Giovanni and the Year of Tropical Convection
Lack of fundamental knowledge and practical capabilities in tropical convection leaves the global climate community disadvantaged in modeling and predicting prominent phenomena of the tropical atmosphere, such as the Intertropical Convergence Zone (ITCZ), El Niño-Southern Oscillation events (ENSO), monsoons and their active/break periods, the Madden-Julian Oscillation (MJO), subtropical stratus decks, near-surface ocean properties, tropical cyclones, and even the diurnal cycle. The Year of Tropical Convection (YOTC), a joint activity of the World Climate Research Programme (WCRP) and World Weather Research Programme (WWRP)/THORPEX, is a 2-year period (May 2008 – April 2010) of coordinated observing, modeling, and forecasting with a focus on organized tropical convection, its prediction, and predictability.
The goal of the Goddard Giovanni for YOTC project at the NASA Goddard Earth Sciences (GES) and Data Information Services Center is to facilitate NASA satellite data usage by providing a way the YOTC community can easily read, subset, visualize, access, and harmonize data from multiple space-borne sensors.
The dissemination framework for the YOTC satellite data archive is based on the Giovanni system. Giovanni is a web-based application developed by the NASA Goddard Earth Science (GES) Data and Information Service Center (DISC) that provides a simple and intuitive way to visualize, analyze, and access/download vast amounts of Earth science remote sensing data.
The YOTC page at the GES DISC is located here: http://disc.sci.gsfc.nasa.gov/YOTC
Two beta Giovanni prototypes have been released:
- YOTC-GS L3 is a web-based graphics and analysis tool to explore Level 3 data products (MODIS Terra, Aqua AIRS, AMSR-E, TRMM, etc.). Go to YOTC-GS L3!
YOTC-GS L3 contains daily mosaics of ~88 parameters ranging from cloud top temperature to aerosol optical depth, providing environmental conditions of both global and regional scales in 2 and 3 dimensions. 7 functions are available for data analysis and visualization. Users can download analysis results, original data or subsets for further analysis as well.
- YOTC-GS L2 is a web-based graphics and analysis tool to explore Level 2 data products (TRMM, AIRS, Merged IR, QuikSCAT, AMSR-E, etc.). Go to YOTC-GS L2!
YOTC-GS L2 provides an easy access to Level-2 satellite orbital data (also known as swath data). Currently there are ~14 parameters which can be viewed as atmospheric profiles, and 60 parameters in satellite swath format. With YOTC-GS L2, users can plot a profile or generate a swath map for an event displayed in the map selection area (see Figure 1).
An additional tool is the Hurricane Data Analysis Tool (HDAT: http://disc.gsfc.nasa.gov/HDAT) allowing access to 11 years of geostationary IR data, and the capability to generate customized black-and-white or false color images and animations.
Applications of YOTC-Giovanni: Madden-Julian Oscillation & African Easterly Waves
Please refer to the captions below the figures for explanation.
Figure 1. Example of a MJO event using YOTC-GS and other Giovanni tools. a) Hovmöller diagram showing an eastward propagation of precipitation; b) relative humidity time-pressure cross section map showing a dry period after the rain event; c) averaging of OLR maps showing the eastward propagation of convective clouds; d) relative humidity latitude-pressure cross section map averaged during the rain event, showing a high concentration of moisture near the surface in the south of the raining area and dry areas centered at 600 mb in both north and south of the raining area; e) accumulated rainfall maps showing the eastward propagation of precipitation; and f) overlay of the TRMM daily rainfall and the QuikSCAT streamlines showing cyclonic flows near the southern edge of the rainband.
Figure 2. Example of an African Easterly Waves (AEW) event and tropical cyclone using the YOTC-GS and other Giovanni tools. a) black/white satellite imagery from the Hurricane Data Analysis Tool (HDAT) showing Tropical Storm Josephine; b) MODIS aerosol product showing a Saharan Air Layer (SAL) is located in the north of Josephine; (c) and d) relative humidity longitude- and latitude-pressure cross section maps showing the dry SAL, respectively; e) false color satellite imagery of a) and X denotes the location of the vertical hydrometeor profiles (f) from the TRMM microwave imager.