Regional scale simulation of atmospheric structure using VAS data

Investigations with both Subsynoptic Scale Model (SSM) and Limited Area Mesoscale Prediction System (LAMPS) are directed at model static initializations using Visible Infrared Spin Scan Radiometer Atmospheric Sounder (VAS) derived temperatures and moistures and also satellite derived winds. The general approach for each day's case study is similar. A 12-hour control forecast (no satellite data) is made 12Z-OZ, using a radiosonde analysis at 12Z as the initial field. For the satellite data experiments, reanalyses are performed at intermediate times, using VAS soundings or VAS soundings in combination with satellite winds. Forecasts are subsequently made from the reanalysis time(s) to the same validation hour (OZ) as the control forecasts. Comparisons are then made between the control forecast and satellite experiments

The Payload Advisory Panel and the Data and Information System Advisory Panel of the Investigators Working Group of the Earth Observing System: A joint report

The Payload Advisory Panel of the Investigators Working Group (IWG) for the Earth Observing System (EOS) met 4 to 6 October 1993 in Herndon, Virginia. The Panel, originally composed of the Interdisciplinary Science Principal Investigators, was expanded to include all Principal Investigators and as such is now the IWG itself. The meeting also addressed directly a report from the EOS Data and Information System (EOSDIS) Advisory Panel. The meeting focused on payload issues in the years 2000 to 2005; however, some subjects in the nearer-term, most significantly EOSDIS, were considered. The overarching theme of convergence in Earth observations set a backdrop for the entire meeting. Other themes included: atmospheric chemistry; remote sensing of the global cycles of energy, water, and carbon in EOS; ocean and land-ice altimetry; and the EOSDIS. The Totol Solar Irradiance Monitoring Report and results from the Accelerated Canopy Chemistry Program are included as appendices

An Investigation of the Characterization of Cloud Contamination in Hyperspectral Radiances

In regions lacking direct observations, the assimilation of radiances from infrared and microwave sounders is the primary method for characterizing the atmosphere in the analysis process. In recent years, technological advances have led to the launching of more advanced sounders, particularly in the thermal infrared spectrum. With the advent of these hyperspectral sounders, the amount of data available for the analysis process has and will continue to be dramatically increased. However, the utilization of infrared radiances in variational assimilation can be problematic in the presence of clouds; specifically the assessment of the presence of clouds in an instantaneous field of view (IFOV) and the contamination in the individual channels within the IFOV. Various techniques have been developed to determine if a channel is contaminated by clouds. The work presented in this paper and subsequent presentation will investigate traditional techniques and compare them to a new technique, the C02 sorting technique, which utilizes the high spectral resolution of the Atmospheric Infrared Sounder (AIRS) within the framework of the Gridpoint Statistical Interpolation (GSI) 3DVAR system. Ultimately, this work is done in preparation for the assessment of short-term forecast impacts with the regional assimilation of AIRS radiances within the analysis fields of the Weather Research and Forecast Nonhydrostatic Mesoscale Model (WRF-NMM) at the NASA Short-term Prediction Research and Transition (SPORT) Center

Sensitivity of Tropical Cyclone Tracks and Intensity to Ocean Surface Temperature: Four Cases in Four Different Basins

This study investigates the sensitivity of tropical cyclone (TC) motion and intensity to ocean surface fluxes that, in turn, are directly related to sea surface temperatures (SSTs). The Advanced Research version of the Weather Research and Forecast (WRF-ARW) model is used with an improved parameterisation of surface latent heat flux account for ocean salinity. The WRF-ARW simulations compare satisfactorily with the NCEP/NCAR reanalysis for atmospheric fields and remotely sensed precipitation fields, with the model providing details lacking in coarse resolution observations. Among four TCs investigated, except the one re-developed from a previous TC remnant, the stretching term dominates the relative vorticity generation, and a bottom-up propagation mechanism holds for the three TCs. For the Tropical Rainfall Measuring Mission (TRMM) precipitation, the spatial ranges are accurate but actual rainfall rates are significantly larger than those remotely sensed. This indicates the value of numerical simulation in quantitative rainfall precipitation estimation (QPE) for TCs. Sensitivity experiments are performed with altered SSTs and changes in tracks and intensity are examined. A TC-dependent threshold wind speed is introduced in defining total kinetic energy, a measure of TC intensity, so arbitrariness in domain setting is avoided and inter-basin comparisons are possible. The four TCs selected from different global basin show that the intensity increases with increasing SST.Within a domain, a power–law relationship applies. More important, warmer SST indicates a more rapid intensification, quicker formation and reduced warning issuance time for emergency services. The influence of SSTs on TC track is more complex and lacks a generic relationship. For the South Pacific basin, higher SSTs favour a more northerly track. These TCs occasionally cross continental Australia and redevelop in the southern Indian Ocean basin, affecting the resource-rich onshore and offshore industrial developments in northwest Western Australia. In the Atlantic basin (e.g. Katrina 2005), when SSTs increase, the TC tracks tend to curve over warm pools but generally have a shorter ocean-residence time. When the synthesised SST fields are raised 2°C above Katrina (i.e. >32°C), the possibility exists of generating two TCs in close proximity. That lack of unanimity of the impacts on TC tracks, in response to synthesised SSTs, partly arises from the complicated response of subtropical highs, which may be disintegrated into several pieces and dispersed with relatively lower pressure regions, which may become the shortcuts when a TC traces the periphery of the subtropical high

Towards validation of SMOS using airborne and ground data over the Murrumbidgee Catchment

With the launch of the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) satellite scheduled for mid 2009, the first long-term space-borne passive microwave observations at L-band (∼ 1.4 GHz) will soon be available. Consequently, SMOS will be the first mission dedicated to global mapping of near-real-time surface soil moisture information. Though space-borne microwave instruments have measured global data at high frequencies (e.g. C- and X-band) for the last 20 years, this innovative L-band radiometer will use a new synthetic aperture concept that will provide observations at multiple incidence angles. Consequently, the observed brightness temperature data and derived soil moisture product must be validated. To achieve this, intensive field campaigns are being planned world-wide to support the satellite mission with reliable data from i) passive microwave airborne observations at L-band, ii) detailed ground measurements of surface soil moisture content and associated environmental parameters, and iii) long-term soil moisture monitoring network data from anchor sites (e.g. Murrumbidgee in Australia, Valencia in Spain, Upper Danube in Germany etc.). With the SMOS launch likely to take place in the later part of 2009, Australia is particularly well positioned for conducting the first intensive SMOS validation campaign during its spring. The Australian Airborne Cal/val Experiment for SMOS (AACES) will provide one of the most comprehensive assessments world-wide, due to its combined airborne and in-situ data collection strategy across an extensive transect of the Murrumbidgee catchment in south-eastern Australia. This area is unique as it comprises a distinct variety of topographic, climatic and land cover characteristics, and therefore represents an excellent validation site for the land component of this satellite mission. Moreover, a large database of previous campaign measurements, continuous soil moisture monitoring stations, and meteorological data over the past seven years is available for this region. A total of four airborne campaigns are planned to cover a 100 km x 500 km (more than 20 SMOS pixels) transect of the Murrumbidgee catchment in its entirety at 1 km resolution using an L-band radiometer. The primary airborne instruments will include the Polarimetric L-band Multibeam Radiometer (PLMR) and thermal infrared sensors, supported by surface soil moisture content, soil temperature and rainfall data from the Murrumbidgee monitoring network. This will be further complemented by intensive soil moisture observations with the Hydraprobe Data Acquisition System (HDAS), short-term soil moisture and temperature monitoring stations with additional leaf wetness and thermal infrared measurements, and extensive vegetation characterisation. The four separate month-long campaigns are planned to extend across a two year timeframe, enabling the effects of seasonal variation in vegetation condition and land cover change to be assessed in addition to soil moisture. Consequently, issues related to snow cover, litter, vegetation dynamics etc. will be assessed in relation to soil moisture retrieval. This paper outlines the airborne campaigns and related ground monitoring for the first SMOS validation campaign, together with some of the major science questions to be addressed. Persons interested in participating in these campaigns are encouraged to contact the authors

Southern hemisphere circulation anomalies associated with extreme Antarctic peninsula winter temperatures

The Southern Hemisphere reveals markedly different circulation patterns associated with extreme warm and cold Antarctic Peninsula (AP) winter temperatures. Warm winters are associated with negative 500 hPa height anomalies in the Amundsen Sea-Bellingshausen Sea (AS-BS) and positive anomalies in the South Pacific (SP) and Scotia Sea with opposing anomalies existent in cold winters. Furthermore, a switch in the relative strength of the two arms of the New Zealand split jet, the subtropical jet (STJ) and polar front jet (PFJ), occurs with the PFJ (STJ) strengthened and the STJ (PFJ) weakened in warm (cold) years leading to increased cyclonic activity in the AS-BS (SP) and a corresponding decrease in the SP (AS-BS). These hemispheric anomaly patterns bear a strong resemblance to those associated with El Niño-Southern Oscillation (ENSO) events, and their origins can be ascribed to tropical sea surface temperatures (SST) changes. However, the correspondence between warm (cold) ENSO events and cold (warm) winters is not perfect. Potential contributors to this non-linearity include intraseasonal tropical SST variations (not necessarily represented in the usual filtered ENSO indices) and the persistence of local sea ice anomalies west of the Peninsula