SHIP-TIME REQUEST FY-2001

NOAA/NSF EPIC20011 CRUISE

Program: Climate and Global Change Pan-American Climate Studies (PACS), Dr. Mike Patterson, 301-427-2089 x 102

Subprogram Name: Eastern Pacific Investigation of Climate Processes in the Coupled Ocean-
Atmosphere System (EPIC) (see http://www.atmos.washington.edu/gcg/EPIC/ ). The specific scientific objectives of EPIC are:

Objective I.	To observe and understand the ocean-atmosphere processes responsible for the structure and evolution of the large-scale atmospheric heating gradients in the equatorial and northeastern Pacific portions of the cold-tongue/ITCZ complex, including

(a)	mechanisms governing temperature and salinity field evolution across the oceanic cold tongue through the ITCZ

(b)	atmospheric planetary boundary layer structure and evolution from the equator through the ITCZ, primarily in the southerly monsoonal regime; and

(c)	the processes determining the existence, character and strength of deep convection in the northeast Pacific ITCZ.

Objective II.	To observe and understand the dynamical, radiative and microphysical properties of the extensive boundary layer cloud decks in the southeasterly tradewind and cross-equatorial flow regime and their interactions with the ocean below.

Specific Project Name: The EPIC2001 field program consists of a detailed atmospheric and oceanic study of the Cold-Tongue and Inter-Tropical Convergence Zone (ITCZ) complex (CTIC), which deals with objective I of EPIC, followed by a pilot observation study of the stratocumulus systems associated with Objective II.

Chief Scientists: Dr. C. Fairall, ETL (cfairall@etl.noaa.gov; 303-497-3253) and Dr. R. Houze, UW ( houze@atmos.washington.edu; 206-543-6922)

EPIC 2001 Project Description

The EPIC program including the CTIC and stratocumulus components are described in detail in the EPIC science plan available at the website given above. An Overview and Implementation Plan for the 2001 field program can be found at ftp//:kestrel.nmt.edu/pub/raymond. ITCZ process studies will concentrate on the monsoonal regime around 95 degrees W. longitude near 10 degrees N. latitude (see Figure 1); intensive oceanographic and atmospheric measurements will be made. Atmospheric boundary layer (ABL) aspects will be investigated via measurements made in transects from 12 N to 8 S along 95 W. The stratocumulus pilot study will be done in transects from 95 W 8 S to an IMET buoy at 85 W 18 S, into a port stop at Lima, Peru, followed by a return transect, via the IMET buoy, from 8 S to 12 N along 95 W (see Figure 1). The NCAR Electra research aircraft and R/V New Horizon participate at the 10 N and 95 W location. A NOAA P-3 research aircraft will also participate.

EPIC2001 Measurement Strategy

The EPIC2001 field program can be divided into four subject areas termed 'bundles'. They are: ITCZ, ABL, Ocean, and Stratocumulus. The ITCZ and most of the Ocean and ABL aspects will be done in the first cruise segment, about 31 days beginning in San Diego and ending with a short port stop in the Galapagos Islands. The remaining Ocean/ABL plus the Stratocumulus aspects will be done in the second segment from the Galapagos to Lima Peru, returning through the study area and ending in Manzanillo, Mexico (see Figure 1).

The first cruise leg features a two-ship study period of 21 days in the vicinity of the ITCZ at 10 N 95 W. The ship requested here will contain comprehensive atmospheric sensors, ocean microstructure profilers plus the scanning C-band Doppler radar and will remain on station at the selected location. The second ship will execute a continuous butterfly pattern with a scale of 130 km about the fixed ship using seasoar and ADCP measurements to define the advective terms in the thermal and salinity budgets (similar to the approach taken in TOGA COARE). It will also measure air-sea fluxes and have some atmospheric profiling and precipitation measurement capabilities. While the ships are on station, the NCAR Electra will appear periodically making Doppler radar measurements in deep convection using the ELDORA system.

The ABL part of the study features meridional cross sections from 12 N to 8 S at 95 W. During August these will be done every few days by the NOAA P-3. The P-3 will use dropsondes and air-launched AXBTs. The research vessel requested here will make two transects of the same meridian during the cruise. Also, two transects will be made thru 18 S to the IMET buoy and to the coast of Peru The primary focus will be investigation of the atmospheric boundary layer and surface fluxes through the transition regions, but some oceanographic data will also be obtained.

The research vessel requested here will make a transect from 8S and 95 W to the IMET buoy at 18 S 85 W and then into Lima, Peru. This transect will go into the unexplored southern hemisphere stratocumulus region off Peru. The ship will continue to launch sondes and obtain data with onboard measurement systems. While in the ship is in the vicinity of the IMET buoy, the NOAA P-3 will make several research flights. Stratocumulus clouds may also be encountered in the equatorial cold tongue region.

The EPIC2001 Ship Request

A Class-I research vessel from the U.S. is requested to be equipped with a suite of instruments for atmospheric observations of deep convection, atmospheric profiles of winds, temperature, humidity, cloud properties, air-sea fluxes, and aerosols. Oceanic measurements will include near-surface properties, microstructure, and optical properties. The emphasis will be on observations of precipitating systems, clouds, and atmospheric boundary layer structure and their coupling to oceanic mixed layer structure through the sea surface temperature field. The R/V Ronald H. Brown is the ship of choice because the scanning Doppler C-band radar will be the single most critical observing system. Other atmospheric measurement systems to be provided by PI's (primarily NOAA ETL and PMEL) include: mm-wave Doppler cloud radar, one or more atmospheric lidar, microwave and IR radiometers, air-sea turbulent and radiative fluxes, precipitation, bulk meteorological variables, and aerosols. The UW/APL group will operate an ocean microstructure profiling system off the stern continuously during the 21-day stop at 10 N 95 W. The ship will go very slow ahead to keep the line out of the screws and relocate periodically. Profiles of optical properties and bottles will be taken daily or every other day while on station and at half-degree increments will underway along 95 W. The ship's Doppler wind profiling radar, ADCP, CTD, navigational data, IMET observations, autosal, and satellite receiver will all be required.

On the first leg, the ship will operate primarily predominantly in the ITCZ region near 95 W 10 N. The second leg will being after a one-day stop in the Galapagos to exchange personnel; the ship will make a transit to TAO buoy at 8 S and 95 W, to the IMET buoy, and then on to Lima, Peru. After a three day stop in Lima, it will retrace the original transect and continue on for a final stop in Manzanillo, Mexcio. A cruise scenario is given below:

Leg-1

Transit from San Diego to 95 W 10 N:	7 days

On station ITCZ:	21 days

Cold tongue transit (10N-0N)	:	2.5 days

Transit Galapagos (0.5 S 81.5 W)	0.75 days

1 day stop, Galapagos	1.0 days

Leg-2

Return to 0 N 95 W	0.75 days

Cold tongue transit (0N-8S)	:	2.5 days

IMET buoy transit (95 W 8 S – 85 W 18 S)	:	2.5 days

Transit to Lima Peru (12 S 77.1 W):	2 days

In port, Lima:	3 days

Transit back to IMET buoy:	2 days

IMET to 8 S	2.5 days

8S – 12 N:	4 days

Transit to Manzanillo, Mexico drop off port:	2.5 days

Total request=54 days

Relevance to NOAA's Mission and Relationship to Strategic Plan Elements

PACS is critically important for improving NOAA's capability to forecast Seasonal to Interannual events, to reliably predict Decadal to Centennial Change, and to improve forecasts of Short Term events.

Relationship to Other Programs

EPIC is endorsed by the CLIVAR Variability of the American Monsoon (VAMOS) Program and will be strongly linked to other climate studies in the Pacific Ocean and pan-American region. Many of the investigators on EPIC2001 will be funded by NSF ATM and OCE. There will also be a strong cooperation with the NASA FIRE program. We also anticipate cooperation with Dr. R. Wanninkhof of AOML for measurements of CO2 and other trace gases as part of the OACES program. Note that OACES is requesting the Ron Brown for a CO2 flux process study in the equatorial Pacific earlier in the year. Data obtained on this cruise will be valuable for NOAA's interests in improving satellite retrievals and weather forecasts.

Key Co-Investigators

Dr. M. Gregg, UW/APL

Dr. S. Yuter, UW

Drs S. Rutledge and R. Cifelli, CSU

Drs. C. Ohlman, D. Siegel, UCSD

Drs. T. Uttal, J. Intrieri, S. Frisch, D. Hazen, B. Orr, and G. Feingold, NOAA ETL

Drs. Gage and Ecklund, NOAA AL

Drs. R. Weller and S. Anderson, WHOI

Drs. M. Cronin, P. Quinn, and N. Bond, PMEL

Dr. C. Bretherton, UW

Drs. C. Paulson and H. Wijeskera, OSU

Drs. B. Albrecht and C. Zhang, U. Miami

Other platforms involved

Two or more research aircraft

TAO array