 0.45 ppm. TES exhibits an r2 of 0.75, μ of 0.34 ppm, and σ of 1.13 ppm. For AIRS, we find an r2 of 0.37, μ of 1.11 ppm, and σ of 1.46 ppm, with latitude-dependent biases. For these comparisons at least 6, 20, and 50 atmospheric soundings have been averaged for GOSAT, TES, and AIRS, respectively. Overall, we find that GOSAT soundings over the remote Pacific Ocean mostly meet the stringent accuracy requirements of about 0.5 ppm for space-based CO2 observations.

Liquid‐top mixed‐phase cloud detection from shortwave‐infrared satellite radiometer observations: A physical basis

Abstract: Meteorological clouds often exist in the liquid phase at temperatures below 0°C Traditionally, satellite-derived information on cloud phase comes from narrow bands in the shortwave and thermal infrared, with sensitivity biased strongly toward cloud top In situ observations suggest an abundance of clouds having supercooled liquid water at their tops but a predominantly ice phase residing below Satellites may report these clouds simply as supercooled liquid, with no further information regarding the presence of a subcloud top ice phase Here we describe a physical basis for the detection of liquid-top mixed-phase clouds from passive satellite radiometer observations The algorithm makes use of reflected sunlight in narrow bands at 16 and 225 µm to optically probe below liquid-topped clouds and determine phase Detection is predicated on differential absorption properties between liquid and ice particles, accounting for varying Sun/sensor geometry and cloud optical properties When tested on numerical weather prediction model simulated cloud fields, the algorithm provided threat scores in the 06–08 range and false alarm rates in the 01–02 range A case study based on surface and satellite observations of liquid-top mixed-phase clouds in northern Alaska was also examined Preliminary results indicate promising potential for distinction between supercooled liquid-top phase clouds with and without an underlying mixed-phase component

On the effects of Islands' geometry and size on inducing sea breeze circulation

Abstract: Model scaling of the characteristics of the sea breeze circulation involved with circular and slab elongated-symmetric midlatitude islands was performed. Larger horizontal and vertical velocities were indicated over the small circular islands as compared to those over corresponding elongated islands. The circulation characteristics of both types of islands become similar when the half-width of the island is about the same as the distance of inland penetration of the sea breeze in a nonisland case. Evaluation of the results through a scale analysis is presented.