Derek Brown

University of Colorado Boulder | CUB · Department of Atmospheric and Oceanic Sciences (ATOC)

The D/H isotope ratio is used to attribute boundary layer humidity changes to the set of contributing fluxes for a case following a snowstorm in which a snow pack of about 10 cm vanished. Profiles of H₂O and CO₂ mixing ratio, D/H isotope ratio, and several thermodynamic properties were measured from the surface to 300 m every...

Regional tropospheric water balance depends on local mixing rates, moistening and precipitation efficiency associated with cloud processes, and large-scale moisture advection. Conventional data sets are insufficient to disentangle how these processes affect the regional humidity, and models are limited by their need to parameterize many of the pert...

The D/H isotope ratio is used to attribute boundary layer humidity changes to the set of contributing fluxes for a case following a snowstorm in which a snow pack of about 10 cm vanished. Profiles of H2O and CO2 mixing ratio, D/H isotope ratio, and several thermodynamic properties were measured from the surface to 300 m every 15 min during four win...

Evaluating the representation of processes controlling tropical and subtropical tropospheric relative humidity (RH) in atmospheric general circulation models (GCMs) is crucial to assess the credibility of predicted climate changes. GCMs have long exhibited a moist bias in the tropical and subtropical mid and upper troposphere, which could be due to...

The goal of this study is to determine how H2O and HDO measurements in water vapor can be used to detect and diagnose biases in the representation of processes controlling tropospheric humidity in atmospheric general circulation models (GCMs). We analyze a large number of isotopic data sets (four satellite, sixteen ground-based remote-sensing, five...

Water vapor in the subtropical troposphere plays an important role in the radiative balance, the distribution of precipitation, and the chemistry of the Earth's atmosphere. Measurements of the water vapor mixing ratio paired with stable isotope ratios provide unique information on transport processes and moisture sources that is not available with...

This study identifies the large-scale processes that balance regional relative humidity (H), and utilizes satellite measurements of HDO/H2O to characterize moisture processes that influence large-scale humidity. Using the MERRA reanalysis, dynamical and thermodynamical processes that balance zonal mean H are presented. The controls on H vary region...

We conducted experiments with an atmospheric general circulation model to determine the effects of non-Rayleigh, postcondensation exchange (PCE) on the isotopic composition of water in the atmosphere. PCE was found to universally deplete vapor of heavy isotopes but had differential effects on the isotopic composition of precipitation. At low latitu...

The isotopic composition of water vapor, as measured by the Tropospheric Emission Spectrometer, can be used to characterize localized moistening of the low to mid-troposphere. A Lagrangrian mass transport model that is constrained by specific humidity values and water isotopic ratios from the Tropospheric Emission Spectrometer is used here to estim...

The exchange of water and carbon between the atmosphere and land remains poorly understood, particularly in regions of complex terrain and in the case of stable nighttime boundary layers. Profile measurements of the isotopic composition of water vapor were made at the 300 meter NOAA Boulder Atmospheric Observatory tall tower facility in Erie in Feb...

The Aura satellite Tropospheric Emission Spectrometer (TES) instrument is capable of measuring the HDO/H2O ratio in the lower troposphere using thermal infrared radiances between 1200 and 1350 cm-1. However, direct validation of these measurements is challenging due to a lack of in situ measured vertical profiles of the HDO/H2O ratio that are spati...

The Aura satellite Tropospheric Emission Spectrometer (TES) instrument is capable of measuring the HDO/H2O ratio in the lower troposphere using thermal infrared radiances between 1200 and 1350 cm−1. However, direct validation of these measurements is challenging due to a lack of in situ measured vertical profiles of the HDO/H2O ratio that are spati...

New Global satellite observations of water vapor and its isotopes from TES, IASI, and SCIAMACHY add a new constraint for estimating evaporation and precipitation rates and partitioning ocean versus terrestrial moisture sources. Here we show the results of a validation campaign between measurement of the HDO/H2O ratio from the Tropospheric Emission...

Interpretation of many long-term climate records depends on interpreting variations in the isotopic composition of deposited precipitation. However, it can be unclear as to whether these isotopic variations are due to changes in moisture source, transport, convection, precipitation efficiency, or temperature. In this study we use new observations o...

Further understanding of the variations in the seasonal sources of mid-tropospheric moisture, including the contributions from surface evaporation and the re-evaporation of falling rain, can provide refined knowledge of the global hydrological cycle. Stable water isotope measurements from the Tropospheric Emission Spectrometer (TES) are useful in t...

Global measurements of the 500-825 hPa layer mean HDO/H2O ratio from the Tropospheric Emission Spectrometer (TES) are used to expose differences in the dominant hydrologic processes in the Amazon, north Australian, and Asian monsoon regions. The data show high regional isotopic variability and numerous values unexpected from classical Rayleigh theo...

The hydrologic regimes of monsoonal regions contain complex balances of large-scale advective supply of water, surface exchange and atmospheric condensation, which are important for the regional energy balance and climate. Stable water isotopes are powerful tools for studying such processes, as isotopic fractionations occurring during evaporation a...

We present an overview of three years of tropical tropospheric measurements of HDO and H2O from the Tropospheric Emission Spectrometer aboard the Aura satellite. The TES water vapour isotope data set spans September 2004 through the present. Uncertainties in the tropical measurements are approximately 12 parts per thousand relative to SMOW for the...

The hydrologic cycle of the Amazon is a complex balance between large-scale advective supply of water, surface exchange and atmospheric condensation, and is important for the energy balance and climate of the region. Variation in the deuterium content of water vapor seen by the Tropospheric Emission Spectrometer (TES) reflects changes in the convec...

Water isotope measurements are known to be extremely useful for identifying hydrologic exchange processes at both single site scales and at larger scales from networks of, for instance, precipitation. Recent advances in observational techniques have allowed the development of a global scale dataset of the HDO to H2O isotope ratio in lower troposphe...