Profiling the Lower Troposphere over the Ocean with Infrared Hyperspectral Measurements of the Marine-Atmosphere Emitted Radiance Interferometer

Abstract Measurements of the spectra of infrared emission from the atmosphere were taken by a Marine-Atmospheric Emitted Radiance Interferometer (M-AERI) deployed on the NOAA ship Ronald H. Brown during the Aerosol and Ocean Science Expedition (AEROSE) in the tropical Atlantic Ocean from 29 February to 26 March 2004. The spectra are used to retrieve profiles of temperature and humidity in the lower troposphere up to a height of 3000 m. The M-AERI retrievals of the atmospheric structure require an initial guess profile. In this work, retrievals obtained from four separate initializations are compared, using 1) radiosondes launched from the Ronald H. Brown, 2) NOAA/NWS/NCEP model reanalyses, 3) ECMWF model analyses, and 4) ECMWF model forecasts. The performance of the M-AERI retrievals for all four first-guess sources is then evaluated against the radiosonde measurements. The M-AERI retrievals initialized using radiosondes reproduce the radiosonde profiles quite well and capture much of the observed vertical structure as should be expected. Of the retrievals initialized with model fields, those obtained using the ECMWF data yielded results closest to the radiosonde observations and enabled detection of the Saharan air layer (SAL) evident during AEROSE. However, the NCEP reanalysis, as well as the corresponding retrievals, failed to detect the SAL. These results demonstrate the ability of the M-AERI profile retrievals to identify the anomalous humidity distributions in the lower troposphere, but underscore the need for suitable vertical resolution in the first-guess profile used in the retrievals under such conditions

To be submitted to Monthly Weather Review

On the morning of 12 June 2002, a series of boundary layer water vapor oscillation events occurred at the “Homestead ” site of the International H2O Project (IHOP_2002). Atmospheric water vapor magnitude within the boundary layer decreased and increased within a matter of minutes. High temporal-resolution data of the water vapor oscillations collected by an array of instruments deployed for this intensive observation period are presented. The results of an Advanced Regional Prediction System (ARPS) mesoscale numerical simulation of the weather conditions around the time period in question are also discussed. The ARPS model reproduced the water vapor oscillations with a remarkable accuracy. Both the observational data and ARPS numerical model output indicate that the water vapor oscillations were due to interaction between a dry air mass descending from the Rocky Mountains and a cold pool/internal undular bore couplet propagating over the Homestead site from a mesoscale convective complex to the north. The water vapor oscillations are believed to be a secondary indicator of such bores. This type of water vapor oscillation was observed at other times during IHOP_2002, and the oscillations are believed to be a relatively rare occurrence

Toward an Objective Enhanced-V Detection Algorithm

The area of coldest cloud tops above thunderstorms sometimes has a distinct V or U shape. This pattern, often referred to as an "enhanced-V' signature, has been observed to occur during and preceding severe weather in previous studies. This study describes an algorithmic approach to objectively detect enhanced-V features with observations from the Geostationary Operational Environmental Satellite and Low Earth Orbit data. The methodology consists of cross correlation statistics of pixels and thresholds of enhanced-V quantitative parameters. The effectiveness of the enhanced-V detection method will be examined using Geostationary Operational Environmental Satellite, MODerate-resolution Imaging Spectroradiometer, and Advanced Very High Resolution Radiometer image data from case studies in the 2003-2006 seasons. The main goal of this study is to develop an objective enhanced-V detection algorithm for future implementation into operations with future sensors, such as GOES-R

An Overview of the International H₂O Project (IHOP_2002) and Some Preliminary Highlights

International audienceThe International H2O Project (IHOP_2002) is one of the largest North American meteorological field experiments in history. From 13 May to 25 June 2002, over 250 researchers and technical staff from the United States, Germany, France, and Canada converged on the Southern Great Plains to measure water vapor and other atmospheric variables. The principal objective of IHOP_2002 is to obtain an improved characterization of the time-varying three-dimensional water vapor field and evaluate its utility in improving the understanding and prediction of convective processes. The motivation for this objective is the combination of extremely low forecast skill for warm-season rainfall and the relatively large loss of life and property from flash floods and other warm-season weather hazards. Many prior studies on convective storm forecasting have shown that water vapor is a key atmospheric variable that is insufficiently measured. Toward this goal, IHOP_2002 brought together many of the existing operational and new state-of-the-art research water vapor sensors and numerical models.The IHOP_2002 experiment comprised numerous unique aspects. These included several instruments fielded for the first time (e.g., reference radiosonde); numerous upgraded instruments (e.g., Wyo-ming Cloud Radar); the first ever horizontal-pointing water vapor differential absorption lidar (DIAL; i.e., Leandre II on the Naval Research Laboratory P-3), which required the first onboard aircraft avoidance radar; several unique combinations of sensors (e.g., multiple profiling instruments at one field site and the German water vapor DIAL and NOAA/Environmental Technology Laboratory Doppler lidar on board the German Falcon aircraft); and many logistical challenges. This article presents a summary of the motivation, goals, and experimental design of the project, illustrates some preliminary data collected, and includes discussion on some potential operational and research implications of the experiment

A New Raman Water Vapor Lidar Calibration Technique and Measurements in the Vicinity of Hurricane Bonnie

The NAcA/Goddard Space Flight Center Scanning Raman Lidar has made measurements of water vapor and aerosols for almost ten years. Calibration of the water vapor data has typically been performed by comparison with another water vapor sensor such as radiosondes. We present a new method for water vapor calibration that only requires low clouds, and surface pressure and temperature measurements. A sensitivity study was performed and the cloud base algorithm agrees with the radiosonde calibration to within 10- 15%. Knowledge of the true atmospheric lapse rate is required to obtain more accurate cloud base temperatures. Analysis of water vapor and aerosol measurements made in the vicinity of Hurricane Bonnie are discussed

Profile observations of the Saharan air layer during AEROSE 2004

This paper describes 3‐hourly radiosonde observations of the Saharan air layer (SAL) acquired from the NOAA Ship Ronald H. Brown during the 2004 Aerosol and Ocean Science Expedition (AEROSE). The sampling frequency allows for unique vertical cross‐sectional analyses of SAL phenomena, including dust events detected by shipboard Sun photometers, observed during March 2004. The observational analyses provide, for the first time, a coherent, 2‐dimensional space‐time depiction of the SAL as an expansive warm, dry, stable column located above the marine boundary layer. Midlevel easterly wind maxima are also observed to occur near the leading edge of the dry layers. The AEROSE sounding data will be useful for studies of the SAL, as well as for validation of environmental satellite sensors, especially the Aqua Atmospheric Infrared Sounder (AIRS)

Ship‐based measurements for infrared sensor validation during Aerosol and Ocean Science Expedition 2004

This paper describes a unique validation data set acquired from a marine intensive observing period (IOP) conducted on board the NOAA Ship Ronald H. Brown (RHB) during the 2004 Aerosol and Ocean Science Expedition (AEROSE) in the tropical North Atlantic Ocean from 29 February to 26 March 2004. The radiometric and in situ data complement includes marine observations of the Saharan air layer (SAL), including two significant Saharan dust outbreaks over the Atlantic Ocean. Because the impact of tropospheric dust aerosols on satellite infrared (IR) radiometric observations has not yet been fully characterized, the AEROSE data are particularly valuable for IR sensor validation. Shipboard radiometric data germane to satellite validation include observations from a Marine Atmospheric Emitted Radiance Interferometer (M‐AERI), a Calibrated Infrared In situ Measurement System (CIRIMS), and Microtops handheld sunphotometers. Among other things, these data provide, for the first time, coincident IR spectra of the dry, dusty SAL from both the uplooking M‐AERI and the downlooking Atmospheric Infrared Sounder (AIRS) on board the Aqua satellite. In situ data collected throughout the cruise include Vaisala RS80/90 radiosondes, launched ≃3‐hourly to include Aqua overpass times. The Aqua matchup profiles provide data for validation of AIRS in the presence of high dust loading, along with temperature and water vapor profile retrievals of the SAL. The frequency of sonde launches also enables validation of coincident uplooking M‐AERI boundary layer profile retrievals. Preliminary analyses of the AEROSE data are presented here. Focused AEROSE validation studies are the subjects of separate papers