ECPC Contributions to the Coordinated Enhanced Observing Period

(CEOP)

Alex RuaneJohn Roads Masao Kanamitsu

ECPC/Scripps

Outline

CEOP Overview

- Participants

- ECPC contributions

Spinup Characteristics

Diurnal Cycles

- Methodology

- Comparison of diurnal precipitation to TRMM results

- Other diurnal cycles’ relation to precipitation cycle

CEOP Opportunity

- Take advantage of ongoing continental-scale experiments and new Earth-observing satellites to examine our ability to understand and model the water cycle

Source: CEOP Implementation Plan

- 41 observation sites located in diverse settings - 42-month observing period, from July 2001 - December 2004 - In-situ, model, and satellite data collected for each station

CEOP Participants

6 Satellite Centers:

- NASA EOS - NOAA GOES- NOAA POES - USAF DMSP- NASDA GMS - Meteosat

10 Modeling Centers: contributing global grids as well as Model Output Location Time Series (MOLTS) files

- ECPC - NCEP - ECMWF- NASA - JMA - CPTEC- NCMRWF - UKMO - BMRC- Environment Canada

41 Observing Stations: equipped with radiation and hydrologic instrumentation

ECPC Contributions to CEOPF36 36 36F33 33 33F30 30 30F27 27 27F24 24 24F21 21 21F18 18 18F15 15 15F12 12 12F09 09 09F06 06 06 06 06 06 06 06 06F03 03 03 03 03 03 03 03 03A 12p 18p 00 06 12 18 00f 06f

3 Model Versions: (allowing intercomparisons)

- NCEP/DOE Reanalysis-2 (RII) driven by RII initial conditions,

- ECPC’s Seasonal Forecast Model (SFM) driven by RII initial conditions

- Version of the SFM using the NOAH Land Surface Model driven by its own initial conditions

2 Experiment Types: (allowing internal comparisons)

- 6-hr Analysis runs initialized at 00, 06, 12, and 18 GMT with 3-hr resolution

- 36-hr Forecast runs initialized at 12 GMT with 3-hr resolution

Central Collection of Model Output:

- Model Output Location Time Series (MOLTS) files store values and profiles of 108 variables at each CEOP location

- Full grid variables as well; over 6 Terabytes of data in total

Hydrological Issues in Spinup

2002 mean of RII 36-hr forecasts over ARM Southern Great Plains Site

- In idealized long-term mean, expect diurnal cycle to repeat 1.5 cycles during 36 hours

- Spinup error drops off as forecast moves forward

- Hydrological Variables particularly affected by initial soil moisture conditions

- Need to be careful when running SFM using RII initializations

- Motivation for comparing RII/SFM experiment with SFM/SFM experiments

Diurnal Cycle Examinations

- Least-Squares fit of diurnal and bidiurnal harmonics to variable time series.

- Result does not accurately regenerate time series, but draws out phase and comparative amplitude information

Source: JJA 2002, from RII ft15-36

TRMM Observations of the Diurnal Cycle

Source: Nakamura, May 2004 GEWEX Newsletter

- Tropical Rainfall Measuring Mission (TRMM) shows late afternoon peak over most land areas - Not broadly consistent, definite land-sea contrast - Only covers ±40˚ latitude

GSM Diurnal Cycle Reproduction

- Land/Sea differences - Argentina early morning max - Guiana Coast afternoon max - Caribbean morning max - Central US evening max - Himalayan morning max - Low amplitude regions

- Smaller-scale features can be seen in Africa, India, Indonesia, and China

Source: JJA 2002, from RII ft15-36

Making Sense Of the Diurnal Precipitation Cycle

Can we explain the geographical variations?

Model allows global coverage and CEOP period allows for several intervals to be examined.

Making Sense Of the Diurnal Precipitation Cycle

Approaches using normalized amplitudes and other statistical processes may allow us to examine:

- areas with lower mean amplitudes - oceanic cycles - specific regions

(No Amplitude Fading)

Making Sense Of the Bidiurnal Precipitation Cycle

- Inclusion of bidiurnal cycle, seems to constructively interfere at diurnal harmonic’s max

- Overall smaller amplitude than diurnal harmonic, but in some places comparable

Other Diurnal Cycles - Latent Heat Flux

- Radiatively-forced, could explain mid-afternoon maxima.

- Seasonal cycle in amplitudes leans toward Summer Hemisphere

Other Diurnal Cycles - Vapor Flux Divergence

- Dynamically forced by features such as the low level jet.

- Vapor Flux Convergence peak is 12 hours later, could explain later precipitation maximum over the Western U.S. and earlier precipitation maximum over Himalayas.

Other Diurnal Cycles - Convective Heating Rate

- Allows examinations of diurnal convection cycles

Other Diurnal Cycles - 2-meter Temperature

Mostly as expected

- note polar night

Other Diurnal Cycles - 2-meter Temperature

Subtle coastal structure could merit some further study, probably with coupled version of the RSM.

Conclusions

- CEOP provides opportunity to validate GSM results and to compare GSM to other major models

- GSM performs fairly well in diurnal precipitation cycle comparison with TRMM

- Further study of regional diurnal cycle components may help us to better understand the model’s performance