Moisture Budget Analysis of TOGA COARE Area Using SSM/I-Retrieved Latent Heating and Large-ScaleQ2Estimates

This study aims to explore the contrasting characteristics of large-scale circulation that led to the precipitation anomalies over the northern parts of Sumatra Island. Further, the impact of varying the Asian–Australian Monsoon (AAM) was investigated for triggering the precipitation variability over the study area. The moisture budget analysis was applied to quantify the most dominant component that induces precipitation variability during the JJA (June, July, and August) period. Then, the composite analysis and statistical approach were applied to confirm the result of the moisture budget. Using the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Anaysis Interim (ERA-Interim) from 1981 to 2016, we identified 9 (nine) dry and 6 (six) wet years based on precipitation anomalies, respectively. The dry years (wet years) anomalies over the study area were mostly supported by downward (upward) vertical velocity anomaly instead of other variables such as specific humidity, horizontal velocity, and evaporation. In the dry years (wet years), there is a strengthening (weakening) of the descent motion, which triggers a reduction (increase) of convection over the study area. The overall downward (upward) motion of westerly (easterly) winds appears to suppress (support) the convection and lead to negative (positive) precipitation anomaly in the whole region but with the largest anomaly over northern parts of Sumatra. The AAM variability proven has a significant role in the precipitation variability over the study area. A teleconnection between the AAM and other global circulations implies the precipitation variability over the northern part of Sumatra Island as a regional phenomenon. The large-scale tropical circulation is possibly related to the PWC modulation (Pacific Walker Circulation).

Download Full-text

Human Contribution to the Increasing Summer Precipitation in Central Asia from 1961 to 2013

Journal of Climate ◽

10.1175/jcli-d-17-0843.1 ◽

2018 ◽

Vol 31 (19) ◽

pp. 8005-8021 ◽

Cited By ~ 15

Author(s):

Dongdong Peng ◽

Tianjun Zhou ◽

Lixia Zhang ◽

Bo Wu

Keyword(s):

Central Asia ◽

Vertical Motion ◽

Summer Precipitation ◽

Specific Humidity ◽

Moisture Budget ◽

Anthropogenic Forcing ◽

Radiative Forcings ◽

Budget Analysis ◽

Community Atmosphere Model ◽

Advection Term

The ecosystem and societal development over arid Central Asia, the core connecting region of the Silk Road Economic Belt, are highly sensitive to climate change. The results derived from multiobservational datasets show that summer precipitation over Central Asia has significantly increased by 20.78% from 1961 to 2013. It remains unclear whether anthropogenic forcing has contributed to the summer wetting trend or not. In this study, the corresponding physical processes and contributions of anthropogenic forcing are investigated by comparing reanalysis and experiments of the Community Atmosphere Model, version 5.1 (CAM5.1), from the CLIVAR Climate of the Twentieth Century Plus (C20C+) Project. The observed wetting trend is well reproduced in the simulation driven by all radiative forcings (CAM5-All), but poorly reproduced in the simulation with natural forcings only (CAM5-Nat), confirming the important role of human contribution in the observed wetting trend. Moisture budget analysis shows that the observed wetting trend is dominated by the increasing vertical moisture advection term and results from enhanced vertical motion over nearly all of Central Asia. The observed contributions of moisture budget components to the wetting trend are only captured by CAM5-All experiments. The dynamic contribution is determined by the warm advection anomalies in association with a human-induced meridional uneven warm pattern. Human-induced warming increases the specific humidity over all of Central Asia, increasing (decreasing) the precipitation over the climatological ascent (descent) region in eastern (western) Central Asia.

Download Full-text

Spectral Retrieval of Latent Heating Profiles from TRMM PR Data. Part IV: Comparisons of Lookup Tables from Two- and Three-Dimensional Cloud-Resolving Model Simulations

Journal of Climate ◽

10.1175/2009jcli2919.1 ◽

2009 ◽

Vol 22 (20) ◽

pp. 5577-5594 ◽

Cited By ~ 34

Author(s):

Shoichi Shige ◽

Yukari N. Takayabu ◽

Satoshi Kida ◽

Wei-Kuo Tao ◽

Xiping Zeng ◽

...

Keyword(s):

Three Dimensional ◽

Latent Heating ◽

3D Simulations ◽

Toga Coare ◽

Trmm Pr ◽

Lookup Tables ◽

Cloud Resolving Model ◽

Heating Profiles ◽

Maximum Heating ◽

Melting Level

Abstract The spectral latent heating (SLH) algorithm was developed to estimate latent heating profiles for the Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR). The method uses TRMM PR information (precipitation-top height, precipitation rates at the surface and melting level, and rain type) to select heating profiles from lookup tables (LUTs). LUTs for the three rain types—convective, shallow stratiform, and anvil rain (deep stratiform with a melting level)—were derived from numerical simulations of tropical cloud systems from the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) using a cloud-resolving model (CRM). The two-dimensional (2D) CRM was used in previous studies. The availability of exponentially increasing computer capabilities has resulted in three-dimensional (3D) CRM simulations for multiday periods becoming increasingly prevalent. In this study, LUTs from the 2D and 3D simulations are compared. Using the LUTs from 3D simulations results in less agreement between the SLH-retrieved heating and sounding-based heating for the South China Sea Monsoon Experiment (SCSMEX). The level of SLH-estimated maximum heating is lower than that of the sounding-derived maximum heating. This is explained by the fact that using the 3D LUTs results in stronger convective heating and weaker stratiform heating above the melting level than is the case if using the 2D LUTs. More condensate is generated in and carried from the convective region in the 3D model than in the 2D model, and less condensate is produced by the stratiform region’s own upward motion.

Download Full-text

Moisture Tendency Equations in a Tropical Atmosphere

Journal of the Atmospheric Sciences ◽

10.1175/jas3424.1 ◽

2005 ◽

Vol 62 (5) ◽

pp. 1601-1613 ◽

Cited By ~ 17

Author(s):

C. López Carrillo ◽

D. J. Raymond

Keyword(s):

Temperature Profile ◽

Diagnostic Evaluation ◽

Moisture Convergence ◽

Tropical Atmosphere ◽

Moisture Budget ◽

High Confidence ◽

Tropical Ocean ◽

Space And Time ◽

Toga Coare ◽

Ocean Atmosphere

Abstract Direct diagnostic evaluation of the moisture tendency in the moisture equation is very difficult in practice because two poorly measured terms, moisture convergence and precipitation, dominate the equation. Using the near constancy in space and time of the tropical temperature profile, a variety of energy and entropy based equations have been employed to obtain indirect estimates of the moisture budget. In this paper rigorous versions of the energy and entropy equations are developed. The strengths and weakness of these two formulations are complementary, allowing the authors to estimate moistening and drying tendencies with high confidence when the two formulations are used together. This study applies the theory to data from Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE). The results demonstrate how convection regulates the tropospheric humidity, drying the atmosphere when it becomes too moist, and moistening it when it becomes too dry.

Download Full-text